JPH08265130A - Reflection type photoelectric switch provided with retro-reflecting plate - Google Patents

Abstract

PURPOSE: To extend a distance between a main body section and a retro-reflecting plate by discriminating the presence of a sensed object on the basis of a degree of change in a ratio of a luminous quantity of a reflected light relating to a polarized emitted light to a luminous quantity of a reflected light relating to an emitted light not subjected to polarization. CONSTITUTION: A polarized emitted light 21b and an emitted light 211a not subjected to polarization are emitted as a light beam, a reflected light 222a of the light 211a and a reflected light 222b of the light 211b are made incident onto a light receiving section 5. Presence of a sensing object reflecting a light irregularly such as a coarse face existing between a main body section 2 and a retro-reflecting plate 91 is compared with absence thereof. The luminous quantity of the reflected light 221b is reduced double because of irregular reflection and difference from the polarization plane. Moreover, the luminous quantity of the reflected light 222a receives only the reduction in the luminous quantity due to irregular reflection. Thus, the signal effected by the luminous quantity of the light 221b is much reduced than the signal independently of the luminous quantity and a detection output signal denoting the presence of the sensing object is outputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is arranged such that a light projecting portion and a light receiving portion are arranged side by side, and light emitted from the light projecting portion is reflected by a retroreflective plate and returned to the light receiving portion. It is related to a reflection type photoelectric switch equipped with a regressive reflection plate that detects the presence or absence of a detection object based on the amount of light received at, and has been improved so that the interval between the light projecting / receiving unit and the regressive reflection plate can be expanded. Concerning the composition of that.

[0002]

2. Description of the Related Art In devices and systems in a wide range of fields such as a rotation speed measuring device, a relay circuit device, a moving direction detecting device, a tape reader, a sequence control device, etc., the presence or absence of a detected object, the position of the detected object, etc. can be detected without contact. A reflection type photoelectric switch equipped with a retroreflector is used as a device for detection. An example of a conventional reflective photoelectric switch provided with such a retroreflective plate will be described with reference to FIGS. Here, FIG. 9 is a configuration explanatory view showing a configuration of a main part of a reflection type photoelectric switch including a regression reflection plate of a conventional example together with a detection object. 10 is a block circuit diagram showing a main part of the control circuit unit shown in FIG. 9 together with a light emitting body and a photoelectric conversion element, and FIG. 11 is provided with the regressive reflection plate shown in FIGS. 9 and 10. FIG. 7 is a waveform chart of a main part for explaining the operation of the reflective photoelectric switch.

In FIGS. 9 and 10, 9 is a main body portion 7.
And a control circuit unit 8 and a retroreflective plate 91. The retroreflective plate 91 is arranged with a space from the main body 7, and is basically based on a prism or mirror having a special shape called a corner cube reflector, and a plurality of small corner cube reflectors are formed in a planar shape. It is also known to be arranged in.
Examples of common uses of a retroreflective plate consisting of a plurality of small corner cube reflectors arranged in a plane are colored reflectors as a safety device for road guardrails, etc., and as a safety device mounted on the rear part of an automobile. There is a colored reflector. The retroreflective plate including the retroreflective plate 91 has a property of reflecting the light incident on the retroreflective plate in a direction opposite to the incident direction (such reflection is called regressive reflection). In addition, with respect to polarized light, it has the property of converting into polarized light having a polarization plane that is orthogonal to the polarization plane of the incident polarized light and performing return reflection. ing.

The main body portion 7 includes a light projecting portion 71 and a light receiving portion 72 arranged adjacent to each other, and the light projecting portion 71 to the light receiving portion 72.
A light-blocking wall 73 for preventing light from directly entering the light source (this light-blocking wall 73 is not shown for the main body portion 7 or for housing the control circuit portion 8 in addition to the light projecting portion 71 and the light receiving portion 72). In some cases, it also serves as part of the case.). The light projecting unit 71 converts a light emitting diode 711, which is a light emitting body and a semiconductor light emitting element, and emitted light (in most cases, infrared light or red light) 711a emitted from the light emitting diode 711 into parallel light rays. The optical system 712 is installed when necessary for conversion, and the emitted light 711a is converted into substantially parallel light from the optical system 712.
It is emitted as a.

Emitted light 71a emitted from the light projecting section 71
When there is no obstacle such as a detection object between the main body portion 7 and the retroreflective plate 91, the retroreflective plate 91 enters from the light receiving surface 91a of the retroreflective plate 91, and Due to the nature of 91, the reflected light 72 from the light receiving surface 91a
It becomes a and is reflected back. The light receiving unit 72 includes a photoelectric conversion element 722 and an optical system 721 that collects the reflected light 72a on the photoelectric conversion element 722, and thus the reflected light that is substantially parallel light reflected from the regressive reflection plate 91. 72a
Is reliably incident on the photoelectric conversion element 722. Optical system 7
The photoelectric conversion element 722 that receives the reflected light 72 a that has entered the photoelectric conversion element 722 enters the photoelectric conversion element 722.
The electric signal S ₇₂₂ having a value corresponding to the light quantity of a is output.

The control circuit section 8 includes a light emission signal generation section 81,
The received light signal processing unit 82 is provided. Light emission signal generator 8
1 includes a pulse oscillation circuit unit 811 and a drive circuit unit 812.
The received light signal processing unit 82 has a signal amplification unit 82.
1, detection circuit section 822, integration circuit section 823 and comparator
And a lator 824. After that, in the first half of FIG.
Using the waveforms of each part shown, also use the reflective photoelectric switch.
The operation of the switch 9 will be described. Pulse oscillation circuit section 8
Reference numeral 11 is a signal S having a constant period which is a rectangular wave pulse signal. ₈₁₁To
Output. Signal S₈₁₁Is the current amplification in the drive circuit unit 812.
Is the emission signal S ₈₁₂Converted into a light emitting diode 71
1 is supplied. Therefore, the emitted light 711a is the signal S
₈₁₁It is a pulsed light with a constant period that is the same as that of
Therefore, the reflected light 72a is basically the signal S₈₁₁The circumference of
It becomes a pulsed light with the same fixed period as the period.

In the received light signal processing unit 82, the electric signal S ₇₂₂
Is amplified by the signal amplifier ₈₂₁ and first converted into the signal S ₈₂₁ . In order to remove noise components that may be included in the signal S _821, the signal S ₈₂₁ is the detector circuit 822
At, the effective component is taken out in synchronization with the signal S ₈₁₁ . From this effective component, the component exceeding the discrimination level (which is set corresponding to the predetermined light amount level of the reflected light 72a) A is output from the detection circuit unit 822 as a signal S ₈₂₂ having a rectangular wave pulse. Is output.
The signal S ₈₂₂ is converted into an analog amount in the integrating circuit portion 823 and then input to the comparator 824, and is at a high level (hereinafter, may be abbreviated as “H”) or low depending on the presence or absence of a detected object. A detection output signal S ₈ having a level (hereinafter sometimes abbreviated as “L”) is obtained. This detection output signal S ₈ is output from the output terminal 8a to the outside of the reflective photoelectric switch 9. In the case of the reflective photoelectric switch 9, the detection output signal S ₈ when the detection object does not exist is “L”.

Then, as shown by the dotted line in FIG.
The detection object 99 enters between the body part 7 and the retroreflective plate 91.
In this case, the emitted light 71a is blocked by the detection object 99.
It is reflected by the surface of the detection object 99. Detected object
The light reflected by the body 99 reflects the surface properties of the detection object 99.
In many cases, however, it will be diffusely reflected. this
Therefore, the reflected light reflected by the surface of the detection object 99 (see FIG.
It is indicated by a dotted arrow inside. ) 72a enters the light receiving section 72
The amount of light applied is reflected from the retroreflective plate 91 that is retroreflected.
Compared with the case of reflected reflected light 72a, the amount of light is reduced
Is done. That is, between the main body 7 and the retroreflective plate 91
When the detection object 99 enters, the photoelectric conversion element 72
The amount of light incident on 2 will be reduced. this thing
Between the main body 7 and the retroreflective plate 91.
If 99 is present, signal S ₈₂₁The level of detection
It is below the discrimination level A of the circuit section 822,
The signal S output from the detection circuit unit 822₈₂₂Square wave
The number of lus becomes zero. This signal S₈₂₂Integration circuit section 823
The comparator 824 input via the
Force signal S₈Is output.

[H] or [L] depending on whether or not the detection object 99 exists between the main body 7 and the retroreflective plate 91.
By using the above-mentioned detection output signal S ₈ output from the reflection type photoelectric switch 9,
It becomes possible to know the existence of. By the way, a reflection type photoelectric switch 9 equipped with a conventional retroreflective plate
Is a detection object 9 that performs specular reflection such as a specular surface.
When applied to 9, it is almost impossible to detect the presence or absence of the detection object 99. The reason is that, unlike the case where the amount of light input to the light receiving unit 72 by the reflected light specularly reflected from the surface of the detection object 99 is diffusely reflected by the detection object 99 described above, the light is returned by the regression reflection plate 91. Reflected light 72 obtained by being reflected
This is because the amount of light becomes substantially equal to that in the case of a. A reflective photoelectric switch 9A shown in FIG. 12 is known as a reflective photoelectric switch equipped with a return reflector of a different conventional example corresponding to such a case. Here, FIG. 12 is a configuration explanatory view showing a configuration of a main part of a reflection type photoelectric switch provided with a return reflection plate of a different conventional example together with a detection object. In FIG. 12, the same parts as those of the reflection type photoelectric switch provided with the return reflection plate according to the conventional example shown in FIG. 9 are designated by the same reference numerals, and the description thereof will be omitted. In addition, in FIG. 12, only the representative reference numerals are shown as the reference numerals given in FIG. 9.

