JP2004039298A - Lighting control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To construct a circuit for gain change for carrying out lighting control of a lighting apparatus with a high precision and at a low cost. <P>SOLUTION: This lighting control system comprises an illumination intensity sensor 1 that outputs a signal corresponding to the illumination intensity of the light detected from the surrounding, an A/D conversion circuit 21 that converts the analog signal outputted from this illumination intensity sensor 1 into a digital signal, and a light control part 32 that compares the level of the digital signal converted by this A/D conversion circuit 21 with the target reference value stored (set) beforehand in the conversion table memory part 31 and judges whether it is an insufficient gain or not, and when insufficient gain, outputs a gain change signal to the A/D conversion circuit 21 so as to change the gain of the A/D conversion circuit 21 to double, and controls lighting of the lighting apparatus 4 with the digital signal inputted from the A/D conversion circuit 21 according to the gain changed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination control system for detecting a wide illuminance range by, for example, switching output characteristics of an illuminance sensor circuit.
[0002]
2. Description of the Related Art For example, a conventional lighting control system used in an office or the like is composed of an illuminance sensor, an amplifier circuit, a control circuit, lighting equipment and the like. The illuminance sensor is usually mounted on a ceiling and measures the illuminance of the ceiling.
In this type of lighting control system, the target value that is the optimum illuminance generally sets the illuminance of the floor, so that the relationship between the floor illuminance and the ceiling illuminance, or the relationship between the floor illuminance and the illuminance sensor is used. It is necessary to save the relationship as a calibration value.
For example, the current illuminance A is checked with an illuminometer or the like, and when the current AD conversion value is B, the actual illuminance D for an arbitrary AD value C is
D = C × A ÷ B
Can be represented by
Normally, the illuminance is set as a discrete value, and is set in steps of 10 Lx to 100 Lx. Here, it is necessary to change the output of the illuminance sensor so that at least one bit is incremented after the AD conversion of the output of the illuminance sensor per minimum step.
The maximum target illuminance that can be set is about 2500 Lx to 35001 Lx. At the maximum brightness, it is necessary that the brightness after the A / D conversion does not overflow.
Further, since the illuminance sensor actually detects the illuminance of the ceiling instead of the illuminance of the floor surface, the required gain of the illuminance sensor also changes depending on the ratio of the illuminance of the floor surface and the illuminance of the ceiling. In the conventional lighting control system, since the illuminance sensor is usually installed on the ceiling as described above, the relationship with the floor illuminance is larger depending on the installation environment, that is, the height of the ceiling, the floor, the weight, and the reflectance of the ceiling. It depends.
Assuming that the A / D converter for A / D converting the output voltage of the illuminance sensor is 8 bits, if the reflectance to the ceiling is 0.4 when the target value is 3000 Lx, the illuminance on the ceiling is 1200 Lx. . At this time, if the target value setting steps are 50 Lx steps, the ceiling illumination changes by 20 Lx steps. That is, when the illuminance of the ceiling changes by 20 Lx, the A / D converter is set to change by 1 or more, and a signal is output from the illuminance sensor such that the illuminance of the ceiling does not exceed 1200 Lx and the A / D value does not exceed 255. There is.
(1/20) <G <(255/1200)
That is, 0.05 <G <0.2125 must be satisfied.
If the reflectance is 0.05 and the target value is 3000 Lx, the illuminance on the ceiling is 150 Lx. At this time, if the target value setting step is 50 Lx at a time, the ceiling illuminance changes by 20 Lx.
That is, when the illuminance on the ceiling changes by 20 Lx, the A / D converter needs to change by 1 or more, and the illuminance sensor output needs to be such that the illuminance on the ceiling is 150 Lx and the A / D value does not exceed 255.
(1/1) <G <(255/150)
That is, 1 <G <1.7 must be satisfied.
In other words, the required gain is different when the reflectance to the ceiling is 0.4 and the required gain is 0.05 when the reflectance is 0.05. In such a case, it is necessary to switch the gain of the illuminance sensor.
