JPH0820209B2 - Optical measuring device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring device using reflected light of an object to be measured, which is an optical device used for measuring the height of an automobile, measuring the amount of spring deflection, measuring the distance of a camera, etc. Regarding measuring device.

[0002]

2. Description of the Related Art There are various measuring devices using reflected light of an object to be measured, and one example is shown in FIG. The first light source 10 and the second light source 11 such as LEDs arranged with a difference in the optical path length of the distance d illuminates the DUT 12. Near the first light source 10 and the second light source 11, the light receiving elements 13, 1 arranged so as to face the respective light sources 10, 11.
4 are provided.

The device under test 12 has a diffuse reflection surface,
It is separated from the first light source 10 by a distance D + d, and is separated from the second light source 11 by a distance D. In addition, the light receiving lens 15
A light receiving means including the light receiving element 16 and the light receiving element 16 is provided, and the light receiving means receives the reflected light from the DUT 12. Photodiodes are used for the light receiving elements 13, 14 and 16 described above.

When light is projected from the two light sources 10 and 11, a part of the light from the first light source 10 is received by the light receiving element 13,
The light receiving element 14 receives a part of the light of the second light source 11. Then, the light receiving elements 13 and 14 each convert the received light into an electric signal and generate an output signal.

This output signal is taken into a light amount control circuit provided in the measuring device. The light amount control circuit calculates the light amount ratio between the first light source 10 and the second light source 11, and when the light amount ratio does not reach a predetermined constant ratio, the light amount of the first light source 10 or the second light source 11 is calculated. It is controlled to change and maintain a constant ratio.

FIG. 6 shows the above-mentioned light amount control circuit. The light amount control circuit 17 defines the ratio of the light amounts of the first light source 10 and the second light source 11 as 2: 1. The photoelectric conversion signals Ip and Is output from the light receiving elements 13 and 14 are amplifiers 18 and 19, respectively.
After being sent to and amplified, the rectifying and smoothing circuits 20 and 21 rectify and smooth.

The photoelectric conversion signal Ip of the first light source 10 becomes a 1/2 signal by the potentiometer 22 and is input to the differential amplifier 23, and the photoelectric conversion signal Is of the second light source 11 is used as it is as a signal. Entered in. Then, the differential amplifier 23 calculates the difference between the two photoelectric conversion signals and sends the difference signal to the current control circuit 24.

At this time, the differential amplifier 23 sends a + signal to the current control circuit when the above calculation result is +, that is, when the light quantity of the first light source 10 is more than twice the light quantity of the second light source 11. Send to 24. Further, when the above calculation result is −, that is, when the light amount of the first light source 10 is less than or equal to twice the light amount of the second light source 11, a − signal is sent to the current control circuit 24.

When the current control circuit 24 receives a + signal, the current control circuit 24 drives the power amplifier 25 of the first light source 10 to reduce the light amount of the first light source 10. Further, when the current control circuit 24 receives the signal of −, the power amplifier 26 of the second light source 11
Is driven to reduce the light amount of the second light source 11.

The control of the current control circuit 24 is continued until the difference between the electric powers supplied to the respective light sources becomes zero. Than this,
The light emitted from the two light sources 10 and 11 always has a light quantity ratio of 2: 1 and illuminates the DUT 12. In the figure, 27 is a main controller including a signal processing circuit described later.

The reflected light of the object to be measured 12 is condensed by the light receiving lens 15 and received by the light receiving element 16. Light receiving element 16
Converts the received light into an electrical signal to generate an output signal,
This output signal is taken into the signal processing circuit included in the main controller 27, and the measurement distance D is calculated from the luminance ratio of the DUT 12.

That is, the DUT 1 by the first light source 10
The illuminance E ₁ of 2 is given by E ₁ = I / (d + D) ² (1) when the radiation intensity of the first light source 10 is 1. When the reflectance of the DUT 12 is ρ, the brightness B ₁ of the DUT 12 is proportional to ρE ₁ , and when the proportional constant is K, B ₁ = KρE ₁ (2) .

