DE19709310A1 - Optoelectronic adjusting aid for adjusting optical structures, e.g. light barriers esp. photo diodes - Google Patents

Abstract

The adjusting aid consists of a multiple of photo sensors (1-4), esp. photo diodes, which are arranged preferably symmetrically on a substrate. The signals of the photo sensors are called up for the determining of the optical centre of gravity of the incident light, which is compared with a desired position (12). Depending on the position of the optical centre of gravity, illuminating one or more optical signal transmitters (6-10) such as LEDs to a different brightness. An information concerning this position is optically transmitted, so that the incident light beam can be so corrected, that it finally coincides with the desired position on the adjusting aid.

Description

The invention relates to an optoelectronic adjustment aid from a multi number of photosensors.

When adjusting optical structures, light beams usually have to be large Distances through direct deflection of the light beam or indirect Distraction can be focused as precisely as possible on a point, which is, for example, an optical sensor for detecting the light or a mirror for reflecting the light onto such an optical one Sensor is located. Examples of such structures are reflex and on Path sensors, rangefinders and optical data transmission systems. With the naked eye, this can be due to the large distances between the light source and target can only be adjusted inaccurately. In addition to the Large distances make it difficult that often in such systems working with infrared light not visible to the naked eye, so that adjustment by eye is not necessary or only with IR viewing devices can be carried out. In most cases you are on it instructed to optimize the signal detected at the optical sensor, the sensor, however, initially at least partially from the light beam must be taken. This extends the time to set up and Setting up such a system.

Another option is to position sensitive components such. B. Line semiconductors to display the size of the misalignment.

The invention is therefore based on the object of an adjustment aid for To create optical structures that can be realized simply and inexpensively sieren and is particularly in the adjustment of reflex and disposable light barriers, rangefinders and optical data transmission systems can be used.

The object is achieved by an optoelectronic Adjustment aid, consisting of a plurality of photosensors, ins special photodiodes, and at least one optical signal transmitter, in particular a light-emitting diode and a measuring and evaluation unit, the measuring and evaluation unit is capable of being used in the lighting case to evaluate currents flowing through the photosensors such that the optical focus of the incident light is determined and with a target  position is compared and the degree of their agreement using an optical signal generator is displayed.

The adjustment aid thus provides the user with a long distance visible optical signal when the optical focus of the incident light comes close to the predetermined target position and / or achieved this. The strength of the optical signal correlates preferably with proximity to the target position. This target position is a fixed one Position on the adjustment aid. The adjustment aid is then held so that this target position coincides with the position to which the Light beam and especially its optical focus should fall. Most of the time it is in the beam direction directly behind that through the Target position excellent point of the optical sensor z. B. the light barrier or a reflector aimed at a sensor so that the light beam is set to this point after removing the adjustment aid and only the fine adjustment with the aid of the sensor signal has to be carried out.

The photosensors are preferably in one plane and symmetrical a center of symmetry because of a symmetrical arrangement the evaluation of the sensor currents and the assignment to a spatial one Position of the addressed sensor simplified. This symmetry The center preferably coincides with the target position of the optical gravity points match.

Advantageously, n photosensors of the adjustment aid are combined to form a subunit, within which they are connected in parallel relative to one another. The sensor currents I _m are read out via a resistance chain of n + 1 resistors connected in series, the edge currents I _a and I _b discharged by the resistance chain being fed to the measuring and evaluation unit.

All the resistors in the resistor chain preferably have the same resistance value R. This simplifies the evaluation of the sensor currents to form the optical center of gravity within the subunit, since when the sensors of a subunit are numbered, the average order number m corresponding to the optical center of gravity results from the quotient of the edge currents :

n is the number of sensors. In this case, the edge current I _a or I _{b is} proportional to the average order number of the sensor on which the optical focus of the light distribution falls.

The output signal is preferably generated by suitable amplifier circuits with analog mathematical operations and can be supplied to the optical signal generator, for example, as a supply current. This enables it to emit an optical signal corresponding to the misalignment. Therefore, each subunit is preferably assigned at least one optical signal transmitter - if possible two - whose luminosity is controlled with the aid of the edge current I _a or I _b or a signal proportional to it.

