CA2192922A1 - Method of and apparatus for data communications between portable information terminals - Google Patents
Method of and apparatus for data communications between portable information terminalsInfo
- Publication number
- CA2192922A1 CA2192922A1 CA002192922A CA2192922A CA2192922A1 CA 2192922 A1 CA2192922 A1 CA 2192922A1 CA 002192922 A CA002192922 A CA 002192922A CA 2192922 A CA2192922 A CA 2192922A CA 2192922 A1 CA2192922 A1 CA 2192922A1
- Authority
- CA
- Canada
- Prior art keywords
- data
- bits
- portable information
- compressed
- battery
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
Abstract
Data communications are carried out between port-able information terminals through infrared radiation with an energy source which may be either a battery in each of the portable information terminals or an exter-nal power supply therefor, at a data transmission rate which is relatively low when the portable information terminal is operated by the battery. If the power source is the incased battery, the data transmission rate is switched to a low rate, data to be transmitted are compressed, and the respective numbers of bits "0"
and "1" contained in the compressed data are compared with each other. If the number of bits which require a greater amount of electric energy for transmission is greater than the other number of bits, then the value of bits is inverted. Data indicative of the low data transmission rate, the compression of the data, and whether the value of bits has been inverted or not are coded into header data which are added to the com-pressed data for transmission. The data transmission rate is adjusted, the compressed data are expanded, and the inverted value of bits is inverted back by a con-troller in response to the header data at the receiver side.
and "1" contained in the compressed data are compared with each other. If the number of bits which require a greater amount of electric energy for transmission is greater than the other number of bits, then the value of bits is inverted. Data indicative of the low data transmission rate, the compression of the data, and whether the value of bits has been inverted or not are coded into header data which are added to the com-pressed data for transmission. The data transmission rate is adjusted, the compressed data are expanded, and the inverted value of bits is inverted back by a con-troller in response to the header data at the receiver side.
Description
- ` 2 1 92922 -METHOD OF AND APPARATUS FOR DATA COMMnNICATIONS
BETWEEN PORTABLE INFORMATION TE~MT~T
RAC~OUND OF THE INVENTION
1. Field of the Invention:
The present invention relates to a method of and an apparatus for carrying out data communications between portable information terminals, and more par-ticularly to a method of and an apparatus for carrying out data communications between portable information terminals through a wireless communication medium such as infrared radiation with an energy source which may either be a battery of limited capacity housed in each of the portable information terminals or an external power supply of unlimited capacity.
BETWEEN PORTABLE INFORMATION TE~MT~T
RAC~OUND OF THE INVENTION
1. Field of the Invention:
The present invention relates to a method of and an apparatus for carrying out data communications between portable information terminals, and more par-ticularly to a method of and an apparatus for carrying out data communications between portable information terminals through a wireless communication medium such as infrared radiation with an energy source which may either be a battery of limited capacity housed in each of the portable information terminals or an external power supply of unlimited capacity.
2. Description of the Related Art:
One known portable information terminal, as dis-closed in Japanese patent application laid-open No.
63-246048, which is used in a wireless signal transmis-sion system which employs a wireless signal such as a radio signal for transmitting data between main and auxiliary units, transmits data at different transmis-sion rates depending on the condition in which the wireless signal is propagated. Such a portable infor-mation terminal is usually powered by a battery, and communicates with another terminal through a wireless ` 2192922 .
communication medium such as infrared radiation.
Generally, the portable information terminal consumes a large amount of electric energy for wireless communica-tions through infrared radiation, and the incased bat-tery of the portable information terminal has a limitedcapacity because the portable information terminal is relatively small in size and light in weight. Conse-quently, the portable information terminal which ef-fects wireless communications through infrared radia-tion cannot be used continuously for a long period oftime due to the limited battery capacity.
The wireless signal transmission system disclosed in the laid-open no. 246048/1985 is capable of increas-ing the reliability of data transmission by varying the lS data transmission rate according to the propagation condition of the wireless signal. However, the dis-closed wireless signal transmission system gives no solution to prevent the high consumption of the elec-tric energy of the portable information terminal with-out degrading the efficiency of the data transmission.
SUMMARY OF THE lNv~ lON
It is an object of the present invention to pro-vide a method of and an apparatus for carrying out data communications between portable information terminals while ~inirizing the consumption amount of electric energy when the portable information terminal is in operation without degrading the efficiency of data transmission.