[0003]
Here, the configuration of the amplifier circuit of the conventional lighting control system will be described with reference to FIG. FIG. 10 is a diagram showing a configuration of an amplifier circuit of a conventional illumination control system. As shown in FIG. 10, the amplifier circuit of the conventional illumination control system includes a photodiode PD as an illuminance sensor, resistors R5, R6, R7, an operational amplifier IC1, an analog switch Q5, and the like. The photodiode PD converts light into a current. The current that is photoelectrically converted is substantially proportional to the illuminance. This current is converted to a voltage by the resistor R1. The operational amplifier IC1 is an operational amplifier for switching a gain.
In this amplifier circuit, when the analog switch Q5 is OFF, the gain is 1 due to 100% negative feedback. If the resistors R6 and R7 have the same value, when the analog switch Q5 is ON, the gain becomes 2 and a double output is obtained.
By the way, in the case of the conventional amplifying circuit, since the gain is switched by the operational amplifier IC1, it is naturally necessary to use the operational amplifier IC1 which is more expensive than the resistance element or the like. Further, since the gain switching is performed by switching the feedback resistance element, it is necessary to use, for example, an FET as the analog switch Q5.
[0004]
As described above, in the case of an amplifier circuit using expensive integrated components such as an operational amplifier and an FET, there is a problem that the cost of the entire illumination control system becomes high.
Further, since the resistors R2 and R3 used together with the FET are discrete components, each of which has a manufacturing error, there is a problem that it is difficult to obtain the amplification degree at an accurate magnification such as n times or 1 / n times.
[0005]
The present invention has been made in order to solve such a problem, and the cost of the entire system can be reduced by configuring a circuit for performing gain switching for performing dimming control of a lighting fixture with high accuracy and at low cost. It is intended to provide a lighting control system.
[0006]
In order to solve the above-mentioned problems, a lighting control system according to the first aspect of the present invention is a lighting control system for dimming a lighting fixture according to the illuminance of the surroundings. An illuminance sensor for outputting a current corresponding to the illuminance of the light; an A / D conversion circuit for converting a current input from the illuminance sensor into a digital signal; a level of the digital signal converted by the A / D conversion circuit And a predetermined reference value to determine whether the gain is excessive or insufficient, and switch the signal amplification of the A / D conversion circuit to 1 / n or n times according to the determined gain. Gain switching means for controlling switching of the signal amplification degree for the A / D conversion circuit; a digital signal input from the A / D conversion circuit; and a signal amplification switched by the gain switching means. It is characterized by comprising a; and dimming means for dimming control the luminaire on the basis of and. Note that the illuminance sensor may be configured to output a voltage by not only outputting a current but also forming a circuit through a resistor.
According to the first aspect of the present invention, it is determined whether the gain is excessive or insufficient based on the level of the digital signal converted by the A / D conversion circuit and a preset reference value. Since the switching control of the signal amplification for the A / D conversion circuit is performed so as to switch the signal amplification of the A / D conversion circuit to 1 / n or n times, the gain can be switched with a simple configuration.
[0007]
According to a second aspect of the present invention, in the illumination control system according to the first aspect, the A / D conversion circuit converts a current input from the illuminance sensor into a voltage; and the voltage; A current mirror circuit interposed between the conversion element and the illuminance sensor.
According to the second aspect of the present invention, since the A / D conversion circuit includes the voltage conversion element that converts the current input from the illuminance sensor into a voltage and the current mirror circuit, it is possible to reduce component costs. Note that the A / D conversion circuit can be realized with high accuracy by using a multi-transistor configuration in which the current mirror circuit is formed on the same pellet.
[0008]
4. The illumination control system according to claim 3, wherein the illumination system outputs a current corresponding to the illuminance of light detected from the periphery in the illumination system for dimming the luminaire in accordance with the illuminance of the periphery; An A / D conversion circuit for converting a current output from the A / D converter into a digital signal; comparing the level of the digital signal converted by the A / D conversion circuit with a preset target reference value, A digital input from the A / D conversion circuit is determined so as to determine whether the gain is excessive or deficient and to switch the signal amplification of the A / D conversion circuit to 1 / n or n times in accordance with the situation of the gain. A bit shift unit for shifting a read bit of a signal; and the lighting fixture by reading data from the digital signal with the read bit shifted by the bit shift unit. It is characterized by comprising a light control means for controlling dimming.
