JPH0656284B2 - Position detector - Google Patents

Description

The present invention relates to a position detector which is effective when applied to a distance measuring device using an optical system.

[Prior Art] FIG. 4 shows a configuration diagram of a conventional non-contact type distance measuring position to which a position detector of this type is applied. In FIG. It is a light projecting lens that focuses the light flux emitted from the light source 1 and projects it onto the target object 3 to be measured. The light source 1, the light projecting lens 2 and the target object 3 are located on the axis (A), and the light emitted from the light source 1 is irradiated onto the target object 3 by the light projecting lens 2 and the light spot 4 of the light beam is emitted. To form.

Reference numeral 5 is a light receiving lens for forming an image of the light spot 4, and 6 is a light receiving element for generating an electric signal corresponding to the image forming position P of the image of the light spot 4 formed by the light receiving lens 5. The spot 4, the light receiving lens 5, and the light receiving element 6 are located on the axis (B), and in this case, the axis (B) forms an angle θ with the axis (A).

Then, the two electric signals i _A and i output from the light receiving element 6 are outputted.
_B is input to the adder 7 and the subtracter 8, respectively, and the adder 7 obtains the sum (i _A + i _B ) of both signals, and the subtracter 8 obtains the difference (i _A −i _B ) between the two signals. Raru Reference numeral 9 is a divider for dividing the output of the subtractor 8 by the output of the adder 7, and 10 is a converter for converting the position output P of the divider 9 into a distance output l.

In the above, the light source 1, the light projecting lens 2, the light receiving lens 5,
The light receiving element 6 constitutes the detection head 11.

Next, the operation will be described. The light beam emitted from the light source 1 is transmitted by the light projecting lens 2 to the light spot 4 having an appropriate size.
The target object 3 is irradiated with. The light receiving lens 5 takes an image of the light spot 4, and an image of the light spot 4 is formed on the light receiving surface of the light receiving element 6. The light receiving element 6 is also called an optical position detector and generates electric signals i _A and i _B corresponding to the image forming position of the optical spot image. The electrical signals i _A , i _B
By the value of, the image forming position P of the optical spot image is Can be asked as By the way, the output of the light receiving element 6 produces an output signal corresponding to the image forming position P of the optical spot image and its intensity. Therefore, in the above formula (1),
The term (i _A + i _B ), which is a signal that changes in proportion to the intensity change of the optical spot image, is introduced into the denominator to obtain a signal that is proportional only to the image formation position of the optical spot image.

The adder 7, the subtractor 8, and the divider 9 are circuits for performing the operation shown in the above equation (1) based on the output signals i _A and i _B of the light receiving element 6, and thus, An output value P corresponding to the image forming position of the optical spot image is obtained at the output of the divider 9.

On the other hand, if the distance to the target object 3 is l and the installation interval between the light projecting lens 2 and the light receiving lens 5 is L, then l is Can be asked as Here, θ is the light receiving lens 5
Is determined by the focal length, the installation distance between the light receiving element 6 and the light receiving lens 5, and the output P related to the image forming position of the optical spot image. Of these, the values other than the position output P can be set as fixed values, so that the distance l to the target object 3 is eventually obtained.
Is obtained as l = K · P (3). In this case, K is a constant determined by each fixed value, and is set by prior calculation or experiment. The converter 10 carries out the equation (3), inputs the position output P, and outputs the distance output l.

[Problems to be solved by the invention]

Since the position detector applied to the conventional non-contact type distance measuring device is the light receiving element having the electric circuit section as described above, it is necessary to take measures to use it in a place where explosion proof is required. Therefore, there is a problem that the distance measuring device becomes large in size as a whole.

The present invention has been made to solve such a problem, and an object thereof is to obtain a position detector that can be easily linked with an optical fiber and that is suitable for eliminating the explosion-proof structure of a distance measuring device. .

[Means for solving problems]

The position detector according to the present invention emits a plurality of optical signals proportional to the image forming position of the incident optical signal.

[Action]

The incident light of the position detector according to the present invention is scattered by the mixed scattering absorber and is emitted from the plurality of emitting portions.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. First
In the figure, 12 is a position detector composed of a glass material 12a and a scattering material such as metal powder 12b, 13a,
Reference numeral 13b is an optical fiber for transmitting the light emitted from the end face of the position detector 12 to a desired position.