To achieve the above object, there is provided in accordance with the present invention a method of carrying out data communications between portable information terminals through infrared radiation with a power source which may be either an incased battery of limited capacity each of the portable information terminals or an external power supply of unlimited capacity, at a data transmission rate which is rela-tively low when the portable information terminal is operated by the battery, comprising the steps of com-pressing data to be transmitted from one of the port-able information terminals to another portable informa-tion terminal if the energy source is the battery, comparing the number of bits "0" contained in the compressed data and the number of bits "1" contained in the compressed data with each other, inverting the value of bits if the number of bits which require a greater amount of electric energy to be consumed for transmission is greater than the other number of bits, transmitting the compressed data together with at least one of data representing that the data have been com-pressed and whether the value of bits has been invertedor not, from the one of the portable information termi-nals to the other portable information terminal if the energy source is the battery, and expanding the com-pressed data and inverting back the inverted value of bits in response to the data at the receiver side information terminal.
The signal representing the modified content of data comprises coded header data added to the com-pressed data, and receiver side portable information terminal decodes the coded header data.
According to the present invention, there is also provided an apparatus for carrying out data communica-tions between portable information terminals through infrared radiation with an energy source which may be either an incased battery of limited capacity housed in each of the portable information terminals or an exter-nal power supply of unlimited capacity therefor, at a data transmission rate which is relatively low when the portable information terminal is operated by the in-cased battery, comprising a power supply detector for detecting whether the energy source is the battery or the external power supply, means for compressing data to be transmitted from one of the portable information terminals to another portable information terminal if the energy source is the incased battery as detected by the power supply detector, means for comparing the number of bits "0" contained in the compressed data and - ` ~1 9292~
the number of bits "1" contained in the compressed data with each other, means for inverting the value of bits if the number of bits which require a greater amount of electric energy to be consumed for transmission is greater than the other number of bits, means for trans-mltting the compressed data together with coded header data representing that the data have been compressed and whether the value of bits has been inverted or not, from the one of the portable information terminals to the receiver side portable information terminal if the energy source is the incased battery, and means for decoding the header data, expanding the compressed data, and inverting back the inverted value of bits in response to the header head at the receiver side port-able information terminal.
The above and other objects, features, and advan-tages of the present invention will become apparent from the following description with reference to the accompanying drawings which illustrate an example of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a block diagram of a portable informa-tion terminal to which a method of carrying out data communications between portable information terminals according to the present invention is applied;
.
Fig. 2 is a detailed block diagram of a power supply detector, a controller, and an infrared communi-cation unit of the portable information terminal shown in Fig. 1;
Fig. 3 is a flowchart of an operation sequence of the portable information terminal for detecting the type of a power supply; and Fig. 4 is a flowchart of an operation sequence of the portable information terminal for transmitting data when the portable information terminal is powered by a battery.
DETATT.~n DESCRIPTION OF THE PREFERRED ~MRODIMENT
As shown in Fig. 1, a portable information termi-nal to which a method of carrying out data communica-tions between portable information terminals according to the present invention is applied, generally com-prises a power supply detector 101 for detecting the type of a power supply which supplies electric energy to the portable information terminal, a controller 102, an infrared (IR) communication unit 103 for transmit-ting data to and receiving data from another portable information terminal through infrared radiation, a memory 104, a display controller 105, and a display unit 106.
Fig. 2 shows in detailed block form the power - ` 21 92922 supply detector 101, the controller 102, and the infra-red communication unit 103.
As shown in Fig. 2, the portable information terminal can be powered by either a incased battery 201 or an AC power supply connected to an AC adapter 202.
The power supply detector 101 comprises a jack 203 to which the AC adapter 202 can be connected, and a sensor 206 in the controller 102. When an input cur-rent supplied to the jack 203 is detected by the sensor206, the sensor 206 sends a control signal 207 to a power supply selector 204 which selects one of the electric energy supplied from the jack 203 and the electric energy supplied from the battery 201 for supply to a power supply circuit 205.
The controller 102 has a compander 208 for com-pressing data to be transmitted and expanding data which have been received, using the memory 104.
The infrared communication unit 103 has an infra-red communication controller 209 for controlling thetransmission of data to and the reception of data from another portable information terminal, an infrared data transmitter 210 for transmitting data to another port-able information terminal, and an infrared data receiv-er 211 for receiving data from another portable infor-mation terminal.
