JPH0650928Y2 - Photoelectric sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a photoelectric sensor, and more particularly to a photoelectric sensor that detects a mark attached to a conveyed sheet or the like.

(B) Conventional Technology Generally, in an automatic packaging machine or the like, a reflective photoelectric sensor or a transmissive photoelectric sensor is used to detect a mark conveyed by a roller. A conventional reflection type photoelectric sensor irradiates a sheet to be detected with light emitted from a light projecting portion through an optical system including a half mirror and a lens, and light reflected by the sheet or a mark is received by a light receiving portion through the optical system. Receive and detect the mark. In addition, in the transmissive photoelectric sensor, a light projecting section and a light receiving section are separately provided on the upper side and the lower side of the U-shaped case body to sandwich the conveyed sheet, and the light from the projecting section transmits through the sheet. The mark is detected depending on whether or not the light is received by the light receiving section.

(C) Problems to be solved by the invention In general, a single automatic packaging machine uses many kinds of packaging films. Therefore, for example, when a reflective photoelectric sensor is attached to an automatic packaging machine, when detecting a mark printed on an opaque film, reflected light is obtained for both the film and the mark, and the mark can be detected by the amount of light, but it is transparent. The print marks on the film cannot be detected stably. Rather, in this case, it is desirable to use a transmissive photoelectric sensor. Therefore, in order to perform stable mark detection regardless of the type of film, the photoelectric sensor is replaced and used according to the type of film, but this requires a great deal of time for replacement, which is not efficient. Two types of photoelectric sensors have to be purchased, which raises the problem of increasing the price of the automatic packaging machine.

In view of the above, the present invention has an object to provide a photoelectric sensor capable of detecting a mark printed on any kind of film, regardless of whether it is transparent or opaque, by the first photoelectric sensor.

(D) Means for Solving the Problems The photoelectric sensor of the present invention has a case body (1) having first and second storage parts (3, 4) facing a body with a space (2) having a predetermined width. And a light projecting part (5) provided in the first storage part of the case body (1) and projecting light toward the space (2).
And the space (2) of the light projected from the light projecting section (5), which is provided in the first housing section of the case body (1).
A first light receiving part (8) for receiving the reflected light reflected by the object to be detected existing in the above and a second storage part of the case body (1), and the light is projected from the light projecting part (5). The second light receiving portion (9) that receives the transmitted light that has passed through the space (2) or the detected object among the reflected light and the outputs of the first and second light receiving portions (8, 9). A signal processing circuit (29) that receives and outputs a detection output.

(E) Function In this photoelectric sensor, the light from the light projecting portion is applied to the sheet passing through the space of the case body through the optical system. The light reflected by the sheet is received by the first light receiving portion via the optical system, and when the sheet is a transparent body,
The light that has passed through the sheet is received by the second light receiving unit. When the sheet is an opaque body, the mark detection output is obtained by the first light receiving unit, and when the sheet is a transparent body, the mark detection output is obtained by the second light receiving unit.

(F) Example <Example 1> FIGS. 1 (a) and 1 (b) are a side view and a front view of an optical system of a photoelectric sensor showing an example of the present invention.

The case body 1 is formed in a U-shape, sandwiches the space 2, and has an upper case portion (first storage portion) 3 and a lower case portion (second storage portion) 4. The upper case portion 3 has a light emitting diode (light emitting portion) 5 and an optical axis from the light emitting diode 5 45
A half mirror 6 having an angle of °, a raise 7, and a composite photodiode (first light receiving portion) 8 are provided, and a composite photodiode (second light receiving portion) 9 is provided in the lower case portion 4. Has been. Here, the composite photodiodes 8 and 9 are two photodiodes 8a,
8b and 9a, 9b, photodiodes 8a and 8b,
9a and 9b have the same light receiving area. These photodiodes 8a and 8b and 9a and 9b are, as shown in FIG. 1 (b),
The seats 10 are arranged so as to be displaced in the traveling direction.

In this photoelectric sensor, the light from the light emitting diode 5 passes through the half mirror 6 and the raise 7, and then passes through the space 2 into the sheet 10.
Alternatively, the mark 11 is illuminated and the reflected light is reflected by the lens 7,
The light is received by the composite photodiode 8 via the half mirror 6. When the sheet 10 is transparent, the light emitted from the light emitting diode 5 passes through the sheet 10 through the half mirror 6 and the raise 7, and is received by the composite photodiode 9.

FIG. 2 is a block diagram showing the circuit configuration of the photoelectric sensor of the embodiment.

When the light emitted from the light emitting diode 5 is received by the light receiving regions 8a and 8b of the composite photodiode 8, the signal is amplified to some extent by the amplifiers 21 and 22, and then amplified by the differential amplifier 25 to be used as a window comparator. Entered in 27. The window comparator 27 has Vth ₁ and Vt around 0V.
It has two threshold voltages of h ₂ and outputs a signal when the output of the differential amplifier 25 exceeds the threshold Vth ₁ or falls below the threshold Vth ₂ . Further, the composite photodiode 9 is also subjected to the same signal processing as that of the composite photodiode 8, and the window comparator 28 outputs a signal in the same operation as the window comparator 27. Furthermore, the outputs of the window comparators 27 and 28 are OR (logical sum) circuit 29.
When any one of the window comparators 27 and 28 has a signal output, the OR circuit 29 outputs a signal and the object detection output is output to the outside through the output circuit 30.

Next, the operation of the photoelectric sensor of the above embodiment will be described in the case of using three typical types of films. The film used is an opaque film with a mark with low reflectance, a transparent film with a mark with low reflectance,
There are three types of transparent films with high reflectance marks. First, when a sheet having a mark with a low reflectance on an opaque film is passed through the space 2, as shown in FIG. 3 (a), since the sheet 10 is opaque, the sheet 10 and the mark 11 are formed. The light that hits is reflected and returns to the upper case body 3 again, so that it is not received by the composite photodiode 9 of the lower case portion 4. Therefore,
The outputs of the light receiving regions 9a and 9b of the composite photodiode 9 are both 0. On the other hand, the amount of light reflected by the sheet 10 and the mark 11 is larger in the amount of light reflected by the sheet 10, and an optical signal having a level difference between them is shifted to the light receiving regions 8a and 8b of the composite photodiode 8 with a time shift. The received light signals are amplified by amplifiers 21 and 22, respectively, differentially amplified by a differential amplifier 25, and a window comparator 27 derives a signal that achieves a threshold value at a high level. Through,
Two pulse signals are output to the output circuit 30, whereby the mark can be detected.

When a mark having a low reflectance is attached to the transparent film, as shown in FIG. 3 (b), the sheet 10 is transparent and light passes through, but the mark 11 has a low reflectance, There is almost no reflected light at all times, so the composite photodiode 8
The outputs of the light receiving areas 8a, 8 of the differential amplifier 2 are almost 0.
5, the output of the window comparator 27 also becomes 0. On the other hand, the light that has passed through the sheet 10 is received by the light receiving regions 9a and 9b of the composite photodiode 9, so that the received light output is derived, and at a level where it exceeds the predetermined threshold values Vth ₁ and Vth ₂ , Since the output is respectively derived from the window comparator 28, the window comparator 28,
Two pulse signals are also output through the OR circuit 29 and the output circuit 30, and the mark 11 is detected.

Further, when the clear film is provided with a mark having a high reflectance, as shown in FIG. 3 (c), there is no reflected light in the transparent portion of the sheet 10 but only transmitted light, and this transmitted light is a composite. The light is received by the light receiving regions 9a and 9b of the type photodiode 9, and an output is obtained, while the light reflected by the mark 11 having a high reflectance is also received by the light receiving regions 8a and 8b of the composite type photodiode 8. Output can be obtained from these. Therefore, the pulse output is obtained from each of the differential amplifier 25, the window comparator 27 and the differential amplifier 26, and the window comparator 28, and these are output from the output circuit 30 via the OR circuit 29, so that the mark 11 is also detected. can do.

As described above, in the photoelectric sensor of this embodiment, the light emitting diode 5 and the composite photodiode 8 constitute a reflective photoelectric sensor, and the light emitting diode 5 and the composite photodiode 9 constitute a transmissive photoelectric sensor. Since the logical sum of the detection outputs of both the photoelectric sensor and the transmissive photoelectric sensor is taken as the output, the sheet 10 is transparent / opaque, and the mark 11 having a low reflectance or a high reflectance can be used. Since only one detection output can be obtained, it is not possible to detect all kinds of marks with one photoelectric sensor without preparing two photoelectric sensors specially.

<Embodiment 2> FIG. 4 is a side view of a photoelectric sensor of Embodiment 2 showing a different optical system of the present invention.

This photoelectric sensor includes a light emitting diode 5, a lens 7 and a composite photodiode 8 in an upper case portion 3 of a U-shaped case body 1, and a composite photodiode 9 in a lower case portion 4 through a space 2. 1 is similar to the embodiment shown in FIG. 1 in that the light emitting diode 5 is placed on the central axis of the lens 7, and the lens 7 and the light emitting diode 5 are arranged in the space 2 It is different in that it is made to face the transmissive composite photodiode 9 through the body.

Further, the composite photodiode 8 is provided on the back surface of the light emitting diode 5 on the optical axis, and the composite photodiode 8 and the lens 7 are held by the fixing holder 12.

In the photoelectric sensor of this embodiment, the light from the light emitting diode 5 is applied to the sheet 10 having the mark 11 passing through the space 2, and if the sheet 10 is transparent, the light transmitted through the sheet 10 is the composite photodiode. When the sheet 10 and the mark 11 are opaque, the light from the light emitting diode 5 is reflected and is received by the composite photodiode 8 via the lens 7 around the light emitting diode 5. The signal processing may be the same as that of the circuit of FIG.

According to the photoelectric sensor of this embodiment, since the half mirror is unnecessary, a more simplified photoelectric sensor can be obtained.

Example 3 The circuit shown in FIG. 5 is a circuit block diagram of Example 3, and the optical system of this example uses the optical system shown in FIG. 1 or 4.

The feature of the photoelectric sensor of this embodiment is that the light emitting diode is modulated and driven by the oscillation circuit 37, and the signals received by the composite photodiodes 8 and 9 are modulated light, that is, pulsed light. Accordingly, the outputs of the window comparators 27 and 28 are a large number of pulse signals, the gates 31 and 32 of which are opened in synchronization with the pulse signals, and the integration circuit 3
Waveform shaping circuit 35, 3 by integrating many pulse signals with 3, 34
Waveform is shaped at 6. It is different from the circuit of FIG. 2 in that it further includes these gates, an integrating circuit, and a waveform shaping circuit.
However, the point that a signal is output from the output circuit 30 via the OR circuit 29, that is, the logical sum of the signal outputs of the reflective photoelectric sensor and the transmissive photoelectric sensor is taken, is the same as in the first embodiment.

In the photoelectric sensor of this embodiment, since the light receiving circuit receives only the modulated light (pulse light), it is not affected even if noise outside the light emission period enters, and the ambient light characteristics and noise resistance are improved. There is.

Example 4 FIG. 6 is a sectional view of an optical system of a photoelectric sensor of Example 4, and FIG. 7 is a circuit block diagram of the photoelectric sensor.

The photoelectric sensor of this embodiment also has the above-mentioned embodiments in that the upper case portion 3 of the U-shaped case body 1 is provided with a light projecting portion and a reflective light receiving portion, and the lower case portion 4 is provided with a transmissive light receiving portion. Similar to the example, but with two light emitting diodes as the light emitter,
That is, a red light emitting diode 61 and a green light emitting diode 62 are provided, the lights from the red light emitting diode 61 and the green light emitting diode 62 are mixed by a half mirror 63, and a space is obtained via a lens 64, a mirror 65, and lenses 66 and 68. While the sheet passing through 2 is irradiated with light, the irradiated light is reflected by the sheet 10
Alternatively, the light is reflected by the mark 11 and is received by the composite photodiode 8 for light reception through the lenses 66 and 67. Further, in the circuit portion, the pulse signal oscillated and output by the oscillation circuit 37 is divided by the frequency dividing circuit 38, and the red light emitting diode 61 and the green light emission are generated by the two signals output from the frequency dividing circuit 38 in a time division manner. The diodes 62 are alternately turned on and off in a time-division manner. The light output from the red light emitting diode 61 or the green light emitting diode 62 is received by the composite photodiode 8 or 9 depending on the form of the sheet passing through, and is output from the output circuit 30 through each light receiving circuit unit or OR circuit 29. In that respect, it is the same as each of the above embodiments.