According to the third aspect of the present invention, the read bits of the digital signal input from the A / D conversion circuit are shifted, so that the bit-shifted data is only read, and there is no influence from a manufacturing error of the electronic component. The gain can be switched easily and with high accuracy.
As a result, the cost of the entire system can be reduced by configuring the circuit for performing gain switching for performing the dimming control of the lighting fixture with high accuracy and at low cost.
[0009]
Embodiments of the present invention will be described below in detail with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a lighting control system according to a first embodiment of the present invention.
[0010]
As shown in FIG. 1, the illumination control system includes an illuminance sensor 1, an A / D signal, an amplification circuit 2 to which a gain switching signal is input, and an A / D signal input from the amplification circuit 2. It has a control circuit 3 for performing dimming control based on the gain and a gain switching control for the amplifier circuit 2, and a lighting device 4 for turning on and off a lamp such as a fluorescent lamp or an incandescent lamp by the dimming control from the control circuit.
The illuminance sensor 1 is a means for converting light into a current, and converts a predetermined gain given from the amplifier circuit 2 into a current according to the amount of received light.
The A / D conversion circuit 21 is built in the amplification circuit 2. The A / D conversion circuit 21 converts the current generated in the illuminance sensor 1 into a voltage, and outputs an amplified and digitized voltage (8-bit A / D signal).
As the control circuit 3, for example, a microcomputer (8-bit microcomputer) that processes an input A / D signal (digital signal) in 8-bit units is used. The control circuit 3 includes a conversion table 31, a dimming control unit 32, and the like. The conversion table 31 stores a conversion table (see FIG. 3) as an illuminance target value. The dimming control unit 32 calculates the actual illuminance based on the A / D signal (8-bit voltage) input from the illuminance sensor 1 through the amplification circuit 2, and calculates the calculated illuminance and the illuminance target value of the conversion table 31. When the calculated illuminance is equal to or less than the illuminance target value, for example, a gain switching signal is output to the amplifier circuit 2. When the calculated illuminance is equal to or more than the illuminance target value, for example, the output of the gain switching signal is output. To stop. Further, the dimming control unit 32 controls the dimming of the luminaire 4 so that the illuminance obtained from the input A / D signal and the illuminance target value match.
That is, the control circuit 3 controls the dimming of the luminaire 4 based on the A / D signal input from the amplifier circuit 2, and has insufficient gain such that the dimming control cannot be performed from the digitally input A / D signal. Gain switching means for outputting to the amplifier circuit 2 a gain switching signal for performing switching control to make the gain (amplification degree) of the amplifier circuit 2 twice (2n) the current gain (n) when falling into Function as Note that n is an integer. The control circuit 3 also performs control to return to the original gain (n) when the gain becomes excessive when the current gain has already been doubled (2n). In this case, n / 2n = 1/2 times. In this embodiment, the gain is doubled or halved. However, the gain can be quadrupled or octupled.
[0011]
FIG. 2 shows an example of a conversion table for calibration and gain switching.
The dimming control unit 32 refers to (reads out) the contents of the conversion table stored (set) in the conversion table storage unit 31 in advance, and sets the target illuminance value at the time of calibration and the level obtained from the illuminance sensor 1 ( AD value), and the gain is switched based on the ratio.
As shown in FIG. 2, for example, if the AD value of the illuminance sensor 1 is 20 when the calibration is performed at 1000 Lx, the ratio is 0.05. If the number of setting steps is 50 Lx, the value of the illuminance sensor 1 is 2.5 per step, so that one gain is not changed. Similarly, if the AD value of the illuminance sensor 1 at the time of calibration is 50, the ratio is 0.02. Similarly, if the number of setting steps is 50 Lx, the gain of the illuminance sensor 1 will be insufficient because the AD value of the illuminance sensor 1 is 1 per step. In this case, since the dimming control cannot be performed, the input gain needs to be switched to twice. Therefore, by inputting a gain switching signal from the control circuit 3 to the amplifier circuit 2, the amplifier circuit 2 is instructed to switch the amplification degree of the A / D signal, and the gain is switched.
Similarly, if the AD value of the illuminance sensor 1 at the time of calibration is 10, the ratio is 0.01. Similarly, if the number of setting steps is 50 Lx, the gain of the illuminance sensor 1 is 0.5 per step, resulting in insufficient gain. Therefore, the amplification of the A / D signal is increased by four times.