The infrared data transmitter 210 has a light-emitting element such as a light-emitting diode ILED) or the like, and selectively turns on and off the light-emitting element depending on bits of data to be transmitted for thereby transmitting the data. For example, the infrared data transmitter 210 turns on the light-emitting element for transmitting a bit "1" of data, and turns off the light-emitting element for transmitting a bit "0" of data.
The infrared data receiver 211 has a light-detect-ing element such as a photodiode (PD) or the like, and receives infrared radiation transmitted from another portable information medium as data represented by a train of bits "1" and "0".
Operation of the portable information medium will be described below.
Fig. 3 shows an operation sequence of the portable information terminal for detecting the type of a power supply.
The operation sequence of the portable information terminal for detecting the type of a power supply will be described below with reference to Figs. 1 through 3.
The power supply detector 101 and the controller 102 monitors the jack 203 with the sensor 206 to detect the type of a power supply connected to the portable infor-mation terminal. It is assumed that the portable - ` 2 1 92922 -g information terminal is usually poweréd by the battery 201, and is switched from the battery 201 to the AC
power supply when an input current supplied to the jack 203 is detected by the sensor 206.
When the portable information terminal starts to operate, the jack 203 is monitored by the sensor 206.
If no input current supplied to the jack 203 is detect-ed by the sensor 206 in a step 301 (Fig. 3), then it is determined that the portable information terminal is 10 powered by the battery 201 (YES in the step 301), the compander 208 of the controller 102 is operated in a step 302, and the infrared communication controller 209 is set to effect communications at a low rate in a step 303.
If an input current supplied to the jack 203 is detected by the sensor 206 (NO in the step 301), then the compander 208 is not operated in a step 304, and the portable information terminal is switched from the battery 201 to the AC power supply in a step 305.
20 Thereafter, the infrared communication controller 209 is set to effect communications at a high rate in a step 306.
After the portable information terminal has start-ed to operate, the jack 203 is also monitored by the 25 sensor 206 to detect whether the portable information terminal is switched from the battery 201 to the AC
power supply or from the AC power supply to the battery 201. If power supply switching occurs, then the con-troller 102 controls the start and stop of the opera-tion of compander 208, and setting of communication rate of infrared communication controller 209 in the manner described above.
Fig. 4 shows an operation sequence of the portable information terminal for transmitting data when the portable information terminal is powered by the battery 201.
The operation sequence of the portable information terminal for transmitting data when the portable infor-mation terminal is powered by the battery 201 will be described below with reference to Figs. 1, 2, and 4.
The power supply detector 101 and the controller 102 monitors the ~ack 203 with the sensor 206 to detect the type of a power supply connected to the portable information terminal. If the portable information terminal is energized by the battery 201, then data to be transmitted by the infrared communication unit 103 are compressed by the compander 208 in a step 401.
The compander 208 has therein a dictionary for compressing data, and the data to be transmitted by the infrared communication unit 103 are compressed using the dictionary in the compander 208.
More specifical~y, the compander 208 searches the dictionary for a character or a string of characters contained in the data. If the compander 208 detects such a character or a string of characters in the dictionary, then the compander 208 compresses the data by replacing the character or the string of characters with a number in the dictionary. If the compander 208 does not detect such a character or a string of charac-ters in the dictionary, then the compander 208 regis-ters the character or the string of characters in the dictionary.
The compander 208 registers strings of characters comprising previous and present agreed strings of characters in the dictionary. When the dictionary is full, the compander 208 discards a string of characters which has not been used for a long period of time. The compander 208 manages the dictionary by managing each of strings of characters with a queue, and placing a string of characters at the end of a queue each time a string of characters is used.
Then, the controller 102 calculates the entire length of bits of the compressed data in a step 402, and then calculates the number of bits 1' in the compressed data in a step 403.
The controller 102 calculates the ratio of the bits "1" in the compressed data to the entire length of bits of the compressed data, and determines whether or not the bits "1" in the compressed data is 50 % or more of the entire length of bits of the compressed data in a step 404. If the bits "1" in the compressed data is 50 ~ or more of the entire length of bits of the com-pressed data (YES in the step 404), then the controller102~inverts the value of the bits of the compressed data, i.e., inverts the bits "1" in the compressed data into "bits "0", and the bits "0" in the compressed data into "bits "1", thereby producing data which will be transferred from the infrared communication unit 103 in a step 405.
If the bits `'1~' in the compressed data is less than 50 % of the entire length of bits of the com-pressed data (NO in the step 404), then the controller 102 does not invert the value of the bits of the com-pressed data.