Similarly, in the light emission by the second light source 11, E ₂ = I / D ² (3) B ₂ = KρE ₂ (4)

Next, the reflected light is received by the light receiving lens 15 and the light receiving element 16, and the measured brightness B ₁ , B
_The measurement distance D is obtained from the ratio of ₂ . That is,

[Equation 1] Becomes From this, the measurement distance D can be determined by the reflectance ρ and the proportional constant K.
Can be obtained from the constant d and the luminance ratio (B ₂ / B ₁ ) regardless of

FIG. 7 shows a signal processing circuit 28 included in the controller 27. The output pulse of the oscillator 29 is supplied to the power amplifier 25 of the first light source 10 and the second pulse by the light emission switching circuit 30.
It is alternately sent to the power amplifier 26 of the light source 11 to cause the two light sources 10 and 11 to emit light alternately. Further, the light emission switching circuit 30 sends to the light reception switching circuit 31 a synchronization signal for timing the light reception in accordance with the output pulse of the oscillator 29 described above.

When the object 12 to be measured is illuminated by the light emitted from the first light source 10 and the second light source 11, and the reflected light of the object 12 to be measured is received by the light receiving element 16, the reflected light is photoelectrically converted. The received light signal is amplified by the amplifier 32, and the received light switching circuit 3
Sent to 1. The light receiving switching circuit 31 determines whether the first light source 10 or the second light source 11 emits light based on the synchronization signal from the light emitting switching circuit 30, and accordingly, the photoelectric conversion signal of the first light source 10 is detected. To the first arithmetic circuit 33 and the photoelectric conversion signal of the second light source 11 to the second arithmetic circuit 34.

Based on this photoelectric conversion signal, these first
The arithmetic circuit 33 and the second arithmetic circuit 34 perform arithmetic operations for obtaining the brightness B ₁ of the DUT 12 in the first light source 10 and the brightness B ₂ of the DUT 12 in the second light source 11, respectively, and the results are processed by the processing circuit 35. Then, the brightness ratio (B ₂ / B ₁ ) is calculated and the output signal related to the measurement distance D is output from the output terminal 36.

The measuring device described above comprises two light sources 10, 1
Since the light quantity ratio of 1 is always kept constant, the measured distance D is accurate and the two light sources 10 and 11 are arranged so that when one of the light sources is dark, the other light source is adjusted to the darkened light source. Since the light amount of the light source is controlled, the life of the light source can be extended and the durability of the device is improved.

On the other hand, the light receiving element 13 of the above measuring device,
14 can also be composed of one light receiving element 37 as shown in FIGS. The first light source 10 and the second light source 11 are alternately emitted by the signal processing circuit 28 described above. Then, a part of each emitted light is received by the light receiving element 37 arranged as shown in FIG. 8 and converted into an electric signal, and the light amount control circuit 38 shown in FIG. And the light amount of the second light source 11 is calculated, and the light amount of the first light source 10 or the second light source 11 is controlled according to the difference, and the light amount of the first light source 10 and the second light source 11 is set to a predetermined constant value. The ratio of In this light quantity control circuit 38, the light quantity ratio between the first light source 10 and the second light source 11 is 2: 1.
Has been defined.

The photoelectric conversion signal output from the light receiving element 37 is amplified by the amplifier 39 and then separated by the separator 40 into the first signal.
The photoelectric conversion signal Ip generated by the light source 10 emits light and the second light source 1
The first light source 1 is separated into the photoelectric conversion signal Is generated by the first light emission and is rectified and smoothed by the rectification smoothing circuits 41 and 42, respectively.
The photoelectric conversion signal Ip of 0 is 1/2 with the potentiometer 43.
Signal is input to the differential amplifier 44, and the second light source 11
The photoelectric conversion signal Is of is input to the differential amplifier 44 as it is.

Then, the differential amplifier 44 calculates the difference, and the current control circuit 45 drives the power amplifier 46 of the first light source 10 or the power amplifier 47 of the second light source 11 based on this difference signal to determine the amount of light. The large light source is controlled to match the light source with a small light amount.

The first light source 10 whose light quantity is controlled in this way,
The light from the second light source 11 is applied to the DUT 12, and the reflected light is collected by the light receiving lens 15 and received by the light receiving element 16. Then, the signal processing circuit 28 calculates the measurement distance D based on the output signal of the light receiving element 16.