An adjustment aid that is not only an optical signal transmitter is advantageous to display the amount of misalignment, but more with which one Direction of misalignment can be signaled. In an advantageous Embodiment of the invention are the photosensors in one line arranged, being in the center of symmetry of the row and on the two An optical signal transmitter is located at each end of the line. The optical signal The encoder in the center shows a centered adjustment of the optical center of gravity of an incident light beam and the signal transmitter at the ends of the Line a misalignment of the optical center of gravity in the direction of the respective Line end.

It is also advantageous to have two such sensor lines crosswise in one to arrange at right angles and with a common center. This allows misalignments in two dimensions perpendicular to the beam axis what is generally occurring. However, there are others e.g. B. target-like, arrangements of the sensors conceivable.

The number of photo sensors of the adjustment aid depends on the application purpose chosen. To adjust over very long distances, it is expedient to choose the area of the adjustment aid so large that it from the Distance is still clearly visible and this over the full length and / or To be equipped with photo sensors across the width or area. At very long distances it is also an advantage to have more than just two optical ones Signalers to use in each coordinate direction, as brightness is lower differences over long distances may no longer be recognized.  

A plurality of signal transmitters are then preferably switched per line react to their immediate surroundings.

The adjustment aid is advantageously accommodated in a housing, which is a transparent front plate to protect the photosensors and the Signaling mechanical damage. Furthermore, this can Housing preferably on the respective retroreflector or optical Put on or plug on the sensor to be adjusted so that the adjustment aid is attached to it during the adjustment process.

An example of the invention is shown in the drawing and below described. Show

Fig. 1 is a plan view of an adjusting aid according to the invention,

Fig. 2 shows a section through such an adjustment aid,

Fig. 3 is an equivalent circuit diagram of the optoelectronic elements of the adjustment aid.

In Fig. 1, an adjustment aid according to the invention is shown in supervision. It has two rows of photosensors 1 , 2 , 3 , 4 , each arranged perpendicular to one another and applied to a square substrate. The photosensors are, for example, photodiodes, e.g. B. PIN diodes. The common center of the lines is the center of symmetry 5 of each individual line as well as the two lines. There is an optical signal transmitter 6 , in particular a light-emitting diode. A further light-emitting diode 7 , 8 , 9 , 10 is arranged at the line ends. The position of the center of symmetry 5 is identical to the position of the target position 12 , to which the optical center of gravity of an incident light beam is to be adjusted. The adjustment aid is introduced into the beam path in such a way that the light beam strikes the adjustment aid vertically or almost perpendicularly. Furthermore, the adjustment aid is arranged so that the point on which the optical focus should fall, for. B. the center of an optical sensor, with the target position 12 in the direction of the surface normal of the adjustment aid.

The photosensors 1 , 2 , 3 , 4 of the adjustment aid shown are combined into sub-units 13 , each comprising an arm of the cross-shaped sensor arrangement, that is to say four photosensors. It is also possible to combine each of the two sensor lines to form such a subunit. Within each subunit, the optical center of gravity of the incident and incident light is determined by evaluating the currents through the individual sensors and this information is used to regulate the luminosity of the light-emitting diodes, which spatially complete the subunit, e.g. B. the light emitting diodes 6 and 9 at subunit 13 .

How the photosensors are read is shown and explained in the equivalent circuit in FIG. 3.

Falls z. B. on the photosensor 2, the optical focus of a light beam, the LED 9 lights up strongly and the LED 6 weakly. This shows a strong misalignment of the optical center of gravity in the direction of the axis defined by LEDs 6 and 9 . This misalignment can be compensated for by a slight change in the direction of propagation of the light beam, so that the optical focus on the adjustment aid after swiping over the sensors 3 and 4 with successively weaker lighting of LED 9 or stronger LED 6 assumes the target position 12 .

If the distribution of the incident light over the adjustment aid is not punctiform, but is extended, so that several sensors of different subunits are also irradiated, the LEDs of the respective subunits light up. As in the one-dimensional case, the luminosity then depends on where the focus of the light radiation lies on the light-sensitive total area of the sensors of a subunit. With an optical focus of the total light distribution, which lies in the quadrant defined by the LEDs 6 , 8 and 9 , these three LEDs shine more or less so that the technician knows in which direction the beam is misaligned and can adjust it accordingly.