Since the number of bits "0" in the compressed data is greater than the number of bits "1" in the compressed data, as a consequence, the entire period of zo time in which the light-emitting element of the infra-red data transmitter 210 is turned on is reduced, thus effectively reducing the electric current consumed by the infrared data transmitter 210. If the infrared data transmitter 210 is arranged such that the light-emitting element emits light when the bits "0" areapplied thereto, then the controller 102 inverts the 2 ~ 92922 value of the bits such that the number of bits "1" in the compressed data is greater than the number of bits ~'0~' in the compressed data.
To the data which have been compressed, there are added header data representing that the data have been compressed and also representing whether a bit invert--ing process has been carried out or not in a step 406.
The compressed data and the added header data make up data which will actually be transmitted ~rom the infra-red communication unit 103.
After the data have thus been processed for trans-mission from the infrared communication unit 103, the data are transmitted from the infrared data transmitter 210 to another portable information terminal under the control of the infrared communication controller 209 in a step 407.
If the portable information terminal is operated ..
by the AC power supply or another other external power supply, then the data to be transmitted are not com-pressed and inverted, and will be transmitted withheader data representing that the data have not been compressed and a bit inverting process has not been carried out.
The other portable information terminal which has received the transmitted data analyzes the added header data to determine whether the data have been compressed or not and also a bit inverting process has been car-ried out or not, and, if necessary, inverts again the value of the bits of the data to restore the original data and expand the compressed data.
As described above, when the portable information terminal is powered by the battery, since data to be transmitted are compressed and the data transmission rate is switched to a low rate, the electric current consumed by the portable information terminal for wireless data transmission through infrared radiation is reduced, and the period of time in which the port-able information terminal can continuously be powered by the battery is extended.
Furthermore, inasmuch as data to be transmitted are compressed, they can be transmitted with a rela-tively high data transfer efficiency even if the data transmission rate is switched to a low rate.
In addition, the value of bits in the compressed data are inverted depending on the proportion of those bits, the electric current consumed by the portable information terminal for wireless data transmission through infrared radiation is further reduced, and the period of time in which the portable information termi-nal can continuously be powered by the battery is further extended.
It is to be understood that although the charac-- ` ~ 2 1 92922 teristics and advantages of the present invention have been set forth in the foregoing description, the dis-closure is illustrative only, and changes may be made in the arrangement of the parts within the scope of the 5 appended claims.
One known portable information terminal, as dis-closed in Japanese patent application laid-open No.
63-246048, which is used in a wireless signal transmis-sion system which employs a wireless signal such as a radio signal for transmitting data between main and auxiliary units, transmits data at different transmis-sion rates depending on the condition in which the wireless signal is propagated. Such a portable infor-mation terminal is usually powered by a battery, and communicates with another terminal through a wireless ` 2192922 .
communication medium such as infrared radiation.
Generally, the portable information terminal consumes a large amount of electric energy for wireless communica-tions through infrared radiation, and the incased bat-tery of the portable information terminal has a limitedcapacity because the portable information terminal is relatively small in size and light in weight. Conse-quently, the portable information terminal which ef-fects wireless communications through infrared radia-tion cannot be used continuously for a long period oftime due to the limited battery capacity.
The wireless signal transmission system disclosed in the laid-open no. 246048/1985 is capable of increas-ing the reliability of data transmission by varying the lS data transmission rate according to the propagation condition of the wireless signal. However, the dis-closed wireless signal transmission system gives no solution to prevent the high consumption of the elec-tric energy of the portable information terminal with-out degrading the efficiency of the data transmission.
SUMMARY OF THE lNv~ lON
It is an object of the present invention to pro-vide a method of and an apparatus for carrying out data communications between portable information terminals while ~inirizing the consumption amount of electric energy when the portable information terminal is in operation without degrading the efficiency of data transmission.
To achieve the above object, there is provided in accordance with the present invention a method of carrying out data communications between portable information terminals through infrared radiation with a power source which may be either an incased battery of limited capacity each of the portable information terminals or an external power supply of unlimited capacity, at a data transmission rate which is rela-tively low when the portable information terminal is operated by the battery, comprising the steps of com-pressing data to be transmitted from one of the port-able information terminals to another portable informa-tion terminal if the energy source is the battery, comparing the number of bits "0" contained in the compressed data and the number of bits "1" contained in the compressed data with each other, inverting the value of bits if the number of bits which require a greater amount of electric energy to be consumed for transmission is greater than the other number of bits, transmitting the compressed data together with at least one of data representing that the data have been com-pressed and whether the value of bits has been invertedor not, from the one of the portable information termi-nals to the other portable information terminal if the energy source is the battery, and expanding the com-pressed data and inverting back the inverted value of bits in response to the data at the receiver side information terminal.