In FIG. 12, 9A is a reflection type photoelectric switch in which a body portion 7A is used instead of the body portion 7 in the reflection type photoelectric switch 9 according to the conventional example shown in FIG. The main body portion 7A includes a light projecting portion 71A having a polarizer 719, which is, for example, a polarizing plate or a polarizing filter, and a polarizer 729, which is, for example, a polarizing plate or a polarizing filter, with respect to the main body portion 7 included in the reflective photoelectric switch 9. The light receiving portion 72A that is held is used. In the case of the reflection type photoelectric switch 9A, since a polarizing plate or a polarizing filter for visible light is generally used in many cases, the light emitting diode 711 included in the light projecting unit 71A should be one that emits visible light. It is generally used. The polarizer 719 is installed at a portion where the emitted light 711a has passed through the optical system 712,
The polarizer 729 is installed at a position before the incident light 72Aa enters the optical system 721. Then, the polarizer 719
Has a polarization characteristic of converting unpolarized light into polarized light having only a component that oscillates in a direction parallel to the paper surface in FIG. In addition, the polarizer 729 is the polarizer 71.
It has the same polarization characteristic as that of No. 9 and is arranged so that the polarization plane of the polarization characteristic is substantially orthogonal to the polarization plane of the polarizer 719. Therefore, the unpolarized light that has entered the polarizer 729 is converted into polarized light having only a component that oscillates in the direction perpendicular to the paper surface in FIG. That is, the polarizer 719 and the polarizer 729 are set so that the polarization planes of the polarized light passing through them are orthogonal to each other.

In the case of the reflection type photoelectric switch 9A, the emitted light 71Aa emitted from the light projecting portion 71A is polarized light having only a component vibrating in the direction parallel to the paper surface in FIG. 12 as described above. . When the detection object 99 does not exist, the outgoing light 71Aa is reflected by the recursive reflection plate 91.
The reflected light 72Aa is regressively reflected as reflected light 72Aa, but due to the above-described property of the reflex reflection plate, the reflected light 72Aa becomes polarized light having only a component that oscillates in the direction perpendicular to the paper surface in FIG. Reflected light 72Aa input to the light receiving unit 72A
Has its polarization plane matched with the polarization characteristic of the polarizer 729, and therefore passes through the polarizer 729 as it is and is incident on the photoelectric conversion element 722.

Then, as indicated by the dotted line in FIG. 12, the detection object 99 is provided between the main body portion 7A and the return reflection plate 91.
When the light enters, the emitted light 71Aa is blocked by the detection object 99 and reflected on the surface of the detection object 99. In this case, when the detection object 99 has a surface texture such as a mirror surface, the polarization plane of the reflected light (indicated by a dotted arrow in FIG. 12) 72Aa specularly reflected by the surface of the detection object 99 is , The polarization plane of the emitted light 71Aa does not change. For this reason, the reflected light 72 reflected by the detection object 99
In the case of Aa, it cannot pass through the polarizer 729, and therefore, in this case, the amount of light incident on the photoelectric conversion element 722 becomes almost zero. Further, in the case of the detection object 99 having a surface texture that performs diffuse reflection, the reflected light 72Aa diffusely reflected by the detection object 99 contains a small amount of a component that can pass through the polarizer 729, but its amount is small. Therefore, as in the case of the reflective photoelectric switch 9 described above,
The amount of light will be reduced. That is, in the case of the reflection type photoelectric switch 9A, it is possible to know the presence or absence of the detection object 99 regardless of the surface properties of the detection object 99.

[0013]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention In a reflection type photoelectric switch provided with a retroreflective plate according to the above-mentioned prior art,
By selecting a reflection type photoelectric switch having an appropriate configuration corresponding to the surface texture of the detection object 99, the detection output signal S ₈ is used to detect the detection object 99 between the regressive reflection plate and the main body. It is possible to know whether or not they are doing it. Then, in this reflection type photoelectric switch, the light receiving portion and the light emitting portion are arranged close to each other,
Compared to other types of photoelectric switches such as transmission type, it has the feature that it can be easily downsized.

However, these reflective photoelectric switches sense the presence or absence of the detection object 99 as a change in the amount of reflected light incident on the light receiving portion thereof.
It has the following problems. That is, when an attempt is made to obtain a reflection type photoelectric switch in which the distance between the main body and the return reflection plate is increased, the light amount of the reflected light reflected from the return reflection plate 91 and input to the light receiving unit is set to a required level. In order to maintain it, it is necessary to take measures such as increasing the amount of emitted light or increasing the amplification factor for amplifying the electric signal output from the photoelectric conversion element that receives the reflected light. But,
Taking the case of increasing the amount of emitted light as an example, as the amount of emitted light increases, the amount of reflected light from the detection object 99 also increases, which causes a problem. The operation of the reflection type photoelectric switch 9 of the conventional example in this case will be described below with reference to the waveform charts of the respective parts shown in the latter half of FIG. (In FIG. 11, it is shown that the light amount of the emitted light is increased at the end portion of the first half part. Note that this is the same also in FIGS. 3 and 6 described later.) The main body part 7 and the return reflection plate 91. When the detection object 99 enters in between, the amount of light input to the light receiving portion 72 by the reflected light 72a, which is the emitted light 71a reflected on the surface of the detection object 99, is equal to that of the main body 7 and the return reflection plate 91. When the detection object 99 is not present in between, the reflected light 72a reflected from the recursive reflection plate 91 reduces the amount of light input to the light receiving unit 72. However, since the amount of the emitted light 71a is increased, when the detection object 99 enters between the main body 7 and the return reflection plate 91, the detection light 99a is received by the reflection light 72a reflected on the surface of the detection object 99. The amount of light input to the unit 72 will be increased. For this reason, the level of the signal S ₈₂₁ does not fall below the discrimination level A of the detection circuit unit 822, and even when the detection object 99 enters between the main body unit 7 and the return reflection plate 91, Detection circuit unit 822
Continues to output the signal S ₈₂₂ from the output signal, and as a result, the detection output signal S ₈ continues to hold "L". Therefore, by increasing the light amount of the emitted light 71a, it is not possible to obtain a reflective photoelectric switch in which the distance between the main body and the return reflection plate is increased. Further, even if an attempt is made to obtain a reflection type photoelectric switch in which the distance between the main body section and the regressive reflection plate is increased by increasing the amplification degree of the signal amplification section 821 while keeping the light amount of the emitted light 71a unchanged, the result is the same. is there.

Further, the above is exactly the same also in the case of the reflection type photoelectric switch 9A of the conventional example, especially in the case of the detection object 99 having a surface texture that causes irregular reflection. The present invention has been made in view of the above-mentioned problems of the conventional art, and an object thereof is to provide a reflection type photoelectric switch having a retroreflective plate, which can widen a distance between the main body and the retroreflective plate. To provide.

[0016]

