JP2823317B2 - Light receiving module - Google Patents

Description

The present invention relates to a light receiving module suitable for a control device or the like using an optical signal.

(B) Conventional technology Conventionally, modulated light such as infrared rays has been used for remote control operations in air conditioners, television receivers, and the like. In this case, Japanese Patent Application Laid-Open No. 58-204573 and Japanese Utility Model Application Publication No. As disclosed in Japanese Patent No. 17643, a light receiving element for receiving the light and performing photoelectric conversion, and an amplifier for increasing the output of the photoelectric conversion element are provided. This amplifier has a large amplification factor of approximately 80 to 90 dB so that it can respond even if the optical signal is weak, so that it is susceptible to noise.

(C) Problems to be Solved by the Invention Generally, measures against noise are made using a shield case or a filter. However, in the above-described modulation of infrared rays or the like, since a receiver such as a remote controller is often of a low-power mobile type, the modulation conditions are substantially determined, and the signal becomes a weak signal. For this reason, even if a shield case is used, the light receiving window must satisfy certain requirements in consideration of the amount of light transmission, directionality, etc., and the filter characteristics also take into account fluctuations in the power supply of the receiver and oscillation during movement. And could not have sharp characteristics.

For this reason, even if the amplified waveform is shaped and a certain ON / OFF signal is taken out, the extracted signal has a high frequency superimposed on it as shown in Fig. 7, and the control circuit of the device determines Make an error. Of such high-frequency, where especially large confirmed in harmonic components (experiments of the flyback transformer noise of a television receiver (1.6.6KH _z vicinity) and the drive of the fluorescent lamp (100～120H _z) It was 2KH _z ~6KH _z). In addition, in recent years, fluorescent lamps and the like are often turned on at high frequencies, and these generate optically and electromagnetically noise, so that it is difficult to remove this noise with the above-described filter characteristics having a low peak degree (Q). there were. Furthermore, a large-scale circuit is required to reshape the output once amplified by the light receiving module inside the device and extract a signal wave of a specific frequency component. At this time, noise is more likely to be added to the signal line Therefore, mounting the light receiving module on the device was a complicated operation.

In devices using these light receiving modules, especially when installed above a room (ceiling or a wall close to the ceiling), light from an oscillator, such as a remote controller, is hard to identify and is hard to receive. It's getting bigger.

(D) Means for Solving the Problems The light receiving module of the present invention includes a light receiving element that receives a modulated light beam such as infrared light and performs photoelectric conversion, and an amplifier that increases the output of the light receiving element. The amplifier has a filter connected between an amplifier and a detection / waveform shaping circuit. The filter includes a band-pass filter in which a fundamental frequency of the modulation is set as a center frequency, and the modulation circuit as a center frequency. Wherein the bandpass filter and the notch filter are directly connected and arranged close to each other.

The light receiving module according to the present invention includes a light receiving element that receives a modulated light beam such as an infrared ray and performs photoelectric conversion, an amplifier that amplifies the output of the light receiving element, and a light receiving element and an amplifier. A band-pass filter in which a fundamental frequency of the modulation is set as a center frequency, and a notch filter in which a frequency near the fundamental frequency of the modulation is set as a center frequency. Are arranged close to each other, and the notch filter is connected to the subsequent stage of the band-pass filter.

The bandpass filter sets the sharpness to 10 to 15,
The notch filter may set the center frequency 48~52KH _z.

(E) Function The light receiving module of the present invention has a band-pass filter in which the fundamental frequency of the modulation is set as the center frequency and a notch filter in which a frequency near the fundamental frequency of the modulation is set as the center frequency. The gain of a specific frequency near the fundamental frequency of the modulation can be greatly reduced by the notch filter while the reception sensitivity is kept high at a certain width around the fundamental frequency of the modulation by the band-pass filter. In particular, since a filter connected between an amplifier and a detection / waveform shaping circuit includes a directly connected bandpass filter and a notch filter, noise removal is performed using a plurality of bandpass filters having a common center frequency. Compared with the configuration, the reception sensitivity can be kept high within a certain width around the fundamental frequency of modulation, and a circuit configuration that is resistant to signal fluctuation of the transmitter can be obtained. In addition, since the band-pass filter and the notch filter are directly connected and arranged close to each other, the wiring of both can be set short, and further noise can be prevented during noise removal.
As a result, the output of the light receiving module has a high signal component, and the light receiving module can be easily handled.