The signal representing the modified content of data comprises coded header data added to the com-pressed data, and receiver side portable information terminal decodes the coded header data.
According to the present invention, there is also provided an apparatus for carrying out data communica-tions between portable information terminals through infrared radiation with an energy source which may be either an incased battery of limited capacity housed in each of the portable information terminals or an exter-nal power supply of unlimited capacity therefor, at a data transmission rate which is relatively low when the portable information terminal is operated by the in-cased battery, comprising a power supply detector for detecting whether the energy source is the battery or the external power supply, means for compressing data to be transmitted from one of the portable information terminals to another portable information terminal if the energy source is the incased battery as detected by the power supply detector, means for comparing the number of bits "0" contained in the compressed data and - ` ~1 9292~
the number of bits "1" contained in the compressed data with each other, means for inverting the value of bits if the number of bits which require a greater amount of electric energy to be consumed for transmission is greater than the other number of bits, means for trans-mltting the compressed data together with coded header data representing that the data have been compressed and whether the value of bits has been inverted or not, from the one of the portable information terminals to the receiver side portable information terminal if the energy source is the incased battery, and means for decoding the header data, expanding the compressed data, and inverting back the inverted value of bits in response to the header head at the receiver side port-able information terminal.
The above and other objects, features, and advan-tages of the present invention will become apparent from the following description with reference to the accompanying drawings which illustrate an example of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a block diagram of a portable informa-tion terminal to which a method of carrying out data communications between portable information terminals according to the present invention is applied;
.
Fig. 2 is a detailed block diagram of a power supply detector, a controller, and an infrared communi-cation unit of the portable information terminal shown in Fig. 1;
Fig. 3 is a flowchart of an operation sequence of the portable information terminal for detecting the type of a power supply; and Fig. 4 is a flowchart of an operation sequence of the portable information terminal for transmitting data when the portable information terminal is powered by a battery.
DETATT.~n DESCRIPTION OF THE PREFERRED ~MRODIMENT
As shown in Fig. 1, a portable information termi-nal to which a method of carrying out data communica-tions between portable information terminals according to the present invention is applied, generally com-prises a power supply detector 101 for detecting the type of a power supply which supplies electric energy to the portable information terminal, a controller 102, an infrared (IR) communication unit 103 for transmit-ting data to and receiving data from another portable information terminal through infrared radiation, a memory 104, a display controller 105, and a display unit 106.
Fig. 2 shows in detailed block form the power - ` 21 92922 supply detector 101, the controller 102, and the infra-red communication unit 103.
As shown in Fig. 2, the portable information terminal can be powered by either a incased battery 201 or an AC power supply connected to an AC adapter 202.
The power supply detector 101 comprises a jack 203 to which the AC adapter 202 can be connected, and a sensor 206 in the controller 102. When an input cur-rent supplied to the jack 203 is detected by the sensor206, the sensor 206 sends a control signal 207 to a power supply selector 204 which selects one of the electric energy supplied from the jack 203 and the electric energy supplied from the battery 201 for supply to a power supply circuit 205.
The controller 102 has a compander 208 for com-pressing data to be transmitted and expanding data which have been received, using the memory 104.
The infrared communication unit 103 has an infra-red communication controller 209 for controlling thetransmission of data to and the reception of data from another portable information terminal, an infrared data transmitter 210 for transmitting data to another port-able information terminal, and an infrared data receiv-er 211 for receiving data from another portable infor-mation terminal.
The infrared data transmitter 210 has a light-emitting element such as a light-emitting diode ILED) or the like, and selectively turns on and off the light-emitting element depending on bits of data to be transmitted for thereby transmitting the data. For example, the infrared data transmitter 210 turns on the light-emitting element for transmitting a bit "1" of data, and turns off the light-emitting element for transmitting a bit "0" of data.
The infrared data receiver 211 has a light-detect-ing element such as a photodiode (PD) or the like, and receives infrared radiation transmitted from another portable information medium as data represented by a train of bits "1" and "0".
Operation of the portable information medium will be described below.
Fig. 3 shows an operation sequence of the portable information terminal for detecting the type of a power supply.
The operation sequence of the portable information terminal for detecting the type of a power supply will be described below with reference to Figs. 1 through 3.