In the present invention, the above-mentioned objects are as follows: 1) a main body having a light projecting portion and a light receiving portion which are arranged in close proximity to each other, and a return reflection arranged with a space from the main body. The light emitted from the plate and the light projecting unit is incident on the light receiving unit, and an electric signal output from the light receiving unit corresponding to the amount of light incident on the light receiving unit is input to input the light amount A control circuit section for determining the level is provided, and whether or not a detection object is present between the main body section and the regressive reflection plate depends on the level of the amount of light emitted from the light projecting section and received by the light receiving section. In the reflection type photoelectric switch provided with a regressive reflection plate for detecting whether or not, the light projecting section of the main body section is a pair of light emitters each emitting light of different wavelengths,
The light receiving section of the main body section has a polarizer that selectively polarizes only the light emitted from one of the light emitters, and the light receiving section of the main body section converts the light from the photoelectric conversion element and the light projecting section of this photoelectric conversion element. It has a polarizer arranged on the light receiving side, and this polarizer has the same polarization characteristics as a polarizer that selectively polarizes only the light emitted from one of the light emitters of the light projecting unit. Have,
In addition, the polarization plane due to this is arranged so as to be substantially orthogonal to the polarization plane due to the above-mentioned polarizer, and the control circuit section is involved in the light emitted by each light emitter of the light projecting section and is incident on the light receiving section. Or 2) In the means described in the above item 1, the light projecting section of the main body section emits lights having different wavelengths. The light emitted from the pair of light-emitting bodies is emitted from the light projecting section through substantially the same optical path, or 3) the means according to 1 or 2 above. The light projecting unit has a structure in which light emitted from a pair of light emitters that emit light having different wavelengths from each other is emitted from the light projecting unit along substantially the same optical path. Beam combination The light beam synthesizing body has a body, and the light beam synthesizing body is configured to synthesize the light from each of the light emitting bodies, which are paired with the light projecting section of the main body section, into an integrated light beam, or ) In the means described in the item 1 or 2, the respective lights emitted from a pair of light emitters, which are included in the light projecting part of the main body part and emit light beams having different wavelengths, have substantially the same optical path. As a configuration for emitting light from the light projecting unit, the light emitting unit of the light projecting unit included in the main body unit is a chip-shaped semiconductor light emitting device, and is integrally housed in a semiconductor device package. Or 5) In the means described in any one of 1 to 4 above, one of the light-emitting body or the semiconductor light-emitting element that is polarized by the polarizer of the light projecting section of the main body is visible light. Luminous body that emits Or a semiconductor light emitting element, and the other light emitting body or semiconductor light emitting element which is not disposed on the light emitting side and is not polarized by the polarizer of the light projecting section of the main body section is a light emitting body that emits infrared rays. Or a semiconductor light emitting element, or 6) in the means described in any one of 1 to 5 above, each of the light projecting sections of the main body section emits light having a different wavelength. A pair of light emitters or semiconductor light emitting elements are made to emit light at mutually different light emission timings,
The control circuit section inputs an electric signal output from the photoelectric conversion element of the light receiving section of the main body section, amplifies the electric signal, and outputs light from each light emitter or semiconductor light emitting element of the light projecting section. And a discrimination circuit section for discriminating the electric signal related to the
And a discrimination circuit portion for discriminating the degree of change in the ratio of the respective light amounts incident on the light receiving portion, and the discrimination circuit portion receives an electric signal corresponding to the light emission timing of each of the light emitters, A configuration for discriminating an electric signal output from a photoelectric conversion element included in a light receiving unit into an electric signal related to light by each light emitting body or semiconductor light emitting element based on the electric signal, or 7) In the means described in any one of the items 1 to 5, the light receiving portion of the main body has two photoelectric conversion elements and one of the photoelectric conversion elements has a main body. An optical filter device for blocking the passage of light from one of the light-emitting body or the semiconductor light-emitting element, which has a light-projecting unit, which is polarized by a polarizer, and the control circuit unit includes the two photoelectric conversion units. Output from element The determination is made by inputting an amplification circuit section that individually amplifies the generated electric signal and an electric signal that is output from each amplification circuit section and determines the degree of change in the ratio of the respective light amounts incident on the light receiving section. Or a circuit section, or 8) in the means described in 6 or 7 above, a pair which is input to the determination circuit section of the control circuit section and which is included in the light projecting section of the main body section is provided. The electric signals respectively corresponding to the light emitted from the light-emitting body or the semiconductor light-emitting element have substantially the same signal level, or 9) in the means described in the above item 8, the control circuit The electric signals, which are respectively inputted to the discrimination circuit section of the main body section and respectively correspond to the light emitted from the light-emitting body or the semiconductor light-emitting element of the light-emitting section of the main body section, Alternatively, by adjusting the amount of light emitted from the semiconductor light emitting element, the configuration is such that the signal level is adjusted to substantially the same level, or 10) In the means described in the above item 8, the determination that the control circuit section has Discrimination circuit section or amplification circuit section which the control circuit section has is inputted to the circuit section, and electric signals respectively corresponding to the light emitted from the light emitting body or the semiconductor light emitting element which is paired with the light projecting section which the main body section has. It is achieved by adjusting the amplification degree of (1) to be adjusted to a substantially equivalent signal level.

[0017]

According to the present invention, in the reflection type photoelectric switch provided with the retroreflective plate, (1) the light projecting portion of the main body, for example, one emits visible light and the other emits infrared light. Such as a pair, each of which emits light having a different wavelength, and a polarizer which selectively polarizes only the light emitted from one of the light emitters, and the main body has The light-receiving unit has a photoelectric conversion element and a polarizer arranged on the side for receiving light from the light-projecting unit of this photoelectric conversion element, and this polarizer is provided from one light-emitting body of the light-projecting unit. It has the same polarization characteristics as a polarizer that selectively polarizes only the emitted light, and it is arranged so that the polarization plane due to it is almost orthogonal to the polarization plane by the polarizer. , The control circuit unit is configured to emit light from each of the light emitting units. When the detection object has a surface texture that causes irregular reflection, it is selected by the polarizer by determining the degree of change in the ratio of the respective amounts of light that are incident on the light receiving part, which is related to the light from the body. One of the outgoing lights that are polarized and emitted from the light projecting unit is similar to the outgoing light 71Aa of the reflection type photoelectric switch 9A of the conventional example described above, and the detected object for the case where the detected object does not exist. The ratio of the amount of light incident on the light projecting portion in the presence of is reduced, but the degree of the reduction is extremely large because it is necessary to change the polarization plane. On the other hand, with respect to the other emitted light that is emitted from the light projecting unit without being polarized by the polarizer, a detected object exists as in the emitted light 71a of the reflection type photoelectric switch 9 of the conventional example described above. The ratio of the amount of light incident on the light projecting part when there is a detected object is reduced compared to the case where the detected object is not present. Is smaller than that of one of the emitted lights which is selectively polarized and emitted from the light projecting unit. Since the control circuit section is concerned with the light emitted from each of the light emitters of the light projecting section and determines the degree of change in the ratio of the respective light quantities incident on the light receiving section, it is related to the light quantity of both outgoing lights. Without it, it becomes possible to detect the presence or absence of the detected object.

When the object to be detected has a surface texture that causes specular reflection, one of the emitted lights emitted from the light projecting portion after being selectively polarized by the polarizer is the same as that of the above-mentioned conventional example. Similar to the emitted light 71Aa of the reflection type photoelectric switch 9A, the amount of light incident on the light projecting portion when the detection object is present is almost zero, so that it is more than when the detection object has a surface texture that causes irregular reflection. More reliably,
It becomes possible to detect the presence or absence of the detection object. Further, (2) in the item (1), the light projecting unit included in the main body unit, for example, the light projecting unit includes a light beam combining unit, and the light beam combining unit includes a light projecting unit included in the main body unit. The light from each of the paired light emitters is combined into an integrated light beam, or the light emitters that the light projecting part of the main body has are chip-shaped semiconductor light emitting elements. ,
By being configured so as to be integrally housed in the semiconductor element package, each light emitted from a pair of light emitters that emit light having different wavelengths from the light projecting unit through almost the same optical path. With the configuration that the light is emitted, the light emitted from the light projecting unit and having different wavelengths is reflected by the regressive reflection plate and reflected by the detection object depending on the wavelength. It is possible to enter the light receiving portion without receiving a difference.
(3) In the items (1) and (2), the light projecting section of the main body section is a pair of light emitters or semiconductor light emitting elements that emit light having different wavelengths. The control circuit section receives the electric signal output from the photoelectric conversion element of the light receiving section of the main body section, amplifies the electric signal, and each of the light emitting elements of the light projecting section. Alternatively, a discrimination circuit unit that discriminates an electric signal relating to light by a semiconductor light emitting element, and a discrimination circuit unit that inputs the discriminated electric signal and discriminates the degree of change in the ratio of the respective light amounts incident on the light receiving unit. The discrimination circuit section receives an electric signal corresponding to the light emission timing of each of the light emitters, and based on this electric signal, an electric signal output from the photoelectric conversion element of the light receiving section. The light emitting elements or the semiconductor light emitting elements emit light having different wavelengths from each other. The electric signal output from the photoelectric conversion element included in the light receiving unit that includes the signal related to the light is discriminated into electric signals corresponding to lights having different wavelengths by the discrimination circuit unit. By using the discriminated electric signals corresponding to the lights having different wavelengths, it is possible to reliably discriminate the degree of change in the ratio of the respective light amounts incident on the light receiving unit by the discrimination circuit unit. Also,
(4) In the above items (1) and (2), the light receiving portion of the main body is provided in two photoelectric conversion elements, and one of the photoelectric conversion elements is provided in the main body. The light projecting unit has an optical filter device for blocking the passage of light from one of the light emitters or the semiconductor light emitting device which is polarized by the polarizer, and the control circuit unit includes the two photoelectric conversion devices. The amplification circuit section that individually amplifies the electrical signal output from each unit and the electrical signal output from each amplification circuit section are input, and the degree of change in the ratio of the respective light amounts incident on the light receiving unit is determined. And a determination circuit section for controlling the light-emitting section, at least one of the electric signals output from the two photoelectric conversion elements of the light-receiving section emits light having wavelengths different from each other. Emitting from semiconductor light emitting element Of the light, so that no information about the amount of at least one light. As described above, by using the electric signals having the information regarding the light amounts of the different lights, it is possible to reliably determine the degree of change in the ratio of the respective light amounts incident on the light receiving unit by the determination circuit unit. Furthermore, (5) above (3)
In the items (4) and (4), electric signals respectively inputted to the discrimination circuit section of the control circuit section and corresponding to the light emitted from the light emitting body or the semiconductor light emitting element, which is paired with the light projecting section of the main body section, respectively. Is almost the same signal level, for example, by adjusting the amount of light emitted from the light emitter or the semiconductor light emitting element, or by adjusting the amplification degree of the discrimination circuit section or the amplification circuit section of the control circuit section. By having a configuration including, in the state where the detection object does not exist between the main body portion and the return reflection plate of the electrical signal corresponding to the light emitted from both the light-emitting body or the semiconductor light-emitting element, respectively. The signal level difference is almost zero. As a result, when there is a detection object between the main body and the retroreflective plate, the degree of change in the ratio of the respective amounts of light that are involved in the light emitted by the light emitters of the light projecting unit and are incident on the light receiving unit. Can be reliably determined.