If the beam diameter is so small that it only has one sensor responds, the location of the beam outside the sensor lines, z. B. within the above Quadrants difficult. In this case, it is cheaper a different, more extensive arrangement of photosensors on one To choose substrate.

The photosensors are also designed for infrared radiation, which means the adjustment aid advantageous as an active target in the adjustment of not visible light.  

FIG. 2 shows a section through the adjustment aid from FIG. 1. The cut was made along the line defined by the light-emitting diodes 7 and 9 . The LEDs 6 , 7 and 9 and the photosensors 1 , 2 , 3 , 4 are designated here by the reference numerals 6 ', 7 ' and 9 'or 1 ', 2 ', 3 ', 4 ', these elements from the two Figures correspond to each other.

The optoelectronic elements 1 ', 2 ', 3 ', 4 ', 6 ', 7 ', 9 'are arranged on a substrate, which here is, for example, part of a housing in which an electronics module is located. This electronics module comprises the measuring and evaluation unit 11 for evaluating the currents flowing through the individual photo sensors and converting them into a signal for controlling the luminosity of the light-emitting diodes. The electronics module also contains the voltage supply for the photosensors.

The optoelectronic elements 1 ', 2 ', 3 ', 4 ', 6 ', 7 ', 9 'and the measuring and evaluation unit 11 are accommodated in a housing, which is only partially shown here. It is covered on the top with a transparent front plate 16 , which protects the optoelectronic elements from mechanical damage. Furthermore, it has baseboards 18 on its underside, with the aid of which it can be fitted or plugged onto a target object, here a retroreflector 17 . On the baseboards there may also be locking screws on the side, with which the adjustment device can be fixed to a target object without play. This ensures that the target position of the adjustment unit is always brought into line with the position to which the optical center of gravity of the light beam on the target object, here the retroreflector 17 , is to be adjusted.

Fig. 3 shows a an equivalent circuit diagram of the optoelectronic elements of the adjusting aid, in particular a possibility for wiring and readout of the photodiode, wherein the information is particularly easy to get over the location of the optical center of gravity.

The four photosensors or photodiodes 1 ″, 2 ″, 3 ″, 4 ″ are connected in parallel with respect to one another and form a subunit 13 ′ which is supplied with the operating voltage of the diodes by a voltage source 23 .

The subunit also has a resistance chain 14 , consisting of five resistors 15 , 19 , 20 , 21 connected in series. Each photo sensor 1 ″, 2 ″, 3 ″, 4 ″ is connected via a connecting line to the adjacent photo sensor (s) and to the voltage source 23 . Each photosensor is also connected to two resistors that are adjacent in the resistor chain. For example, sensor 1 ″ is connected to resistors 15 and 19 , sensor 2 ″ is connected to resistors 19 and 20 and so on.

In principle, the resistors can have any values, but it is advantageous to assign them the same resistance value R since this considerably simplifies the evaluation of the measurement signal.

The ends of the resistance chain 14 are connected to lines 24 , 25 , which lead to the measuring and evaluation unit. This measuring and evaluation unit is, for example, an arrangement of operational amplifiers for amplifying the edge currents dissipated via the resistor chain and for further signal processing thereof.

In the event of light falling on the sensor system, the photosensors or photodiodes act as current sources with generally different amperages I _m . Depending on the spatial arrangement of the photosensors and on the light distribution via the sensor system or via the photosensors, the current intensities I _m for the different order numbers m are of different sizes. If the individual I _m were measured separately, a profile of the light distribution over the sensor system depending on the order number m as a spectrum of discrete lighting values could be created directly on the basis of the known characteristic - or the light-current flow relationship - of the photodiodes. This would make it easy to obtain the location information about the illuminance at the mth photosensor and thus, for example, the location of a light spot if the spatial arrangement of the sensors is known. However, the individual sensor readout leads to great electronics expenditure in a sensor system made up of a large number of photo sensors.

The photodiodes are therefore connected in parallel with one another, and a photodiode is cross-connected to its neighbors via a respective resistor 15 , 19 , 20 , 21 , 22 , the resistors forming a resistor chain of resistors connected in series. Instead of the individual signals I _m , the edge currents I _a and I _b flowing off via the resistance chain are measured by a measuring and evaluation unit common to all photosensors.

The location information is contained in the edge currents I _a and I _b .

