JP2008070203A - Angle-of-light detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small and inexpensive angle-of-light detection device capable of detecting an incident angle of incoming light with high precision, even when the intensity of the light is small. <P>SOLUTION: A first and a second photodetector 4a, 4b are arranged side by side mutually with light shielding elements 3a, 3b between against the outside so that along with receiving remote control signals as rays of incident light and performing their photoelectric conversions, the quantities of the received rays of light differ mutually according to the incident angle θ of the incident rays of light. The outputs of the first and second photodetectors 4a, 4b are amplified with amplifiers 21, 22 respectively to acquire a first and a second signal. A divider 61 finds the ratio between the first signal and the second signal. When an angular resolution which this angle-of-light detection device 2 should have is represented by ±Δθtarget, a constant corresponding to the maximum detection angle θmax is represented by a, and moreover the ratio between a bias current to be applied to the input section of the divider 61 and the sum of currents by the first and second signals is represented by r, the amplification degrees of the amplifiers 21, 22 satisfy a relation of r<a Δθtarget. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light angle detection device, and more particularly to a device that receives a remote control signal in the form of incident light at a light receiving element and identifies the arrival direction of the incident light.

  The present invention also relates to an electronic apparatus including such a light angle detection device.

  In general, a sensor that detects the direction in which light arrives arranges two photodiodes side by side through a light shielding material or the like so that the amount of light received differs according to the incident angle of light, The direction of light arrival is detected based on the output difference between the two photodiodes. That is, the principle of a so-called sundial is used.

For example, in the device described in Patent Document 1 (Japanese Patent Laid-Open No. 8-264826), a light shielding region corresponding to half of each light receiving area is provided above the light receiving surfaces of two photodiodes. And using the amplified outputs I1 and I2 from the two photodiodes,
θ = tan ⁻¹ [(L _D / 2H) · (I1−I2) / (I1 + I2)]
The light incident angle θ is obtained by performing the following calculation. Incidentally, the incident angle θ is an angle measured from a perpendicular (this is assumed to be 0 °) with respect to the light receiving surfaces of the two photodiodes. L _D is the total length of the light receiving surface (the length along the surface including the light arrival direction), and H is the distance between the light shielding material and the light receiving surface.

Further, the device described in Patent Document 2 (Japanese Patent Application Laid-Open No. 8-340124) has two photodiodes arranged side by side through an aperture window with respect to the outside, and an amplified output V1 from the two photodiodes. , V2 and V ₀ = log V1−log V2 = V1 / V2 in a circuit using a log amp.
An operation is performed. Then, the incident angle θ of light is obtained according to V ₀ .

In addition, in the thing of patent document 2 and patent document 3 (Unexamined-Japanese-Patent No. 9-49733), the output of two photodiodes is A / D converted, respectively, and the incident angle is calculated | required by digital arithmetic processing. .
JP-A-8-264826 JP-A-8-340124 JP-A-9-49733

Generally, in order to perform multiplication or division with an analog signal, a log amplifier is often used as in Patent Document 2 because the current versus voltage characteristic of a semiconductor PN junction exhibits a logarithmic compression characteristic. Specifically, when the current flowing through the PN junction is I and the applied voltage of the junction is V, it is expressed by the following formula (1).
I = Is · {exp (eV / kT) −1} (1)

Here, Is is a saturation current, e is an elementary charge, k is a Boltzmann constant, and T is a temperature. When this is solved for V, the following equation (2) is obtained, and the output voltage is a logarithmically compressed form of the input current.
V = kT / e · ln {(I + Is) / Is} to kT / e · ln {I / Is}
... (2)

In addition, the sum of logarithms is represented by the logarithm of the product of true numbers like following Formula (3).
ln (A) + ln (B) = ln (A · B) (3)

Further, the difference between the logarithms is expressed by the logarithm of the quotient between the true numbers as in the following equation (4).
ln (A) -ln (B) = ln (A / B) (4)

FIG. 14 shows an example of a divider that uses these relationships. The divider includes an operational amplifier (hereinafter referred to as “op-amp”) 91, a first log amplifier 81 including a diode D1 and a resistor R1, a second log amplifier 82 including an operational amplifier 92, a diode D2, and a resistor R2. An operational amplifier 93 and resistors R11, R12, R13, and R14, and a differential amplifier 83 that amplifies the difference between the outputs of the first and second log amplifiers 81 are included. When the input currents applied to the log amplifiers 81 and 82 by the input signals V1in and V2in to the divider are I1 and I2, the outputs V1out and V2out of the log amplifiers 81 and 82 are respectively expressed by the following equation (2). It is expressed as equation (5).
V1out = kT / e · ln (I1 / Is)
V2out = kT / e · ln (I2 / Is) (5)

The output Vout of the differential amplifier 83 at the subsequent stage is expressed by the following equation (6) using the equations (4) and (5).
Vout = V2out-V1out
= KT / e · ln (I2 / I1) (6)

  Thereby, the division value of the input current logarithmically compressed can be obtained. However, all the resistors R1, R2, R11 to R13 in the figure have the same value, and the characteristics of the diodes D1, D2 and the operational amplifiers 91, 92, 93 are also equivalent.

  The operational amplifier's positive and negative input terminals are called imaginary shorts, and ideally no potential difference occurs between both terminals. However, in practice, an input offset voltage Vof exists between both terminals. The input offset voltage Vof of the operational amplifier varies depending on the operational amplifier, but is usually about μV to mV. For example, in the operational amplifier NJU2747 manufactured by New Japan Radio Co., Ltd., the typical value is 1 [mV]. The potential is set to the reference potential (0 V).) Even when the input signal V1in is in a no-signal state, a potential difference is always generated by Vof at both ends of the input resistance. When the value of the input resistance is R, current always flows by Vof / R. Further, the impedance of the input terminal of the operational amplifier is ideally infinite, and current does not flow into (flow out of) both input terminals. However, in practice, there is an input bias current at the input terminal of the operational amplifier. The input bias current of the operational amplifier differs depending on the input transistor of the operational amplifier, but the typical value is 100 [nA] in the operational amplifier NJU2747 manufactured by New Japan Radio Co., Ltd.

  As described above, even when no signal exists due to the input offset voltage or the input bias current, a current flows between the negative input terminal and the output terminal of the operational amplifier, and an offset is given to the output. Hereinafter, the current resulting from the input offset voltage and the input bias current is referred to as “bias current” and is appropriately expressed by using the symbol “Ibias” (see, for example, FIG. 14). If the example using the operational amplifier NJU2747 made by New Japan Radio Co., Ltd. is used, the bias current Ibias has a magnitude of | 1 μA ± 100 nA |.