[0019]

Embodiments of the present invention will be described in detail below with reference to the drawings. Embodiment 1; FIG. 4 is a constitutional explanatory view showing a constitution of a main part of a reflection type photoelectric switch provided with a regressive reflection plate according to an embodiment of the present invention corresponding to claims 1 to 3, 5 and 7 to 10. Is. FIG. 5 is a block circuit diagram showing a main part of the control circuit unit shown in FIG. 4 together with a light emitter and a photoelectric conversion element, and FIG. 6 is provided with the regressive reflection plate shown in FIGS. FIG. 7 is a waveform chart of a main part for explaining the operation of the reflective photoelectric switch. 4 to 6, the same parts as those of the reflection type photoelectric switch having the regression reflection plate according to the conventional example shown in FIGS. 9, 10 and 12 are designated by the same reference numerals, and the description thereof will be omitted.
Note that, in FIGS. 4 and 5, as for the reference numerals given in FIGS. 9, 10, and 12, only representative reference numerals are shown.

In FIGS. 4 and 5, reference numeral 1A denotes a reflection type photoelectric switch 9A provided with a return reflection plate according to the conventional example shown in FIG. 12, instead of the main body portion 7A and the control circuit portion 8.
The photoelectric conversion switch is a reflection type photoelectric switch provided with a return reflection plate adapted to use the main body portion 2A and the control circuit portion 3, respectively. The main body portion 2A uses a light emitting portion 21 and a light receiving portion 22 in place of the light emitting portion 71A and the light receiving portion 72A with respect to the main body portion 7A included in the conventional reflective photoelectric switch 9A.

The light projecting section 21 is a light receiving section 71A according to the conventional example.
On the other hand, in addition to having the light emitting diodes 211 and 212 which are light emitters and semiconductor light emitting elements and the known light beam combiner 213 which is a light beam combiner, the polarizer 719 of the light projecting unit 71A of the conventional example has Instead, it has a polarizer 214. The light emitting diode 211 is a light emitting diode that emits, as the emitted light 211a, red light that is the visible light having the highest energy at present among the light emitting diodes that emit visible light. The light emitting diode 212 is a light emitting diode that emits infrared light as the emitted light 212a. That is, the emitted light 21 from the light emitting diode 211
The wavelengths of the light 1a and the light 212a emitted from the light emitting diode 212 are different from each other. Although various types of light beam combiners are known, the light beam combiner 213 in this case joins two right-angle prisms to each other at their slopes, and a half mirror is formed on this join surface. It is what Then, the emitted light 2 that is incident on the light beam combiner 213 at a right angle to each other.
11a and the emitted light 212a are emitted from the light beam combiner 213 as an integrated light beam. (In FIG. 4, in order to facilitate understanding, it is divided and shown for convenience.) The polarizer 214 is, for example, a polarizing plate or a polarizing filter, and only the emitted light 211a that is red light is printed on the paper surface in FIG. It is a polarizer that converts polarized light having only a component that oscillates in a direction parallel to, and allows it to pass, and does not convert emitted light 212a that is infrared light into polarized light. From the polarizer 214 of the light projecting unit 21, the outgoing light 211a and the outgoing light 212a, which are the polarized light of the outgoing light 211a by the polarizer 214, are emitted as an integrated light beam. Since the emitted light 211b and the emitted light 212a are parallel lights of an integrated light beam,
When no detection object is present between the main body 2A and the return reflection plate 91, the reflection light 221b with respect to the emission light 211b and the reflection light 222a with respect to the emission light 212a that are both return-reflected from the return reflection plate 91. Are incident on the light receiving portion 22 as parallel light of an integrated light beam. Then, the reflected light 221b is polarized light having only a component that oscillates in the direction perpendicular to the paper surface in FIG. 4 due to the above-described property of the return reflection plate.

The light receiving portion 22 is a light receiving portion 72A according to the conventional example.
On the other hand, in addition to having photoelectric conversion elements 221, 222, a light beam splitter 223, and an optical filter 224 installed as necessary, a polarizer 225 is used instead of the polarizer 729 of the light receiving section 72A of the conventional example. have. Various types of light beam splitters are known,
The light beam splitter 223 in this case is one in which two right-angle prisms are joined to each other at their slopes, and a half mirror is formed on this joined surface. Then, the light beam incident on the light beam splitter 223 is split into two optical paths that are orthogonal to each other and emitted. The optical filter 224 is a known optical filter that cuts visible light (and thus allows infrared light to pass). The polarizer 225 is, for example, a polarizing plate or a polarizing filter, has the same polarization characteristics as the polarizer 214,
Moreover, the plane of polarization by this is arranged so as to be substantially orthogonal to the plane of polarization by the polarizer 214. The reflected light 221b and the reflected light 222a, which have been retroreflected from the retroreflective plate 91 and have been incident on the light receiving unit 22, first have a polarizer 225.
However, due to the polarization characteristics of the polarizer 225 and the polarization plane of the reflected light 221b, the reflected light 221b and the reflected light 222a pass through as they are. The reflected light 221b and the reflected light 222 that have passed through the polarizer 225 in the state of this integrated light beam
The light beam a is split into two light paths by the light beam splitter 223 so as to have a mutually perpendicular relationship.

Of these, the reflected light 221b, 2 of one optical path
22a is incident on the photoelectric conversion element 221 as it is.
The photoelectric conversion element 221 that receives the reflected lights 221b and 222a is reflected by the reflected light 22 that is incident on the photoelectric conversion element 221.
An electric signal S ₂₂₁ having a value corresponding to the sum of the light amounts of 1b and the reflected light 222a is output. In addition, the reflected light 2 of the other optical path
21 b and 222 a, the component of the reflected light 221 b is removed by the optical filter 224, and only the reflected light 222 a is incident on the photoelectric conversion element 222. The photoelectric conversion element 222 that receives the reflected light 222a outputs an electric signal _S222 having a value corresponding to the amount of the reflected light 222a that is incident on the photoelectric conversion element 222.

Although not shown in FIG. 4, a detection object (reference numeral 99 in FIG. 9 for explaining the reflection type photoelectric switch 9 of the conventional example) is provided between the main body 2A and the return reflection plate 91.
Indicated by. ) Is present, the output light 2
11b and the emitted light 212a are shielded by the detection object and reflected on the surface of the detection object. In this case, when the detection object has a surface texture that causes diffused reflection such as a rough surface, the emitted light 211b that is polarized red light is diffusedly reflected on the surface of the detection object to the reflected light 221b. There are few components that can pass through the child 225. Further, the outgoing light 212a, which is unpolarized infrared light, is diffusely reflected on the surface of the detection object and becomes reflected light 222a. Therefore, in this case, the light amount of the reflected light 221b that has passed through the polarizer 225 is diffusely reflected as compared with the case where the detection object does not exist between the main body 2A and the return reflection plate 91. This results in a double decrease in the amount of reflected light and the decrease in the component that can pass through the polarizer 225 due to the non-regressive reflection. Further, in this case, the light amount of the reflected light 222a that has passed through the polarizer 225 is equal to the above-mentioned main body 2A.
As compared with the case where no detection object is present between the return reflection plate 91 and the return reflection plate 91, the amount of reflected light is reduced due to diffused reflection.

When the detection object has a surface texture such as a specular surface that specularly reflects, the emitted light 212a which is unpolarized infrared light is specularly reflected by the surface of the detection object, so that the main body described above is used. Reflected light 222 having a light amount value equivalent to that when there is no detection object between the portion 2A and the retroreflective plate 91.
a. In addition, the emitted light 2 which is the polarized red light
11b is a reflected light 221 that is specularly reflected on the surface of the detection object.
b is incident on the light receiving unit 22 without being further polarized. The reflected light 221b cannot pass through the polarizer 225, and therefore, in this case, the amount of the reflected light 221b passing through the polarizer 225 becomes almost zero.

The control circuit section 3 includes a light emission signal generation section 31 and
The received light signal processing unit 32 is provided. Light emission signal generation unit 3
1 is a pulse oscillation circuit unit 811 and a drive circuit unit 311.
The light reception signal processing unit 32 includes a signal amplification unit 321, 321 and a detection circuit unit 323, 324.
It has an attenuator 325 installed as necessary, a differential amplifier 326 as a discrimination circuit unit, and a comparator 327. Hereinafter, the operation of the reflective photoelectric switch 1A will be described using the waveforms of the respective parts shown in the first half of FIG. The signal S ₈₁₁ is supplied to the drive circuit portion 311 and
The light emission signals S ₃₁₁ and S 3
_It is converted into ₃₁₂ and applied to the light emitting diodes 211 and 212, respectively. Therefore, the emitted lights 211a and 211b and the emitted light 212a are pulsed lights having the same fixed cycle as the cycle of the signal S ₈₁₁ , and the reflected lights 221b and 222a.
Also, basically, the pulsed light has a constant cycle that is the same as the cycle of the signal S ₈₁₁ .