As described above, since this measuring device is composed of one light receiving element 37, the number of parts is reduced and the structure of the device is simplified.

The above-mentioned measuring device has already been proposed and applied for a patent by the present inventors, but it is sufficient if the first light source 10 and the second light source 11 project light so that the illuminance characteristics are different. If the gain of the amplifier for amplifying the output signal of each light receiving element is adjusted, these light sources 1
The light amount ratio of 0 and 11 may not be set to 2: 1 or 1: 1.

[0025]

The above-described conventional measuring apparatus has a light amount control circuit even when the intensity of the projected light changes due to deterioration of one of the two light sources 10, 11 or the like. Since 17, 38 keep the light quantity ratio of the two light sources 10, 11 constant, the distance D to the DUT 12 can be accurately calculated.

However, this measuring device has a problem in accuracy because the light used for distance measurement and the light used for light quantity measurement are not the same light. That is, the two light sources 10,
Among the light projected from 11, the light on each optical axis is used for distance measurement, whereas the light apart from each optical axis is used for light amount measurement, and therefore the distance measurement is performed. It is not possible to accurately detect the change in the light used for.

Therefore, an object of the present invention is to develop an optical measuring device of this kind which can use the same light for measuring a distance and the like and for measuring a light quantity.

[0028]

In order to achieve the above object, according to the present invention, two light sources having different light characteristics which vary depending on the projection distance and the light from the two light sources arranged so that their optical axes intersect. A light projecting unit that includes a mirror that is arranged on the axis and divides the light of each light source into two, and that projects one of the two divided light beams onto the object to be measured; First light receiving means for receiving the other light at the optical axis intersection of the two light sources and photoelectrically converting it, second light receiving means for receiving and photoelectrically converting the reflected light of the object to be measured, and the first light receiving means. A light quantity control means for processing the photoelectric conversion signal output from the light receiving means to control the light quantity of at least one of the two light sources so that the light quantity of these two light sources has a predetermined constant ratio, and the second light receiving means outputs Signal processing that outputs the measured information by dividing the photoelectric conversion signal into signals for each light source Suggest optical measuring apparatus characterized by a more configuration and means.

[0029]

When light is projected from two light sources arranged so that their optical axes intersect, each light is divided into two by the mirrors arranged on the optical axes of these two light sources. One of the two divided lights is received by each light source and photoelectrically converted by the first light receiving means provided at the intersection of the optical axes of the two light sources . And
Based on the photoelectric conversion signal output from the first light receiving unit, the light amount control unit sets the light amount of at least one of the two light sources so that the light amount ratio of these two light sources becomes a predetermined constant ratio. To control.

The other half of the light is projected onto the object to be measured and is received by the second light receiving means as reflected light of the object to be measured and photoelectrically converted. Then, the signal processing means calculates the luminance ratio of the measured object based on the photoelectric conversion signal output from the second light receiving means, and outputs the measurement information.

In this measuring apparatus, the light for measuring the object to be measured and the light for measuring the light quantity are the same light, so that 2
The two light sources have a constant amount of light for measuring the object to be measured, which greatly improves the measurement accuracy.

[0032]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 shows a basic example of the present invention, and is a simplified diagram of a light projecting means and first and second light receiving means in this basic example . Half mirrors 52 and 53 that divide the light projected on the optical axis of the two light sources 50 and 51 composed of LEDs are arranged at a predetermined angle with respect to the optical axis.

[0033] Each of the light source 50 and 51 and the half-mirror 5
At the extended position of the optical axis connecting 2 and 53, the light receiving elements 54 and 55 as the first light receiving means have their light receiving surfaces on the respective light sources 5.
It is provided facing 0 and 51. An object to be measured 56 having a diffuse reflection surface is provided on the reflection optical paths of the half mirrors 52 and 53 described above.

The distance from the light sources 50 and 51 to DUT 56, the first light source 50 is _{d +} D 1 + _{D 2,} the second light source 51
Is D ₁ + D ₂ and D ₁ + D ₂ = D,
D is the measurement distance.

Further , a second light receiving means including a light receiving lens 57 and a light receiving element 58 is provided, and the second light receiving means receives the reflected light from the object 56 to be measured. Photodiodes are used as the above-mentioned light receiving elements 54, 55 and 58.