When this bias current Ibias is present, the output Vout (see equation (6)) of the divider shown in FIG. 14 is expressed as the following equation (7).
Vout = kT / e · ln {(I1 + Ibias) / (I2 + Ibias)}
... (7)

FIG. 15 shows the change in the output Vout with respect to the input current I1 (and I2) when Ibias = 1 [μA] with reference to the example of the operational amplifier NJU2747 manufactured by New Japan Radio Co., Ltd. The ratio (I1 / I2) is shown as a parameter. The x-axis is I1 and the y-axis indicates the output Vout (arbitrary unit). A plurality of values 0.25, 0.5, 1.0, 2.0, and 4.0 taken by (I1 / I2) indicate that the actual incident angle θ is −a °, −b °, 0 °, + a °. , + B °, and so on. As can be seen from FIG. 15, when the input current I1 is small due to the presence of the bias current Ibias, that is, when a remote control signal is received from a distance, the output Vout is the original value (the actual incident angle θ is changed). Change from the value shown). That is, even if the actual incident angle θ is constant, the value of the output Vout when the input current I1 = 1 [μA] becomes small, for example, the original value, for example, the input current I1 = 1.0. It changes from the value of the output Vout when × 10 ⁻³ [A]. For this reason, an error is caused.

FIG. 16 shows another example of the divider. This divider includes three operational amplifiers 94, 95, 96, NPN transistors TR1, TR2, TR3 connected between input / output terminals of the operational amplifiers 94, 95, 96, respectively, and an NPN transistor TR4. Although a detailed description of the circuit operation is omitted, the divider receives input currents I0, I1, and I2 and outputs an output current Iout represented by the following equation (8) to the collector of the transistor TR4.
Iout = I0 · (I1 / I2) (8)

I0 is a reference current for determining the magnitude of the output current, and is usually supplied by a constant current source. As in the previous example of the divider, the bias current Ibias also exists in this divider as shown in FIG. Therefore, the actual output current Iout is expressed as the following equation (9).
Iout = {I0 + Ibias} · {(I1 + Ibias) / (I2 + Ibias)} (9)

  FIG. 17 shows the change in the output Iout with respect to the input current I1 (and I2) when Ibias = 1 [μA] with reference to the example of the operational amplifier NJU2747 manufactured by New Japan Radio Co., Ltd. The ratio (I1 / I2) between the currents I1 and I2 is shown as a parameter. Also in this case, as in the case of FIG. 15, when the input current I1 is small due to the presence of the bias current Ibias, that is, when receiving a remote control signal from a distance, the output Iout is the original value (actual value). It changes from the value indicating the incident angle θ. For this reason, an error is caused.

  As described above, when division is performed by analog calculation as shown in Patent Document 1 and Patent Document 2, the angle accuracy is poor particularly when a remote control signal is received from a distance due to the characteristics of the divider. It will be enough.

  Also, as shown in Patent Document 2 and Patent Document 3, in the case of performing digital operation after converting an analog signal into a digital signal, in addition to the analog device, a digital device such as an A / D converter, a memory, or a processor Is required. This increases the size of the device and increases the cost of the device.

  Therefore, an object of the present invention is to provide a small and inexpensive optical angle detection capable of detecting the incident angle of light with high accuracy even when the intensity of incoming light is small as when receiving a remote control signal from a distance. To provide an apparatus.

In order to solve the above problems, the optical angle detection device of the present invention is:
Each remote control signal is received in the form of incident light and photoelectrically converted, and the light receiving amounts are different from each other according to the incident angle of the remote control signal, and are arranged side by side with a light shielding element to the outside. First and second light receiving elements;
An amplifier for amplifying outputs of the first and second light receiving elements to obtain first and second signals, respectively;
A divider for determining a ratio between the first signal and the second signal;
The angle resolution that the optical angle detection device should have is ± Δθ target, the constant corresponding to the maximum detection angle of the optical angle detection device is a, the bias current applied to the input unit of the divider and the first When the ratio of the first and second signals to the sum of currents is r, the amplification factor of the amplifier is
r <a · Δθtarget
It is set to satisfy the following relationship.

  Here, the “incident angle” means an angle measured from a perpendicular (this is 0 °) with respect to the light receiving surfaces of the first and second light receiving elements.

  The “maximum detection angle” means the maximum incident angle that can be detected by the optical angle detection device. The maximum detection angle is determined from the arrangement of the first and second light receiving elements and the light shielding element.

  Further, Δθ target in the angular resolution ± Δθ target is assumed to be a positive value.

  The “light shielding element” includes, for example, a light shielding material, a diaphragm window, and the like provided so as to cover a part of the first and second light receiving elements.

  In addition, “amplifier” includes a case where input and output are both current and voltage.

In the optical angle detection device of the present invention, the amplification degree of the amplifier is
r <a · Δθtarget
Is set so as to satisfy the above relationship, the signal current is sufficiently larger than the bias current steadily acting on the input section of the divider (that is, the current due to the first and second signals). Can be applied to the input of the divider. Therefore, even when the intensity of incoming light is small as when receiving a remote control signal from a distance, the incident angle of light can be detected with high accuracy. Further, since there is no need to provide a digital device such as an A / D converter, a memory, or a processor, the optical angle detection device is small and inexpensive.

  The first and second light receiving elements have IV converters for converting the photocurrents output from the first and second light receiving elements into first and second voltage signals corresponding to the current values, respectively. It is desirable to amplify the second voltage signal. In such a case, a commercially available operational amplifier widely used as the amplifier can be used.

  An optical angle detection device according to an embodiment includes a filter circuit for substantially reducing direct current components included in the first and second signals.

  In the optical angle detection device of this embodiment, the direct current components contained in the first and second signals are substantially reduced by the filter circuit. Therefore, accurate angle detection is possible even in a measurement environment where strong background light exists, such as outdoors.

  The filter circuit may reduce a low frequency component having a frequency lower than that of the original remote control signal in addition to the direct current component.

  In an optical angle detection device according to an embodiment, the filter circuit is provided at a stage subsequent to the amplifier.

  In the optical angle detection device of this embodiment, the input offset voltage amplified by the amplifier is removed. Therefore, more accurate angle detection is possible.

  In one embodiment, the light angle detection device detects the background light level with respect to the remote control signal based on the photocurrent output from the light receiving elements, and cancels the background light. A background light removing unit that causes a current corresponding to the background light level to act on the output unit is provided.

  In the light angle detection device of this embodiment, the background light removal unit detects the background light level with respect to the remote control signal based on the photocurrent output from each light receiving element, and cancels the background light. In addition, a current corresponding to the level of the background light is applied to the output portion of each light receiving element. As a result, the background light is canceled even in an environment where strong background light exists such as outdoors. Therefore, the output does not saturate in the amplifier provided downstream of the light receiving elements, and the range of use of the optical angle detection device is greatly expanded.

  In addition, applying an electric current means flowing in or drawing out an electric current.

In the light angle detection device of one embodiment,
The divider includes first and second logarithmic compressors for logarithmically compressing currents applied by the first and second signals to an input section of the divider, and an output of the first logarithmic compressor. And a subtractor that takes the difference between the output of the second logarithmic compressor,
When the maximum detection angle is θmax, the a is a <7.5 × 10 ⁻⁵ · θmax + 7.2 × 10 ^−3.
It is characterized by satisfying the following relationship.