As described above, the gain of the illuminance sensor 1 is determined based on the ratio between the illuminance at the time of performing the calibration and the output (AD value) of the illuminance sensor 1, and the gain is switched. The resolution of the read AD value can be kept substantially constant.
[0012]
That is, in the case of this illumination control system, the dimming control unit 32 converts the level (AD value) of the 8-bit A / D signal (digital signal) converted and input by the A / D conversion circuit 21 in advance. An excess or deficiency of the gain is determined based on the target reference value stored (set) in the table storage unit 31, and the signal amplification degree of the A / D conversion circuit is reduced by 1 / in accordance with the determined excess or deficiency of the gain. The gain switching control for the A / D conversion circuit 21 is performed so as to switch to n times or n times. Further, the dimming control unit 32 controls dimming of the lighting fixture 4 based on the digital signal input from the A / D conversion circuit 21 and the switched gain.
[0013]
Next, a specific configuration of the amplifier circuit 2 will be described with reference to some circuit examples.
First, a first embodiment of the amplifier circuit will be described with reference to FIG.
As shown in FIG. 3, the amplifier circuit of the first embodiment has a dual transistor configuration in which a photodiode PD as an illuminance sensor 1, a resistor R1, a resistor R2, two transistors Q1, and a transistor Q2 are formed in the same pellet. A transistor Q3 and the like are provided according to a current mirror circuit CM and a gain switching signal from a control circuit.
The cathode end of the photodiode PD is connected to a power supply. The anode end of the photodiode PD is connected to the reference current side of a current mirror circuit composed of the transistors Q1 and Q2. The photodiode PD generates a current corresponding to the amount of received light, and this current is converted to a voltage by flowing through the resistor R1 as a voltage conversion element together with the duplicated current.
The current mirror circuit CM is inserted and connected between the photodiode PD and the resistor R1.
Specifically, in the current mirror circuit CM, the reference current side (the side of the transistor Q1) is connected to the photodiode PD, and the copy current side (the side of the transistor Q2) is connected to a controllable power supply, that is, the collector of the transistor Q3. The configuration is such that both the reference current and the duplication current flow through the resistor R3, which is a voltage conversion element.
The collector of the transistor Q2 is connected to the collector of the transistor Q3 so that connection to a power supply can be opened and closed. When the transistor Q3 is turned on and the transistor Q2 is connected to the power supply, the current of the photodiode PD is duplicated by the current mirror circuit CM, and the current flowing through the resistor R1 is doubled.
On the other hand, when the power supply to the transistor Q2 is cut off by turning off the transistor Q3, the transistor Q2 acts as a diode between the base and the emitter, and the current of the photodiode PD is merely shunted to double the current. Absent.
As the transistors Q1 and Q2 of the current mirror circuit CM, a dual transistor in which two elements are formed in the same pellet is used. This makes it possible to accurately (accurately) generate a double current with good element characteristics.
[0014]
As described above, according to the illumination control system using the amplifier circuit of the first embodiment, as the gain switching means, the current mirror circuit CM inserted between the photodiode PD and the resistor R1 as a voltage conversion element is used. By providing a circuit capable of changing the ratio of the output voltage to the illuminance obtained by the photodiode PD by an integral multiple, a gain switching signal is output from the control circuit 3 to the amplifier circuit 2 and A / A amplified by the amplifier circuit 2 is output. The amplification degree of the D signal, that is, the gain can be switched. In other words, when calibrating the photodiode PD, the gain is switched based on the ratio between the illuminance at the time of calibration and the read value of the digital signal from the photodiode PD at that time. The optimum gain of the illuminance sensor can be set by a simple method without measuring.
Further, by using the dual-transistor current mirror circuit CM, it is not necessary to use an expensive analog switch such as an FET, so that the cost of the entire system can be reduced together with the cost of parts.
Furthermore, the current mirror circuit CM has a dual transistor configuration in which the two transistors Q1 and Q2 are formed in the same pellet, so that the gain can be switched at low cost without being affected by the accuracy of the resistance element or temperature change. Can be.
[0015]
Next, a second embodiment of the amplifier circuit 2 will be described.
