JPS6349739Y2 - - Google Patents

Description

[Detailed description of the device] (a) Technical field of the device This device illuminates an article with light emitted from a light-emitting element, receives reflected light from the article with a light-receiving element, and identifies the presence or absence of an article from the output of the light-receiving element. This is about an article detector.

(b) Conventional technology and problems In mass production factories, it is difficult to count manufactured goods,
When inspecting the shape of an article, an optical article detector is often used.

In the article detector used in such cases, the article is moved by a belt conveyor or the like, and the article that reaches a certain position reflects the light emitted from the light emitting element. Then, this reflected light is generally received by a light receiving element, and the number and shape of the articles are inspected from the output of this light receiving element.

In this case, the output of the light-receiving element only needs to be turned on and off in response to the presence or absence of an article, but if another light source, such as for illumination, illuminates the light-receiving element, the light-receiving element is turned on regardless of the presence or absence of an article. This will result in a malfunction.

Therefore, it is necessary to prevent detector output from being output from light sources other than the light-receiving element, or to shield the detector portion to prevent other light sources from entering.

(c) Purpose of the invention This invention turns the light-emitting element on and off, and the light-receiving element outputs an output in synchronization with the on-off of the light-emitting element, and when a light source other than the light-emitting element illuminates the light-receiving element, the object is An object of the present invention is to provide an article detector that notifies you that it cannot be detected.

(d) Example of the invention Next, a system diagram of an example of this invention is shown in Fig. 1.

In FIG. 1, 1 is a light emitting element, 2 is an article, 3 is a light receiving element, 4 is a signal source, 5 is a monostable multivibrator, 6 is a coincidence detection circuit, 7 is a shift register, 8
is the output terminal.

In FIG. 1, the light emitting element 1 is turned on and off by the output of the signal source 4. The light emitted from the light emitting element 1 is reflected by the article 2, and this reflected light is received by the light receiving element 3. Article 2
If there is no reflected light, the light-receiving element 3 will not output any output, so the presence or absence of the article 2 can be determined from the output of the light-receiving element 3.

Therefore, if the light-emitting element 1 and the light-receiving element 3 are fixed and the article 2 is sequentially moved so that the light reflected by the article 2 reaches the light-receiving element 3 when the article 2 reaches a specific position, then the light emitting element 1 and the light-receiving element 3 can be fixed. You can know the number 2.

Next, a circuit diagram of an embodiment of the coincidence detection circuit 6 of FIG. 1 is shown in FIG.

In FIG. 2, 61 is a terminal for connecting the output of the light receiving element 3, 62 is a terminal for connecting the branch output of the signal source 4,
63 is a terminal to which the output of the monostable multivibrator 5 is connected.

64 is an exclusive OR circuit, and when the output of the light receiving element 3 and the output of the signal source 4 are in phase, the output becomes "0". On the other hand, when the external light source enters the light receiving element 3 and turns on the light receiving element 3, "1" or "0" is output from the exclusive OR circuit 64 as the signal source 4 is turned on and off. .

65 is a flip-flop which receives the output of the exclusive OR circuit 64 and the output of the monostable multivibrator 5 as inputs. The flip-flop 65 is for checking the output of the exclusive OR circuit 64 at the center of the waveform, and applies the output of the monostable multivibrator 5, which has a shorter period than the signal source 4, to the T input.

Next, a circuit diagram of an embodiment of the light emitting element 1 and the light receiving element 3 is shown in FIG.

In Fig. 3, 9 is the power supply terminal, 10 is the light receiving element 3
, and terminal 10 is the output terminal of terminal 61 in FIG.
Connect to.

The shift register 7 in FIG. 1 uses the branch output of the signal source 4 as a clock input, and the output 66 of the coincidence detection circuit 6 as a reset input. Then, it is set so that an output is output if there is no reset input from the coincidence detection circuit 6 between three or more clock signals.

Therefore, it can be confirmed from the output of the shift register 7 whether the light reflected by the article 2 continues to reach the light receiving element 3 or not.

Next, an example of the waveform diagrams shown in FIGS. 1 to 3 is shown in FIG. 4.

The waveforms A to A in FIG. 4 correspond to the waveforms A to A in FIGS. 1 to 3, respectively.

4A shows the output waveform of the signal source 4, and FIG. 4B shows the output waveform of the monostable multivibrator 5.

The shaded area in FIG. 4C is the period during which the light emitting element 1 emits light, and the light emitting element 1 repeats on and off.

Figure 4D shows the output waveform of the light receiving element 3, and the period
_T0 to _T1 indicate a state in which there is no light reflected by the article 2.

T ₁ to _{T 2} in FIG. 4E indicate a state in which an external light source is incident on the light receiving element 3.

The period T ₂ to _{T 4} in FIG.
In response to the light emission, the output of the light receiving element 3 also repeats on and off.

FIG. 4E shows the output waveform of the exclusive OR circuit 64, and the output changes to "1" and "0" during the period _T0 to _T1 and the period _T1 to _T2 .

During the period T ₂ to _{T 4} shown in FIG. 4E, FIG. 4A and FIG. 4E are in phase, so the output of the exclusive OR circuit 64 remains at "0".

FIG. 4F shows the output waveform of the flip-flop 65, which repeats "1" and "0" during the period _T0 to _T2 , but continues in the "1" state during the period _T2 to _T4 .

Therefore, when the output of the flip-flop 65 remains "1" during the period T ₂ to _{T 4} , it indicates that the light reflected by the article 2 has reached the light receiving element 3, and the output of the flip-flop 65 remains "1". When the output repeats "1" and "0", it indicates that there is no light reflected by the article 2 or that an external light source is incident on the light receiving element 3.

FIG. 4G shows the output waveform of the shift register 7.

It is "0" during the period _T0 to _T3 , and is "1" during the period _T3 to _T4 .

This is because the output of the coincidence detection circuit 6 is "1" after the period _T2 , and in FIG. 1, a shift register 7 is used which outputs an output when three clocks are input.

If the shift register 7 is one that outputs eight clock signals, the reflected light can be detected reliably.

(e) Effect of the invention According to this invention, even if the reflected light from the article reaches the light receiving element, when the external light source reaches the light receiving element, the output of the shift register is "0".
Since the output of the shift register is "1" when there is no influence from an external light source, the condition for detecting the presence or absence of an article can be known with certainty.

[Brief explanation of the drawing]

Figure 1 is a system diagram of an embodiment based on this invention, Figure 2
The figure is a circuit diagram of an embodiment of the coincidence detection circuit 6 of FIG.
FIG. 3 is a circuit diagram of an embodiment of the light emitting element 1 and the light receiving element 3, and FIG. 4 is a waveform chart of FIGS. 1 to 3. DESCRIPTION OF SYMBOLS 1... Light emitting element, 2... Article, 3... Light receiving element, 4... Signal source, 5... Monostable multivibrator, 6... Coincidence detection circuit, 64... Exclusive OR circuit, 65... Flip-flop, 7...shift register.

Claims (1)

[Claims for Utility Model Registration] In an article detector in which the light emitted from a light emitting element 1 is applied to an article 2, the reflected light from the article 2 is received by a light receiving element 3, and the presence or absence of the article 2 is determined from the output of the light receiving element 3. , a signal source 4 for turning on and off the light emitting element 1, a monostable multivibrator 5 that receives the branch output of the signal source 4 as input, and an exclusive OR that receives the output of the light receiving element 3 and the branch output of the signal source 4 as input. A circuit 64, a flip-flop 65 which receives the output of the exclusive OR circuit 64 and the output of the monostable multivibrator 5, the output of the flip-flop 65 as a reset input, the branch output of the signal source 4 as a clock input, and a signal source. 4. A shift register 7 which outputs an output if there is no reset input from a flip-flop 65 during three or more clock signals according to 4.