In the optical angle detection device of this embodiment, the divider is configured as the simplest analog divider using a so-called log amplifier. Thus, even when the divider is configured as an analog divider, the a is the above-described a <7.5 × 10 ⁻⁵ · θmax + 7.2 × 10 ^−3.
By satisfying this relationship, an optimum setting is obtained for both the angular resolution and the maximum detection angle.

The optical angle detection device of one embodiment
A temperature detector for detecting the temperature around the divider or the divider;
According to the temperature detected by the temperature detection unit, a temperature dependency correction unit that performs correction to cancel the temperature dependency of the output of the divider is provided.

  Generally speaking, the output of an analog divider varies with temperature, and tends to cause a decrease in angle detection accuracy. Here, in the light angle detection device of this embodiment, the temperature detection unit detects the temperature around the divider or the divider. Then, the temperature dependence correction unit performs correction to cancel out the temperature dependence of the output of the divider according to the temperature detected by the temperature detection unit. Therefore, even when the divider is configured as the simplest analog divider, the detection accuracy of the incident angle can be further increased, and the use range of the optical angle detector can be greatly expanded. .

The optical angle detection device of one embodiment
An adder for calculating a sum of the first signal and the second signal;
A subtractor for obtaining a difference between the first signal and the second signal;
The divider is designed to determine the ratio between the output of the adder and the output of the subtractor,
a <1.5 × 10 ⁻⁴ · θmax + 1.4 × 10 ⁻²
It is characterized by satisfying the following relationship.

In the light angle detection device of this embodiment, the divider determines a ratio between the output of the adder and the output of the subtractor. That is, the divider determines a ratio between the sum of the first signal and the second signal and the difference between the first signal and the second signal. Therefore, even when the divider is composed of the circuit shown in FIG. 16, the output range is limited to −1 to +1 compared to the case where the outputs of the first and second light receiving elements are divided as they are. Therefore, the output potential of the signal can be easily processed. At the same time, the angle signal is not affected by the ambient temperature without providing a temperature detection unit. Further, the a is the above-mentioned a <1.5 × 10 ⁻⁴ · θmax + 1.4 × 10 ⁻²
By satisfying this relationship, the optimum setting is obtained for both the angular resolution and the maximum detection angle.

The optical angle detection device of one embodiment
The filter circuit comprises a bandpass filter, and the center frequency of the bandpass filter is substantially the same as the frequency of the remote control signal,
A hold circuit that temporarily holds the output of the bandpass filter and transfers it to the divider is provided at a stage subsequent to the bandpass filter.

  In the optical angle detection device of this embodiment, the filter circuit is composed of a bandpass filter, and the center frequency of the bandpass filter is substantially the same as the frequency of the remote control signal. It is possible to effectively remove noise having a frequency other than (including noise included in incident light and noise generated by an electric circuit). Therefore, it is possible to detect the angle with higher accuracy. Generally speaking, a signal after passing through a narrow-band bandpass filter is output as a sine wave having one frequency, and an angle signal is given by its peak value (or bottom value; the same applies hereinafter). . Since the signal after passing through the band pass filter is a sine wave or a signal close to it, it is very difficult to determine the time when the peak comes. Here, in the optical angle detection device of this embodiment, the hold circuit temporarily holds the output of the bandpass filter and transfers it to the divider. That is, the peak value giving the angle signal is held for a certain period of time. Therefore, the angle signal can be accurately extracted.

  The filter circuit is preferably a narrow bandpass filter as long as it includes the frequency of the remote control signal.

The optical angle detection device of one embodiment
An adder for calculating a sum of the first signal and the second signal;
And a false detection prevention unit for prohibiting the output of the divider when the output level of the adder is below a certain threshold value.

  As described above, the light angle detection device of the present invention can detect the incident angle of light with high accuracy even when the intensity of incoming light is small, such as when receiving a remote control signal from a distance. Can do. However, when the intensity of incoming light becomes extremely small, the denominator value of the ratio between the first signal and the second signal obtained by the divider becomes extremely small, and the output value of the divider becomes unstable. Therefore, the angle value error tends to become very large. Here, in the optical angle detection device of this embodiment, when the adder calculates the sum of the first signal and the second signal, and the output level of the adder is below a certain threshold value, false detection is performed. The prevention unit prohibits the output of the divider. That is, when the intensity of incoming light is extremely small such that the output level of the adder is below a certain threshold, the output is cut off as a measurement error. Therefore, erroneous detection is eliminated, and as a result, the detection accuracy of the incident angle can be further increased.

The optical angle detection device of one embodiment
Only one amplifier is provided in common for the first and second light receiving elements,
A switch unit that switches the outputs of the first and second light receiving elements at a predetermined timing and applies them to the amplifier;
Hold for temporarily holding at least one of the first or second signal output from the amplifier and transferring it to the divider so that the first and second signals are simultaneously applied to the divider. And a section.

  In the optical angle detection device of this embodiment, the output of the first light receiving element is applied to the amplifier at a certain timing by switching by the switch unit, and the first signal is output by the amplifier. For example, the first signal is temporarily held in the sample hold unit. At another timing subsequent to the timing, the output of the second light receiving element is applied to the amplifier by switching by the switch unit, and the second signal is output by the amplifier. This second signal is applied to the divider simultaneously with the first signal held in the sample and hold unit. Then, the divider determines a ratio between the first signal and the second signal applied simultaneously.

  Since this optical angle detection device requires only one amplifier, the circuit configuration is reduced, and the device is small and inexpensive.

  And an IV converter that converts the photocurrents output from the first and second light receiving elements into first and second voltage signals corresponding to the current values, respectively, and the amplifier includes the first and second voltage signals. When amplifying the second voltage signal, only one IV converter is required as in the case of the amplifier. Therefore, the circuit configuration is further reduced, and the configuration is small and inexpensive.

  An electronic apparatus according to the present invention is an electronic apparatus provided with the light angle detection device according to the present invention.

  In the electronic device of the present invention, the operation of the electronic device can be controlled using the angle signal output from the light angle detection device. Therefore, the application range of electronic equipment can be expanded. As this electronic device, an air conditioner is mentioned, for example. By detecting the incident angle of the remote control signal and the air conditioner detects the position of the remote control signal sender, the room temperature optimized for the position of the remote control signal sender can be controlled. As a result, not only can a comfortable living space be provided, but there is no need to air-condition a useless space, so that energy saving can be achieved.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

  FIG. 1A shows an aspect in which a remote control transmitter 1 and a light angle detection device 2 according to an embodiment of the present invention are used in combination, as viewed from a direction perpendicular to a plane on which the remote control transmitter 1 moves. However, it shows. The remote control transmitter 1 transmits a remote control signal as an optical signal, and the optical angle detection device 2 receives the remote control signal in the form of incident light. The direction of arrival of light to be detected by the light angle detection device 2 is determined as an incident angle θ measured from a perpendicular line NL to the light angle detection device 2 (light receiving element thereof). Δθ represents the angular resolution of the optical angle detection device 2. Note that reference numeral 1 ′ in FIG. 1A indicates a position when the remote control transmitter 1 is deviated from a certain angle θ by Δθ.