The power supply detector 101 and the controller 102 monitors the jack 203 with the sensor 206 to detect the type of a power supply connected to the portable infor-mation terminal. It is assumed that the portable - ` 2 1 92922 -g information terminal is usually poweréd by the battery 201, and is switched from the battery 201 to the AC
power supply when an input current supplied to the jack 203 is detected by the sensor 206.
When the portable information terminal starts to operate, the jack 203 is monitored by the sensor 206.
If no input current supplied to the jack 203 is detect-ed by the sensor 206 in a step 301 (Fig. 3), then it is determined that the portable information terminal is 10 powered by the battery 201 (YES in the step 301), the compander 208 of the controller 102 is operated in a step 302, and the infrared communication controller 209 is set to effect communications at a low rate in a step 303.
If an input current supplied to the jack 203 is detected by the sensor 206 (NO in the step 301), then the compander 208 is not operated in a step 304, and the portable information terminal is switched from the battery 201 to the AC power supply in a step 305.
20 Thereafter, the infrared communication controller 209 is set to effect communications at a high rate in a step 306.
After the portable information terminal has start-ed to operate, the jack 203 is also monitored by the 25 sensor 206 to detect whether the portable information terminal is switched from the battery 201 to the AC
power supply or from the AC power supply to the battery 201. If power supply switching occurs, then the con-troller 102 controls the start and stop of the opera-tion of compander 208, and setting of communication rate of infrared communication controller 209 in the manner described above.
Fig. 4 shows an operation sequence of the portable information terminal for transmitting data when the portable information terminal is powered by the battery 201.
The operation sequence of the portable information terminal for transmitting data when the portable infor-mation terminal is powered by the battery 201 will be described below with reference to Figs. 1, 2, and 4.
The power supply detector 101 and the controller 102 monitors the ~ack 203 with the sensor 206 to detect the type of a power supply connected to the portable information terminal. If the portable information terminal is energized by the battery 201, then data to be transmitted by the infrared communication unit 103 are compressed by the compander 208 in a step 401.
The compander 208 has therein a dictionary for compressing data, and the data to be transmitted by the infrared communication unit 103 are compressed using the dictionary in the compander 208.
More specifical~y, the compander 208 searches the dictionary for a character or a string of characters contained in the data. If the compander 208 detects such a character or a string of characters in the dictionary, then the compander 208 compresses the data by replacing the character or the string of characters with a number in the dictionary. If the compander 208 does not detect such a character or a string of charac-ters in the dictionary, then the compander 208 regis-ters the character or the string of characters in the dictionary.
The compander 208 registers strings of characters comprising previous and present agreed strings of characters in the dictionary. When the dictionary is full, the compander 208 discards a string of characters which has not been used for a long period of time. The compander 208 manages the dictionary by managing each of strings of characters with a queue, and placing a string of characters at the end of a queue each time a string of characters is used.
Then, the controller 102 calculates the entire length of bits of the compressed data in a step 402, and then calculates the number of bits 1' in the compressed data in a step 403.
The controller 102 calculates the ratio of the bits "1" in the compressed data to the entire length of bits of the compressed data, and determines whether or not the bits "1" in the compressed data is 50 % or more of the entire length of bits of the compressed data in a step 404. If the bits "1" in the compressed data is 50 ~ or more of the entire length of bits of the com-pressed data (YES in the step 404), then the controller102~inverts the value of the bits of the compressed data, i.e., inverts the bits "1" in the compressed data into "bits "0", and the bits "0" in the compressed data into "bits "1", thereby producing data which will be transferred from the infrared communication unit 103 in a step 405.
If the bits `'1~' in the compressed data is less than 50 % of the entire length of bits of the com-pressed data (NO in the step 404), then the controller 102 does not invert the value of the bits of the com-pressed data.
Since the number of bits "0" in the compressed data is greater than the number of bits "1" in the compressed data, as a consequence, the entire period of zo time in which the light-emitting element of the infra-red data transmitter 210 is turned on is reduced, thus effectively reducing the electric current consumed by the infrared data transmitter 210. If the infrared data transmitter 210 is arranged such that the light-emitting element emits light when the bits "0" areapplied thereto, then the controller 102 inverts the 2 ~ 92922 value of the bits such that the number of bits "1" in the compressed data is greater than the number of bits ~'0~' in the compressed data.
To the data which have been compressed, there are added header data representing that the data have been compressed and also representing whether a bit invert--ing process has been carried out or not in a step 406.