Since the transistor Q3 shown in the first embodiment operates as a constant current circuit, its current does not depend on the power supply voltage. Therefore, it may be different from the power supply to which the photodiode PD is connected.
Therefore, in the second embodiment, as shown in FIG. 4, the transistor Q3 is not used, and the diode D1 is used, and the cathode of the diode D1 is connected to the collector of the transistor Q2 of the current mirror circuit CM. The anode side is configured to be directly attached to a port of a microcomputer capable of outputting a certain amount of current. The microcomputer indicates the control circuit 3. Since the diode D1 is used as a means for obtaining a power supply for controlling the duplication transistor Q2 of the current mirror circuit CM from the port of the microcomputer as described above, the A / D is compared with the case where the integrated element such as the transistor Q3 is used. The conversion circuit 21 can be configured at low cost.
[0016]
As described above, according to the illumination control system using the amplifier circuit of the second embodiment, by using the diode D1 instead of the transistor Q3 of the first embodiment, the component cost is further increased as compared with the case of the first embodiment. Can be reduced.
[0017]
Next, a description will be given of a third embodiment of the amplifier circuit.
The third embodiment is a modified example in which the gain is set to a magnification other than 2 or 1/2. As shown in FIG. 5, the current mirror circuit CM is used as a gain switching means. By mounting three Q2s in parallel, the gain can be quadrupled.
[0018]
As described above, according to the illumination control system using the amplifier circuit of the third embodiment, the current mirror circuit CM has a configuration in which three transistors Q2 on the duplication side are attached in parallel, so that the current mirror circuit CM is quadrupled or 1 / A circuit capable of switching gain four times can be configured with high accuracy and at low cost. Further, by connecting the diode D1 to a port such as a microcomputer capable of outputting a current, the gain of the photodiode PD can be switched with a circuit configuration that is less expensive than in the first embodiment.
[0019]
Next, a description will be given of a fourth embodiment of the amplifier circuit.
The fourth embodiment is a modification in which the gain is set to a magnification other than 2 or 1/2, and as shown in FIG. 6, a current mirror circuit having the circuit configuration shown in the second embodiment (FIG. 4). The gain can be quadrupled by connecting the CMs in series, for example, in two stages.
[0020]
As described above, according to the illumination control system using the amplifier circuit of the fourth embodiment, the current mirror circuit CM is connected in two stages in series, so that the gain can be switched four times or one quarter. A circuit that can be performed can be configured with high precision and at low cost. Further, by connecting the diode D1 to a port capable of outputting a current, such as a microcomputer, the gain of the illuminance sensor 1 can be switched with a circuit configuration that is less expensive than in the first embodiment.
That is, in the second to fourth embodiments, the transistor Q1 on the reference current side and the plurality of replica transistors Q2 are formed in parallel on the same pellet, or the dual transistor Q1 and the transistor Q2 are formed on the same pellet. By using a multi-transistor current mirror circuit formed by connecting transistors in multiple stages, manufacturing errors between elements can be substantially eliminated.
[0021]
Next, a lighting control system according to a second embodiment of the present invention will be described.
In the lighting control system of the first embodiment, the amplifier circuit is configured by a circuit in which actual electronic components and elements are combined, but equivalent to these configurations, digital signal processing (or software processing) only on the microcomputer side is performed. Since the gain can be switched, it will be described below.
As a technique, the number of bits of the A / D conversion circuit of the amplifier circuit is set higher than that of the control circuit (microcomputer), and the data reading timing is shifted, that is, the data input to the microcomputer is shifted by n times or n times. An amplification degree (gain) of 1 / n times is obtained.
[0022]
As shown in FIG. 7, the illumination control system according to the second embodiment includes an illuminance sensor 1, an amplification circuit 2 that outputs an A / D signal, and dimming control based on an A / D signal input from the amplification circuit 2. And a lighting device 4 for turning on and off a lamp such as a fluorescent lamp or an incandescent lamp by dimming control from the control circuit.
The illuminance sensor 1 is a means for converting light into a current, and converts a predetermined gain given from the amplifier circuit 2 into a current according to the amount of received light.