In the received light signal processing unit 32, the electric signals S ₂₂₁ and S ₂₂₂ are amplified by the signal amplification units 321 and _{322, and} are first converted into the signals S ₃₂₁ and S ₃₂₂ . Signal S
_321, S ₃₂ in order to remove possible noise components contained in the _2, the signal S _321, S ₃₂₂ is the detector circuit 323,
At 324, the active components are extracted as signals S ₃₂₃ and S ₃₂₄ synchronously with signal S ₈₁₁ . Here, the signal S ₃₂₃ is a signal having a value corresponding to the sum of the light amounts of the reflected light 221 b and the reflected light 222 a, which is incident on the photoelectric conversion element 221, and the signal S ₃₂₄ is incident on the photoelectric conversion element 222. It is a signal having a value corresponding to only the light quantity of the reflected light 222a. In the reflective photoelectric switch 1A, the main body 2
When there is no detected object between A and the retroreflective plate 91, the light amount of the reflected light 221b and the light amount of the reflected light 222a are set to the same value, and in this case, the signal amplification unit. If the amplification degrees of the signal amplification unit 321 and the signal amplification unit 322 are the same, the signal S ₃₂₃ has a value almost twice that of the signal S ₃₂₄ .

For this reason, in the received light signal processing section 32,
Attenuator 325 is installed and signal S ₃₂₃Level of 1 /
Signal S converted to 2₃₂₅From the attenuator 325
I try to do my best. Thus, the signal S₃₂₅And signal S
₃₂₄And means that they are set to almost the same signal level.
It Signal S with such a value₃₂₅And signal S₃₂₄Is differential
The signal is input to the amplifier 326, and the differential amplifier 326 receives the signal S.
₃₂₄From signal S₃₂₅Calculate the analog amount
Signal S which is₃₂₆Output as. This signal S ₃₂₆Is
It is input to the comparator 327. Comparator 327
Compares with the reference voltage value which has the value of the input signal
If the input signal value is higher than the reference voltage value, “H” is
It is a known circuit device that outputs "L" when it is low. Anti
In the flash type photoelectric switch 1A, the main body 2A and the return reflector 9
If there is no detected object between 1 and the signal S,
₃₂₆Since the value of is almost zero, this signal S₃₂₆Enter
The comparator 327 confirms that there is no detected object.
“L” detection output signal S that means₃Is output. This
Detection output signal S₃Is a reflection type photoelectric switch from the output terminal 3a.
It is output to the outside of switch 1A.

Further, when there is a detection object having a surface texture such as a rough surface, which is a rough surface, between the main body 2A and the return reflection plate 91 (FIG. 6 shows this case as an object). .), The reflected light 22 after passing through the polarizer 225 is different from that in the case where no detection object is present between the main body 2A and the return reflection plate 91.
The light amount of 1b is double-decreased due to the irregular reflection and the difference in polarization plane, and the light amount of the reflected light 222a is only reduced due to the irregular reflection. Therefore, the signal S ₃₂₅ affected by the light amount of the reflected light 221b
Is much smaller than the signal S ₃₂₄ that does not depend on the light amount of the reflected light 221b. As a result, the signal S _{32 6} will have a positive value, the comparator 327 detects the output signal S of "H", which means that the detected object is present
Outputs ₃ .

Further, when there is a detection object having a surface texture such as a specular surface that performs specular reflection between the main body 2A and the retroreflective plate 91, the main body 2A and the retroreflective plate 91.
In comparison with the case where there is no detection object between and, the amount of the reflected light 221b after passing through the polarizer 225 becomes almost zero due to the difference in polarization plane, as described above.
In addition, the light amount of the reflected light 222a is hardly reduced. Therefore, the signal S _{323, which} is affected by the light amount of the reflected light 221b, has almost the same value as the signal S ₃₂₄ . As a result, the signal S ₃₂₆ has a positive value that is half the value of the signal S _324.
Outputs a detection output signal S ₃ of “H” meaning that a detection object is present. That is, in the reflective photoelectric switch 1A, when the detection object is present between the main body 2A and the return reflection plate 91, the detection output signal S of "H" is output regardless of the surface texture of the detection object. _It outputs ₃ .

Next, regarding the reflection type photoelectric switch 1A,
In order to obtain a reflection type photoelectric switch in which the interval between the main body portion 2A and the return reflection plate 91 is long, the reflection type photoelectric switch in the case where the light amount of the emitted light 211b (and hence also the emitted light 211a) and the emitted light 212a is increased. The operation of the switch 1A is shown in FIG.
The following description will be made with reference to the waveform charts of the respective parts shown in the latter half of FIG.

In the case where a detection object is present between the main body 2A and the regressive reflection plate 91, and the detection object has a surface texture that causes irregular reflection, as described above, the emitted light 211b is first detected. The reflected light 221b reflected by the surface of No. 1 is not reflected by the diffused light and the amount of reflected light is reduced by diffuse reflection, as compared with the case where no detection object is present between the main body 2A and the return reflection plate 91. This results in a double decrease with the decrease in the components that can pass through the polarizer 225. The reflected light 222a in which the emitted light 212a is reflected on the surface of the detection object has a quantity of reflected light due to irregular reflection, as compared with the case where the detection object does not exist between the main body 2A and the return reflection plate 91. Will be reduced. However, since the amount of reflected light 222a is reduced only by being diffusely reflected, the reflected light 22a
Compared with the degree of decrease in the light amount of 1b, the degree of decrease is small. Further, as described above, the control circuit unit 2A is
From the value of the signal S ₃₂₄ corresponding to the light quantity of the reflected light 222a,
1 of the sum of the light quantity of the reflected light 221b and the light quantity of the reflected light 222a
The value of the signal S ₃₂₆ , which is a value obtained by subtracting the value of the signal S ₃₂₅ corresponding to the / 2 value, is higher or lower than the reference voltage value of the comparator 327. Is a circuit device that outputs a detection output signal S ₃ that is “H” or “L” corresponding to whether or not a detection object is present between the two.

Reflected light 22 due to the presence of the detection object 22
1b and the reflected light 222a, the reflection type photoelectric switch 1A determines whether or not a detection object is present and reflects the reflected light 221b that is incident on the light receiving unit 2 from the above-described difference in the degree of decrease and the function of the control circuit unit 2A. It can be said that the control circuit unit 2A determines the degree of change in the ratio of the light amounts of the reflected lights 222a. For this reason, in the reflective photoelectric switch 1A, the presence / absence of a detection object is determined by the reflection light 221b and the reflection light 22 when the detection object does not exist.
This can be performed regardless of the light amount value of 2a. Then, at that time, of the signal S ₃₂₄ and the signal S ₃₂₅ ,
Since the reference voltage value of the comparator 327 can be lowered by setting the values when the detection object does not exist to be substantially the same, the main body portion 2A and the return reflection plate 91 can be reduced.
This is advantageous in lengthening the interval between and.

Further, in the case where the detected object is present between the main body 2A and the regressive reflection plate 91, and the detected object has a surface texture that causes specular reflection, as described above, the main body described above is used. It is possible to more reliably determine the presence or absence of the detection object than when the detection object existing between the 2A and the retroreflective plate 91 has a surface texture that causes irregular reflection. Therefore, in the reflective photoelectric switch 1A, the possibility of determining the presence / absence of a detection object may be examined mainly in the case where the detection object has a surface texture that causes irregular reflection.

Embodiment 2; FIG. 7 shows claims 1, 2, 4,
It is the structure explanatory view which shows the structure of the principal part of the reflection type photoelectric switch provided with the regression reflection board by one Example of this invention corresponding to 5, 7-10. In FIG. 7, a reflection type photoelectric switch equipped with a regressive reflection plate according to an embodiment of the present invention corresponding to claims 1 to 3, 5, 7 to 10 shown in FIGS. 4 to 6, and FIGS. 10, the same parts as those of the reflection type photoelectric switch provided with the regressive reflection plate according to the conventional example shown in FIG. 12 are designated by the same reference numerals, and the description thereof will be omitted. Note that, in FIG. 7, as for the reference numerals given in FIG. 4, FIG. 5, FIG. 9, FIG. Furthermore, FIG.
According to the embodiment of the present invention, the operation of the reflection type photoelectric switch including the control circuit portion and the return type reflection plate of the reflection type photoelectric switch including the return reflection plate according to the embodiment of the present invention shown in FIGS. Since it is the same as the reflection type photoelectric switch 1A having the retroreflective plate according to the embodiment, the block circuit diagram of the control circuit and the re-presentation of the waveform diagram for explaining the operation of the reflection type photoelectric switch having the regressive reflection plate are not presented. Omitted.