The compressed data and the added header data make up data which will actually be transmitted ~rom the infra-red communication unit 103.
After the data have thus been processed for trans-mission from the infrared communication unit 103, the data are transmitted from the infrared data transmitter 210 to another portable information terminal under the control of the infrared communication controller 209 in a step 407.
If the portable information terminal is operated ..
by the AC power supply or another other external power supply, then the data to be transmitted are not com-pressed and inverted, and will be transmitted withheader data representing that the data have not been compressed and a bit inverting process has not been carried out.
The other portable information terminal which has received the transmitted data analyzes the added header data to determine whether the data have been compressed or not and also a bit inverting process has been car-ried out or not, and, if necessary, inverts again the value of the bits of the data to restore the original data and expand the compressed data.
As described above, when the portable information terminal is powered by the battery, since data to be transmitted are compressed and the data transmission rate is switched to a low rate, the electric current consumed by the portable information terminal for wireless data transmission through infrared radiation is reduced, and the period of time in which the port-able information terminal can continuously be powered by the battery is extended.
Furthermore, inasmuch as data to be transmitted are compressed, they can be transmitted with a rela-tively high data transfer efficiency even if the data transmission rate is switched to a low rate.
In addition, the value of bits in the compressed data are inverted depending on the proportion of those bits, the electric current consumed by the portable information terminal for wireless data transmission through infrared radiation is further reduced, and the period of time in which the portable information termi-nal can continuously be powered by the battery is further extended.
It is to be understood that although the charac-- ` ~ 2 1 92922 teristics and advantages of the present invention have been set forth in the foregoing description, the dis-closure is illustrative only, and changes may be made in the arrangement of the parts within the scope of the 5 appended claims.
Claims (3)
1. A method of carrying out data communications between portable information terminals through infrared radiation during when the terminal is opereated with power fed by an incased battery, at a relatively low data transmission rate, comprising the steps of:
compressing data to be transmitted at a transmitting portable information terminal;
comparing the number of bits "0" contained in the compressed data and the number of bits '1" con-tained in the compressed data with each other;
inverting the value of bits if the number of bits which require a greater amount of electric energy for transmission than the number of the other bits;
transmitting a signal representing transmis-sion data format, at least either the transmission data are compressed or invertion of bit value, to the receiver side portable information terminal; and expanding the compressed data and inverting back the inverted value of bits in response to said signal at the receiver side portable informatoin termi-nal.
compressing data to be transmitted at a transmitting portable information terminal;
comparing the number of bits "0" contained in the compressed data and the number of bits '1" con-tained in the compressed data with each other;
inverting the value of bits if the number of bits which require a greater amount of electric energy for transmission than the number of the other bits;
transmitting a signal representing transmis-sion data format, at least either the transmission data are compressed or invertion of bit value, to the receiver side portable information terminal; and expanding the compressed data and inverting back the inverted value of bits in response to said signal at the receiver side portable informatoin termi-nal.
2. A method according to claim 1, wherein said modified content of signal representing the transmis-sion data format is coded into a header data adding to said compressed data, and said receiverside portable information terminal decodes said coded header data.
3. An apparatus for carrying out data communica-tions between portable information terminals through infrared radiation with an energy source which may be either an incased battery of limited capacity in each of the portable information terminals or an external power supply of unlimited capacity therefor, at a data transmission rate which is relatively low when the portable information terminal is operated by the bat-tery, comprising:
a power supply detector for detecting whether the energy source is the incased battery or the exter-nal power supply;
means for compressing data to be transmitted when the transmitting portable information terminal detects that the energy source is the incased battery;
means for comparing the number of bits "0"
contained in the compressed data and the number of bits "1" contained in the compressed data with each other;
means for inverting the value of bits if the number of bits which require a greater amount of elec-tric energy for transmission than the other number of bits;
means for transmitting the compressed data together with coded header data representing that the data have been compressed and whether the value of bits has been inverted or not when transmitting the data during the power source is the incased battery; and means for decoding the header data, expanding the compressed data, and inverting back the inverted value of bits in response to said received header data.