Further, in the light receiving module of the present invention, the amplifier is
A bandpass filter in which the fundamental frequency of the modulation is set as the center frequency, and a notch filter in which a frequency near the fundamental frequency of the modulation is set as the center frequency. While keeping the receiving sensitivity high at a certain width in the center,
The notch filter can significantly reduce the gain at a specific frequency near the fundamental frequency of modulation. Further, since the notch filter and the band-pass filter are arranged close to each other, the wiring between them can be set short, and furthermore, by covering with a shield case, it is possible to prevent noise from being further removed during noise removal. Further, since the notch filter is connected downstream of the bandpass filter, noise near the fundamental frequency, which is difficult to attenuate by the bandpass filter, can be more reliably removed by the notch filter.

(F) Embodiment FIG. 1 is a sectional view of a light receiving module according to an embodiment of the present invention.
FIG. 2 is a block diagram thereof. In these figures,
(1) is a light receiving element that receives a modulated light beam such as an infrared ray and performs photoelectric conversion by reverse biasing, and includes a silicon PIN photodiode, a phototransistor, a pyroelectric element, and the like. Reference numeral (2) denotes an amplifier for amplifying the output of the light receiving element (1). The amplifier includes, for example, amplifier (21), filter (22), detection (23), and waveform shaping (24) circuits. (26), a block resistor (27), a capacitor (28), etc., which are fixed to the substrate (3) together with the light receiving element (1). The output of the amplifier (2) is output as it is or via a transistor. (5) is a shield case enclosing the light-receiving element (1) and the amplifier (2). The light-receiving window (6) is formed of a through-hole, a mesh-like hole or a light-transmitting electromagnetic shield film, and the substrate (3). ) Protrudes from the shield case only.

In such a configuration, the amplifier (2) has an amplification factor of 80 to 90 dB around the fundamental frequency of modulation of infrared rays or the like, and has a notch filter characteristic near the fundamental frequency. More specifically, the filter of the amplifier (2) (2
2) Op-amps (2a) forming a band-pass filter BPF having an amplification factor and op-amps (2b) (2b) forming a notch filter KF having a high Q as shown in FIG.
Can be configured. In the configuration shown in FIG. 3, that is, the configuration including the directly connected bandpass filter BPF and notch filter KF, the bandpass filter BP
F as the center frequency of F is the modulation frequency ₀ = _{37~40KH z,} Q
_{= F 0 / (| f-} f a | × 2) = 10~15 the selection set, the center frequency f ₁ (respectively the series resistance of the double-T bridge R, the branch resistors R / 2 of the notch filter KF, series Capacitors are each C,
When the branch capacitor to a value of _{2C, f 1 (1 / 2πRC} ) a be selected set 48～52KH _z commonly used in high frequency lighting fluorescent lamp, increasing width unit characteristics such as shown by the solid line in FIG. 4 Can be obtained. Has 20KH _z ~43KH Thus for example the 38KH _z peak
The characteristic of −10 dB or more can be maintained at _z .

Thus, by disposing the amplifier (2) in the space surrounded by the shield case (5), the directly connected band-pass filter BPF and notch filter KF in the amplifier (2) are arranged close to each other. As a result, both wirings can be set short. Since the filter (22) including the directly connected bandpass filter BPF and notch filter KF is connected between the amplifier (21) and the detection / waveform shaping circuits (23) and (24), the amplifier (21) The gain of a specific frequency can be greatly increased before receiving external noise compared to the case where a band-pass filter BPF and a notch filter KF are separately placed before the stage and after the detection / waveform shaping circuits (23) and (24). Can be reduced to As a result, it is possible to prevent noise from being further added during noise removal and to facilitate noise removal.