  The upper stage VV in FIG. 1B shows the arrangement of the light receiving element portions in the light angle detection device 2 when viewed from the same direction as in FIG. 1A. The middle HV in FIG. 1B shows the top VV viewed from above. As can be seen from these, the light angle detection device 2 includes light shielding plates 3a and 3b as light shielding elements, a photodiode 4a as a first light receiving element, and a photodiode 4b as a second light receiving element. Yes. The photodiodes 4a and 4b are arranged side by side in the same plane with respect to the outside via the light shielding plates 3a and 3b, respectively. In this example, each of the photodiodes 4a and 4b has a square light receiving surface, and the length of one side of each light receiving surface is set to l. The dimensions of the light shielding plates 3a and 3b are set to l / 2 so as to cover half of the corresponding photodiodes 4a and 4b in the direction along the surface along which the remote control transmitter 1 moves, and are perpendicular to the direction. The direction is set to 1 in the same manner as the side dimensions of the photodiodes 4a and 4b. The photodiodes 4a and 4b each receive a remote control signal in the form of incident light, perform photoelectric conversion, and output a current signal.

  Θmax shown in the upper stage VV in FIG. 1B represents the maximum detection angle of the light angle detection device 2. θmax will be described in detail later.

  In this example, in FIG. 1B, the left light shielding plate 3a faces the left half of the left photodiode 4a, and the right light shielding plate 3b faces the right half of the right photodiode 4b. Thereby, the received light amounts of the photodiodes 4a and 4b are different from each other in accordance with the incident angle θ of the remote control signal. The light shielding plates 3a and 3b do not necessarily face the left and right halves of the photodiodes 4a and 4b, respectively. The amount of light incident on one of the photodiodes varies depending on the change in the incident angle θ of light. What is necessary is just to arrange | position so that when it reduces, the light quantity which injects into the other photodiode increases.

  The lower part of FIG. 1B shows a block configuration of a circuit unit of the light angle detection device 2. The circuit unit of the optical angle detection device 2 is roughly divided into a light receiving signal unit 5 that amplifies the outputs of the photodiodes 4a and 4b, and an output of the light receiving signal unit 5 to calculate an angle signal SigA corresponding to the incident angle of light. And an operation unit 6 to be obtained.

  In this example, the light reception signal unit 5 includes a first circuit unit 5a that amplifies the output of the photodiode 4a and a second circuit unit 5b that amplifies the output of the photodiode 4b. The first circuit unit 5a includes an IV converter 11 that converts a current signal output from the photodiode 4a into a voltage signal, an amplifier 21 that amplifies the output of the IV converter 11 to an appropriate signal strength, and an amplifier. A band-pass filter (hereinafter referred to as “BPF”) 31 as a filter circuit for filtering the voltage signal output from the signal 21 and a hold device 41 as a hold circuit for holding a signal that has passed through the BPF 31 are provided in this order. Yes. Similarly, the second circuit unit 5b includes an IV converter 12 that converts a current signal output from the photodiode 4b into a voltage signal, and an amplifier 22 that amplifies the output of the IV converter 12 to an appropriate signal strength. And a BPF 32 as a filter circuit for filtering the voltage signal output from the amplifier 22 and a hold device 42 as a hold circuit for holding a signal that has passed through the BPF 32 are provided in this order. The elements 11, 21, 31, 41 of the first circuit section 5a and the elements 12, 22, 32, 42 of the second circuit section 5b have the same performance. The output of the first circuit unit 5a and the output of the second circuit unit 5b (both are voltage signals) are referred to as a first signal and a second signal, respectively.

  The arithmetic unit 6 includes a divider 61 having a circuit configuration of either type shown in FIG. The first signal and the second signal applied to the input unit of the divider 61 are once converted into current signals by resistors. The divider 61 obtains the ratio between the first signal and the second signal, and outputs the obtained ratio as the angle signal SigA. The angle signal SigA substantially corresponds to the incident angle θ of light with respect to the photodiodes 4a and 4b.

  As shown in FIG. 14 and FIG. 16 showing a typical divider circuit, the two signals inputted to the input section of the divider 61 in FIG. 1B always have a certain magnitude (the intensity of the optical signal). The bias currents 7a and 7b are substantially constant regardless of the bias currents 7a and 7b, and the bias currents 7a and 7b may cause an error in the output of the divider 61 (angle signal SigA). This error amount will be examined in detail. The bias currents 7a and 7b acting on the input unit of the divider 61 are represented as Ibias.

When the remote control signal is incident at an incident angle θ as shown by the dotted line in the upper part of FIG. 1B, the intensity of the photocurrent output from the photodiodes 4a and 4b is the amount of light received by the photodiodes 4a and 4b, and thus the photodiode. Is proportional to the area of the irradiated region, and is expressed as follows.
Photocurrent intensity by the photodiode 4a: l / 2−d · tan θ
Photocurrent intensity from the photodiode 4b: l / 2 + d · tan θ

Here, when the substantial current amplification degree of the first circuit unit 5a and the second circuit unit 5b with respect to the outputs (photocurrents) of the photodiodes 4a and 4b is α, the first circuit unit 5a and the second circuit unit. The signal current intensities I1 and I2 input to the input unit of the divider 61 from 5b are expressed by the following equation (10).
I1 = α (l / 2−d · tan θ)
I2 = α (l / 2 + d · tan θ) (10)

When the ratio of the bias current Ibias input to the divider 61 to the sum of the signal currents I1 and I2 from the first circuit portion 5a and the second circuit portion 5b (hereinafter referred to as “bias current ratio”) is r. , Ibias is expressed by the following equation (11).
Ibias = r · (I1 + I2)
= R · α · l (11)

When the divider 61 is a type of divider using a log amplifier as shown in FIG. 14, the output SigA of the divider 61 is obtained by referring to the equations (7), (10), and (11). Is expressed in a form that does not depend on the current amplification factor α as in the following equation (12).

Here, from the geometrical relationship shown in the upper part of FIG. 1B, the maximum detection angle θmax uses, for example, the length l of one side of the photodiodes 4a and 4b and the distance d between the light shielding plate 3a and the photodiodes 4a and 4b. Is expressed as the following equation (13).
tan (θmax) = l / 2d (13)

  As an example, when l = 1 mm and d = 0.19 mm, θmax = 69 ° from equation (13).