The general case of m photosensors D _{m is} discussed below. (In Fig. 3, m = 4.)

As a special case, the case is first considered that there is a point illumination of a sensor system consisting of n photodiodes and n + 1 resistors, in which only the mth photosensor is addressed. Thus, only the mth current source has a current flow I _m , ie all other I _n = 0 for n ≠ m. Current flow I _m at the mth point in the sensor system means that a current I _a over m individual resistances R or the total resistance mR and a current I _b over n + 1-m individual resistances R or the total resistance (n + 1- m) R flows off as an edge current. Current conservation I _a + I _b = I _m applies.

For the current flow I _b follows in this case

and follows for the order number m of the addressed photosensor

or m ∞ I _b for I _a + I _b = I _m = const. (constant incidence of light).

The current I _b therefore contains the location information about the light spot if it is known where the sensor m is located.

The edge currents I _a and I _{b also} carry location information when a single photosensor is not spot-lit but when light is irradiated via the sensor system. One can show that for the quotient

the following generally applies:

The quotient is thus - apart from the factor n + 1 - with the sensor currents I _m weighted mean atomic number of m, that corresponds to the number of the sensor with the center of gravity of light. Again, the middle order number is proportional to the edge current: m ∞ I _b .

This information is sufficient for the use of such a sub-unit of photodiodes in the adjustment aid according to the invention, which is not about generating a line or two-dimensional profile or an image of the light distribution, but the location of the center of gravity of the light radiation in one or two Determine dimensions on the front surface of the adjustment aid. To convert the average atomic number into the actual spatial position, only the spatial arrangement of the sensors needs to be known. B. is designed as in Fig. 1. The current signal I _b or I _a is directly proportional to the spatial distance of the sensor with the number m or m from a reference point at the start of a sensor line if the sensors are arranged equidistantly within the sensor line.

Because m is not necessarily an integer, intermediate values can also be assigned between the numbered sensors. m = 2.5 means, for example, that the optical center of gravity lies halfway between sensor 2 and sensor 3 if the sensors are arranged equidistantly in a straight line.

In principle, the illuminance of the optical signal transmitters can be regulated directly with the aid of the edge currents I _a and I _b , since I _{a / b} increases the closer the optical center of gravity of the incident light is to the spatial position of the resistor chain end a / b or the first one or last sensor of the subunit. A light-emitting diode is then operated with the amplified current I _{a / b} , which are located at the respective ends of the subunit in accordance with the spatial position of the first or last sensor of the subunit. In the example of the adjustment aid shown in FIG. 1, I _{a is} greatest when the optical center of gravity is at photosensor 1 — reference number 1 ″ in FIG. 3. I _a thus controls the brightness of the light-emitting diode 9 . Likewise, I _{b is} greatest when the optical center of gravity is at photosensor 4 - reference number 4 ″ in FIG. 3. The brightness of the LED 6 is controlled with I _b .

LED 6 from FIG. 1 is preferably supplied by a current signal which is composed of the sum of the corresponding edge currents I _{b of} the respective four subunits. LED 6 thus serves to display the position of all four subunits and finally to indicate that the optical center of gravity in two dimensions agrees with the target position as well as can be determined within the measurement accuracy.

In order to equalize different illuminance levels and / or wavelengths and thus different maximum current intensities I _m by means of a photodiode and to achieve an almost constant optical signal from the light-emitting diodes with optimal adjustment or (within the area of the adjustment unit) maximum misalignment, it is advantageous to Operate measuring and evaluation unit with variable degrees of gain. At the beginning of the adjustment, a high gain can be set to get an optical signal. This serves as a rough guide to where the optical center of gravity is on the surface of the adjustment unit. Overdrive the LEDs, since the current strength increases due to the better adjustment, the gain factor is simply reduced.

Another way of obtaining a constant optical signal in the case of optimal adjustment is to normalize the edge currents I _a and I _b by dividing the individual currents by the total edge current I _a + I _b , that is to say the quotient

is formed.

The evaluation methods for forming the quotient

are at known PSDs, in which this quotient is also formed to get the desired location information.  

