JPH02126719A - reflective photoelectric switch - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reflective charging switch used for controlling the opening and closing of automatic doors.

[Conventional technology]

2. Description of the Related Art Sensors using pyroelectric elements have conventionally been used as human body detection sensors for controlling the opening and closing of automatic doors. This detects the intrusion of a human body by detecting the temperature change when the human body enters the detection area.

[Problem to be solved by the invention]

The pyroelectric method is a moving object detection method that detects temperature changes within a predetermined period of time in a detection area, and has the following problems. First, if a human body enters the detection area and remains stationary there for a predetermined period of time or more, detection becomes impossible. Second, unlike the human body, which has a heat source,
If something that has the same ambient temperature as a trolley enters the detection area, it cannot be detected. Third, if a mat that absorbs sunlight is installed within the detection area, this will generate heat, so if wind blows there, the temperature of the mat will change within a certain amount of time. , this will cause malfunction.

Therefore, the present invention can detect when the human body is stationary, can also detect when something other than the human body has entered the body, and can also detect when there is a temperature change due to sunlight irradiation etc. It is an object of the present invention to provide a reflective photoelectric switch that does not malfunction even when

[Means to solve the problem]

The reflective photoelectric switch according to the present invention includes a light projecting means that projects a beam of light in two slit shapes onto a predetermined reference object, and a condenser that focuses the reflected light flux of the beam light on two slit-shaped spots. It has an optical means and three independent light receiving parts, and each of the light receiving parts receives a photocurrent t and I, respectively.
, I BC is placed at the focal point of the two slit-shaped spots, and based on changes in photocurrent, it is detected that the object to be detected has entered the front side of the reference object. and a detection means, and when the light-receiving element receives the reflected light flux from the reference object, the photocurrent is I L! IB, and the detection means determines that the object to be detected has entered when the photocurrent becomes IA>IB and IC-IA changes.

Here, the light projecting means may include two light sources and a cylindrical lens having an axis perpendicular to the direction in which these light sources are disposed, and a plurality of light emitting elements arranged in parallel directions. It is also possible to have two groups of light sources configured as follows.

[Effect]

According to the present invention, a beam of light is projected in a slit shape (band shape), and intrusion of a human body or the like into this area is detected by a change in the photocurrent of a light receiving element. Therefore, objects with the same temperature as the ambient temperature, such as trolleys, can be detected in the same way as the human body, and even if there is a change in the temperature of the reference object due to sunlight irradiation, it will not be detected incorrectly. There is no.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an overall configuration diagram of a reflective photoelectric switch according to an embodiment of the present invention. As shown in the figure, a resistor R1°R and a capacitor C form a power supply section 10 for the light sources L 1 and L2, which is connected to the anode terminals of the light sources L 1 and L 2 . Transistors Q and Q2 are connected to the power source terminal of the light source L, so that the light sources L and L can be pulsed alternately at timings T and T. Light source, L2
The emitted light flux is focused by a projection lens 1 onto a floor (or ground) 3, which is a reference object. Further, this condensed light beam is spread by a cylindrical lens 2 at a predetermined angle θ in a direction perpendicular to the plane of the paper of FIG. In other words, the floor (or ground) is the reference object.
3, two slit lights are alternately irradiated at timings T and T2. As a method for forming the irradiation slit light, instead of using the cylindrical lens 3, the light source L2 may be configured by arranging a plurality of light emitting diodes in two rows in a direction perpendicular to the paper surface.

FIGS. 2 and 3 show how such light sources L1 and L2 are arranged. That is, in FIG. 2, two light sources are combined with a cylindrical lens 2 for L2, and a beam of light is projected onto a slit-shaped area shown by hatching in the figure with respect to a reference object 3. . On the other hand, in the example shown in FIG. 3, two (two groups) of light sources L 1 and L 2 are formed by arranging a plurality of light emitting elements in each column. Further, no cylindrical lens is provided. In this case, the spots are lined up as indicated by hatching on the reference object, making it possible to project a substantially slit-shaped beam of light. These essentially form two linear light sources, and the projection lens 1 can project slit light onto the object. In reality, the use of a line light source method as shown in FIG. 3 allows the irradiation intensity to be increased, making it possible to stably detect intruding objects.

The light beam reflected by the floor (or ground) 3, which is a reference object, is focused in the form of a slit onto a light receiving element 5 having three independent light receiving parts by a light receiving lens 4 located at a distance B. The two slit lights shining on the floor (or ground) 3, which is the reference object, are generated by the three light-receiving parts of the light-receiving element 5 when they are not blocked by the trolley or human body, which is the detection object. The photocurrents are IB and I, respectively.
When setting CB and I, adjustment is made by moving the light receiving element 5 in the direction of the arrow shown in the figure so that the conditions of I - I, 1 - constant, and c ABC are satisfied. In other words, the reflected luminous flux of the light source L generates a photocurrent 1, I
The light receiver 2 is arranged so that the boundary of the light receiving part AB is irradiated, and the reflected light flux of the light source L generates light sources 1 and I.
^C If the position of the light receiving element 5 is adjusted so that the boundary of the tip is irradiated, the following condition will be obtained: 1-IS 1-1 (constant) BCA.

Next, as a detection target, a trolley (shown by a two-dot chain line in Fig.
When a human body (6) enters the irradiation area of the two slit lights, the reflected light flux passes through the optical path indicated by the dotted line, is condensed by the light receiving lens 4, and enters the light receiving element 5. At this time, the state of the photocurrent changes from the state of 8 BCA to 1 > 1. The state changes to 1 >I ABC^. Therefore, by detecting this amount of change using a signal processing circuit, it is possible to control the opening and closing of the automatic door.

FIG. 4 shows an embodiment of the signal processing circuit used in the above embodiment.

Photocurrent 1,! and ■ is the operational amplifier UIAB
After current-voltage conversion in C to U3, only the AC component is amplified. Furthermore, it is inverted and amplified by operational amplifiers U4 to UB, and then by differential amplifiers U and U8! -1, I-
1 operation is executed. The differential operation output of this BCA is sample-and-hold circuit S-
Transferred to S4, the sample-and-hold circuit S samples and holds the state immediately before the pulse lighting of the light source L1 at the sampling time SHI. The sample and hold circuit S is connected to the light source L.
The sampling time SH is the state in which l is pulse lit.
2 to sample and hold. Similarly, the sampling and hold circuit S3 detects the pulse lighting state of the light source L2 immediately before the pulse lighting state, and the sampling and hold circuit S4 detects the pulse lighting state at the sampling time SH3.
, SH4 to sample and hold.

Differential amplifier U9 has two sample-and-hold circuits S
, S2, and the differential amplifier U calculates the output difference of the sample-and-hold circuits S and S2. The sample-and-hold circuits s, s, s3, and S4 and the differential amplifier U9゜Ulo can extract only the signal components (IA-IB and IC-1 person) from the photocurrent on which the disturbance light component is superimposed. .

The calculated outputs IA and IB of the differential amplifier U are input to a low-pass filter U11, where high frequency components are removed. That is, the voltage value of the calculation output fluctuates due to noise generated from the light receiving element 5 and each operational amplifier. this is,
Signal current 1 obtained from light receiving element 5 = Is and I. This is because the weaker the voltage, the larger the amplification gain must be, and the greater the voltage fluctuation. Therefore, by averaging and stabilizing the calculated values, it becomes possible for the comparator C1 to make a reliable determination without malfunction.

Also, the calculation output of the differential amplifier U! . -1A is input to the O bandpass filter U12, and only the fluctuation components within the set time are output. Sunawachi, -y
Due to the action of the comparator C1, the trolley (or human body) that is the object to be detected intrudes into the floor (or ground) that is the reference object, and detection can be performed while it is stationary (so-called stationary detection). Become. On the other hand, the action of the comparator C10 enables detection (so-called moving object detection) in a state where the detection target object, such as a cart (or a human body), is changing within a set time.

The comparator C changes from the eft LOW state to the HIGH state when the static displacement at IA-IB exceeds the determination reference voltage V 1 . On the other hand, comparators C and C are
When the dynamic variation amount of c I A exceeds the determination voltage range set by the three resistors and the plus and minus power supplies, the LOW state changes to the HIGH state. The outputs of the comparators C2 and C3 are outputted as dynamic detection signals via the OVER gates, and are ANDed and ORed with the static detection signals of the comparator C1 to produce output signals 0UT.
I,0UT2 can be obtained.