In FIG. 7, 1B is shown in FIGS.
For the reflection type photoelectric switch 1A according to the present invention,
Reflective type in which body 2B is used instead of body 2A
It is a photoelectric switch. The main body portion 2B is the
It emits light to the main body 2A of the flash photoelectric switch 1A.
Light emitting diode 4 instead of photodiodes 211 and 212
1 and does not use the light beam combiner 213
The light projecting unit 4 is used. Light emitting diode 41
Is a reflection type photoelectric switch according to the present invention shown in FIG.
1A has a light emitting diode 211 and a light emitting diode 21
The same chip-shaped semiconductor light-emitting device used in 2
Adjacent to each other in the semiconductor device package of
It is configured to be stored in. These chips
As a matter of course, each semiconductor light emitting device
Light emission signal S from control circuit unit 3₃₁₁, S ₃₁₂Is supplied
Becomes

Since the embodiment shown in FIG. 7 has the above-mentioned structure, the emitted light 211 emitted from the light emitting diode 41 is emitted.
Since a and 212a are emitted from the fine chip-shaped semiconductor light emitting elements arranged adjacent to each other, they are emitted from the light projecting section 2B through substantially the same optical path. Therefore, regarding the emitted lights 211b and 212a emitted from the light projecting unit 2B, the reflected light when reflected by the recursive reflection plate 91 and the reflected light when reflected by the detection object are different depending on the wavelength. It becomes possible to enter the light receiving portion 22 without any light. As a result, the reflection type photoelectric switch 1B has the same operation and effect as the reflection type photoelectric switch 1A, but it becomes possible to eliminate the installation of the light beam combiner 213 in the main body 2B.

In the above description of the first and second embodiments,
The light beam splitter 223 included in the light receiving portion 22 of the reflection type photoelectric switches 1A and 1B has a configuration in which two right angle prisms are joined to each other at their slopes, and a half mirror is formed on the joint surface. Although it has been stated that the incident light beam is divided into two optical paths which are orthogonal to each other and is emitted, the present invention is not limited to this, and for example, red light may be applied to the joining surface of two right-angle prisms. A selective reflection film that reflects external light and transmits red light may be formed. In such a case, the optical filter 224 and the attenuator 325 can be dispensed with.

Also, in connection with this,
In the above description of the first embodiment, the light beam combiner 213 included in the light projecting unit 21 of the reflective photoelectric switch 1A is
Similar to the light beam splitter 223, it has been described that two right-angle prisms are joined to each other at their slopes and a half mirror is formed on this joined surface, but the present invention is not limited to this. For example, a selective reflection film that reflects infrared light and transmits red light may be formed on the joint surface of two right-angle prisms similar to the above-mentioned optical beam splitter. Is. With this configuration, it is possible to reduce the amount of light that passes through the half mirror and leaks out of the light beam combiner.

Embodiment 3; FIG. 1 shows claims 1, 2, 4 to
FIG. 6 is a configuration explanatory view showing a configuration of a main part of a reflection type photoelectric switch including a regressive reflection plate according to an embodiment of the present invention corresponding to 6, 8 to 10. FIG. 2 is a block circuit diagram showing a main part of the control circuit unit shown in FIG. 1 together with a light emitter and a photoelectric conversion element, and FIG. 3 is provided with the regressive reflection plate shown in FIGS. FIG. 7 is a waveform chart of a main part for explaining the operation of the reflective photoelectric switch. 1 to 3, a reflection type photoelectric switch equipped with a regressive reflection plate according to an embodiment of the present invention corresponding to claims 1 to 3, 5, 7 to 10 shown in FIGS. 4 to 6, and FIG. A reflection type photoelectric switch equipped with a regressive reflection plate according to an embodiment of the present invention corresponding to claims 1, 2, 4, 5, 7 to 10 shown above, and the conventional type shown in FIGS. 9, 10 and 12. The same parts as those of the reflection type photoelectric switch provided with the regression reflection plate according to the example are designated by the same reference numerals, and the description thereof will be omitted. Note that, in FIGS. 1 and 2, as for the reference numerals given in FIGS. 4, 5, 7, 9, 10, and 12, only representative reference numerals are shown.

In FIGS. 1 and 2, reference numeral 1 denotes a body 2 and a control circuit 6 in place of the body 2B and the control circuit 3 in the reflection type photoelectric switch 1B according to the present invention shown in FIG. Is a reflection type photoelectric switch. The main body 2 uses the photoelectric conversion element 51 in place of the photoelectric conversion elements 221, 222 in the main body 2B included in the reflection type photoelectric switch 1B according to the present invention, and includes a light beam splitter 223 and an optical filter 224. The light receiving unit 5 that is not used is used. The reflected light 221b and the reflected light 222a incident on the light receiving section 5 are almost the same as the case of the light receiving section 22 included in the reflection type photoelectric switches 1A and 1B according to the present invention, and are located at the site where the photoelectric conversion element 51 is installed. To reach. In the light receiving unit 5, these reflected lights 221b, 2
22a is incident on the photoelectric conversion element 51 as it is. The photoelectric conversion element 51 that receives the reflected lights 221b and 222a receives the reflected light 22 that is incident on the photoelectric conversion element 51.
1b, the electric signal S ₅₁ having a value corresponding to the light quantity of the reflected light 222a is output.

The control circuit section 6 includes a light emission signal generation section 61,
And a light reception signal processing unit 62. Light emission signal generation unit 6
1 is a pulse oscillation circuit unit 811 and a frequency dividing circuit unit 611.
And the drive circuit units 311 and 312, and the received light signal processing unit 62 includes a signal amplification unit 621, peak hold circuit units 622 and 623 which are discrimination circuit units, and sample hold circuit units 624 and 625. It has a differential amplifier 326, which is a discrimination circuit unit, and a comparator 327.

Hereinafter, the operation of the reflection type photoelectric switch 1 will be described by using the waveforms of the respective parts shown in the first half of FIG. The pulse oscillating circuit portion 811 outputs a signal S ₈₁₁ having a constant cycle which is a rectangular wave pulse signal. Signal S
Frequency dividing part 611 which enter the ₈₁₁ divides the period of the signal S _811, has three times the period relative to the period of the signal S ₈₁₁ has, and the same period and the period of the signal S ₈₁₁ has mutually It is a rectangular wave pulse signal with a timing shifted by
The signals S _611a , S _611b , and S _611c having a constant cycle are output. The signals S _611a and S _611b are current-amplified by the drive circuit units 311 and ₃₁₂ , converted into light emission signals S ₃₁₁ and S ₃₁₂ , and applied to the light emitting diode 41. Therefore, the emitted light 211a (that is, 2
The same applies to 11b. ) And the emitted light 212a is the signal S
_611a and S _611b are pulsed light having a constant cycle same as that of the reflected light 221b and 222a.
The pulsed light has a constant cycle that is the same as the cycle of the signals S _{61 1a} and S _611b .

In the received light signal processing unit 62, the electric signal S ₅₁ is amplified by the signal amplification unit ₆₂₁ and first converted into the signal S ₆₂₁ . The peak hold circuit units 622 and 623 both receive the signal S ₆₂₁ . Further, the peak hold circuit unit 622 sends the signal S _611a to the peak hold circuit unit 623.
Respectively inputs the signal S _611b . Then, the peak hold circuit unit 622 holds the value of the signal S ₆₂₁ at each timing when the rectangular wave pulse of the signal S _611a is input, and outputs the value as the signal S ₆₂₂ . In addition, the peak hold circuit unit 623 outputs the signal S _611b.
The value of the signal S ₆₂₁ at each timing when the rectangular wave pulse is input is held and the value is output as the signal S ₆₂₃ .

Here, the signal S ₆₂₂ corresponds to the signal S ₆₂₁ having a value corresponding to the sum of the light amounts of the reflected light 221b and the reflected light 222a incident on the photoelectric conversion element 51, and the output light 21 is
Since the peak hold is performed at the timing when 1a is emitted, it is a signal corresponding to the reflected light 221b. Further, the signal S ₆₂₃ peaks at the timing at which the emitted light 212 a is emitted with respect to the signal S ₆₂₁ that has a value corresponding to the sum of the amounts of the reflected light 221 b and the reflected light 222 a that are incident on the photoelectric conversion element 51. Since the signal is held, it is a signal corresponding to the reflected light 222a. In this way, even if only one photoelectric conversion element 51 is installed in the light receiving section 5, by using the signals S _611a and S _611b , the emitted light 211a (also the reflected light 211b) and the emitted light can be obtained. It is possible to reliably discriminate the signal corresponding to 212a.

The signal S ₆₂₂ and the signal S having the above contents
₆₂₃ is input to the sample hold circuit units 624 and 625. The sample and hold circuit units 624 and ₆₂₅ also _receive the signal S _611c output from the frequency dividing circuit unit 611. Then, the sample hold circuit unit 624 holds the value of the signal S ₆₂₂ at each timing when the rectangular wave pulse of the signal S _611c is input, and outputs the value as the signal S ₆₂₄ . Further, the sample-hold circuit unit 625 holds the value of the signal S ₆₂₃ at each timing when the rectangular wave pulse of the signal S _611c is input (this point is the same as the sample-hold circuit unit 624), and The value is output as signal S ₆₂₅ . These signals S ₆₂₄ and S ₆₂₅ are used as the differential amplifier 3
26, the differential amplifier 326 receives the reflected light 222a.
From the signal S ₆₂₅ which is a signal corresponding to
The signal S ₆₂₄ , which is a signal corresponding to, is subtracted, and output as a signal S ₃₂₆ that is an analog amount. This signal S ₃₂₆ is input to the comparator 327. The comparator 327 compares the input signal value with a reference voltage value, and outputs “H” when the input signal value is higher than the reference voltage value and outputs “L” when the input signal value is lower than the reference voltage value. In the reflective photoelectric switch 1, when the detection object does not exist between the main body 2 and the return reflection plate 91, the output light 211a and the output light 212a are set so that the value of the signal S ₃₂₆ becomes substantially zero. Since the light amount is set, the comparator 327 to which the signal S _{32 6} is input outputs the detection output signal S ₃ of “L” which means that the detection object does not exist. This detection output signal S ₃ is output from the output terminal 6a to the outside of the reflective photoelectric switch 1.

