JPH0541365Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an optical position sensor.

BACKGROUND ART A vehicle height adjustment mechanism consisting of a hydraulic ram is provided between a wheel support member and a vehicle body member above the wheel support member, and a movable contact that slides up and down in conjunction with the vertical movement of the wheel support member and an upper and lower contact point fixed to the vehicle body member are provided. An automobile vehicle height adjustment device has already been developed that maintains a constant vehicle height by supplying and discharging oil to and from the hydraulic ram in response to signals from a vehicle height detection switch consisting of two fixed contacts. Published (for example, Tokuko Sho 47)
-Refer to Publication No. 13327).

Furthermore, a so-called photocoupler in which a light emitting element and a light receiving element are opposed to each other is used, a shutter is provided between them, and the shutter is configured to move in conjunction with vertical displacement of the wheel support member relative to the vehicle body member, thereby transmitting and blocking light. An optical vehicle height sensor that detects the vertical displacement of a wheel support member relative to a vehicle body member, that is, the vehicle height, has already been developed.

Problems to be solved by the invention As mentioned above, the so-called contact-type vehicle height detection consists of a movable contact that slides up and down in conjunction with the up and down movement of the wheel support member, and two fixed contacts, upper and lower, fixed to the vehicle body member. Switches are susceptible to the effects of dirt and dust, and have durability problems.In addition, optical vehicle height sensors using photocouplers, which were devised to avoid such problems, are non-contact, so the above-mentioned Although this method does not have the durability problem of the contact type, it does have the problem that it can only detect specific positions corresponding to the number of photocouplers and cannot continuously measure the vehicle height.

Also, a shutter with a slit that moves the position of the incident light of a one-dimensional position detection element having a light-receiving surface of a predetermined length and capable of detecting the position of incident light incident on the light-receiving surface relative to the one-dimensional position detection element. In an optical position sensor that can continuously detect changes in position by changing the position using a light beam that passes through a slit, the amount of change in position that can be detected is greater than the length of the one-dimensional position detection element. Therefore, as the slit-equipped shutter moves relative to the light-receiving surface of the one-dimensional position detecting element, which is arranged to be substantially perpendicular to the direction of relative movement of the slit-equipped shutter, one end of the light-receiving surface A plurality of slits are provided obliquely with respect to the moving direction so as to be repeatedly positioned opposite to each other from one end to the other end, and which of the plurality of slits is located opposite to the light-receiving surface of the one-dimensional position detection element is determined in the vicinity of the slit. In the case where detection is performed by transmitting or blocking the light beam from the light emitting element of the photo interrupter using a band detecting slit provided in the shutter with a slit, the one-dimensional position is determined by the leakage light from the light emitting element of the photo interrupter. There is a problem in that an error occurs in the position detected by the detection element.

The present invention aims to address such problems.

Means for Solving the Problems The present invention provides a one-dimensional position detection element having a light-receiving surface of a predetermined length and capable of detecting the position of incident light incident on the light-receiving surface, and a one-dimensional position detection element having a predetermined length of the one-dimensional position detection element. A light source capable of emitting substantially parallel light beams over the entire surface of the light receiving surface; a photo interrupter integrally formed with a light emitting element and a light receiving element facing each other;
A slit that is located between the light-receiving surface of the dimensional position detection element and transmits a portion of the light ray from the light source, and a slit that is located between the light-emitting element and the light-receiving element of the photointerrupter and transmits the light ray from the light-emitting element. A shutter with a hole provided therein, and an optical position sensor that is a combination of the light source, a one-dimensional position detecting element, and a photo interrupter, and an optical position sensor that is attached to two members that move the shutter relative to each other, the one-dimensional position detecting element The invention is characterized in that a means is provided for eliminating the overlap between the light receiving wavelength sensitivity band of the photointerrupter and the light emission wavelength band of the light emitting element of the photointerrupter.

Effect: As described above, it is possible to eliminate the influence of leakage light from other light sources such as the light emitting element of the photointerrupter, thereby reducing the position detection error of the one-dimensional position detection element.

Example Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 and 2A and 2B show a basic configuration example of an optical position sensor used in the present invention, in which 1 is a light-emitting element 1a such as a light-emitting diode element LED, and a light-emitting element 1a is connected to the light-emitting element 1a. Collimator lens 1b that converts emitted diverging light into parallel light
2 is a rectangular shutter with a slit; 3 is a one-dimensional position detection element that detects the incident position of light using a silicon photodiode; The configuration is such that the parallel light beam 1 that has passed through is incident on the one-dimensional position detection element 3.

The one-dimensional position detecting element 3 is configured such that the photocurrent generated by the incident light is divided in inverse proportion to the distance between the incident light position and the electrodes provided at both ends of the one-dimensional position detecting element 3. Therefore, the photocurrent extracted from each electrode using the arithmetic circuit 4
The above incident light position can be determined by taking the sum and difference of I ₁ and I ₂ and their ratio.