When output signal 0UT1 is used to control the opening and closing of automatic doors,
The door will open only when static detection and dynamic detection are performed at the same time. For example, if we assume that a potted plant is placed within the detection range, static detection alone will keep the door open, but the output signal is 0UT.
If I is used, the dynamic detection becomes LOW, so even if the door is opened once, it can be controlled to close within a predetermined time. On the other hand, if the output signal 0UT2 is used, the door will open if either the dynamic detection or static detection signal is detected.

FIG. 5 is a timing chart for explaining the operation of the embodiment of the present invention shown in FIGS. 1 and 4. FIG.

The light Fi,L repeats pulse lighting at a constant cycle of Tt shown in FIG. In synchronization with timing T1, the calculation output IA-1° of the differential amplifier U7 shown in FIG. Only the signal component of IA■ is extracted by U9.

The light RL2 has a constant period of timing T2 shown in FIG.
Pulse lighting is repeated in the same manner as timing T1. The timings T and T control the light sources L and L so that they alternately repeat the pulse 1 2 l 2 lighting, and therefore the light sources L
, L will not light up at the same time. Below is the same eaves I. -Only the change component of IA is sampling time SH
3. Sampled at SH4, and only signal components are extracted.

In the embodiment, for example, the repetition frequency in the pulse lighting operation of the light sources Ll and L2 is 1 (kHz).
, the pulse width is set to 30 (μ5ec), the cutoff frequency of the low-pass filter U11 is set to 10 (Hz), and the transmission frequency range of the band-pass filter U1□ is 0.
What is necessary is just to set it to 1-10 (Hz). As a result, the ripple (variation width) of the output voltage after averaging can be suppressed to about one tenth of the ripple before averaging, and stable determination can be performed.

〔Effect of the invention〕

As described in detail above, in the present invention, a beam of light is projected onto a slit (band-shaped), and intrusion of a human body or the like into this area is detected by a change in the photocurrent of a light receiving element. Therefore,
It can detect when the human body is stationary, it can also detect when something other than the human body enters, and it also malfunctions when there is a temperature change due to sunlight etc. There's nothing to do.

If the reflective photoelectric switch of the present invention is applied to automatic door opening/closing control, it will not only be possible to detect trolleys, etc., which was impossible with conventional pyroelectric methods, but it will also be possible to combine dynamic detection and static detection. This allows for a variety of controls.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the overall configuration of a reflective photoelectric switch according to an embodiment of the present invention, FIGS. 2 and 3 are perspective views showing an example of the arrangement of light sources, and FIG. 4 is a diagram showing an example of the arrangement of light sources. The circuit diagram of the signal processing circuit, FIG. 5, is a timing chart showing the operation of the signal processing circuit. 1... Light projection lens, 2... Cylindrical lens, 3
... Reference object (floor), 4... Light receiving lens, 5...
・Light receiving element, 6... Detection target (truck), L, L
···light source. Patent applicant Hamamatsu Photonics Co., Ltd. Representative Patent Attorney
Yoshiki T for Hase;

Claims (1)

[Claims] 1. A light projecting means for projecting a light beam in the form of two slits onto a predetermined reference object;
It has a condensing means for condensing light onto a slit-shaped spot of a book, and three independent light-receiving parts, and the two slit-shaped spots are arranged so that photocurrents I_A, I_B, and I_C can be obtained from each light-receiving part, respectively. a light-receiving element disposed at a light-converging position, and a detection means for detecting that a detection object has entered the front side of the reference object based on a change in the photocurrent, and the light-receiving element is arranged at a light-converging position of the reference object. The detector is positioned so that the photocurrent satisfies I_A≒I_B when receiving the reflected light flux from an object, and the detecting means detects when the photocurrent becomes I_A>I_B and I_C−I_A changes. A reflective photoelectric switch that determines that an object has entered. 2. The reflective photoelectric switch according to claim 1, wherein the light projecting means includes two light sources and a cylindrical lens having an axis perpendicular to the direction in which these light sources are arranged. 3. The reflective photoelectric switch according to claim 2, wherein the light projecting means includes a drive circuit for time-divisionally driving the two light sources. 4. The reflective photoelectric switch according to claim 1, wherein the light projecting means includes two groups of light sources each having a plurality of light emitting elements arranged in parallel directions. 5. The reflective photoelectric switch according to claim 4, wherein the light projecting means includes a drive circuit for time-divisionally driving the two groups of light sources.