A / D conversion circuit 22 is built in amplification circuit 2. The A / D conversion circuit 22 converts the current from the illuminance sensor 1 into a voltage, amplifies the voltage, and outputs a digitized voltage (10-bit A / D signal).
As the control circuit 3, for example, a microcomputer (8-bit microcomputer) that processes an input A / D signal (digital signal) in 8-bit units is used. The control circuit 3 includes a conversion table storage unit 31, a bit shift unit 35, a dimming control unit 36, and the like. The conversion table storage unit 31 stores a conversion table (see FIG. 3) as an illuminance target value. The dimming control unit 36 calculates the actual illuminance based on the voltage of the A / D signal input through the amplifier circuit 2, compares the calculated illuminance with the illuminance target value of the conversion table 31, and calculates the calculated illuminance. Is smaller than or equal to the illuminance target value, the bit shift unit 35 is instructed to perform a bit shift of −1 bit, and if the calculated illuminance is equal to or greater than the illuminance target value, for example, Indicates one bit shift. The bit shift unit 35 is an A / D signal (10-bit voltage) input from the illuminance sensor 1 through the amplification circuit 2 according to an instruction from the dimming control unit 36, and is different between the gain switching time and the normal time. And outputs an 8-bit A / D signal that has been bit-shifted to the range of. The dimming control unit 36 extracts an arbitrary extracted bit from the 8-bit A / D signal input from the bit shift unit 35 and obtains an amplification factor of the A / D signal. Further, the dimming control unit 32 controls the dimming of the luminaire 4 so that the illuminance obtained from the input A / D signal matches the illuminance target value corresponding to the amplification factor obtained from the extracted bits. In this example, three bits are used as the arbitrary extracted bits.
[0023]
In the case of this illumination control system, as shown in FIG. 8, the dimming control unit 32 converts the level of a 10-bit A / D signal (digital signal) input by being converted by the A / D conversion circuit 22 (see FIG. 8). 9 (a) is compared with a target reference value (M shown in FIG. 9 (b)) stored (set) in the conversion table storage unit 31 in advance to determine whether the gain is excessive or insufficient. In step S101, the bit shift unit 35 is instructed to switch the signal amplification of the A / D conversion circuit 22 to 1 / n or n times according to the determined gain excess or deficiency. The shift unit 35 shifts the read bit of the digital signal input from the A / D conversion circuit 22 (S103). The dimming control unit 32 reads the data from the A / D signal with the read bits shifted by the bit shift unit 35, thereby controlling the dimming of the lighting fixture 4.
That is, the control circuit 3 controls the dimming of the luminaire 4 based on the A / D signal input from the amplifier circuit 2, and has insufficient gain such that the dimming control cannot be performed from the digitally input A / D signal. (No in S102), the bit shift unit 35 shifts a bit to read one (or two bits) from the current 8-bit range to a predetermined bit from the shifted (bit-shifted) range. To calculate the magnification.
In this case, as shown in FIG. 9C, the data of bit shift = 0 is bit-shifted in the direction of the arrow (←) to receive the data of bit shift = −1, and the data in the extraction range (extraction bit) ) Is extracted (S103). At the original data position where the bit shift = 0, the extracted bit is “001”, but becomes “010”, which is doubled as a result of the magnification calculation in the binary number.
On the other hand, when the gain of the current A / D signal is already multiplied by the control circuit 3 and it is determined that the gain is excessive (Yes in S102), the A / D signal is returned to the original gain. Perform return control.
In this case, as shown in FIG. 9D, the data of bit shift = 0 is bit-shifted in the direction of the arrow (→) to receive the data of bit shift = 1, and the data in the extraction range (extraction bits) Is extracted (S104). At the position of the data where the bit shift = 0 before the bit shift, the data whose extraction bit is “010” becomes “001”, and as a result of the magnification calculation in the binary number, it becomes 倍 times.
For example, an 8-bit microcomputer (hereinafter referred to as an 8-bit microcomputer) is used as a one-chip microcomputer as the control circuit 3. At this time, since data larger than 8 bits requires a memory of 2 bytes or more, a large amount of memory is consumed and the operation speed is reduced. Therefore, it is desirable that the A / D signal (digital data after A / D conversion) inputted from the illuminance sensor 1 to the amplifier circuit 2 and subjected to A / D conversion is also 8 bits long.