FIG. 2 shows the relationship between the actual incident angle θ of light and the angle signal SigA (here, Vout) expressed by Expression (12). The relationship in FIG. 2 is under the condition that the bias current ratio r = 0.05 and the maximum detection angle θmax = 69 °. A thick line ln (I1 / I2) shown in FIG. 2 represents an ideal line when Ibias does not exist. Reference symbols “+ / +”, “+/−”, “− / +”, and “− / −” indicate signs of the bias current Ibias in the equation (12). Specifically, the sign of the numerator in each reference symbol corresponds to the sign in the numerator of Equation (12), and the sign of the denominator in each reference symbol corresponds to the sign in the denominator of Equation (12). As can be seen from FIG. 2, the angular resolution Δθ under this condition is about 30 °. FIG. 3 shows the relationship between the bias current ratio r thus obtained and the angular resolution Δθ determined therefrom using the maximum detection angle θmax as a parameter. As can be seen from FIG. 3, when the maximum detection angle θmax increases, the angle resolution Δθ increases even at the same bias current ratio r, and the angle detection accuracy decreases. In FIG. 3, fit_69, fit_64, and fit_60 indicate straight lines obtained by linearly approximating the relationship between the bias current ratio r and the angular resolution Δθ when θmax = 69 °, 64 °, and 60 °, respectively. Yes. FIG. 4 shows a relationship (fit_a) between the maximum detection angle θmax and the gradient (reciprocal number) a of these straight lines fit_69, fit_64, and fit_60a in this case. From these results, when the desired angular resolution that the optical angle detection device 2 should have is ± Δθtarget, r <a · Δθtarget shown in the following equation (14) using a constant a corresponding to the maximum detection angle θmax. ... (14)
It is desirable to satisfy this relationship. This is because the optical angle detection device 2 can have the desired angular resolution ± Δθ target when the bias current ratio is r, if the relationship of the formula (14) is satisfied. Specifically, the specifications of the gains of the amplifiers 21 and 22, the light amounts of the light emitting elements, the light receiving lens, the resistance value of the input unit of the divider 61, and the distance between transmission and reception are comprehensive so as to satisfy the relationship of the above formula (14). Should be set to.

Further, from the above results, it is desirable that the value of the above a satisfies the relationship expressed by the following equation (15) with respect to the angular resolution Δθ and the maximum detection angle θmax (both units: °).
a <7.5 × 10 ⁻⁵ · θmax + 7.2 × 10 ⁻³ (15)

  If the relationship of the equation (15) is satisfied, the setting is optimal for both the angular resolution Δθ and the maximum detection angle θmax.

Next, the case where the divider 61 is a divider of the type shown in FIG. 16 will be described. In this case, when the first signal and the second signal (signal current intensity I1 and I2) are directly connected to the two systems of the input section of the divider 61, either output is obtained when the incident angle θ of light is large. Is extremely small, and the dynamic range of the angle signal SigA becomes very large, which is disadvantageous. Therefore, according to a known general technique, the sum (sum signal) of the first signal and the second signal is obtained by an adder (not shown), and the difference (difference signal) between the first signal and the second signal is obtained. ) Is obtained by a subtracter (not shown). The divider 61 performs division using the difference signal as a numerator and the sum signal as a denominator to obtain a quotient. From the equation (10), the sum signal and the difference signal are respectively expressed by the following equation (16).
I1 + I2 = α · l
I1−I2 = −2α · d · tanθ (16)
It becomes. In such a case, Iout as the output SigA of the divider 61 is expressed as the following equation (17) with reference to equations (9), (10), and (11).

  Here, the second line of Expression (17) is such that the reference current I0 is set to be sufficiently larger than the bias current Ibias (I0 >> rαl) so that Iout does not depend on the current amplification factor α. is there.

FIG. 5 shows the relationship between the actual incident angle θ of light and the angle signal SigA (here, Iout) expressed by Expression (17). The relationship of FIG. 5 is under the conditions of l = 1 mm, d = 0.19 mm, bias current ratio r = 0.05, and maximum detection angle θmax = 69 °, as in FIG. A thick line ln (I1 / I2) shown in FIG. 5 represents an ideal line when Ibias does not exist. Reference symbols “+ / +”, “+/−”, “− / +”, and “− / −” indicate the signs of the bias current Ibias in the equation (17), as in FIG. As can be seen from FIG. 5, the angular resolution Δθ under this condition is about 15 °. FIG. 6 shows the relationship between the bias current ratio r thus obtained and the angular resolution Δθ determined therefrom using the maximum detection angle θmax as a parameter, as in FIG. As can be seen from FIG. 6, when the maximum detection angle θmax increases, the angle resolution Δθ increases even at the same bias current ratio r, and the angle detection accuracy decreases. 6, fit_69, fit_64, and fit_60 indicate straight lines obtained by linearly approximating the relationship between the bias current ratio r and the angular resolution Δθ when θmax = 69 °, 64 °, and 60 °, respectively. Yes. FIG. 7 shows a relationship (fit_a) between the maximum detection angle θmax and the gradient (reciprocal number) a of these straight lines fit_69, fit_64, and fit_60a in this case. From these results, when the desired angular resolution that the optical angle detection device 2 should have is ± Δθtarget, a constant a corresponding to the maximum detection angle θmax is used, and r < a · Δθtarget
It is desirable to satisfy this relationship. This is because the optical angle detection device 2 can have the desired angular resolution ± Δθtarget when the bias current ratio is r, if the relationship of the formula (14) is satisfied.

Further, from the above results, it is desirable that the value a satisfies the relationship expressed by the following equation (18) with respect to the angular resolution Δθ and the maximum detection angle θmax (both in units of degrees).
a <1.5 × 10 ⁻⁴ · θmax + 1.4 × 10 ⁻² (18)

  If the relationship of the equation (15) is satisfied, the setting is optimal for both the angular resolution Δθ and the maximum detection angle θmax.

  As apparent from comparison between FIG. 3 and FIG. 5, the angular resolution Δθ is greater when the divider 61 has the circuit configuration of the type shown in FIG. 16 than the circuit configuration of the type shown in FIG. Improved. The number of elements constituting the divider 61 is larger in the divider shown in FIG. 16 than in the divider shown in FIG.

  Further, as apparent from the comparison between the equations (12) and (17), the divider of the type shown in FIG. 16 has no temperature dependency (theoretically), but the divider of the type shown in FIG. As shown in equation (12), the angle signal SigA increases or decreases in proportion to the temperature. For this reason, when the divider 61 has a circuit configuration of the type shown in FIG. 14, as shown in FIG. 1B, the calculation unit 6 has a temperature detection unit that detects the temperature of the divider 61 or its surroundings. You may provide the temperature sensor 62 and the correction circuit 63 as a temperature dependence correction | amendment part which correct | amends the temperature dependence of the output of the divider 61 according to the temperature which the temperature sensor 62 detected. As a result, even when the divider 62 is configured as the simplest analog divider, the detection accuracy of the incident angle θ can be further increased, and the use range of the light angle detection device 2 can be greatly expanded. be able to. When the divider 61 has a circuit configuration of the type shown in FIG. 14, the temperature sensor 62 and the correction circuit 63 may be omitted.

  Regarding the circuit configuration of the divider 61, the type of the circuit configuration shown in FIG. 14 or FIG. 16 is selected in consideration of the temperature dependence, the angular resolution, and the cost required by the optical angle detection device 2. Is desirable.