By the way, when there is a detection object having a surface texture such as a rough surface between the main body 2 and the recursive reflection plate 91 (FIG. 3 shows this case as an object). .), Compared with the case where no detection object is present between the main body 2 and the retroreflective plate 91.
As described above, the light amount of the reflected light 221b after passing through the polarizer 225 is double-decreased due to the irregular reflection and the difference in the polarization plane, and the light amount of the reflected light 222a is reduced due to the irregular reflection. Will only receive. For this, the signal S _{62 4} affected by the amount of reflected light 221b is greatly reduced than the signal S ₆₂₅ that is independent of the amount of reflected light 221b. As a result, the signal S
_{Since 326} has a positive value, comparator 3
27 is "H", which means that a detected object exists
The output of the detection output signal S ₃ of 1 is the same as that of the reflection type photoelectric switch 1A according to the first embodiment.

Further, when there is a detection object having a surface texture such as a specular surface that performs specular reflection between the main body 2 and the retroreflective plate 91, a space between the main body 2 and the retroreflective plate 91 is present. In comparison with the case where there is no detected object in the first embodiment,
As described above, the light quantity of the reflected light 221b after passing through the polarizer 225 becomes almost zero due to the difference in the polarization plane, and the light quantity of the reflected light 222a is hardly reduced. As a result, the signal S ₃₂₆ has a positive value larger than that in the case where there is a detection object having a surface texture such as a rough surface between the main body 2 and the regressive reflection plate 91, which has a surface texture. It will be. Therefore, the comparator 327 outputs the detection output signal S ₃ of “H” which means that the detection object is present. That is, also in the reflection type photoelectric switch 1, as in the case of the reflection type photoelectric switch 1A according to the first embodiment, when the detection object exists between the main body 2 and the return reflection plate 91, the detection object has the detection object. The detection output signal S ₃ of “H” is output regardless of the surface texture.

Next, regarding the reflection type photoelectric switch 1, in order to obtain a reflection type photoelectric switch in which the interval between the main body 2 and the return reflection plate 91 is long, the emitted light 211b (thus also the emitted light 211a) and: The operation of the reflective photoelectric switch 1 when the amount of the emitted light 212a is increased will be described below with reference to the waveform diagrams of the respective parts shown in the latter half of FIG.

Reflected light 22 when a detected object is present between the main body 2 and the retroreflective plate 91 and when no detected object is present between the main body 2 and the retroreflective plate 91
The degree of reduction of 1b and reflected light 222a has already been described in the first embodiment. In addition, as described above, the control circuit unit 2
Is a value obtained by subtracting the value of the signal S ₆₂₄ corresponding to the light quantity of the reflected light 221b from the value of the signal S ₆₂₅ corresponding to the light quantity of the reflected light 222a, the value of the signal S ₆₂₆ is the reference voltage value of the comparator 327. A circuit that outputs a detection output signal S ₆ that is “H” or “L” corresponding to whether or not a detection object is present between the main body 2 and the recurrence reflection plate 91 depending on whether the detection object is higher or lower than It is a device.

Reflected light 22 due to the presence of the detection object 22
1b and reflected light 222a, the reflection type photoelectric switch 1 is the reflection type photoelectric switch 1 according to the first embodiment because of the difference in the reduction degree and the function of the control circuit unit 2 described above.
Similar to A, it can be said that the control circuit unit 2 determines the presence or absence of a detected object by the degree of change in the ratio of the light amounts of the reflected light 221b and the reflected light 222a incident on the light receiving unit 2. it can. Therefore, in the reflective photoelectric switch 1, it is possible to determine the presence or absence of the detection object regardless of the light quantity values of the reflected light 221b and the reflected light 222a when the detection object does not exist. Then, by the time, the signal S ₆₂₄ and the signal S _{62 5,} is substantially the same value the value of the case where the detection object does not exist,
Since the reference voltage value of the comparator 327 can be lowered, it is advantageous in increasing the distance between the main body 2 and the return reflection plate 91.

The reflective photoelectric switch 1 shown in FIGS.
As is clear from the above description, the projecting section 4 having the same operation and effect as the reflective photoelectric switch 1A and the same configuration as the reflective photoelectric switch 1B is simple, and its light receiving section is It is possible to use only one photoelectric conversion element, and it becomes possible to eliminate the installation of the optical beam splitter 223 and the optical filter 224.

In the above description of the second and third embodiments,
Although the light emitting diode 41 used for the light projecting section has the chip-shaped semiconductor light emitting element for red light and the chip-shaped semiconductor light emitting element for infrared light separately, it is not limited to this. Instead, for example, the light emitting source for red light and the light emitting source for infrared light may be integrally formed in the same chip-shaped semiconductor light emitting element by using a semiconductor manufacturing technique. In this case, the distance between the emission center of red light and the emission center of infrared light can be further shortened.

[Embodiment 4] FIG.
FIG. 6 is a configuration explanatory view showing a configuration of a main part of a reflection type photoelectric switch including a regressive reflection plate according to an embodiment of the present invention corresponding to 6, 8 to 10. In FIG. 8, a reflection type photoelectric switch equipped with a regressive reflection plate according to an embodiment of the present invention corresponding to claims 1, 2, 4 to 6, and 8 to 10 shown in FIGS. Claims 1 to 3, 5, 7 to 10 shown in claim 6.
7. A reflection type photoelectric switch equipped with a retroreflective plate according to one embodiment of the present invention, which corresponds to FIG.
4, 5 and 7 to 10, a reflection type photoelectric switch provided with a retroreflective plate according to an embodiment of the present invention, and a conventional retroreflective plate shown in FIGS. 9, 10 and 12. The same parts as those of the reflection type photoelectric switch are designated by the same reference numerals, and the description thereof will be omitted. In addition, in FIG. 8, about the reference numerals given in FIGS. 1, 2, 4, 4, 5, 7, 9, 10, and 12, only representative reference numerals are shown. further,
The operation of the reflection type photoelectric switch including the control circuit portion and the return type reflection plate of the reflection type photoelectric switch including the return reflection plate according to the embodiment of the present invention shown in FIGS. Since it is the same as the reflection type photoelectric switch 1 having the retroreflective plate according to the embodiment of the present invention, a block circuit diagram of the control circuit and a waveform diagram for explaining the operation of the reflection type photoelectric switch having the return reflection plate are reproduced. The presentation is omitted.

In FIG. 8, reference numeral 1C is a reflection type photoelectric switch in which a body portion 2C is used in place of the body portion 2 in the reflection type photoelectric switch 1 according to the present invention shown in FIGS. is there. Then, the main body portion 2C uses the light projecting portion 21 included in the reflective photoelectric switch 1A according to the present invention as a light emitting portion, and uses the light receiving portion 5 included in the reflective photoelectric switch 1 according to the present invention as a light receiving portion. It is the one. Therefore, the reflection type photoelectric switch 1C is a reflection type photoelectric switch which can obtain the same action and effect as the reflection type photoelectric switches 1, 1A and 1B according to the present invention have. Since it overlaps with the above, its explanation is omitted.

In the above description of Examples 1 to 4,
The polarizers 214 and 225 provided in the light projecting unit and the light receiving unit are
Although it is described as a polarizing plate or a polarizing filter, it is not limited to this, and may be an appropriate polarizer such as a polarizing prism. Further, in the above description of Examples 1 to 4, it is assumed that the emitted light that is polarized is the red light and the emitted light that is not polarized is the infrared light, but it is not limited to this. However, if one is the outgoing light that is polarized and the other is the outgoing light that is not polarized, it is possible to use a light beam having an appropriate wavelength. Of course, then, a suitable polarizer should be used, depending on the wavelength of light used.

Furthermore, in the above description of the first to fourth embodiments, the signal to be compared, which is input to the differential amplifier 326, which is the discrimination circuit unit included in the control circuit unit, is the light amount of the reflected light 221b. By setting the light amount of the reflected light 222a and the light amount of the reflected light 222a to the same value, the same value can be obtained when the detection object does not exist between the main body and the return reflection plate 91. However, the present invention is not limited to this. However, it may be performed, for example, by adjusting the amplification degree of the amplification circuit unit or the like included in the control circuit unit.

[0058]

According to the present invention, the following effects can be obtained by adopting the structure described in the section of the means for solving the above problems. The presence / absence of a detection object is determined based on the degree of change in the ratio between the amount of reflected light related to the polarized outgoing light and the amount of reflected light related to the unpolarized outgoing light. The light intensity value of the emitted light and the amplification degree with respect to the output of the photoelectric conversion element that receives the reflected light do not affect the determination of the presence or absence of the detection object. With this, it is possible to increase the light intensity value of the emitted light or increase the amplification degree with respect to the output of the photoelectric conversion element that receives the reflected light, and thus the interval between the main body portion and the return reflector is widened, and the return reflector is provided. It is possible to provide a reflective photoelectric switch.