For the high-frequency components shown in FIG. 7, a light-receiving module is arranged at a place directly exposed to the proof light, such as in front of a fluorescent lamp or in front of a neon tube. investigated. As a result 50
H _z or 60H _z despite the using commercial power, high noise frequency of incidence of determination errors is harmonic 100 times 40 times the commercial frequency, especially in the range of 2KH _z ~6KH _z (neon tubes 2.2~2.4KH _z) were substantially gain 30dB~40dB in. Therefore, noise in away from such a center frequency f _o is, to reduce the sharpness Q of the band-pass filter BPF can be removed corresponding to the. And even more preferably attenuates a characteristic such as shown by the broken line in FIG. 4 below 17KH _z noisy f ₂ ≒ 16.6KH _z of the flyback transformer by a high-pass filter (low-cut filter).

In this way, when selectively increasing the increasing width ratio of Zohaba instrument at approximately 20～43KH _z, since the operation even near the appliance or the like using the commercial frequency is ensured, for example, disposed near the ceiling light It can also be used as a light receiving module for an optical remote controller with extremely few malfunctions even in a ceiling-mounted air conditioner that has been manufactured.
However, in equipment installed above the remote controller, the elevation angle from the remote controller (transmitter) to the light receiving module is large, and the effective light receiving angle of the light receiving module is too narrow for the movement of the operator, making it difficult to operate. In some cases,
In such a case, instead of using two light receiving modules, the light receiving distribution of the light receiving module itself may be expanded. One method is to cover a silicon light-receiving pellet or the like in the light-receiving element with an amorphous film having a refractive index of 3 or more. However, what is simpler and more effective is to use two light receiving elements in the light receiving module.

5 and 6 show a cross-sectional view and a block diagram of such a light receiving module. The light receiving elements (11) and (11) are provided in different directions (X) and (Y), and the shield case ( 50) has a light receiving window (60) on the top surface and a total of five surfaces around it, and when the aperture ratio of the light receiving window (60) is large, the light-transmitting electromagnetic shield film (61) is attached to the inner wall of the shield case (50). It is provided along. The light receiving elements (11) and (11) are connected in parallel, and the output terminal thereof is connected to an amplifier (200) for amplifying only a signal of a predetermined frequency width.
The output sum of the two light receiving elements (11) and (11) is input to 0).

More specifically, the light receiving element (11) (11)
Are fixed with the light receiving elements (11) and (11) having an effective light receiving angle of ± 45 degrees arranged so that the light receiving surfaces are orthogonal to each other, and both are connected to the first stage amplifier (201) of the amplifier (200). . The amplifier (200) has a limiter (202) in addition to the first stage amplifier (201),
It consists of a bandpass filter (203), a detector (204), and a waveform shaping circuit (205).
The Q sharpness Dosa 3), or a sufficient gain in the frequency band 20～45KH _z is made so as to obtain the bandwidth limitations and combinations or bandwidth limit and the notch filter and the combination of the high-pass filter of the notch filter, 2～17KH _z as a whole with respect to the peak value of the amplifier (200), 48~52KH _z
Attenuation of 60dB or more in the frequency band of, for example, A _{f = 2.4KHZ} -60dB
Are constants set to be _{≦ A f = 40KHZ ≧ A f} = 50KHz -60dB.

In such a light receiving module, the light receiving sensitivity characteristics (azimuth dependence) of each light receiving element (11) (11)
(A) Although the center of (A) is oriented in the X-axis and Y-axis directions,
The two light receiving elements (11) (1
High light receiving sensitivity (B) is obtained as the output sum of 1). Considering the case where the magnitude of the photocurrent of the light receiving elements (11) and (11) or the magnitude of the voltage drop generated depending on the magnitude of the photocurrent is led to the first-stage amplifier (201), the X-axis Alternatively, for incident light from the direction of the Y-axis, a saturated current flows through the light-receiving elements (11) and (11) in the front direction, whereas for incident light from the S-axis direction, which is an intermediate direction. Since the operating current i of both light receiving elements (11) and (11) flows, about two light receiving elements are required for one light receiving element for the first stage amplifier (201).
It is equal to the flow of the operating current i, and has a role of averaging noise components that have a phase difference due to reflection or the like. Therefore, the output of the amplifier (200) can obtain a good light receiving sensitivity characteristic which cannot be obtained even when the two light receiving modules are arranged in two places in the same form even in the intermediate S axis. Thereby, for example, there is a certification device in front of the air conditioner, such as a ceiling in a general home, and reliable light receiving control can be performed even when the remote control device moves largely in the room.

(G) Effect of the Invention As described above, according to the light-receiving module of the present invention, the reception sensitivity is kept high at a certain width around the fundamental frequency of the modulation by the bandpass filter, and the vicinity of the fundamental frequency of the modulation is maintained by the notch filter. Because the gain of the specific frequency can be greatly reduced, reliable reception can be performed even if noise near the fundamental frequency or signal fluctuation of the transmitter occurs.
Handling can be facilitated. Further, the band-pass filter and the notch filter can be directly connected to each other so that the wiring between them can be set short, and further noise can be prevented from being removed during noise removal. As a result, the output of the light receiving module has a high signal component, and the light receiving module can be easily handled.

By including the light receiving element and the amplifier in the shield case, external noise can be further reduced. Further, if the notch filter is connected after the band-pass filter, noise near the fundamental frequency, which is difficult to attenuate by the band-pass filter, can be more reliably removed by the notch filter.

[Brief description of the drawings]

FIG. 1 is a sectional view of a light receiving module according to an embodiment of the present invention, and FIG.
The figure shows the block diagram, and the figure 3 shows the amplifier (its filter).
FIG. 4 is a frequency characteristic diagram of the amplifier, FIG. 5 is a sectional view of a light receiving module according to another embodiment of the present invention, FIG. 6 is a block diagram thereof, and FIG. It is a waveform diagram. (1) ... light receiving element, (2) ... amplifier, (21) ... amplifier, (22) ... filter, (23) ... detection circuit, (2)
4) Waveform shaping circuit, (5) Shield case, (B
PF) Band pass filter, (KF) Notch filter.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Susumu Maeda 3-201 Minamiyoshikata, Tottori City, Tottori Prefecture Tottori Sanyo Electric Co., Ltd. (56) References 56-110347 (JP, A) Jiko 61-17643 (JP, Y2)

Claims (3)

(57) [Claims] 1. A light receiving element (1) for receiving a modulated light beam such as an infrared ray and performing photoelectric conversion, and an amplifier (2) for amplifying an output of the light receiving element (1). Amplifier (2)
Has a filter (22) connected between an amplifier (21) and a detection / waveform shaping circuit (23, 24), and this filter (22)
Has a band-pass filter (BPF) in which a fundamental frequency of the modulation is set as a center frequency and a notch filter (KF) in which a frequency near the fundamental frequency of the modulation is set as a center frequency. A light receiving module, wherein the BPF) and the notch filter (KF) are directly connected and arranged close to each other. 2. A light receiving element (1) for receiving a modulated light beam such as an infrared ray and performing photoelectric conversion, an amplifier (2) for increasing the output of the light receiving element (1), and a light receiving element (1). 1) and a shield case (5) enclosing an amplifier (2), wherein the amplifier (2) is a band-pass filter (BPF) in which a fundamental frequency of the modulation is set as a center frequency. And a notch filter (KF) in which a frequency near the fundamental frequency of the modulation is set as the center frequency, and this notch filter (KF) is placed in the band-pass filter (BP
F) A light receiving module, which is connected to the subsequent stage. Wherein said band-pass filter (BPF) sets the sharpness 10-15, said notch filter (KF) is claim 1, characterized in that set the center frequency 48～52KH _z or 2. The light receiving module according to 2.