  As described with reference to FIG. 1B, the outputs of the photodiodes 4a and 4b are converted from current signals to voltage signals by the IV converters 11 and 12, amplified by the amplifiers 21 and 22, and output as voltage signals. In this process, an offset voltage is generated with respect to the reference potential of the remote control signal (generally a rectangular wave signal). If this offset voltage is included in the first and second signals and directly input to the divider 61, current is converted by the resistance of the input section of the divider 61 to become a bias current, so that the angular resolution Δθ is lowered. It becomes a factor. In view of this, BPFs 31 and 32 as filter circuits are provided at a stage subsequent to the amplifiers 21 and 22 (in this example, the next stage). The BPFs 31 and 32 cut direct current (DC) components included in the outputs of the amplifiers 21 and 22. In addition, by setting the center frequency that the BPFs 31 and 32 pass to be the same as the oscillation frequency of the remote control signal, noise components other than the remote control signal are cut, which is optimal. Since the filter circuit is provided after the amplifier 61, the offset voltage is not further amplified. Thereby, the bias current input to the divider 61 can be effectively reduced. Therefore, more accurate angle detection is possible.

  Generally, the waveform of the remote control signal is a rectangular wave, but since the signal only around the center frequency passes through the BPFs 31 and 32, the signal waveform becomes a sine wave after passing through the BPFs 31 and 32. Since the intensity of the sine wave constantly changes, it is very difficult to determine the timing for detecting the angle. Therefore, hold devices 41 and 42 typified by a peak hold circuit are provided downstream of the BPFs 31 and 32. These hold devices 41 and 42 hold the peak value of the signal for a certain period of time, so that the angle signal can be accurately taken out. Therefore, more accurate angle detection is possible.

  FIG. 8 shows a circuit configuration in which the periphery of the photodiode 4 in FIG. 1B (4 is a generic name of 4a and 4b) is improved. In this example, the second IV converter 13 that converts the photocurrent output from the photodiode 4 into a voltage signal, the level detection circuit 14 that detects the DC level of the voltage signal, and the DC level are canceled out. As described above, a constant current source 8 for allowing a DC current to flow into the photodiode 4 is provided. The 2nd IV converter 13 consists of resistance in this example. The level detection circuit 14 includes a known bottom hold circuit. The constant current source 8 is simply configured using a known current mirror circuit. The detailed description of the configuration is omitted here. The added elements 13, 14, and 8 in FIG. 8 constitute a background light removing unit.

  In an environment where the remote control transmitter 1 is operated, strong background light such as sunlight may exist. In such a case, if the amplifiers 21 and 22 amplify the background light signal as it is together with the remote control signal, the photocurrent due to the strong background light flows into the subsequent stage and lowers the S / N (signal to noise ratio). At the same time, the amplifiers 21 and 22 are saturated. Therefore, it is desirable to provide a background light removal unit as shown in FIG. The level detection circuit 14 detects the background light level with respect to the remote control signal as the DC level. The constant current source 8 causes a current corresponding to the DC level, that is, the background light level, to act on the output portion (the cathode in this example) of the photodiode 4 so as to cancel the background light. Thereby, the level of background light can be removed from the output of the photodiode 4. Therefore, the S / N can be improved and the amplifiers 21 and 22 can be prevented from being saturated by the background light. Therefore, the use range of this light angle detection device is greatly expanded.

  FIG. 9 shows a modification of the circuit unit of the light angle detection device 2. In this modified example, an adder 58 that adds the outputs of the BPFs 31 and 32 and a comparator 59 that compares the output of the adder 58 with a certain threshold value are provided as compared with the circuit unit shown in FIG. 1B. The point is different. The comparator 59 constitutes a false detection prevention unit, and when the output level of the adder 58 is equal to or higher than a threshold value, the comparator 59 is at an H (high) level, and when the output level of the adder 58 is equal to or lower than the threshold value, an L (low) level. Is output as an error signal SigE. The output of the calculation unit 6 is allowed when the error signal SigE is at the H level, while the output of the calculation unit 6 is prohibited when the error signal SigE is at the L level.

  When the intensity of the light arriving as the remote control signal becomes extremely small, the denominator value of the ratio between the first signal and the second signal obtained by the divider 61 becomes extremely small, and the output value of the divider 61 becomes invalid. There is a tendency for the angle value error to become very large. Further, there are cases where Expression (14), Expression (15), and Expression (18) are not satisfied. Therefore, with the configuration shown in FIG. 9, when the output level of the adder 58 is equal to or lower than the threshold value and the error signal SigE becomes L level, the output of the arithmetic unit 6 is prohibited. That is, when the intensity of light that arrives as a remote control signal is extremely small, the output is cut off as a measurement error. Accordingly, there is no false detection, and as a result, the detection accuracy of the incident angle can be further increased, and a desired angular resolution can be reliably obtained.

  In the example of FIG. 9, the adder 58 adds the outputs of the BPFs 31 and 32, but the outputs of the hold devices 41 and 42 may be added.

  FIG. 10 shows another modification of the circuit unit of the light angle detection device 2. In this modification, one IV converter 11, one amplifier 21, one BPF 31, and one hold device 41 are provided in common to the photodiodes 4a and 4b as compared with the circuit unit shown in FIG. 1B. Is basically different. Further, a switch 51 as a switch unit is interposed between the photodiodes 4 a and 4 b and the IV converter 11. A switch 52 and a sample hold unit 53 are provided downstream of the hold device 41.

  The switch 51 switches the outputs of the photodiodes 4 a and 4 b at a predetermined timing and inputs the same to the IV converter 11. At a certain timing, the output of the photodiode 4 a is applied to the amplifier 21 via the IV converter 11 and amplified by the amplifier 21. The output of the amplifier 21 is shaped by the BPF 31 and the hold device 41. The first signal after waveform shaping is temporarily held in the sample hold unit 53 by switching by the switch 52. At another timing subsequent to the above timing, the output of the photodiode 4b is applied to the amplifier 21 via the IV converter 11 by the switching by the switch 51, and is amplified by the amplifier 21. The output of the amplifier 21 is shaped by the BPF 31 and the hold device 41. The second signal after waveform shaping is applied to the divider 61 simultaneously with the first signal held in the sample hold unit 53. Then, the divider 61 obtains the ratio of the first signal and the second signal applied simultaneously and outputs the ratio as the angle signal SigA.

  As illustrated in FIGS. 11A and 11B, a general remote control signal includes a burst signal of several tens of kHz and a code signal composed of a plurality of cycles thereof. FIG. 11A shows a burst signal of about 38 kHz, and FIG. 11B shows a plurality of groups of code signals. 11A shows a part of FIG. 11B in an enlarged manner with respect to the time axis (horizontal axis). For example, when a first group code signal (0 to about 0.07 seconds) is detected among the remote control signals, the switch 51 shown in FIG. 10 connects the photodiode 4a and the IV converter 11. The switch 52 connects the hold device 41 and the sample hold unit 53. Based on the first group of code signals, a first signal based on the output of the photodiode 4 a is stored in the sample hold unit 53. Next, when the second group of code signals (about 0.13 second to about 0.2 second) shown in FIG. 11B is detected, the switch 51 shown in FIG. 10 is connected to the photodiode 4b and IV conversion. The switch 52 connects the hold unit 41 and the divider 61.

  In such a case, each of the IV converter 11, the amplifier 21, the BPF 31, and the hold device 41 can be configured one by one, and the optical angle detection device 2 can be downsized.

  Note that the signal for controlling the switching of the switches 51 and 52 is preferably created using, for example, the error signal SigE shown in FIG. For example, a period in which the first group of code signals (0 to about 0.07 seconds) shown in FIG. 11B is detected, a blank period (about 0.07 seconds to about 0.13 seconds), During the period in which the code signal (about 0.13 seconds to about 0.2 seconds) is detected, the error signal SigE transitions to approximately H level, L level, and H level (burst signal is ignored). ). According to such a level transition of the error signal SigE, for example, the switches 51 and 52 may be switched every time the error signal SigE becomes H level.

  The light angle detection device 2 can be mounted on various electronic devices. The application range of the electronic device can be expanded by controlling the operation of the electronic device using the angle signal SigA output from the optical angle detection device 2.

  FIG. 12A shows a mode in which the light angle detection device 2 is mounted on an air conditioning control device 109 such as an air conditioner. Here, the air-conditioning control device 109 is an air conditioner, a fan, a cooling fan, a halogen heater, a heater such as a fan heater, a cooling device, an air purifier, or the like. The light angle detection device 2 is attached near the front surface of the air conditioning control device 109 with the light receiving surfaces of the photodiodes 4a and 4b facing forward. Note that NL indicates a perpendicular to the light receiving surfaces of the photodiodes 4a and 4b (the same applies hereinafter). In this case, the person 110 operates the remote control transmitter 1 with his / her hand, and transmits a remote control signal to the air conditioning control device 109. Then, the light angle detection device 2 detects the incident angle θ, that is, the direction in which the person 110 is present with respect to the air conditioning control device 109, and outputs an angle signal representing it. With this angle signal, the air conditioning control device 109 can perform temperature control only in the vicinity of the person 110 as the control area 111. Therefore, not only the comfort of the person 110 is improved, but it is not necessary to control the temperature of the extra area, so that an energy saving effect can be expected.

  FIG. 12B shows a mode in which the light angle detection device 2 is mounted on a video equipment 112 such as a television receiver. Here, the video equipment 112 is a television receiver, a liquid crystal projector, a PC monitor, or the like. The light angle detection device 2 is mounted near the front surface of the video equipment 112 with the light receiving surfaces of the photodiodes 4a and 4b facing forward. In this case, the person 110 holds and operates the remote control transmitter 1 to transmit a remote control signal to the video equipment 112. Then, the light angle detection device 2 detects the incident angle θ, that is, the direction in which the person 110 exists with respect to the video equipment 112, and outputs an angle signal representing it. With this angle signal, the video equipment 112 can direct the display screen in the direction in which the person 110 exists. Therefore, the person 110 can appreciate the video in an optimal state. Further, it is possible to capture an image with a color tone and brightness most suitable for the direction in which the person 110 exists. Therefore, not only the person 110 is comfortable, but also the energy saving effect of the video equipment 112 can be expected.

  In recent years, a car navigation system equipped with a dual view liquid crystal (appearance image is different from that in FIG. 12B) has been developed as one of the video equipments 112. In this car navigation system, the images seen from the driver and the passenger on the passenger seat are different. When the light angle detection device 2 is mounted on such a car navigation system, the passenger on the passenger seat operates the remote control transmitter 1 in his / her hand and transmits a remote control signal to the system. For example, when receiving a remote control signal instructing to increase the volume, the system can increase the sound in accordance with the image seen from the passenger on the passenger seat. In this case, the convenience of the car navigation system can be greatly enhanced.

  FIG. 12C shows a mode in which the light angle detection device 2 is mounted on the stage 114 for the camera device 113. Here, the camera device 113 is a silver salt camera, a digital camera, a digital video camera, or the like. The stage 114 is attached to a tripod or the like, and has a mechanism for rotating the camera device 113 around a vertical axis (not shown). The light angle detection device 2 is mounted near the front edge of the stage 114 with the light receiving surfaces of the photodiodes 4a and 4b facing forward. In this case, the person 110 holds and operates the remote control transmitter 1 to transmit a remote control signal to the video equipment 112. Then, the light angle detection device 2 detects the direction in which the person 110 exists with respect to the camera device 13 and outputs an angle signal representing it. With this angle signal, the stage 114 can point the camera device 113 in the direction in which the person 110 exists. Therefore, the shooting area 115 can be automatically adjusted to a desired area, and the work accompanying the person 110 shooting himself / herself can be greatly reduced. In addition, it is more convenient to operate the automatic shutter of the camera device 113 by a remote control signal.

  FIG. 13A shows a modification of the light receiving element portion of the light angle detection device 2. In this modification, four photodiodes 4A, 4B, 4C, and 4D as light receiving elements are arranged two-dimensionally vertically and horizontally along the same plane (the paper surface of FIG. 13A). FIG. 13A is a view seen from a direction perpendicular to the light receiving surfaces of the photodiodes 4A, 4B, 4C, and 4D. Above these photodiodes 4A, 4B, 4C, and 4D, light shielding plates 3A, 3B, 3C, and 3D are disposed as light shielding elements, respectively. The light shielding plates 3A, 3B, 3C, and 3D are each formed in an L shape, and portions corresponding to 3/4 areas of the light receiving surfaces of the corresponding photodiodes 4A, 4B, 4C, and 4D (indicated by hatching). Covering. A portion (indicated by a white background) corresponding to a quarter of the light receiving surface of the photodiodes 4A, 4B, 4C, and 4D faces the outside. The photodiodes 4A, 4B, 4C, and 4D and the light shielding plates 3A, 3B, 3C, and 3D are separated by a certain distance d in the vertical direction (direction perpendicular to the paper surface of FIG. 13A).

  When such a light receiving element portion is provided, for example, the outputs of the photodiodes 4A and 4B arranged side by side (or the outputs of the photodiodes 4C and 4D) are the same circuit portions 5 and 6 as shown in the lower stage in FIG. 1B. By processing according to, an angle in one direction can be detected. Further, for example, by processing the outputs of the photodiodes 4A and 4C arranged vertically (or the outputs of the photodiodes 4B and 4D) by the same circuit units 5 and 6 as shown in the lower part of FIG. The angle in another direction perpendicular to can be detected. That is, the biaxial angle can be detected. Therefore, the function of the light angle detection device 2 can be improved.

  FIG. 13B shows another modification of the light receiving element portion of the light angle detection device 2. This modification corresponds to a configuration in which two sets of light receiving element portions shown in the middle HV in FIG. 1B are arranged so that four photodiodes are arranged in one direction. In FIG. 13B, the distance (distance between the centers) between the set of photodiodes 4a and 4b arranged on the left side and the set of photodiodes 4c and 4d arranged on the right side is set to w. .

  When such a light receiving element portion is provided, the outputs of the photodiodes 4a and 4b are processed by the same circuit portions 5 and 6 as shown in the lower part of FIG. 1B, that is, into a set of the photodiodes 4a and 4b. On the other hand, the direction in which the remote control transmitter 1 exists can be detected as the incident angle θ1. At the same time, by processing the outputs of the photodiodes 4c and 4d by the same circuit units 5 and 6 as shown in the lower part of FIG. 1B, the remote control transmitter 1 exists for the set of the photodiodes 4c and 4d. Can be detected as the incident angle θ2. The triangle having the vertexes at the remote control transmitter 1 and the centers of the two photodiode pairs is uniquely determined by the distance w and the two incident angles θ1 and θ2. Therefore, the position where the remote control transmitter 1 exists with respect to the light angle detection device 2 can be specified. Therefore, the function of the electronic device can be further improved.

It is a figure which shows the place which looked at the aspect used in combination with the remote control transmitter and the optical angle detection apparatus of one Embodiment of this invention from the direction perpendicular | vertical with respect to the surface to which a remote control transmitter moves. It is a figure which shows the structure of the light receiving element part and circuit part of the optical angle detection apparatus of one Embodiment of this invention. FIG. 15 is a diagram illustrating a relationship between an actual incident angle θ of light and an angle signal output from the divider when the divider included in the circuit unit has the circuit configuration of the type illustrated in FIG. 14. FIG. 3 is a diagram showing a relationship between a bias current ratio r and an angular resolution Δθ determined therefrom in the case of FIG. 2 using a maximum detection angle θmax as a parameter. FIG. 3 is a diagram showing a relationship between a maximum detection angle θmax and a constant a connecting a bias current ratio r and an angular resolution Δθ in the case of FIG. 2. FIG. 17 is a diagram illustrating a relationship between an actual incident angle θ of light and an angle signal output from the divider when the divider included in the circuit unit has a circuit configuration of the type illustrated in FIG. 16. FIG. 6 is a diagram showing a relationship between a bias current ratio r and an angular resolution Δθ determined therefrom using the maximum detection angle θmax as a parameter in the case of FIG. 5. FIG. 6 is a diagram showing a relationship between a maximum detection angle θmax and a constant a connecting the bias current ratio r and the angular resolution Δθ in the case of FIG. 5. It is a figure which shows the circuit structure which improved the periphery of the photodiode in FIG. 1B. It is a figure which shows the modification of the circuit part of the said optical angle detection apparatus. It is a figure which shows another modification of the circuit part of the said optical angle detection apparatus. It is a figure which shows the burst signal of about 38 kHz contained in the general remote control signal. It is a figure which shows the code signal contained in the general remote control signal. It is a figure which shows the aspect at the time of mounting the said optical angle detection apparatus in air-conditioning control apparatuses, such as an air conditioner. It is a figure which shows the aspect at the time of mounting the said optical angle detection apparatus in video equipment, such as a television receiver. It is a figure which shows the aspect which mounted the said optical angle detection apparatus in the stage for camera apparatuses. It is a figure which shows the modification of the light receiving element part of the said optical angle detection apparatus. It is a figure which shows another modification of the light receiving element part of the said optical angle detection apparatus. It is a figure which shows the circuit structure of the divider of the type using a log amplifier. It is a figure explaining the malfunction which may occur in the optical angle detection apparatus provided with the divider of the type shown in FIG. FIG. 15 is a diagram illustrating a circuit configuration of a divider of a type different from that illustrated in FIG. 14. It is a figure explaining the malfunction which may occur in the optical angle detection apparatus provided with the divider of the type shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Remote control transmitter 2 Optical angle detection apparatus 3a, 3b, 3c, 3d, 3A, 3B, 3C, 3D Light-shielding plate 4, 4a, 4b, 4c, 4d, 4A, 4B, 4C, 4D Photodiode 5 Light reception signal part 6 Arithmetic Units 7a, 7b Bias Current 8 Constant Current Source 110 Operator 111 Temperature Control Area 112 Video Equipment 113 Camera Equipment 114 Stage 115 Shooting Area

Claims (11)

Each remote control signal is received in the form of incident light and photoelectrically converted, and the light receiving amounts are different from each other according to the incident angle of the remote control signal, and are arranged side by side with a light shielding element to the outside. First and second light receiving elements;
An amplifier for amplifying outputs of the first and second light receiving elements to obtain first and second signals, respectively;
A divider for determining a ratio between the first signal and the second signal;
The angular resolution that the optical angle detection device should have is ± Δθ target, the constant corresponding to the maximum detection angle of the optical angle detection device is a, the bias current applied to the input unit of the divider and the first When the ratio of the first and second signals to the sum of currents is r, the amplification factor of the amplifier is
r <a · Δθtarget
An optical angle detection device characterized by being set to satisfy the following relationship. The light angle detection device according to claim 1,
An optical angle detection device comprising a filter circuit for substantially reducing the direct current components contained in the first and second signals. The light angle detection device according to claim 2,
The optical angle detection device according to claim 1, wherein the filter circuit is provided downstream of the amplifier. The light angle detection device according to claim 1,
Corresponding to the background light level at the output portion of each light receiving element so as to detect the background light level with respect to the remote control signal based on the photocurrent output from each light receiving element and cancel the background light A light angle detection device comprising a background light removal unit that causes a current to act. The light angle detection device according to claim 1,
The divider includes first and second logarithmic compressors for logarithmically compressing currents applied by the first and second signals to an input section of the divider, and an output of the first logarithmic compressor. And a subtractor that takes the difference between the output of the second logarithmic compressor,
When the maximum detection angle is θmax, the a is a <7.5 × 10 ⁻⁵ · θmax + 7.2 × 10 ^−3.
An optical angle detector characterized by satisfying the following relationship. The light angle detection device according to claim 1,
A temperature detector for detecting the temperature around the divider or the divider;
An optical angle detection device comprising: a temperature dependency correction unit that performs correction to cancel out the temperature dependency of the output of the divider according to the temperature detected by the temperature detection unit. The light angle detection device according to claim 1,
An adder for calculating a sum of the first signal and the second signal;
A subtractor for obtaining a difference between the first signal and the second signal;
The divider is designed to determine the ratio between the output of the adder and the output of the subtractor,
a <1.5 × 10 ⁻⁴ · θmax + 1.4 × 10 ⁻²
An optical angle detector characterized by satisfying the following relationship. The light angle detection device according to claim 2,
The filter circuit comprises a bandpass filter, and the center frequency of the bandpass filter is substantially the same as the frequency of the remote control signal,
An optical angle detection device comprising a hold circuit that temporarily holds the output of the bandpass filter and transfers it to the divider after the bandpass filter. The light angle detection device according to claim 1,
An adder for calculating a sum of the first signal and the second signal;
An optical angle detection device comprising: an erroneous detection preventing unit that prohibits the output of the divider when the output level of the adder is equal to or less than a certain threshold value. The light angle detection device according to claim 1,
Only one amplifier is provided in common for the first and second light receiving elements,
A switch unit that switches the outputs of the first and second light receiving elements at a predetermined timing and applies them to the amplifier;
Hold for temporarily holding at least one of the first or second signal output from the amplifier and transferring it to the divider so that the first and second signals are simultaneously applied to the divider. And a light angle detection device.   An electronic apparatus comprising the light angle detection device according to claim 1.

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