In the above item, even if both the polarized light and the unpolarized light are used, the presence or absence of the detection object can be obtained by making the optical paths of the both lights substantially integrated. It is possible to provide a reflective photoelectric switch provided with a retroreflective plate, which can accurately perform the above. In the above item, the number of photoelectric conversion elements is set to 1, and a beam splitter or the like can be eliminated, so that the regression reflecting plate is provided which is small in size and inexpensive in manufacturing cost while having the effect of the above item. It is possible to provide a reflective photoelectric switch.

[Brief description of drawings]

FIG. 1 is a structural explanatory view showing a configuration of a main part of a reflection type photoelectric switch provided with a regressive reflection plate according to an embodiment of the present invention corresponding to claims 1, 2, 4 to 6, 8 to 10.

FIG. 2 is a block circuit diagram showing a main part of a control circuit unit shown in FIG. 1 together with a light emitter and a photoelectric conversion element.

FIG. 3 is a waveform diagram of essential parts for explaining the operation of the reflection type photoelectric switch including the regression reflection plate shown in FIGS. 1 and 2.

FIG. 4 is a structural explanatory view showing a structure of a main part of a reflection type photoelectric switch provided with a regressive reflection plate according to an embodiment of the present invention corresponding to claims 1 to 3, 5 and 7 to 10.

5 is a block circuit diagram showing a main part of a control circuit unit shown in FIG. 4 together with a light emitter and a photoelectric conversion element.

FIG. 6 is a waveform chart of a main part for explaining the operation of the reflection type photoelectric switch including the regression reflection plate shown in FIGS. 4 and 5.

FIG. 7 is a structural explanatory view showing a structure of a main part of a reflection type photoelectric switch provided with a return reflection plate according to an embodiment of the present invention corresponding to claims 1, 2, 4, 5, 7 to 10.

FIG. 8 is a structural explanatory view showing the structure of a main part of a reflection type photoelectric switch provided with a regressive reflection plate according to one embodiment of the present invention corresponding to claims 1 to 3, 5, 6, 8 to 10.

FIG. 9 is an explanatory diagram showing a configuration of a main part of a reflection type photoelectric switch including a regression reflection plate of a conventional example together with a detection object.

FIG. 10 shows a main part of the control circuit section shown in FIG.
The block circuit diagram shown together with the photoelectric conversion element

FIG. 11 is a waveform diagram of essential parts for explaining the operation of the reflection type photoelectric switch including the regression reflection plate shown in FIGS. 9 and 10.

FIG. 12 is a configuration explanatory view showing the configuration of a main part of a reflection-type photoelectric switch including a regression reflector of a different conventional example together with a detection object.

[Explanation of symbols]

 1 Reflective Photoelectric Switch 2 Main Body 211b Emitted Light 212a Emitted Light 214 Polarizing Plate 221b Reflected Light 222a Reflected Light 225 Polarizing Plate 4 Light Emitting Unit 41 Light Emitting Element (Light Emitting Diode) 5 Light Receiving Section 51 Photoelectric Conversion Element 6 Control Circuit Section 91 Regression reflector

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location H01L 31/12 H01L 31/10 G

Claims (10)

[Claims] 1. A main body portion having a light projecting portion and a light receiving portion which are arranged in close proximity to each other, a return reflection plate arranged with a space from the main body portion, and light emitted from the light projecting portion. And a control circuit unit for determining the level of the light amount by inputting an electric signal output from the light receiving unit corresponding to the amount of light incident on the light receiving unit. A reflection type photoelectric switch equipped with a regressive reflection plate for detecting whether or not a detection object is present between the main body part and the regressive reflection plate according to the level of the amount of light emitted from the receptive part. In the above, the light projecting section of the main body section is composed of a pair of light emitters that emit light having different wavelengths, and a polarizer that selectively polarizes only the light emitted from one light emitter. And the light receiving section of the main unit is a photoelectric conversion element. And a polarizer arranged on the side that receives the light from the light projecting unit of the photoelectric conversion element, and this polarizer is for the light emitted from one of the light emitters of the light projecting unit. It has the same polarization characteristics as a polarizer that selectively polarizes only, and is arranged so that the polarization plane due to the polarization is substantially orthogonal to the polarization plane due to the above-mentioned polarizer. A reflection-type photoelectric switch equipped with a regressive reflection plate, which is characterized by determining the degree of change in the ratio of the respective amounts of light incident on the light-receiving portion, which is related to the light emitted by each light-emitting body of the light-emitting portion. 2. A reflection type photoelectric switch provided with a retroreflective plate according to claim 1, wherein the light projecting section of the main body section emits light from a pair of light emitting bodies which emit light having different wavelengths from each other. Light is emitted from the light projecting portion through almost the same optical path. A reflection type photoelectric switch provided with a regressive reflection plate. 3. A reflection type photoelectric switch provided with the regressive reflection plate according to claim 1 or 2, wherein light is emitted from a pair of light emitters provided in a light projecting section of the main body section and emitting lights of different wavelengths. Each of the emitted lights is emitted from the light projecting unit through substantially the same optical path, and the light projecting unit has a light beam synthesizing unit, and the light beam synthesizing unit has the light projecting unit included in the main body unit. A reflection type photoelectric switch having a regressive reflection plate, characterized in that the light from each of the light emitters forming a pair is combined into an integrated light beam. 4. A reflection type photoelectric switch provided with the regressive reflection plate according to claim 1 or 2, wherein light is emitted from a pair of light emitting bodies provided in a light projecting section of the main body section and emitting lights of different wavelengths. In the structure in which the respective emitted lights are emitted from the light projecting unit through substantially the same optical path, the light emitting unit which the light projecting unit of the main body has is a chip-shaped semiconductor light emitting device, and a semiconductor device package. A reflection type photoelectric switch having a return reflection plate, which is integrally housed inside. 5. A reflection type photoelectric switch provided with the regressive reflection plate according to any one of claims 1 to 4, wherein one light-emitting body is polarized by a polarizer of a light projecting section of the main body section. Alternatively, the semiconductor light emitting element is a light emitting body or a semiconductor light emitting element which emits visible light, and the other light emitting body which is not disposed on the light emitting side and is not polarized by the polarizer of the light projecting section of the main body section. Alternatively, the semiconductor light emitting device is a light emitting body that emits infrared light or a semiconductor light emitting device, and a reflection type photoelectric switch having a regressive reflection plate. 6. A reflection type photoelectric switch provided with the regressive reflection plate according to claim 1, wherein the light projecting section of the main body section is a pair that emits lights having different wavelengths from each other. The light emitting body or the semiconductor light emitting element is made to emit light at different light emission timings, and the control circuit section inputs the electric signal output from the photoelectric conversion element of the light receiving section of the main body section and amplifies this electric signal. Together with the discrimination circuit section for discriminating the electric signal relating to the light by each light emitter or semiconductor light emitting element of the light projecting section, and inputting the discriminated electric signal, the amount of each light incident on the light receiving section A discrimination circuit section for discriminating the degree of change in the ratio, and the discrimination circuit section inputs an electric signal corresponding to the light emission timing of each of the above-mentioned light emitters, and based on this electric signal. Then, a reflection provided with a regressive reflection plate characterized by discriminating an electric signal output from the photoelectric conversion element of the light receiving section into an electric signal related to light by each light emitter or semiconductor light emitting element. Type photoelectric switch. 7. A reflection type photoelectric switch provided with the regressive reflection plate according to claim 1, wherein the light receiving section of the main body has two photoelectric conversion elements and the photoelectric conversion element of the photoelectric conversion element. One of the photoelectric conversion elements has an optical filter device for blocking the passage of light from one of the light-emitting body or the semiconductor light-emitting element, which has a light-projecting section of the main body and is polarized by a polarizer. The control circuit unit inputs an amplification circuit unit that individually amplifies the electric signals output from the two photoelectric conversion elements and an electric signal output from each amplification circuit unit, and inputs them to the light receiving unit. A reflection type photoelectric switch provided with a regressive reflection plate, comprising: a discrimination circuit section for discriminating a degree of change in a ratio of respective incident light amounts. 8. A reflection type photoelectric switch provided with a regressive reflection plate according to claim 6 or 7, wherein the reflection type photoelectric switch is input to a discriminating circuit section included in a control circuit section and is paired with a projecting section included in a main body section. A reflection type photoelectric switch provided with a regressive reflection plate, characterized in that electric signals respectively corresponding to the light emitted from the light emitting body or the semiconductor light emitting element have substantially the same signal level. 9. A reflection type photoelectric switch provided with a regressive reflection plate according to claim 8, which is a luminous body which is input to a discrimination circuit section of a control circuit section and which is paired with a light projecting section of the main body section. Alternatively, the electric signal corresponding to the light emitted from the semiconductor light emitting element is adjusted to a substantially equivalent signal level by adjusting the amount of light emitted from the light emitting body or the semiconductor light emitting element. Reflective photoelectric switch equipped with a retroreflective plate. 10. A reflection type photoelectric switch equipped with a regressive reflection plate according to claim 8, which is a light emitter which is input to a discrimination circuit section included in a control circuit section and which is paired with a light projecting section included in the main body section. Alternatively, electric signals respectively corresponding to the light emitted from the semiconductor light emitting element may be adjusted to substantially the same signal level by adjusting the amplification degree of the discrimination circuit unit or the amplification circuit unit included in the control circuit unit. A reflective photoelectric switch equipped with a characteristic retroreflective plate.