a power supply detector for detecting whether the energy source is the incased battery or the exter-nal power supply;
means for compressing data to be transmitted when the transmitting portable information terminal detects that the energy source is the incased battery;
means for comparing the number of bits "0"
contained in the compressed data and the number of bits "1" contained in the compressed data with each other;
means for inverting the value of bits if the number of bits which require a greater amount of elec-tric energy for transmission than the other number of bits;
means for transmitting the compressed data together with coded header data representing that the data have been compressed and whether the value of bits has been inverted or not when transmitting the data during the power source is the incased battery; and means for decoding the header data, expanding the compressed data, and inverting back the inverted value of bits in response to said received header data.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7347677A JP2723100B2 (en) | 1995-12-15 | 1995-12-15 | Portable information terminal device and its communication system |
| JP347677/1995 | 1995-12-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2192922A1 true CA2192922A1 (en) | 1997-06-16 |
Family
ID=18391836
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002192922A Abandoned CA2192922A1 (en) | 1995-12-15 | 1996-12-13 | Method of and apparatus for data communications between portable information terminals |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US5889604A (en) |
| JP (1) | JP2723100B2 (en) |
| AU (1) | AU716569B2 (en) |
| CA (1) | CA2192922A1 (en) |
| GB (1) | GB2308253B (en) |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2319440B (en) * | 1996-11-05 | 2001-06-06 | Samsung Electronics Co Ltd | Low power consuming operating device for digital signal processing |
| JP3082740B2 (en) | 1998-03-30 | 2000-08-28 | 日本電気株式会社 | Portable information terminal with infrared communication function |
| JP3334753B2 (en) * | 1999-06-15 | 2002-10-15 | 日本電気株式会社 | Mobile terminal, mobile communication system, and method for suppressing power consumption of mobile terminal |
| US7522878B2 (en) * | 1999-06-21 | 2009-04-21 | Access Business Group International Llc | Adaptive inductive power supply with communication |
| JP2001251668A (en) * | 2000-03-02 | 2001-09-14 | Canon Inc | Cordless phone terminal and its communication control method |
| JP3886898B2 (en) * | 2000-06-30 | 2007-02-28 | シャープ株式会社 | Display device and display system |
| US6411608B2 (en) * | 2000-07-12 | 2002-06-25 | Symbol Technologies, Inc. | Method and apparatus for variable power control in wireless communications systems |
| US7171116B2 (en) * | 2002-09-17 | 2007-01-30 | Lucent Technologies Inc. | Provisionable keep-alive signal for physical-layer protection of an optical network |
| JP2007122423A (en) * | 2005-10-28 | 2007-05-17 | Sharp Corp | Infrared transmission terminal equipment |
| US8706448B2 (en) * | 2011-07-07 | 2014-04-22 | Rosemount Inc. | Wireless field device with removable power source |
| JP5940873B2 (en) * | 2012-04-25 | 2016-06-29 | ジャパンネットワークシステム株式会社 | Game table monitoring unit, game room system, information registration device, and game table management system |
| US8867925B2 (en) * | 2012-07-20 | 2014-10-21 | Hewlett-Packard Development Company, L.P. | Reducing electrical current of a signal driver for an optical transmitter |
| CN108337724A (en) * | 2018-03-15 | 2018-07-27 | 浙江工业大学 | A method of sending energy consumption for being reduced in passive reflective communication |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2562140B2 (en) * | 1987-04-01 | 1996-12-11 | 松下電工株式会社 | Wireless signal transmission system |
| US5075792A (en) * | 1989-03-20 | 1991-12-24 | Hewlett-Packard Company | Low power optical transceiver for portable computing devices |
| GB2258370B (en) * | 1991-08-02 | 1995-09-06 | Technophone Ltd | Cellular telephone |
| US5682157A (en) * | 1992-10-19 | 1997-10-28 | Fasirand Corporation | Frequency-alternating synchronized infrared |
-
1995
- 1995-12-15 JP JP7347677A patent/JP2723100B2/en not_active Expired - Fee Related
-
1996
- 1996-12-10 AU AU74257/96A patent/AU716569B2/en not_active Ceased
- 1996-12-11 US US08/763,753 patent/US5889604A/en not_active Expired - Fee Related
- 1996-12-13 CA CA002192922A patent/CA2192922A1/en not_active Abandoned
- 1996-12-16 GB GB9626112A patent/GB2308253B/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH09167997A (en) | 1997-06-24 |
| AU7425796A (en) | 1997-06-19 |
| AU716569B2 (en) | 2000-03-02 |
| GB9626112D0 (en) | 1997-02-05 |
| JP2723100B2 (en) | 1998-03-09 |
| US5889604A (en) | 1999-03-30 |
| GB2308253B (en) | 2000-01-26 |
| GB2308253A (en) | 1997-06-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |