JPS62148878A - Photointerrupter - Google Patents

Abstract

PURPOSE:To reduce the number of external terminals to three, to eliminate the need to incorporates a resistor in an interrupter casing, and to reduce the size and cost of a photointerrupter by composing an output circuit integrated element of a constant voltage circuit, a resistance element, an amplifying circuit, a Schmitt trigger circuit, and an output transistor (TR), and connecting it in series with a light emitting element. CONSTITUTION:The light emitting diode 2 is put in the projection part 1a of the interrupter casing 1 and the output circuit integrated element 4 which includes a photodetecting element 3 in a photodetection part 1b formed across optical coupling path gaps L and C; and the light emitting diode 2 and output circuit integrated element 4 are connected in series between common power source terminals 5 and 6, and an output terminal 7 is led out of the output circuit integrated element 4. Consequently, the number of terminals is reduced to three and the resistor need not to be incorporated in the interrupter casing, so the small-sized photointerrupter is formed at low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical field of the present invention The present invention relates to a method of integrally combining a light emitting element and a light receiving element with an optical coupling path gap in between, and detecting the presence or absence of a specimen in the optical coupling path gap; This relates to a photointerface that optically detects position, phase, etc.

(b) As the prior art and its problems are well known,
A photointerrupter has a single casing that includes a light emitting part and a light receiving part, and houses a light emitting element, typically a light emitting diode, on the light emitting part side, and a photodiode, an amplifier, and an output on the light receiving part side. This is a unit type electronic circuit component that houses photoelectric conversion circuit elements including transistors and the like. This photointerrupter is divided into a transmissive interrupter, in which the light-emitting surface and light-receiving surface of each element face each other to form a linear optical coupling path, depending on the arrangement of the light-emitting element and the light-receiving element; It is classified as a reflective interrupter, which is arranged as follows.

An example of the configuration of a conventional photo-interrogator will be described based on the seventh factors A and B using a transmission type interrupter as an example.

The conventional photointerrupter shown in factor 7 A has a structure in which the light emitting side and the light receiving side are driven by separate power supplies, and the photointerrupter shown in FIG. The configuration is such that both are driven by a common power source. 7th
The photointerrupter of the type shown in factor A houses a light emitting diode with a power terminal and a cap in the interrupter casing (2D light emitting part (21a), and has a light receiving part (21a)).
b) houses an output circuit integrated element (towards) including a light receiving element θ equipped with an integrated element terminal side, C11l and an output terminal, and the head direction current of the light emitting diode
This type is determined by the voltage between 1 and the power supply terminal example.

On the other hand, the type of photo ink converter shown in FIG. 7B is
Interrupter casing (output circuit integrated element (towards) containing a light emitting diode and a resistive element r3z in the 2D light emitting part (21a) and a light receiving element in the light receiving part (21b))
A type in which the light emitting part (21a) is provided with a common power terminal for the light emitting diode and the output circuit integrated element (to), and the light receiving part (21b) is provided with an output terminal. belongs to. These types of photointerrupters have the following problems.

(i) The photo interrogator of the type shown in Figure 17A is
It is said that miniaturization is difficult because five external terminals are required. On the other hand, in the photointerrupter of the type shown in FIG. 7B, although the number of external terminals is reduced to three, a resistor is incorporated inside the casing, so there are still problems in miniaturization and cost reduction.

(In these photointerrupters, the amount of light emitted from the light emitting diode is approximately proportional to the forward current F, and the forward current F depends on the power supply voltage V as shown in Equation 1.

Engineering F=(Voo-■)/R...Equation 1 Here, V
F is the /[ direction voltage of the light emitting diode, and is approximately a constant value (1.0 to 1.5 V).

Therefore, in the photoinverter of the type shown in FIG. 7B, if a fixed resistor R is incorporated, a specific power supply voltage Vc
An appropriate amount of light can be obtained only for o(Vcc-4F@R+VF). That is, it has the disadvantage that it is not possible to realize a photointerrupter with a wide operating power supply range. Also, the seventh
In each of the types of photoinkractors shown in factors A and B, if the power supply voltage V0° changes, IF also changes as shown in equation 2, making it impossible to keep the detection accuracy constant.

...Formula 2 %Formula % (d Technical Problems of the Present Invention Therefore, the present invention is to solve the above-mentioned problems of the conventional photointerrupter, and to reduce the size and cost of the product. To provide a photointerrupter that can be applied to either a transmissive type or a reflective type, which has a wide operating power supply range and can maintain constant detection accuracy even when the power supply voltage fluctuates, while reducing costs. It is in.

Furthermore, the present invention provides wires for the lead frame.
It is an object of the present invention to provide a photointerrupter including means for switching the output on the light receiving side to be ON when receiving light or ON when blocking light, depending on the selective design aspect of bonding.

(d) Technical Means of the Present Invention In order to achieve the above-mentioned object, the present invention specifically includes a pair of light emitting element and light receiving element arranged with an optical coupling path gap in between, and a photoelectronic element of the light receiving element. Integrally combines an output circuit integrated element that amplifies and outputs the converted signal,
In the photointerrupter that optically detects the presence, absence, position, phase, etc. of a test object in the optical coupling path gap, the output circuit integrated element that amplifies and outputs the photoelectric conversion signal includes a constant voltage circuit, and the constant voltage circuit. an amplifier circuit and a Schmitt trigger circuit connected in parallel to the resistor element, and an output transistor connected to the output side of the Schmitt trigger circuit; This is a photointerrupter in which the light emitting element is connected in series to a circuit integrated element.

Further, in the present invention, an output switching circuit having a ground terminal is connected between the Schmitt trigger circuit and the output transistor in the output circuit integrated element, and the ground terminal is grounded or ungrounded with respect to the lead frame. This is a photointerrupter that inverts the output signal of the output transistor by inverting the output signal of the output transistor.

(e) Examples of the present invention Hereinafter, regarding the photointerrupter according to the present invention,
A detailed description will be given based on specific embodiments shown in the drawings.

FIGS. 1A and 1B show the basic configuration of a photointerrupter according to the present invention. The photointerrupter shown in FIG.
A light emitting diode (2) is housed in the optical coupling path gap (L,
A light receiving element (3
), the light emitting diode (2) and the output circuit integrated element (4) are connected in series between the common power terminals (5) and (6), and the output The output terminal (7) is connected by a lead from the circuit integrated element (4). In this example, the output circuit integrated element (4
), the light emitting diode (2
) is configured to draw a constant current from the According to the above configuration, the number of terminals can be reduced to three, and there is no need to incorporate a resistor inside the interrupter casing, so that a small photo-inactivator can be manufactured at low cost. Further, since a constant current flows through the light emitting diode (2), a constant amount of light can be maintained over a wide range of operating power supply voltages. On the other hand, the photo ink converter shown in FIG.
The light emitting diode (2) is housed in the optical coupling path cavity (
An output circuit integrated element (4) including a light-receiving element (3) is housed in a light-receiving part (1b) formed with gaps L and C),
With the common power terminal (6) provided on the light emitter side.

The light emitting diode (2) and the output circuit integrated element (4) are connected in series between the common power supply terminal C51 provided on the light receiving part side, and the output terminal (sword is connected as a lead) from the output circuit integrated element (4). In this example, the output circuit integrated element (4) is connected to the light emitting diode (2) to supply a constant current, and the effect is similar to that of the photointerrupter of the type shown in Figure 1A. Next, the circuit configuration of the output circuit integrated element (4) on the light-receiving section side in the photointerrogator according to the present invention will be explained based on FIG. 2. In this invention, the output circuit integrated element (4) 4) includes a constant voltage circuit (8) and the constant voltage circuit path (8).
) and ground, a resistor (9) connected so that a constant current flows between the resistor (9), a linear amplification port N (10) and a Schmitt trigger circuit f connected in parallel to the resistor (9).
ill, and the Schmitt trigger circuit (11)
It consists of an output transistor (12) connected to the output side of be.

However, the current consumption of the color output transistor (121) of the Schmitt trigger circuit wi+111 varies by about 1.5 to 2.0 times when the photodiode receives light and when it blocks light.In this invention, The above-mentioned current fluctuations can be suppressed to a minimum, and a constant current that is sufficiently large compared to the current fluctuation can be controlled by a resistor (
9), the current consumption of the entire output @J path integrated element (4) is kept almost constant. A specific example of a Schmitt trigger circuit configured to reduce the above-mentioned current fluctuation will be described with reference to FIGS. 3A and 3B together with the circuit configuration of the present invention. The Schmitt trigger circuit σD includes transistors T11T2, T
s, T4 and resistance Rt, R2, R3, R4, R
s. FIG. 3A shows the current flowing when the output transistor (121) is OFF,
FIG. 3B shows the current flowing when the output transistor σ2 is ON. In this circuit configuration, the constant voltage value is v
s, the base-emitter voltage of the transistor is VBE (
(approximately 0.65 V), collector-emitter voltage at saturation is VCE (approximately 0.2 V), R2) R□, Ra
) Ri, then each current value is.

It is approximately expressed by 28-1 and formula 3-2.

Here, if R2=R3, "Hl + Engineering H2 = ILs + IL2.

Also, (2VBE-VCE) XRs = (VS -
If resistors R4 and R5 are selected so that VBE - Vcg ) The implementation data is shown in Figure 4.

This figure shows the relationship of the current consumption on the light receiving circuit side with respect to the power supply voltage.As is clear from the figure, if the power supply voltage is kept constant, the fluctuation in the current consumption on the light receiving circuit side will be reduced by approximately 5.
It can be seen that it is less than 100%. Here, if a constant current of about 77 ffA is passed through the resistor (9), the variation in current consumption on the light receiving circuit side will be about 1%, and the forward current IF
Since is constant, the amount of light emitted from the light emitting diode is also constant. Furthermore, since the variation in current consumption with respect to variation in power supply voltage is sufficiently smaller than in equation 2, a photointerrupter with a conventional configuration can also maintain stable detection accuracy with respect to variation in power supply voltage.

Next, based on FIG. 5, the output transistor (12
The means for switching ON/OFF of 1 will be explained. In FIG. 5, the output transistor (121 is ON/OFF).
The OFF switching means is the Schmitt trigger circuit (1)
) and the output transistor (17J, resistor R6,
It is composed of R7 and wire bonding pad I. In this circuit example, when the wire bonding pad (141) is grounded to the lead frame α mark by wire bonding, as shown in FIG. In this case, the output of the Schmitt trigger circuit (11) is transmitted in reverse phase to the base of the output transistor 2 via transistors T6 and T7. , the emitter of transistor T6 is a constant voltage circuit (
It does not operate because it is pulled up to the output voltage of 8). In this case, the output of the Schmitt trigger circuit 111) is transmitted in phase to the base of the output transistor σ2 via the transistors T5 and T7. Therefore, depending on whether the wire bonding pad OJ is grounded by wire bonding or left open,
It is possible to switch ON/OFF of the output transistor σ2.

Figure 6 shows the output circuit integrated element (4) when the wire bonding pad (141) for output switching is grounded.
) shows an example of wire bonding.

In this case, the output circuit integrated element (4) provided with the light receiving element (3) is fixed to a lead frame stopper. The output circuit integrated element (4) is equipped with wire bonding pads (141, (1ω, α6) and (1η), and the band circle is connected to a lead frame (181
, the pad (151 is another glued σ9), the pad (
Iω is connected to yet another lead. The pad (141) is selectively connected to the lead frame αa as described above.

(f) First of all, the photointerrupter of the present invention, which has a configuration that exceeds the effects of the present invention, can be configured with three external terminals, and there is no need to incorporate a resistor inside the interrupter casing. Therefore, it can be said that it is extremely effective in terms of reducing the size of the product and reducing the cost of the product. Second, in the output circuit integrated element, a resistive element is interposed between the constant voltage circuit and the ground, and a light emitting diode is connected in series to the output circuit integrated element, so that a constant current is applied to the light emitting diode. It has the feature that it has a wide operating power supply range and can maintain constant detection accuracy even when the power supply voltage fluctuates by keeping a constant amount of light over a wide range of operating power supply voltages.

Third, a switching circuit equipped with a wire bonding pad is provided on the input side of the output transistor, and the wire bonding pad is provided on the input side of the output transistor.
By grounding or ungrounding the bonding pad to the lead frame, the output of the output transistor can be designed to be inverted, which is extremely advantageous in that it is easy to form a photointerrupter that matches the detection method of the test object. It can be said that there is.

[Brief explanation of drawings]

1A and 1B are block diagrams illustrating the basic configuration of the photointerrupter according to the present invention in relation to the interrupter casing, and FIG. 2 is a specific example of the output circuit integrated element on the light receiving side. The block diagrams shown in FIGS. 3A and 3B show a specific example of the Schmitt trigger circuit in the output circuit integrated device.
is a block diagram showing the flow of current consumption when the output transistor is OFF, Figure 3B is a block diagram showing the flow of current consumption when the output transistor is ON, and Figure 4 is the relationship between current consumption and power supply voltage. FIG. 5 is a block diagram showing a specific example in which a switching circuit for output inversion is interposed between the Schmitt trigger circuit and the output transistor by wire bonding, and FIG. A front view showing an example of wire bonding of an output circuit integrated device when a bonding pad is grounded, and FIGS. 7A and 7B are principle diagrams showing an example of the configuration of a typical conventional photointerrupter. (1) --- Interrupter casing (la)-
- 1 light emitting part (lb) - 1 light receiving part (2) - 1 light emitting diode f3) - 1 light receiving element (4) - 1 output circuit integrated element (5), (6 ) --- One common power supply terminal (7) --- One output terminal f8) --- Constant voltage circuit (9) --- One resistor (10) --- One linear amplifier circuit fill --- --Schmitt trigger circuit [121
-----One output transistor low 31----All switching circuit (141---Wire bonding pad)
Mei-6 <Nai・; Figure 3 Figure 4 Procedural amendment February 5, 1986

Claims (2)

[Claims] (1) Optical coupling path A pair of light emitting element and light receiving element arranged across a gap, and an output circuit integrated element that amplifies and outputs a photoelectric conversion signal of the light receiving element are integrally combined, and the optical coupling path is In a photointerrupter that optically detects the presence, position, or phase of a test object in an air gap, an output circuit integrated element that amplifies and outputs the photoelectric conversion signal is connected to a constant voltage circuit, and between the constant voltage circuit and ground. It consists of a resistive element connected, an amplifier circuit and a Schmitt trigger circuit connected in parallel to the resistive element, and an output transistor connected to the output side of the Schmitt trigger circuit, and A photointerrupter comprising the light emitting elements connected in series. (2) An output switching circuit equipped with a ground terminal is connected between the Schmitt trigger circuit and the output transistor in the output circuit integrated element, and the ground terminal is grounded or ungrounded with respect to the lead frame. The photointerrupter according to claim 1, wherein the output signal of the output transistor is inverted.