Assuming that the incident light having an intensity of P _O is present in the optical position detector 12 as shown in the figure, the incident light is scattered by the scattering substance mixed inside. As a result, part of the light travels in the left and right transmission directions in the figure, and while being scattered and absorbed, output light with the intensity of P _A and P _B is obtained from both end faces.

Here, when the scattering coefficient in the transmission direction in the optical position detector 12 is α, the distances from both end faces of the incident position are l _A and l _B , and the scattering / absorption coefficient due to the contaminant is β, the optical fiber from each end face is assumed. The intensities P _A and P _B of the output light obtained via 13a and 13b are obtained by the following equations.

P _A = P _O EXP [−αβl _A ] (4) P _B = P _O EXP [−αβl _B ] (5) When the ratio of the two output light intensities is obtained, Therefore, the value of this ratio is proportional only to the difference between l _A and l _B. That is, the ratio of P _A and P _B is proportional to the image forming position of the optical spot image.

FIG. 2 is a side view showing another embodiment of the present invention.
Reference numeral 4 denotes a light reflector (mirror) which surrounds the position detector 12 except for the input / output section of the optical signal (in the illustrated example, the upper surface is the input section and both end surfaces are the output section). With this configuration, the light C emitted from the periphery of the position detector 12 is reflected by the light reflector 14 and returns to the position detector 12 side again as indicated by the dotted line, and the incident light is effectively and efficiently used. It

FIG. 3 is a block diagram of a non-contact type distance measuring device configured by applying the position detector of the present invention.
Reference numerals 5 and 9 to 11 are the same as those of the above conventional device. 15
Is a coupling lens, and 16 is an optical coupling between the light source 1 disposed outside the detection head 11 and the light projecting lens 2 in the detection head 16 via the coupling lens 15, so that one end side is The projection optical fibers 17, 18 having the other end serving as the light receiving end 16a as the light emitting end 16b are provided at both end faces of the position detector 12 provided in the detection head 11 and outside the detection head 16. It is a light receiving optical fiber that optically couples with the photo detectors 19 and 20.

The distance measuring device having the above configuration operates as follows.
The luminous flux emitted from the light source 1 is transmitted to the light projecting lens 2 via the coupling lens 15 and the optical fiber 16 as described above, and is irradiated onto the target object 3 as the light spot 4. On the other hand, the light receiving lens 5 images the light spot 4 and forms an image on the light receiving surface of the position detector 12.

When there is incident light, the position detector 12 scatters the incident light due to the scattering substance mixed inside, and emits an optical signal from both end surfaces as described above.

This emitted light is transmitted by the optical fibers 17 and 18 to the photodetector 1.
It is transmitted to the optical detectors 9 and 20 and converted by the photodetectors 19 and 20 into electric signals i _A and i _B proportional to the intensities P _A and P _B of the output light. Then, as in the case of FIG. 2, the electric signal i
Based on _A and i _B , the arithmetic circuit 21 including the adder, the subtractor, and the divider in FIG. 4 performs arithmetic processing to obtain a distance output 1 related to the distance to be measured.

〔The invention's effect〕

As described above, according to the present invention, the incident light is scattered by the scattering substance mixed inside, and emits a plurality of optical signals proportional to the imaging position of the incident light signal. Since the emitted light signal can be transmitted to a processing unit that is distant by an optical fiber and the light is all-light type that uses only light, an explosion-proof structure is not required and the configuration is simple. Further, since the position detector of the present invention surrounds the portions other than the input / output portion of the optical signal with the light reflector, there is an effect that the incident optical signal is not wastefully consumed and the efficiency is high.

[Brief description of drawings]

FIG. 1 is a front view of a position detector showing an embodiment of the present invention, FIG. 2 is a side view showing another embodiment, and FIG. 3 is a block diagram of a distance measuring device to which the position detector is applied. FIG. 4 is a block diagram of a distance measuring device using a light receiving element. 12 is a position detector, 12a is a glass material, and 12b is a scattering absorber. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] 1. A light-scattering / absorbing substance is mixed in a glass material to form a predetermined shape so as to emit a plurality of light signals in proportion to the image formation position of an incident light signal. And position detector. 2. A light-scattering substance is mixed into a glass material so as to emit a plurality of light signals proportional to the image forming position of an incident light signal, and the light-absorbing substance is formed into a predetermined shape. A position detector characterized in that a portion other than the input / output portion of is surrounded by a light reflector.