Reference symbol list

1

,

1

',

1

'',

2nd

,

2nd

',

2nd

'',

3rd

,

3rd

',

3rd

'',

4th

,

4th

',

4th

'' Photo sensors

5

Center of symmetry

6

,

6

',

7

,

7

',

8th

,

9

,

9

',

10th

optical signal transmitter, light emitting diode

11

Measuring and evaluation unit

12

Target position

13

,

13

'Subunit

14

Resistance chain
a, b ends of the resistor chain

15

,

19th

,

20th

,

21st

,

22

resistance

16

Front panel

17th

Retroreflector

18th

Baseboards

23

Voltage source

24th

,

25th

Connection lines to the measuring and evaluation unit

Claims (13)

1. Optoelectronic adjustment aid, consisting of a plurality of photosensors ( 1 , 1 ', 1 '', 2 , 2 ', 2 '', 3 , 3 ', 3 '', 4 , 4 ', 4 ''), in particular Photodiodes, and at least one optical signal transmitter ( 6 , 6 ', 7 , 7 ', 8 , 9 , 9 ', 10 ), in particular a light-emitting diode, and a measuring and evaluation unit ( 11 ), the measuring and evaluation unit ( 11 ) is able to evaluate the currents flowing through the photosensors in the event of illumination in such a way that the optical center of gravity of the incident light is determined and compared with a desired position ( 12 ) and the degree of their correspondence by means of the optical signal transmitter ( 6 , 6 ', 7 , 7 ', 8 , 9 , 9 ', 10 ) is displayed. 2. Optoelectronic adjustment aid according to claim 1, characterized in that the photosensors ( 1 , 1 ', 1 '', 2 , 2 ', 2 '', 3 , 3 ', 3 '', 4 , 4 ', 4 '' ) are arranged in one plane and symmetrically to a center of symmetry ( 5 ). 3. Optoelectronic adjustment aid according to claim 2, characterized in that the target position ( 12 ) coincides with the center of symmetry ( 5 ). 4. Optoelectronic adjustment aid according to one of claims 1 to 3, characterized in that n photosensors ( 1 , 1 ', 1 '', 2 , 2 ', 2 '', 3 , 3 ', 3 '', 4 , 4 ', 4 '') are combined to form a subunit ( 13 , 13 ') within which they are connected in parallel relative to one another, and the sensor currents I _m via a resistor chain ( 14 ) made up of n + 1 resistors ( 15 , 19 , 20 , 21 ) can be read, the edge currents I _a and I _b discharged through the resistor chain being fed to the measuring and evaluation unit ( 11 ). 5. Optoelectronic adjustment aid according to claim 4, characterized, that the resistors have the same resistance value R, so that the Edge current to the middle order number m of the photosensor is proportional to the optical focus of the light distribution falls within the subunit.   6. Optoelectronic adjustment aid according to claim 5, characterized in that at least one optical signal transmitter is assigned to a sub-unit, the luminosity of which is controlled with the aid of the edge current I _a or I _b or a signal proportional thereto. 7. Optoelectronic adjustment aid according to one of claims 4 to 6, characterized, that the subunit comprises all sensors of the device. 8. Optoelectronic adjustment aid according to one of claims 1 to 7, characterized, that the degree of amplification of the edge currents was adjustable and did so neutrally incident light on the adjustment aid and / or the wavelength of the Light is customizable. 9. Optoelectronic adjustment aid according to one of claims 1 to 8, characterized, that the photosensors are arranged in a line and in the Center of symmetry of the line and at both ends of the line optical signal transmitter is located, with the optical signal transmitter in the center a centered adjustment of the optical center of gravity of an incident Light beam and and the signal transmitter at the ends of the line misalignment the optical center of gravity in the direction of the respective line end are able to display. 10. Optoelectronic adjustment aid according to claim 9, characterized, that it consists of two such lines of photosensors, which via Cross forming a right angle with a common one Center where there is a common optical signal generator, are arranged. 11. Optoelectronic adjustment aid according to one of the preceding Expectations, characterized, that the light intensity of the optical signal transmitter with the proximity of the optical Center of gravity of the incident light on the spatial position of the signal correlated within the adjustment aid.   12. Optoelectronic adjustment aid according to one of the preceding claims, characterized in that the device is covered by means of a transparent front plate ( 16 ). 13. Optoelectronic adjustment aid according to one of the preceding claims, characterized in that the device can be placed or plugged onto a retroreflector ( 17 ) and / or onto an optical sensor.