However, the red light emitting diode 61 and the green light emitting diode 62
Is time-divisionally driven by the frequency dividing circuit 38, the time-division signals are input to the gates 31 and 32, during which the gates are opened, and the respective signal outputs are integrated by the integrating circuits 33 and 34, respectively.
The waveform is shaped by the waveform shaping circuits 35 and 36, and the output is ORed 29
It is designed to be input into.

According to the photoelectric sensor of this embodiment, the red light emitting diode 6
1. If the reflectance or the transmittance of at least one of the green light emitting diodes 62 changes, an output signal can be obtained. Therefore, the combination of the transparency and the color of the sheet 10 and the mark 11 passing through expands the detectable combination of the film and the mark, so that the mark can be detected in a wider range.

It should be noted that, in the case where the composite photodiode is used for the light receiving portion as in each of the above-described embodiments, no switching operation or sensitivity adjustment is necessary due to the difference in the type of sheet or mark.

Of course, in each of the above-mentioned embodiments, the case where each light receiving portion uses the composite type photodiode is shown, but the present invention can be applied to the case where one light receiving photodiode is used.

(G) Effect of the Invention According to the present invention, the first storage part of the one case body in which the first storage part and the second storage part face the space, the light projecting part and the detected object are provided in the first storage part. Since the first light receiving section for receiving the reflected light reflected by the body and the second light receiving section for receiving the transmitted light transmitted through the detected object are provided in the second storage section, the sheet to be detected and Regardless of the mark, the output of either the reflective photoelectric sensor or the transmissive photoelectric sensor can be obtained, and the mark can be reliably detected.

Therefore, even if the types of sheets and marks to be packaged are changed, it is not necessary to replace the photoelectric sensor one by one, labor is saved, and only one photoelectric sensor is required, so that the cost of the entire apparatus can be kept low. There is an advantage.

[Brief description of drawings]

1 (a) is a side view of the case body of the first embodiment, FIG. 1 (b) is a front view of the case body, and FIG. 2 is a circuit block diagram of the photoelectric sensor of the first embodiment. FIG. 4 is a waveform diagram for explaining the operation of the photoelectric sensor of the same embodiment, FIG. 4 is a side view of the photoelectric sensor of the second embodiment, and FIG. 5 is a circuit block diagram of the photoelectric sensor of the third embodiment. FIG. 6 is a side view of the case body of the photoelectric sensor of the fourth embodiment, and FIG. 7 is a circuit block diagram of the fourth embodiment. 1: Case body, 3: Upper case part, 4: Lower case part, 5 ・ 61 ・ 62: Light emitting diode, 6: Half mirror, 7: Lens, 8: Composite photodiode (for reflection type), 9: Composite Type photodiode (for transmissive type), 29: OR circuit.

Claims (1)

[Scope of utility model registration request] 1. A first and a second that face each other with a space of a predetermined width.
A case body having a storage part, a light projecting part provided in the first storage part of the case body, for projecting light toward the space, and provided in the first storage part of the case body, A first light receiving portion that receives reflected light that is reflected by a detection object that is present in the space among the light that is emitted from the light emitting portion, and is provided in a second storage portion of the case body. A second light receiving portion that receives transmitted light that has passed through the space or the detection target among the light projected from the light portion, and outputs a detection output by receiving the outputs of the first and second light receiving portions. A photoelectric sensor, comprising: