JPS6234431A - Receiver for optical communication - Google Patents

Abstract

PURPOSE:To accurately read out only a signal light component corresponding to an optical signal, by providing an inductance which is connected with a photoelectric element in series and making signals of lower than a prescribed frequency to flow out of the signals produced in the photoelectric element. CONSTITUTION:A capacitor C1 is used for cutting off a DC component and an inductance L1 and resistance R1 make a photoelectric current produced by a signal component to flow to the direction of the capacitor C1 and another photoelectric current produced by an outside-of-periphery light component to flow to the direction of the inductance L1. Moreover, a comparator CON1 compares the voltages across both ends of the resistance corresponding to the intensity of the outside-of-periphery light component with a reference voltage and decides whether or not the intensity of the outside-of-periphery light exceeds a prescribed value. In accordance with the results, the comparator CON1 controls the detection sensitivity and prevents noises from being transmitted to a data reading circuit.

Description

[Detailed Description of the Invention] Production 1 Yu! The present invention relates to an optical communication device that uses optical signals for signal transmission, and more particularly to a receiving device thereof.

Obedience! Traditionally, optical communication devices have used a photoelectric element such as a photodiode as a light receiving means, and the photoelectric element receives an optical signal from a transmitting device to enable information transmission and remote control of other devices. Are known. And such reception 5fc
In this case, a configuration in which a resistor is connected in series with a photoelectric element is known.

However, in such a configuration, when the ambient light is bright, such as when used outdoors, the photocurrent increases,
There is a drawback that the potential at the connection point between the photoelectric element and the resistor increases and approaches the power supply voltage, making it difficult for photocurrent to flow and deteriorating sensitivity.

Therefore, in the conventional configuration, the receivable distance becomes shorter when the illumination becomes high, and conversely, if the receivable distance is increased, it can only be used under low illuminance.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an optical communication receiving device that can accurately receive signal light without deteriorating sensitivity due to external light even when used outdoors or in a place where there is a lot of external light. be.

In order to achieve the above object, the present invention provides a receiver for optical communication J that receives optical signals emitted from a remote location.
In the device, a photoelectric element for receiving an optical signal and a light 1! It is characterized by having an inductance that is connected in series with the photoelectric element and allows a signal of a predetermined frequency or lower to flow among the signals generated in the photoelectric element.

Therefore, according to the present invention, the low-frequency extraneous light components flow toward the inductance, so even if there are many extraneous light components, the sensitivity will not deteriorate, and only the signal light component corresponding to the optical signal can be accurately detected. Can be read.

(The following is a margin) Large 11 Examples - Hereinafter, examples of the present invention will be described in detail based on the drawings.

FIG. 1 shows photometry input using the optical communication device according to the embodiment of the present invention.
FIG. 2 is a perspective view showing a camera system that transmits information and controls operations. In Figure 1, (2) is the photographic lens (4)
(6) is an optical communication VC receiver that is electrically and mechanically connected to the camera body (2) as described later, (8) is the bottom surface of the camera body (2). A bracket (10) is electrically and mechanically connected to the camera body (2), and an electronic flash VC device is electrically connected to the camera body (2) via the bracket (8).

As shown in the front view of FIG. 2, the reception fi (6) includes a light receiving window (101) for receiving an optical signal from the transmitter shown in FIG. If the power supply voltage is insufficient due to the battery check circuit, 1! A light emitting diode (103) is provided for a voltage drop warning which is illuminated in the event of a disconnection.

Furthermore, a pair of light receiving lenses (101) are provided within the light receiving window (101).
04) and a pair of upper and lower light shielding doors (105) that can be opened and closed are respectively arranged. Its light shielding 7-door (105)
has a pair of protrusions (105) for manual opening and closing.
a) is formed. (106) is a reception display window, and when a normal reception operation is performed, a reception display light emitting diode (107), which will be described later, placed inside the window will blink, indicating that a normal reception operation has been performed. The operator controlling the transmitter will be informed. Behind the pair of light-receiving lenses (104), there are light-receiving elements (P D , ) (P D 2) each consisting of a photodiode, which will be described later.
is located.

Then, the receiving fi (6) has the upper part (6&) and the lower part (6b
) and a shoe 77) provided at the lower part (6b).
(108) is attached to the camera body (2) by fitting into the seven-piece recess of the camera body (2), and its state is fixed by (109). In this state, the movable M formed on the shoe 77) (108)
, the heating bottle (110) comes into contact with the fixed contact provided on the accessory shoe of the camera body (2), and the receiver R (6) and the camera body (2) are connected to 1! physically connected. As a result, the camera body (2) receives exposure data and control data sent from the transmitter via the reception fi (6'), and further transmits necessary data from the bracket (8). It is also transmitted to the electronic flash device ff1 (10) via the electronic flash unit ff1 (10).

The upper part (6a) of the receiver mR (6') is relatively rotatable about the axis (X) extending in the vertical direction in FIG. The direction in which the light receiving display window (106) faces can be changed.

The exposure data received by the reception ff1 (6) is configured to be transmitted to the camera body (2) via a signal cord (111) connected to the input terminal (2a) of the camera body (2). Alternatively, the exposure data can be transmitted through the movable direct pin (110), while the control data can be transmitted through the signal code (11).
1) and may be configured to be transmitted to the camera body (2).

FIG. 3 is a block diagram showing the electric circuit of this embodiment. In Fig. tjIJ3, (12) shows the transmission modulation of an optical communication device that modulates the dinotal signal to be transmitted to several tens of KHz and transmits it as infrared light.
2), a meter (M) and a transmitting circuit (1'2a) are provided. Here, the meter (M) measures and stores the subject brightness and the amount of V flash light emitted by the incident light method, for example, as proposed by the applicant in Japanese Patent Application No. 59-17897, and measures the film sensitivity. An appropriate shutter speed and aperture value are calculated from setting data such as shutter speed and aperture value and photometry results and output as exposure data. Then, this exposure data is converted into an infrared light signal by the transmitting circuit (12a) and transmitted.
) photodiode consisting of a photodiode (PD, ) (PD
2) is received by.

(E) is a power battery of the receiver (6), and (SW,) is a power switch of the receiver (6). Power switch (S
When W, ) is closed, the photodetector (PD, ) (P
D2) receives the infrared light signal from the transmitter fi (12) and outputs a current (a) according to its intensity. This output current (,) is input to the amplification/detection circuit (14), which amplifies and detects this output current (,) and outputs it as a data signal (b) to the subsequent data reading circuit (16).
to communicate. Furthermore, this amplification/detection circuit (14) transmits! (Receive +j! regardless of the infrared light signal from 12>)
6) outputs a warning signal (c) when the steady light component (hereinafter referred to as external light) incident on the light receiving element (P D , ) (P D 2) reaches a predetermined value or more in intensity. The detailed configuration of this amplification/detection circuit (14) is shown in Figure tj44 and will be described in detail later.

The data reading circuit (16) is a circuit that reads and checks the data signal (b) from the amplification/detection circuit (14), stores the data in order to transmit it to the camera body (2), and transfers the data. Yes, and includes an interface circuit for data transfer. Then, the data reading circuit (1
6) transfers the read exposure data to the camera body (2) via the movable contact pin (110) shown in FIG. Further, the data reading circuit (16) includes an amplification detection circuit (16).
If the data signal (b) transmitted from 4) is correctly read, it outputs a signal (d) indicating that the signal transmitted by optical communication has been correctly read. Hereinafter, this signal (d) will be referred to as a verify signal.

(18) is a timer circuit, and a power switch (SW
+ ) is closed for a certain period of time, and the output timer signal (e) is set to H". This timer signal (e)
is a NOR circuit (N
The output signal (g>) of this NOR circuit (NOR, ) is input to one input terminal of the AND circuit (AND, ).The other input terminal of the AND circuit (AND, ) The output signal (r) of the oscillator (20) is input to , and the output signal (g) of the NOR circuit (NOR3) and the output signal (h) of the AND circuit (AND, ) are input.
) are input to the one-shot circuits (22) and (24), respectively. These one-sided circuits (22) (2
4) are each configured to output a pulse with a constant time width in response to the rise of the input signals (g) and (h).

Output signal (i) of both Funcitat circuits (22) (24)
(j) both pass through an OR circuit (OR1) to a signal (k
) is input to the battery check circuit (26). The lφ lattery tick circuit (26) checks the power supply voltage Vcc at a timing according to the input signal (k), and if the power supply voltage Vcc is below a predetermined value, it latches it and outputs the output signal (1). is output to light the voltage drop warning light emitting diode (BCLED). The operation of this battery check will be described in detail later.

The warning signal (c) of the amplification detection circuit (14), the verify signal (d) of the data reading circuit (16), and the timer signal (e) of the timer circuit (18) are each input to an OR circuit (OR,). Ru. And OR circuit (OR1)
The output of is inputted to the display drive circuit (30) as a signal (Im) via the delay circuit (28), and is input to the display drive circuit (30) via the delay circuit (28).
OR, ), when one input signal becomes “H”,
Then, after a certain period of time determined by the delay circuit (28), the verify display light emitting diode (VLED) is turned on by the display drive circuit (30). That is, the verify display light emitting diode (V L ED ) is
The timer circuit (18) is activated when the intensity of the external light exceeds a predetermined value and when the data is accurately read.
If the timer signal (e) is output from the display drive circuit (30), the display is turned on by the output signal (n) of the display drive circuit (30). Further, when the output of the OR circuit (OR,) becomes L'', the display drive circuit (30) turns on the verification display light emitting diode (V L E D ') after a certain period of time determined by the delay rectangle circuit (28). The lights are turned off.

Next, FIG. 4 shows a detailed configuration of the amplification/detection circuit (14) of this embodiment. In Fig. 4, the light receiving elements (P D , ) (PD 2) consisting of two photodiodes are connected in parallel to each other, and the output from the 7 node side is 3.
The number (,) is extracted. Both photodetectors (PD, ) (PD
The anode of 2) is grounded via an inductance (Ll) and one resistor (R9). Furthermore, the output ID number C
a> is input to the amplifier (32) via the capacitor (C5), and the output signal (, ) is amplified by the amplifier (32). This amplified signal is sent to the detection circuit (34
), and the detection circuit (34) converts the frequency to several tens of KHz.
The signal that has been modulated is detected, demodulated to the original dinotal signal, and transmitted to the subsequent waveform shaping circuit (36). The waveform shaping circuit (36) shapes the waveform of the input signal to be suitable for the subsequent data reading circuit (16), and outputs it as a data signal (b).

The inductance (Ll) is connected in series with the resistor (R1), and the connection point is the humparator (CON,)
is connected to the non-inverting input terminal of On the other hand, the comparator (
A reference power source (Vref, ) that generates a reference voltage is connected to the inverting input terminal of CON, ). Then, the output of the humparator (CON, ) is the above-mentioned warning signal (e).
At the same time, it is also input to the base of the transistor (Tr). This transistor (Tr,
) is connected to the detection circuit (34) via the resistor (R1).
and the emitter is grounded. Furthermore,
The detection circuit 113 (34) is grounded via a resistor (R2). Here, the transistor (Tri) is used as a switch, and the transistor (CONI) is used as a switch.
When the output signal of is "H", it is conductive, and when it is "L", it is non-conductive.

The operation of the amplification/detection circuit having such a configuration will be explained. First, when extraneous light unrelated to the signal to be transmitted enters the light receiving element (P D , ) (P D 2), a photocurrent proportional to the intensity of the extraneous light is generated.

Such a photocurrent has a direct current component or a frequency of 60 Hz x 2
(or 50Hz
Since the low frequency component of Hz)
) and the direction of the resistance (R3). And the resistance (
A voltage corresponding to the photocurrent is generated across R2). This voltage is detected by a comparator (CON) as a reference power supply (Vr).
eL), and the resistance (R
When the voltage across 1) is low, the intensity of the external light component is low and the photocurrent generated in the photodetector (PDI) (PD2) is small, so the output of the comparator (CON, ) becomes L'', and the warning signal ( c) cannot be generated. Therefore, in this case, the transistor (Tr, ) becomes non-conductive, and the current flowing from the detection circuit (34) to the ground is caused by the resistance (R2).
is kept small, and its detection sensitivity is set high. In other words, the light receiving element (PD,)
When the photocurrent generated in (PD2) is small, the sensitivity of the detection circuit (34) is set high.

In this state, the transmitter (12) transmits a frequency of several tens of KHz! The i-tuned infrared light signal is sent to the photodetector (PD).
2), the light receiving element (P D ,) (P D
2) generates a photocurrent due to the external light component and a photocurrent due to the infrared light signal. However, the inductance (L,) has a high impedance to alternating current components, while the impedance of the capacitor (C,) decreases, so the alternating current of the output photocurrent of the photodetector (PD,) (P D2) That is, the photocurrent component due to the infrared light signal component is input to the amplifier (32) via the capacitor (C3) and amplified. Then, the DC component, that is, the photocurrent component due to the external light, is cut by the capacitor (C5), so it flows toward the impedance (Ll) and the resistor (R1).The signal amplified by the amplifier (32) is
The detection circuit (34) is set to high sensitivity as described above.
The waveform is inputted to and detected by the waveform shaping circuit (36), and the waveform is shaped by the waveform shaping circuit (36) and outputted to the data reading circuit (16) as data number 3 (b).

Reverse-2, light-receiving element (P D , ) (P
Resistance (R1) of output light 'SL flow component of )
If the voltage across is greater than the reference voltage, the output of the comparator (CON,) becomes I('', and the warning signal (c)
is emitted and the light-emitting guide for displaying 7T (■L
E D ) is lit to warn the user that accurate signal transmission may be interfered with by extraneous light. Furthermore, the output of the humpator (CON,) is I4''
', the transistor (Tr, ) becomes conductive and the resistance (R
In addition to 2), the detection circuit (34) is grounded via the resistor (R1), and the current flowing from the detection circuit (34) to the ground increases, resulting in low sensitivity.

This is to remove the well-known effects of static noise and fluorescent lighting. In other words, the intensity of shot noise is approximately proportional to the square root of the brightness of the external light, and when the external light is strong,
The above-mentioned sitat noise may be mistaken for a signal component, and pulsed light from a fluorescent lamp may be mistaken for a signal component. If the external light component is strong, the detection circuit (34
) to prevent these noises from being transmitted as signals.

Here, due to the illumination of the AC light source, the output of the comparator (CON) becomes H″g″1. In order to prevent repetition of ``, it may be necessary to provide the humpator (CON) with hysteresis, but since it is not directly related to the present invention, its explanation will be omitted.

That is, to summarize the functions and operations of each electric element in the circuit shown in Fig. 4, first, the capacitor (C1) cuts the DC component, and the inductance (L, The photocurrent due to the component is converted to a condenser (C
1), and serves to cause the photocurrent due to the peripheral light component to flow in the direction of the inductance (L, ). Furthermore, the comparator (CON, ) has a resistance (CON, ) according to the intensity of the peripheral light component.
Ro) is compared with a reference voltage to determine whether the intensity of the peripheral light is equal to or higher than a predetermined value. Here, since the inductance (Ll) has almost no DC resistance value, by reducing the resistance value of the resistor (R1), the light receiving element (
This ends with improving the load characteristics when a load resistor is connected to P D , ) (P D 2). In other words, it is possible to accurately receive optical signals without the circuit becoming saturated even under high illuminance. However, if the illuminance becomes too high, the noise due to the external light component will be transmitted to the data reading circuit (16) as the data signal (b), so in this embodiment, the comparator (CON,
) to prevent noise from being transmitted to the data reading circuit (16), and to display a signal when the external light component is strong.

j! FIG. 35 is a circuit diagram showing a modification of the amplification/detection circuit shown in PIS4. In the configuration shown in Figure 4, the comparator (CO
Although the sensitivity of the detection circuit (34) was changed according to the judgment result of the comparator (C,
The amplification degree of the amplifier (32) is set to 51! according to the t'q constant result of ONI). It's in order. The difference between the configuration shown in FIG. 5 and the configuration shown in FIG. 4 will be explained. The amplifier (32) is grounded via a resistor (R6) and a capacitor (C2). The output of the comparator (CONl), whose non-inverting input and inverting input are opposite to those in FIG. The emitter is connected to the pace of the connected transistor (Trz). Therefore, the amplification degree of the amplifier (32) is determined by the resistance (Rs) (R, ).

That is, when the outer light component is small and the resulting photocurrent is small, the output of the comparator (CON, ) is 'H.
”, and since the transistor (Tr2) is conductive, the amplification degree of the amplifier (32) is determined by both the resistors (R1) and (R6), and is set to a high amplification degree. If the photocurrent is large and the resulting photocurrent is higher than the reference voltage, the output of the comparator (CON, ) becomes ``L'''' and the transistor (Tr2) is made non-conductive, so that the amplification degree of the amplifier (32) decreases. is the resistance (R
2) and is set to a lower amplification degree. Therefore, according to this modification, when the outer light component is strong, by lowering the amplification degree of the amplifier (32),
Noise is detected as a data signal (1,) on the data reading surface vt(1
6). In this modification, the output of the comparator (CON) is input to the inverter (IV), and the output of this inverter (IV) is used as the warning signal (c).

Furthermore, FIG. 6 is a circuit diagram showing another modification of the amplification/detection circuit shown in FIG. 4. This modification is configured to switch the sensitivity of the detection circuit (34) into three levels depending on the determination result of the comparator (CON). In this modification, inductance (L, ) and resistance (R3)
The connection point with CON2 is connected to the non-inverting input terminal of the second comparator (CON2). A second rtA power supply (Vref2) that generates a reference voltage higher than the reference power supply (Vrefl) is connected to the inverting input terminal. The output of this comparator (CON2) is connected to the base of a transistor (Tr3) whose director and emitter are connected in series to a resistor (R1) provided between the detection circuit (34) and the ground. With this configuration, if the voltage across the resistor (R1) corresponding to the intensity number of the external light component is sufficiently low, the comparator (
CON, ) (CON2) are both at their outputs (L), and therefore both transistors (Trl) (Tr*) are non-conducting, so the sensitivity of the detection circuit (34) is determined by the resistance (
Rz), which results in high sensitivity.

When the voltage across the resistor (R1) becomes a little higher than that, the reference voltage of the reference power supply (Vrerl) is lower than the reference voltage of the reference power supply (Vre('z)), so the comparator (CON, ) Only the output becomes "H", only the transistor (Tr) becomes conductive, and the resistor (R7) is connected in parallel to the resistor (R2). Therefore, in this case,
The sensitivity of the detection circuit (34) is reduced by one step. Furthermore,
When the external light component becomes even stronger and the voltage across the resistor (R1) becomes even higher, the comparators (CON 1) (CON 2)
) both outputs become H'' and the transistor (T rl)
(T rs) are both conductive, so a resistor (R1) and a resistor (R2) are connected in parallel to the resistor (R2), and the sensitivity of the detection circuit (34) is further reduced to the second stage. In this way, according to this modification, the sensitivity of the detection circuit (34) can be changed in three stages. In addition, in this modification, the output of the humperator (CONz) is the warning signal (
Used as c).

If it is necessary to change the sensitivity of the detection circuit in four or more stages, the number of resistors, transistors, comparators, and reference power supplies may be increased in the same way. Further, similarly to the modification shown in FIG. 5, it is possible to easily change the amplification degree of the amplifier (32) in three or more stages depending on the intensity of the outer light component.

Figure 7 shows a circuit configuration in which the load characteristics of the e) diodes that make up the light receiving elements (P D 1) (P D 2) can be used even in bright areas, so signals can be read without the circuit becoming saturated. ing. In such a case, the input terminal of the amplifier (32) is connected to the connection point between the light receiving element (PCI) (P D 2) and the inductance (Ll) via the capacitor (C,). In this case, the output photocurrent of the photodetector (PD,) (PD2) has its DC component removed by the capacitor (C,), and the amplifier (
32) and is amplified, only the signal is detected by a detection circuit (34), and the output waveform is shaped by a waveform shaping circuit (36). However, like this! flI#
, the above-mentioned display based on the intensity of the extra-radial light component, sensitivity switching of the detection circuit (34), and amplification f! (32
) cannot be switched.

FIG. 8 is a circuit diagram showing still another modification of the amplification/detection circuit of FIG. 4. In this modified example, the hunparator (
The output of CON, ) is connected to one input terminal of the waveform shaping circuit (
36) is connected to the other input terminal of the connected OR circuit (IC,).

With such a configuration, when the intensity of the external light component is low, the output of the frequency filter (CON, ) is up to L''*, so the waveform shaping circuit (36
) is output as is and input to the data reading circuit (16). On the other hand, when the intensity of the peripheral light component is large, the output of the humpator (CONl) is "H".
The output of the off circuit (rc,) is the waveform shaping circuit (3
6) remains at 'H' regardless of the output.In other words, when the external light component is large, the signal from the waveform shaping circuit (36) is not input to the data reading circuit (16) and remains 'H'.
With this configuration, the noise due to the external light component will not be transmitted to the data reading circuit (16), and the erroneous signal will be transmitted to the data reading circuit (16) as the data signal (b). No malfunction will occur.

The fjS9 diagram shows the photodetector (P D 1) (P D 2)
FIG. 12 is a circuit diagram showing another modification example in which only the DC component corresponding to the outer light component is selected from the photocurrent of . In this modification,
In order to extract only the DC component of the photocurrent of the photodetector (PD, ) (PD2), a resistor (Ra) and a capacitor (C
A smoothing circuit consisting of a) is used. The time constant of this smoothing circuit is set so that an alternating current component of about 60 f (z) such as that of a fluorescent lamp is extracted from the connection point between the resistor (Ra) and the capacitor (Ca).

If the intensity of the external light is determined according to this connection and the output of α, only the external light component can be extracted with a simple configuration.

Next, the operation of the battery check system shown in FIG. 3 will be explained using the time chart shown in FIG. 10. In Fig. 10, (1) shows the operation when the power supply battery (E) has sufficient voltage. II to
1' When the power switch (SW, ) is closed, time t1
A timer signal (e) for a certain period of time T is emitted from the timer circuit (18) until then. Also, Mla switch (SW,
), a signal (r) is emitted from the oscillator (20). In this case, neither the warning signal (C) of the amplification/detection circuit (14) nor the verify signal (d) of the data reading circuit (16) is emitted, and both outputs remain at L''. The output signal (f) of (20) causes the output of the OR circuit (OR, ) to become H'', and therefore the delay circuit opens at a predetermined time τ after the output of the OR circuit (OR, ) becomes H''. The output signal (,) of (28) becomes "H".Furthermore, the display drive circuit (30) is driven by the output signal (theory) of this delay circuit (28), and its output signal (n) becomes "H". As a result, the verification eye display light emitting diode (VLED) is turned on. Here, since the timer signal (e) becomes "H", the output signal (g) of the NOR circuit (NOR) becomes "L", and therefore the output signal D) of the oscillator (20) becomes "H". The output of (ND,) (
11) does not appear.

When the timer signal (e) of the timer circuit (18) becomes L'', the output signal (g) of the NOR circuit (NOR) is inverted to H'', and the one-shot circuit (22)
A short pulse signal (i) is emitted from. This pulse signal (i) is input to the battery check circuit (26) as a signal (k) via an OR circuit (OR2).

Then, the battery check circuit (26) checks the voltage V of the power supply battery (E) at a timing corresponding to this input pulse (k).
cc is checked, and the power supply voltage Vcc is shown in FIG. 10 as Vre.
It is determined whether or not the value is greater than or equal to a predetermined value indicated by r. During this battery check, the delay circuit (2
8) The output signal (m) takes a time τ from the output of the OR circuit (OR, ). The verification display light emitting diode (VLED) continues to be lit because the signal is delayed by 40 seconds and is at "H".

And the time is right. When a certain period of time T1 determined by the timer circuit (18) has elapsed, the timer signal (
e) becomes "L". Then, the output signal (g) of the NOR circuit (NOR) is inverted to "H", so the AND circuit (
A signal synchronized with the oscillation signal (f) of the oscillator (20) is output from the AND circuit (AND, ), and is input as a signal (11) to the one-shot circuit (24). Therefore, the one-shot circuit (24) outputs the signal (h
) A short pulse signal (j) is output every 9 rising edges. The period of this pulse signal (j) is determined by the oscillator (2
0) oscillation signal.

This pulse signal (j) is input to the battery check circuit (26) as a signal (k) through the off circuit (OR2), and the power supply voltage Vec is checked at a timing corresponding to this pulse signal (k). .

The time T2 from time t2 to t in FIG. 10 and the time T2 from time t to t5 are transmission 8! An infrared light signal corresponding to the transmitted data is transmitted from (12), and the signal increases @! It shows the state of each signal when it is amplified and detected by the g2 wave circuit (14) and read by the data reading circuit (16). In this case, the timer circuit (
The timer signal (e) of 18) remains at "L", and since the extra-peripheral light component is small, the warning signal (c) from the amplification/detection circuit (14) also remains at "L".

When the data reading circuit (16) accurately reads the transmitted data, a H'' level 7 eye signal (d) is generated for a certain period of time T2.This verify signal (d) causes an OR circuit (OR, ) is output for a certain period of time T2'
Therefore, the delay circuit (28) outputs the time τ.

After a delay, the signal ')('' is output for time T2. This signal (,) of '!4' causes the display drive circuit (3) to be output.
0) is driven, and a 14" signal (n
), and therefore the verification display light emitting diode (
VLED) is lit for a time T2. Furthermore, since the "H" level 7 eye signal (d) inverts the output signal (g) of the NOR circuit (NOR) to "L", the AND circuit 1i8 (
Since one input of the AND circuit (AND, ) becomes "L", the output signal (11) of the AND circuit (AND, ) remains "■4". Therefore, the output signal (f) of the oscillator (20) no longer appears in the output signal (h) of the AND circuit (AND). Therefore, while reading data, the OR times vr(OR
Since both inputs (i) and (j) of 2) remain at L'', no battery check operation is performed during this time.

Then, when the verification signal (d) of the data reading circuit (16) inverts to "L" at time t or odor, the output signal (i) of the one-shot circuit (22) changes as at time tl. A short pulse signal appears, and the power supply voltage Vcc is checked by the battery check circuit (26) in accordance with the timing of this pulse.

At this time, the delay circuit (28) inverts the verify signal (d) at +ffiτ. Since the signal is inputted to the display drive circuit (30) with a delay of 100 seconds, six verify display light emitting diodes (V L ED ) are turned on.

Next, the operation from time L6 to L7 in FIG. 10 will be explained. This is an operation when the intensity of the external light is high. First, when the amplification and detection circuit (14) determines that the intensity of the external light is equal to or higher than a predetermined value, it outputs "H" as a warning signal (c). As a result, the output of the OR circuit (OR,) becomes "!("), and the verification display light emitting diode (VL
ED) is lit to warn the user that the intensity of the external light is high.

In this case, the timer signal (
e) is "L", and the verify signal (d) of the data reading circuit (16) is also 1 ml, I+. Therefore, the output signal (g) of the NOR circuit (NOR, ) becomes "H", and the output signal (k) of the OR circuit (OR, ) oscillates at W<20.
A short pulse is emitted in response to the oscillation signal (f) of ).

As a result, the battery check circuit (26) periodically checks the power supply voltage Vcc.

Here, the timing pulse (M number (k)) for operating the battery check circuit (26) is an extra-large 1to
to 1+, from t2 to 1I11. The reason why it is not emitted during t5 and only at other times is as follows. First, from time t0 to time 1, it is immediately after the 'It source switch (SW, ) is closed, and for a certain period of time T after the power switch (SW, ) is closed, the verification display light emitting diode (VLED) is ) is turned on, and during that time, the voltage drop warning light emitting diode (BCLED) is not turned on in order to eliminate confusion in the display. Then, from time t2, 1. and,
During the mustard period, if a battery check is performed during this period and it is determined that the power supply voltage Vcc is lower than the predetermined value Vref-, "Ho" is output from the output signal (0) of the battery check circuit (26). The verify signal (d) is input to the reading circuit (16), and the verify signal (d) is input to the reading circuit (16).
7-eye display light emitting diode (v t,
Since it is configured to turn off the LED (ED) and stop its operation, the lighting time of the verification display light emitting diode (VLED) is shortened, and for a certain period of time [
Therefore, in this embodiment, the battery check operation is not performed during the above three times.

Furthermore, in the receiver of such an optical communication device, the light emitting display needs to be visible from a far away position, and therefore the display light emitting diode is driven with a very large current. Therefore, it is not preferable to also light the voltage drop warning light emitting diode (B CL ED) while the verification display light emitting diode (VLED) is lit at time t. The battery check is not performed from t1 to tl, from t2 to 15, and from t to t.

However, time L0+τ. From t1+τ. , t2+τ. While the verification display light emitting diode (VLED) is turned on from t, +τo1 and from t, 10τ0 to t5+τ0, it is thought that the power supply voltage Vcc drops the most just before the light emitting diode (VLED) is turned off. , τ when the light emitting diode (V L ED ) is turned off.

The battery check is performed just before, that is, at time 4, t2, and t, to check whether the electric pressure is stably supplied from now on.

(2) in the time chart of FIG. 10 is the power supply voltage Vcc.
The figure shows the operation when the voltage drops below the predetermined value Vre4-. The battery check circuit (26) is an OR circuit (O
71 source voltage Vc according to the output pulse (k) from R2)
Check c, at time t? ! ! When it is determined that the source voltage Vcc has become below the predetermined value Vrefs, the output (1) (
, ), respectively. As a result, the voltage drop warning light emitting diode (BCLED>) is lit to indicate a drop in the power supply voltage, and the operation of the data reading circuit (16) is stopped. Then, once the power supply voltage Vcc becomes equal to or lower than the predetermined value Vref3, the battery check circuit (26) checks the predetermined value Vref.
Even if the voltage exceeds 4-, the output (1) (o) remains in the "H" state, and this release is done by opening the power switch (SW, )6. (3) on the chart indicates that the power switch (SWI) is I! '
] shows the operation when the power supply voltage Vcc falls below the predetermined value Vref3 while the timer circuit (18) is operating. Here, as mentioned above, the time when the timer signal (e) of the timer circuit (18) is "H" [,
From tl. During the time period T, the battery check is not performed, and the time [
1°, the battery check circuit (26) is activated and it is determined that the power supply voltage Vcc is below the predetermined value Vrefz, and the voltage drop warning light emitting diode (26) is activated.
BCLED) is turned on.

Furthermore, at (4) in the time chart, the power battery (E) is exhausted and the power switch (SW, ) is V! Before time tll, the battery voltage E reaches the limit voltage for circuit operation and light emitting diode drive. This shows the behavior when the value is lower than . In this case, even if the trL source switch (SWI) is closed, the surface emitting light still remains (VLE).
D) (BCLED) +:, # Since both are not lit, a voltage drop in the power supply battery (E) is immediately indicated. Here, as is clear from comparing (1) and (4) of the time chart, in the normal state of (1), the light emitting diode for verification display is activated for a certain period of time T1 after the power switch (SW, ) is closed. If the (VLED) is not turned on, it is not possible to display a display that is distinct from the display when the battery voltage drops (4). Therefore, in this embodiment, the verification display m light-emitting diode (VLED) is turned on for a certain period of time T1 in the normal state. , 1.
The kK lights are turned on.

(5) in the time chart indicates that the data reading circuit (16) accurately reads the sent data (i!).
The operation is shown when the power supply voltage Vec becomes equal to or less than the predetermined value Vre'- while the verify signal (d) of H'' is output and the verify display light emitting diode (VLED) is turned on. In this case, as described above, the battery check circuit (26)
is activated, the power supply voltage Vcc is checked, a drop in it is determined, and a voltage drop warning light emitting diode (BCLED) is lit to warn of a drop in the power supply voltage.

Next, the internal structure of the receiver (6) shown in FIG. 1 will be explained. First, FIGS. 11(a) and (b) are B in FIG.
It is a cross section. In FIG. 11(a)(b), the light receiving window (
101) includes a pair of light-receiving lenses (104), an elbow bandpass filter (112), and a light-receiving element (PD
, )(PD2) are arranged in order from the outside world. Also,
A pair of upper and lower light shields 7=' (105) are provided on the outside side of the light receiving lens (104), respectively. Figure 11 (a
) is when the opening angle of the shading 7-door (ios) is increased,
FIG. 11(b) shows the position of the light-shielding hood (105) and the element chip (P in the photodetector (PDP) (PD2)) when the opening angle of the light-shielding hood (105) is made small.
12 is a perspective view showing the structure of the 1'N light-shielding 7-door (105) and its rotation axis (113).

The light shielding 7-door (105) has a rotating shaft (105b) fixed to the rotating base (105b) and the receiving M'ff1 main body (6).
Due to the frictional force of the friction washer (1, 14) sandwiched between the 9n part (113a) of the rotating shaft (113)
) is held by friction. Then, the light shielding 7-door (105
) can be rotated around the two rotating shafts (1, 13) by manually operating its operating end (105a), and the first
The opening angle can be set continuously and steplessly to the states (,) and (b) shown in Fig. 1 individually.

FIG. 13 is a graph showing the specific sensitivity incidence characteristic of the light receiving element (P D , ) (P D 2) with respect to the incident light beam.

! In the m13 diagram, the curve (A) is the fjS11 diagram (a
) shows the characteristics when the opening angle of the light shielding hood (105) is increased, and the curve CB) shows the characteristics when the opening angle of the light shielding hood (105) is decreased as shown in Fig. 11(b). It shows the characteristics.

The light-shielding door (105) is normally used with the opening angle at its maximum as shown in FIG. (
It is possible to capture the entire surface of the PDa. The specific sensitivity characteristics of the light receiving section in case 2 are shown in Figure 13. The width shown in <A) is wide. On the other hand, when there is an extremely large amount of external light, that is, when the brightness of the background of the transmitter is extremely high, the receiver cannot receive signals normally. In this case, it is effective to reduce the opening angle of the light shielding hood (105) as shown in FIG. 11(b). In this state, only the light beam that is incident almost parallel to the optical axis can be received by the entire surface of the element chip (PDa), and the light beam with an incident angle of β or more does not reach the element chip (PDn) at all. In this case, the specific sensitivity characteristic of the light receiving section becomes narrow as shown by curve 41(B) in FIG. Comparing song #a (A) and curve (B), on the optical axis (θ=
0), the specific sensitivities of both lines are almost equal,
The area surrounded by the curve and the horizontal axis is larger for song #1 (B) than the curve (
It can be seen that it is a fraction of A). Therefore, when the external light is strong, the 11th [Z<1+) state 1. [Light 7
-)' (105), install the transmitter (12) on the optical axis of the receiver (6), and perform communication.
The sensitivity to light remains approximately the same as in the state shown in FIG. 11(a), while the influence of external light can be reduced to a fraction of that. As a result, it is possible to achieve normal reception, which was not possible in the state shown in FIG. 11(a).

In addition, since the two light-shielding doors (105) can be adjusted to open and open separately, it is also possible to set the center of the aperture created by the two seven-doors at a position offset from the optical axis. be. Therefore, it is also possible to set the specific sensitivity characteristic as shown by curve (B) in FIG. 13 with the center shifted from the optical axis.

FIGS. 14(a) and 14(b) respectively show cross section A in FIG. 1. In Figures f514 (a) and (b), a verification display light emitting diode (VLED) is housed inside the receiver 3 display window (10G). FIG. 14(,) shows the outside of the reception display window when the reception display window (106) is viewed from a distance on its optical axis. It shows a reverse trace of the light rays reflected from the side of iL. Moreover, FIG. 14(b) shows a reverse trace of the light ray when the reception display window (106) is viewed from a distance shifted by a certain angle from the optical axis. Also, fpJ1
Figure 5 shows the spectral transmittance characteristics (C) for the wavelength of the reception display window (106) and the light emitting diode for verification display (
Relative intensity characteristics (D
) are shown superimposed on each other.

Regarding the reflected light at the outer surface (106a) of the reception display window (106), as shown in FIGS. 14(a) and (b),
All the light that reaches the eye is transmitted to the pit wall (6c) of the receiver body (6).
). Therefore, the reception display window (1
06), the pit wall (6c) of the receiver body is reflected on its surface (106a). This pit wall portion (6c) is painted black or the like to have a low reflectance. Therefore, with this configuration, direct reflected light from the outside world does not appear reflected on the outer surface (106a) of the reception display window (106), and a surface with low reflectance appears reflected on the reception display window (106). It is possible to keep the brightness of the surface of the (IOC) low. Also, regarding the light emitting diode side surface (106b) of the reception display window (106), the outer surface (10
It has exactly the same effect as 6b). If you configure it like this,
Since the brightness of external light reflected by the reception display window (106) when viewed from the outside world can be reduced, the S/N ratio of the brightness when the internal verify display light emitting diode (VLED) is turned on as seen from the outside world can be reduced. This makes it easier for observers to confirm blinking.

In addition, the reception display window (106) shows the song #R (C) in the Pt515 diagram.
), in the visible range, most of the light emitted by the verification display light emitting diode (VLED) is transmitted;
It is made of a material that absorbs light in other bands. Therefore, the chip surface (a
h) and the majority of the components of external light illuminating the reflective umbrella surface (rp) are blocked by the reception display window (106). On the other hand, most of the light emitted from the verify display light emitting diode (VLED) can pass through the reception display window (106) and exit to the outside world. Therefore, this receiving M display window (106)
The spectral transmittance characteristics of the light-emitting diode (VLED) for displaying the internal 7-eye display can also increase the S/N ratio of the brightness seen from the outside world when it blinks, making it easier for observers to confirm the blinking. .

As described in detail above, according to this embodiment, when the intensity of the external light is strong and there is a possibility that accurate data communication using the signal light cannot be performed, the light emitting diode for the 7-eye display (
V L E D ) lights up to give a warning, so the user can take measures such as changing the orientation of the receiver (6) to ensure accurate data communication.
Malfunctions due to inaccurate information transmission can be prevented. Furthermore, if the intensity of the external light is strong, the amplification detection circuit (1
By lowering the sensitivity of 4), it is possible to reduce the possibility of malfunction due to external light. Furthermore, according to this embodiment,
Power switch (SWI) if the power supply voltage is sufficient
The verification display light emitting diode (VLED) is lit for a certain period of time after the closing of the ? ! ! If the power source voltage has slightly decreased, the verification display light emitting diode (VLED) and voltage drop warning light emitting diode (BCLED) are turned on. Since neither of the two light-emitting diodes (V L E D ) (B CLED) is turned on during this period, three types of states can be distinguished and displayed using the two display elements. Further, according to this embodiment, the amplification and detection circuit (14) can separate the photocurrent according to the extra-frequency light component and the photocurrent according to the signal component, and the above-mentioned display can be performed according to the extra-frequency light component. It is possible to perform accurate optical communication even in places where the external light component is strong, such as outdoors.

In addition, in this embodiment, a light receiving element (P
Although the configuration is such that the extraneous light component is detected from the output of D , )(P D 2), the present invention is not limited to this, and a light-receiving element may be separately provided for extraneous light detection. However, if it is also used as a light receiving element for signal reception as in this embodiment, the configuration can be simplified.

Figure f516 is a circuit diagram showing a main part of another embodiment of the present invention in which one of the light receiving elements (PD, ) (PD2) consisting of a photodiode is selected and used according to the temperature.

In FIG. 16, the voltage (Vcc
) are analog switches (S W 2) connected in series to the cathodes of the photodetectors (PD, ) (PD2), respectively.
(S W 3) respectively. The inverting input terminal of the comparator (CON) is connected to a temperature detection circuit (TD) that detects the temperature and outputs the voltage proportional to the detected temperature. On the other hand, the non-inverting input terminal of the comparator (CON3) is connected to a reference power source (Vref, ) that produces a base *ffl pressure with reference to ground. The output of the comparator (CON, ) is connected to the date of the analog switch (SW2), and is also connected to the date of the analog switch (SW, ) via the inverter circuit (IC3). In addition, the 7 nodes of the light receiving element (P D ,) (P D 2) are connected to the amplification and detection circuit (1) shown in FIG. In FIG. 17, the spectral sensitivity characteristics of the photodetector (P D , ) (P D 2) are shown as curves m (K ) and (F ), respectively.

Next, the operation of this embodiment will be explained. First, in a device that performs remote communication using optical signals, it is best to match the spectral sensitivity of the light-receiving element on the receiver side with the spectral sensitivity of the light-emitting diode on the transmitting Mt91 side. As shown in FIG. 18, the emission peak wavelength of the light emitting diode shifts toward longer wavelengths from (G) to (T1) and (I) as the temperature rises.

Therefore, at low temperatures, the photodetectors (PD, ) (PD2)
Even if the light-emitting diode has the same spectral sensitivity and has the same spectral sensitivity characteristics as the light-emitting diode, the spectral sensitivity of the light-emitting diode changes as the temperature rises, so the photodetector (PD)
Among the photocurrents generated by 2), those that are mainly due to the signal 1 become small, and only the photocurrents that are due to the second peripheral light are generated, resulting in a poor S/N ratio. Therefore, in this embodiment, two photodetectors (PD, ) (PD2) having different spectral sensitivities as shown in FIG. 17 are provided, and at low temperatures, the output of the photodetector (PD, ) is used. When the temperature rises, the output of the photodetector (PD2) is used.
By making one switch, it is possible to operate with a high S/N ratio at both low and high temperatures.

Here, the temperature detection circuit (TD) used in this example
is configured to detect temperature and output a voltage proportional to the temperature. That is, when the temperature is low, the voltage output by the temperature detection circuit (TD) is small, and when the temperature is high, the voltage output is large. Therefore, when the output voltage from the temperature detection circuit (TD) is lower than the voltage from the reference power supply (Vrcf, ), that is, when the temperature is low, the output of the comparator (CON, ) becomes H''. ” signal enters the date of the analog switch (SW2), the analog switch (SW2) becomes conductive, and the photodetector (PD, ) having the spectral sensitivity characteristic shown in song #1 (K) in Figure 17 The output is adopted. Also, at this time, the in-tweeter circuit (IC
The output of the analog switch ( , ) is “1,” so the analog switch (
SV/)) is in a non-conducting state.

And as the temperature rises, the temperature detection circuit (TD)
The voltage output by
When the voltage becomes higher than the voltage from ld (when the temperature rises)
In this case, the output of the comparator (CONs) becomes "L". Then, this signal causes the analog switch (SW2) to
becomes non-conducting, while the inverter circuit (ICz)
Since the output becomes “H”, the analog switch (SVV)
When a signal of "11" is input to the date of ), the analog switch (SW) becomes conductive, and the output of the light receiving element (PD2) is adopted instead of the output of the light receiving element (PD, ).

In this way, two light receiving elements (P
D, ) (PD2) is used to create a light receiving element (P
The output of the light-emitting diode (P
By adopting the output of D,), it is possible to match the spectral characteristics of the light receiving element and the light emitting diode both at low and high temperatures, and it is possible to further improve the S/N ratio.

Note that the spectral sensitivity characteristics of the light-receiving element (P D , ) (P D 2) need only be similar to the spectral characteristics of a light emitting diode (,f:tS17).

Further, FIG. f519 is a circuit diagram showing a modification of the embodiment of FIG. 16. The modification shown in FIG. 19 shows a configuration in which three light receiving elements (with three spectral sensitivities) are provided and one of them is adopted depending on the temperature. FIG. 20 is a graph showing the spectral sensitivity characteristics of the third light receiving element (PD, ) used in addition to the previous two light receiving elements (PD, ) (PD2). Incidentally, here, it may be configured to use four or more light receiving elements and selectively adopt the output of one of them depending on the temperature, but since the h7 configuration can be easily considered from FIG. 19, I will omit the explanation here.

In the tiS19 diagram, the temperature detection circuit (TD) is the first
6 Figure I: As shown, its output is input to a comparison and selection circuit (CS). Then, the comparison and selection circuit (
The output (OtJT, ) of CS ) is connected to the date of the analog switch (SW2) connected in series to the photodetector (PD, ), and the output (OUT2) is connected to the date of the photodetector - (PD, ).
Analog switch (SW v ) connected in series to 3>
The date is connected, and the output (OUT,) is the photodetector T.
- Analog switch (SW) connected in series to (PD2)
<) is connected to DE-F. Here, the comparison selection circuit (CS) takes in a voltage proportional to the temperature from the temperature detection circuit (TD), and when the voltage is small, that is,
When the temperature is low, only the output (OUT,) signal is set to 1 (". At this time, the output (OUT,) and (OUT3) signals are both 1.".Then, the temperature rises a little, When the input voltage of the comparison and selection circuit (CS) increases, only the output (OUT2) signal is set to "H", and the output (OU
The Ibo number of T,) and J-u (OUT,) is set to L'''.Furthermore, when the temperature rises and the input voltage of the comparison and selection circuit (CS) further increases, the comparison and selection circuit (CS) makes only the output (OUT,) signal "+-(").

Next, the operation of this modified example will be explained. Here, the details of the operation will be understood from the explanation of the embodiment shown in the f:rS16 diagram, and will be briefly described here. When the temperature detected by the temperature detection circuit (TI) is low, only the signal of the output (OUT, ) of the comparison and selection circuit (CS) becomes H'', which causes the analog switch (SW
Only 2) is made conductive, and the output of the photodetector (PD, ) is adopted. Then, the temperature rises by 2' and the photodetector (PD)
When the temperature reaches such a point that the S/N ratio is better when using the output of the photodetector (PDff) than when using the output of The output of the light receiving element (PD3) is adopted.Furthermore,
As the temperature rises, the light receiving element (P
When the temperature reaches a point where the S/N ratio is better if the output of D , , ) is adopted, the comparison and selection circuit (CS) changes the output (OUTz
) is set to 11", and the output of the photodetector (PD2) is used.

By using a plurality of light-receiving elements with different spectral sensitivities in this way, the S
/N ratio can be improved.

In addition, here, the light receiving element (P D ,)(PD ,)(P
The spectral sensitivity characteristics of D,) do not need to be as shown in FIG. 17 and fjS20, and may be similar to the spectral characteristics of a light emitting diode.

As described in detail above, the present invention provides a photoelectric element for receiving optical signals and a wf It is characterized by having an inductance that is connected to the photoelectric element and allows a signal of a predetermined frequency or lower to flow among the signals generated in the photoelectric element. Therefore, even if there are many external light components, the sensitivity will not deteriorate, and only the nine optical components corresponding to the optical signal can be read out accurately. Thus, it is possible to obtain an optical communication device that can accurately receive signal light without deterioration of signal light. Further, according to the present invention, a wide receivable distance can be obtained even under high illumination without changing the receivable distance depending on the illuminance. Further, in the present invention, only the peripheral light component can be extracted from the inductance. .

[Brief explanation of the drawing]

Fig. fjS1 is a perspective view showing a camera system using an optical communication receiving device according to an embodiment of the present invention, Fig. 2 is a front view of the receiving device, Fig. tjIJ3 is a block diagram showing the electric circuit of the system, and Fig. 14 is its 5 to 9 are circuit diagrams showing modified examples of the amplification and detection circuit, and FIG. 10 is a time chart showing the operation of the system in FIG. 3. Fig. 11 is a sectional view of B in Fig. @1, Fig. fjS12 is a perspective view showing the structure of the light-shielding 7-door, and Fig. f513 is a graph showing changes in the specific sensitivity of the photodetector T due to opening of the light-shielding 7-door. , FIG. 14 is a cross-sectional view of A in FIG. 1, FIG. Figure 17 is a graph showing the spectral sensitivity characteristics of the light receiving element, and Figure ttS18 is a graph showing changes in the light emitting characteristics of the light emitting diode due to temperature.
FIG. 19 is a circuit diagram showing a modification of FIG. 16, and FIG. 20 is a graph showing the spectral sensitivity characteristics of the light receiving element. (P D ,) (P D 2); Photoelectric element, (L,);
inductance. The above is complete [Figure 1 θ Figure ω (2) and End of Figure 1 for Hitomi/Ruta Camera Co., Ltd.]
(4-2 and f) rl 7
Same sword V (c No. za diagram fL ↓Vrd+ 1shi15 ノ3 diagram → go to murmur Lζ41) No. q diagram

Claims (1)

[Claims] In an optical communication receiving device that receives an optical signal emitted from a remote location, a photoelectric element for receiving the optical signal; and a signal connected in series to the photoelectric element and generated in the photoelectric element; 1. An optical communication receiver comprising an inductance that allows a signal of a predetermined frequency or lower to flow.