As a result of the above, the shutter 2 with a slit moves from the position shown in FIG. 2A to the position shown in FIG. When the position is reached, the photocurrent _{I 1} is extracted from both electrodes due to the movement of the position of the incident light on the one-dimensional position detection element 3.
Although the magnitude relationship of I ₂ and I ₂ is reversed, the amount of movement of the position of the incident light, _that is, the amount of movement of the position of the incident light, that is, the amount of movement of the light source 1 and the one-dimensional position detection element 3
The amount of movement of the slit shutter 2 relative to the position can be continuously determined.

In the optical position sensor as described above, the amount of change in position that can be detected cannot exceed the length of the light receiving surface of the one-dimensional position detection element 2, but in order to increase this, As shown in FIG.
and a shutter 5, which is located between the light source 1 consisting of a lens 1b and the one-dimensional position detection element 3, and has a slit that transmits a part of the light beam from the light source 1.
With respect to the light-receiving surface of the one-dimensional position detection element 3, which is arranged to be substantially orthogonal to the direction of relative movement of the shutter 5, the slit is inserted from one end of the light-receiving surface to the other as the shutter 5 moves relative to the light-receiving surface. A plurality of slits 5a, 5b are arranged diagonally with respect to the moving direction so as to repeatedly face each other toward the end.
(For example, a dogleg shape) is considered.

In this case, the plurality of slits 5a, 5b
A band detection mechanism is required to indicate which part of the shutter 5 is located opposite to the light receiving surface of the one-dimensional position detection element 3. A photo interrupter 6 includes a light emitting element 6a and a light receiving element 6b, and one of the plurality of slits 5a and 5b provided in the shutter 5, such as the slit 5b, faces the light receiving surface of the one-dimensional position detecting element 3. In a device using a so-called optical detection mechanism composed of a linear band detection slit 5c that transmits the light beam from the light emitting element 6a of the photointerrupter 6 only when the photointerrupter 6 is located,
Due to constraints imposed by the size of the shutter 5, the distance between the one-dimensional position detection element 3 and the photo interrupter 6 cannot be made too large, so when the shutter 5 is in the position shown in FIG. 3A, the distance shown in FIG. As shown, the light beam from the light emitting element 6a of the photo interrupter 6 enters the light receiving surface of the one-dimensional position detecting element 3, causing an error in position detection based on the position of the incident light from the light source 1 to the one-dimensional position detecting element 3. There is.

Therefore, in the present invention, for example, as shown in FIG. An optical filter 7 is provided to remove the overlapping portion, and the leakage light from the light emitting element 6a of the photointerrupter 6 passes through the slit 5b or the band detection slit 5c and enters the light receiving surface of the one-dimensional position detection element 3.
This is to prevent deterioration of the position detection accuracy of the dimensional position detection element 3.

GaAs infrared light emitting diodes and GaAlAs which are generally based on the light emitting diode 1a of the light source 1 and the light emitting element 6a of the photointerrupter 6, etc.
The peak emission wavelength of each light emitting diode is λ ₁ =
940nm and λ ₂ =660nm, which are quite far apart, and the half-width of the spectrum is narrow at about 50nm, so they do not overlap on the emission spectrum diagram shown in Figure 4A, whereas the one-dimensional position detection element 3 and The spectral sensitivity characteristics of the Si-type light receiving element, which is generally used as the light receiving element 6b of the photo interrupter 6, are as follows.
As shown in Figure B, the spectral sensitivity is wide ranging from the infrared region to the visible region to the ultraviolet region, so the one-dimensional position detection element 3 that continuously detects the position of the incident light has a spectral sensitivity as shown as 3 in Figure 4 B. If the light source has a peak emission wavelength λ ₂ in FIG. 4A, that is, the light emitting element 6a of the photo interrupter
If there is light leakage from the light emitting diode element 1a, the leakage light will cause the one-dimensional position detection element 3 to output a photocurrent. It will occur.

FIG. 4C shows an optical system attached to the light receiving surface of the one-dimensional position detecting element 3 in order to eliminate the overlap between the light receiving wavelength band of the one-dimensional position detecting element 3 and the light receiving wavelength band of the light emitting element 6a of the photointerrupter 6. The combination of the filter 7 and the one-dimensional position detection element 3 also exhibits spectral sensitivity characteristics, and according to the spectral sensitivity characteristics, the spectral half-width is added to the peak emission wavelength λ ₂ of the light emitting element 6a of the photo interrupter 6. Since no output is generated within the wavelength range, even if there is light leakage from the light emitting element 6a of the photo interrupter 6, it is possible to eliminate the influence of the leakage light on the position detection accuracy of the one-dimensional position detection element 3. can.

If the spectral sensitivity characteristic of the light receiving element 6b of the photointerrupter 6 is wider than the spectral sensitivity characteristic of the one-dimensional position detection element 3 and includes the peak emission wavelength λ ₁ of the light emitting diode element 1a of the light source 1,
Contrary to the above, it is also possible that the photo interrupter 6 malfunctions due to light leaking from the light emitting diode element 1a, but the photo interrupter 6 is ON-
Since it is an OFF operation type, countermeasures can be taken by setting an electrical threshold value, and an optical filter like the one in the present invention is generally unnecessary.

In the above embodiment, an example is shown in which an optical filter is provided on the surface of the one-dimensional position detecting element as a means to eliminate the overlap between the light receiving wavelength sensitivity band of the one-dimensional position detecting element and the emission wavelength band of the light emitting element of the photointerrupter. However, it goes without saying that the same effect can be obtained by using a light receiving element having a spectral sensitivity characteristic that does not detect the emission wavelength band of the light emitting element of the photointerrupter as a one-dimensional position detecting element without using an optical filter.

Further, in the above embodiment, the case where the relative movement between the combination of the light source 1 and the one-dimensional position detection element 3 and the shutter 5 is a linear movement is described, but it is of course applicable to the case where the relative movement is a rotational movement. In addition, the transmission hole and the slit provided in the shutter are located at a predetermined point (for example, in the center) of the light receiving surface of the one-dimensional position detection element 3.
When the light emitting element 6a of the photointerrupter 6 is located opposite to the light source 1 and
Needless to say, the present invention can also be applied to a reference hole for relative positioning between a combination of dimensional position detection elements 3 and shutter 5.

Effects of the Invention As described above, according to the present invention, a shutter having a plurality of slits or transmission holes, and a plurality of combinations of light emitting elements and light receiving elements located opposite to each other across the slits or transmission holes of the shutter, In a multi-channel optical position sensor, a light-receiving element belonging to a certain channel is provided with means for eliminating an overlap between the light-receiving wavelength sensitivity band of the light-emitting element and the emission wavelength band of the light-receiving element belonging to other channels. By doing so, it is possible to prevent malfunctions caused by leakage light that passes through the slit or transmission hole from the light-emitting elements of other channels and enters the light-receiving element. Coupled with the layout advantage of being able to arrange them close together, this can bring about great practical effects.

[Brief explanation of the drawing]

The attached figures show examples of the present invention. Figures 1 and 2 (a) and (b) are diagrams showing an example of the basic configuration of the optical position sensor used in the present invention, and Figures (3) and (b) are illustrations of the shutter and A plan view and a side view showing the relative positional relationship between the one-dimensional position detecting element and the photointerrupter, and Figure 4 A, B, and C respectively show an emission spectrum diagram, a spectral sensitivity characteristic diagram, and the relationship between the optical filter and the one-dimensional position detecting element. It is a spectral sensitivity characteristic diagram of a combination of. 1...Light source, 2...Shutter with slit, 3
...One-dimensional position detection element, 4... Arithmetic circuit, 5...
...Shutter, 5a, 5b...Slit, 5c...
Band detection slit, 6...photo interrupter, 7...optical filter.

Claims (1)

[Claims for Utility Model Registration] (1) A one-dimensional position detection element having a light-receiving surface of a predetermined length and capable of detecting the position of incident light incident on the light-receiving surface, and a predetermined length of the one-dimensional position detection element. a light source capable of emitting substantially parallel light beams over the entire surface of the light-receiving surface; a photo interrupter integrally formed with a light-emitting element and a light-receiving element facing each other; and a photo-interrupter located between the light source and the light-receiving surface of the one-dimensional position detection element. a shutter that is located between the light emitting element and the light receiving element of the photointerrupter and has a transmission hole that allows the light ray from the light emitting element to pass through; In an optical position sensor that is a combination of a one-dimensional position detecting element and a photointerrupter, and an optical position sensor that is attached to two members that move the shutter relative to each other, the light receiving wavelength sensitivity band of the one-dimensional position detecting element and that of the light emitting element of the photo interrupter are An optical position sensor characterized by having a means for eliminating an overlapping portion with a light emission wavelength band. (2) The means for eliminating the overlap between the light reception wavelength sensitivity band of the one-dimensional position detection element and the emission wavelength band of the light emitting element of the photointerrupter is a utility model in which an optical filter is provided on the surface of the one-dimensional position detection element. An optical position sensor according to claim 1. (3) The means to eliminate the overlap between the light reception wavelength sensitivity band of the one-dimensional position detection element and the light emission wavelength band of the light emitting element of the photointerrupter is to detect light with spectral sensitivity characteristics that do not detect the light emission wavelength band of the light emitting element of the photointerrupter. The optical position sensor according to claim 1, which is a one-dimensional position detection element composed of elements. (4) The slit provided in the shutter is placed on the light-receiving surface of the one-dimensional position detection element, which is arranged almost orthogonally to the direction of relative movement of the shutter.
The light-receiving surface has a plurality of bands arranged obliquely to the direction of movement so as to repeatedly face each other from one end to the other end of the light-receiving surface as the shutter moves relative to each other. , detecting in which band the light-receiving surface of the one-dimensional position detecting element is located facing each other among a plurality of bands of a slit provided in the shutter by transmitting or blocking the light beam from the light-emitting element of the photo interrupter. The optical position sensor according to any one of claims 1 to 3, which is a band detection slit. (5) The transmission hole is a reference hole that allows the light from the light emitting element of the photo interrupter to pass through when the slit provided in the shutter is positioned opposite to a predetermined point on the light receiving surface of the one-dimensional position detection element.Registered as a utility model. An optical position sensor according to any one of claims 1 to 3.