When the light projected from the two light sources is incident on the half mirrors 52 and 53, the respective light is divided into transmitted light and reflected light by the half mirrors 52 and 53.
Of the split light, the transmitted light is received by the light receiving elements 54 and 55 provided on the respective optical axes and photoelectrically converted.

[0037] Then, this measuring device, the light-receiving element 54,
The photoelectric conversion signal for each light source, which is output from 55, is taken into a light amount control circuit similar to the conventional example shown in FIG. 6, and this light amount control circuit keeps the light amount of the first light source 50 and the second light source 51 constant. The first light source 50 and the second light source 5 so as to be in proportion.
The light amount of at least one of the light sources 1 is controlled.

Further, of the light separated by the half mirror 52 and 53, the reflected light illuminates the object to be measured 56. The object 56 to be measured is irradiated with two lights having a constant light amount ratio by the light amount control circuit with different illuminance characteristics depending on the difference in optical path length.

The two lights emitted to the object 56 to be measured are reflected by the light receiving lens 57 and are received by the light receiving element 58, and photoelectric conversion signals for each light source are output. And
Based on this photoelectric conversion signal, a signal processing circuit similar to the conventional example shown in FIG. 7 calculates the luminance ratio of the DUT 56 and outputs the output signal of the measurement distance D.

In the measuring device thus constructed, the light on the respective optical axes of the two light sources 50 and 51 becomes the distance measuring light and the light quantity measuring light, so that the light quantity control circuit provides a constant light quantity ratio. The distance D measured by the two lights becomes extremely accurate.

FIG . 2 shows the first embodiment of the present invention and is a simplified diagram of the light projecting means and the first and second light receiving means as in FIG. In this embodiment, the first light receiving means is replaced by one light receiving element 5.
The number of parts is reduced by configuring the device with 9 and the device configuration is simplified.

The two light sources 60 and 61 composed of LEDs are arranged so that their optical axes intersect. Further, a half mirror 62 that divides each projected light into two is provided on each optical axis. As shown in the figure, the half mirror 62 has a pyramidal shape, and a triangular surface portion 6 forming a side surface thereof.
2a and 62b are half mirrors.

At the intersection P of the optical axes of the two light sources 60 and 61, a light receiving element 59 as a first light receiving means is provided. Further, an object to be measured 63 having a diffuse reflection surface is provided on the reflection optical path of the half mirror 62 described above.

[0044] The first light source 60 and the second light source 61 is installed by providing the difference in distance d with respect to the half mirror 62, than this, the distance to the object to be measured 63, the first light source 60 is d +
D ₁ + D ₂ , the second light source 61 becomes D ₁ + D ₂ , and D ₁ +
The measurement distance D is calculated with D ₂ = D.

Further, a light receiving lens 64 as a second light receiving means for receiving light reflected from the measurement object 63 receiving element 65
Are provided.

[0046] The first light source 60 and the second light source 61 emits light alternately by the same signal processing circuit in the conventional example shown in FIG. The light emitted from the first light source 60 is the surface portion 6 of the half mirror 62.
The reflected light and the transmitted light are separated by 2a, and the emitted light of the second light source 61 is separated by the surface portion 26b of the half mirror 62 into the reflected light and the transmitted light.

[0047] Each of the transmitted light is photoelectrically converted are received by the light receiving element 59. This photoelectric conversion signal is taken into a light amount control circuit similar to that of the conventional example shown in FIG. 9 and processed for each light so that the first light source 60 and the second light source 61 have a predetermined constant light amount ratio. To be done.

Further , each reflected light irradiates the DUT 63. The DUT 63 is irradiated with two lights having a constant light amount ratio by the light amount control circuit with different illuminance characteristics according to the difference in optical path length.

[0049] Two of the light applied to the object to be measured 63, the reflected light is condensed by the light receiving lens 64 and the light receiving element 65
The light is received by and becomes a photoelectric conversion signal of light for each light source. The signal processing circuit calculates the luminance ratio of the DUT 63 based on the photoelectric conversion signal and outputs the output signal of the measurement distance D.

FIG . 3 shows an application example of the present invention, and is a simplified diagram of the light projecting means and the first and second light receiving means. In this application example , of the light projected from the first light source 70 and the second light source 71, the light reflected by the half mirrors 72 and 73 is incident on the light receiving element 74 for controlling the light amount, and the half light is received. The transmitted light from the mirrors 72, 73 is configured to irradiate the DUT 75.

The first by the photoelectric conversion signals of the light receiving element 74
The light quantity ratio between the light source 70 and the second light source 71 is controlled to be constant, and the reflected light of the DUT 75 is collected by the light receiving lens 76 and received by the light receiving rod 74, and the photoelectric conversion signal is used to detect the reflected light. Obtaining the distance D to the measurement object is the same as in the above-described embodiment.

FIG . 4 shows a second embodiment of the present invention and is a simplified diagram showing a light projecting means and a first light receiving means. In this embodiment, one light receiving element 83 for controlling the light amount and the first light source 80
And the light emitted by the second light source 81 from one half mirror 8
The feature is that it is divided into 2 by 4.

[0053] That is, among the light projected from the first light source 80, light transmitted through the half mirror 84 is the light receiving element 83
The light reflected by the mirror 84 illuminates the object to be measured. Further, of the light projected from the second light source 81, the light reflected by the half mirror 84 is the light receiving element 8
The light that is incident on the beam No. 3 and transmitted through the mirror 84 illuminates the object to be measured. Others do not have the same as the real施例described above.

The half mirrors 52, 53 and 62 described in the above basic examples and embodiments may be polarization separation mirrors, or wavelength separation mirrors for incandescent lamps and the like. The half mirrors 52, 53, 62 may be not only plane mirrors but also parabolic mirrors, elliptical mirrors, hyperboloidal mirrors, etc. obtained by rotating a curve.

[0055]

As described above, the optical measuring device according to the present invention includes a light amount control circuit for controlling the light amounts of two light sources,
Since the signal processing circuit that calculates the measurement result from the luminance ratio of the DUT responds to the received light signal of the same light projected from the two light sources, the calculated measurement value is extremely accurate. Will be high. Therefore, the reliability of the measuring device is greatly improved.

[Brief description of drawings]

FIG. 1 shows a basic example of the present invention, and is a simplified diagram of a light projecting means and first and second light receiving means provided in a measuring apparatus of this basic example .

FIG. 2 shows the first embodiment of the present invention, and is a simplified diagram of the light projecting means and the first and second light receiving means provided in the measuring apparatus of this embodiment .

FIG. 3 shows an application example of the present invention, and is a simplified diagram of a light projecting means and first and second light receiving means provided in the measuring apparatus of this application example .

FIG. 4 shows a second embodiment of the present invention and is a simplified diagram of a light projecting means and a first light receiving means provided in the measuring apparatus of this embodiment .

FIG. 5 is a simplified diagram of a light projecting unit and first and second light receiving units of an optical measuring device shown as a conventional example.

FIG. 6 is a block diagram showing a light amount control circuit in a conventional example.

FIG. 7 is a block diagram showing a signal processing circuit in a conventional example.

FIG. 8 is a simplified diagram of a light projecting means and first and second light receiving means of an optical measuring device shown as another conventional example.

FIG. 9 is a block diagram showing a light amount control circuit in another conventional example.

[Explanation of symbols]

50, 60, 70, 80 First light source 51, 61, 71, 81 Second light source 52, 53, 62, 72, 73, 84 Half mirror 54, 55, 58, 59, 65, 74, 77, 83 Light receiving element 56, 63, 75 DUT 57, 64, 76 Light receiving lens

Claims (1)

[Claims] 1. A mirror that divides the light of each light source into two by arranging them on the optical axis of the two light sources arranged so that their optical axes intersect with each other, and the two light sources having different light characteristics that change depending on the projection distance. And a light projecting means for projecting one of the two divided light beams to the object to be measured, and another light beam of the two divided light beams received at the optical axis intersection points of the two light sources. And a photoelectric conversion signal output from the first light receiving means to process the photoelectric conversion signal output from the first light receiving means. Light quantity control means for controlling the light quantity of at least one of the light sources so that the light quantity of the light source has a predetermined constant ratio, and photoelectric conversion signals output from the second light receiving means are divided into signals for each light source to be processed and measured. An optical measuring device comprising a signal processing means for outputting information.