For example, if a 10-bit A / D conversion circuit 22 is used and the reference voltage is not changed, the 8-bit microcomputer side is four times as large as when the 8-bit A / D conversion circuit 22 is used. The data can be obtained with the fineness of.
Normally, when the A / D signal output from the 10-bit A / D conversion circuit 22 is input to the 8-bit microcomputer, the 8-bit microcomputer discards and discards the lower 2 bits of the input 10 bits. By shifting the bits from the lower bits to the upper bits of the data obtained by the bit microcomputer, the data of the upper 8 bits is doubled for each shift. This has the same effect as when the gain of the illuminance sensor 1 is switched.
[0024]
As described above, according to the illumination control system of the second embodiment, by using the 10-bit A / D conversion circuit 22 and the 8-bit input microcomputer, a 2-bit bit shift is possible on the microcomputer side. The gain can be doubled, doubled, or doubled, and doubled.
That is, by providing the A / D conversion circuit 22 having an output bit number larger than the processing bit number of the microcomputer, for example, 10 bits, the digital data input to the microcomputer side is doubled, 8 times only by bit-shifting and reading. Since the gain can be switched by a multiple such as double, 1/2, or 1/8, the gain can be switched by an inexpensive method without being affected by a manufacturing error of the electronic component.
[0025]
It should be noted that the present invention is not limited only to the above embodiment.
Although some of the gain switching means have been described in the above embodiment, these may be performed alone or in combination.
In the above embodiment, it is assumed that the reference voltages of the A / D conversion circuits 21 and 22 are not changed. However, there is a method of changing the reference voltages of the A / D conversion circuits 22 and 22.
When the reference voltages of the A / D conversion circuits 21 and 22 are reduced to １ ／, the data obtained by the A / D conversion can obtain the same data as when the gain is doubled.
According to each of the above examples and embodiments, it is possible to provide an illumination control system that can reduce the cost of the entire system by configuring a circuit for performing gain switching with high accuracy and at low cost.
[0026]
As described above, according to the first aspect of the invention, the gain is excessive or insufficient based on the level of the digital signal converted by the A / D conversion circuit and a preset reference value. Is determined, and the switching of the signal amplification for the A / D conversion circuit is controlled so that the signal amplification of the A / D conversion circuit is switched to 1 / n or n times in accordance with the determined gain excess or deficiency. The gain can be switched with a simple configuration.
According to the second aspect of the present invention, the A / D conversion circuit is composed of the voltage conversion element that converts the current input from the illuminance sensor into a voltage and the current mirror circuit, so that the component cost can be reduced. it can.
According to the third aspect of the present invention, by shifting the read bit of the digital signal input from the A / D conversion circuit, the bit-shifted data is simply read, and the influence of the manufacturing error of the electronic component is affected. The gain can be switched easily and with high accuracy without any need.
As a result, the cost of the entire system can be reduced by configuring the circuit for performing gain switching for performing the dimming control of the lighting fixture with high accuracy and at low cost.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a lighting control system according to a first embodiment of the present invention.
FIG. 2 is a diagram showing an amplifier circuit according to a first embodiment in the illumination control system of FIG. 1;
FIG. 3 is a diagram showing a conversion table of a control circuit in the amplifier circuit of FIG. 2;
FIG. 4 is a diagram showing an amplifier circuit according to a second embodiment in the illumination control system of FIG. 1;
FIG. 5 is a diagram showing an amplifier circuit according to a third embodiment in the illumination control system of FIG. 1;
FIG. 6 is a diagram showing an amplifier circuit according to a fourth embodiment in the illumination control system of FIG. 1;
FIG. 7 is a diagram showing a configuration of a lighting control system according to a second embodiment of the present invention.
FIG. 8 is a flowchart showing the operation of the lighting control system of FIG. 7;
FIG. 9 is a conceptual diagram of a bit shift operation by the illumination control system of FIG. 7;
FIG. 10 is a diagram showing a configuration of a conventional amplifier circuit.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Illuminance sensor, 2 ... Amplification circuit, 3 ... Control circuit, 4 ... Lighting equipment, 21,22 ... A / D conversion circuit, 31 ... Conversion table storage unit, 32,36 ... Dimming control circuit, 35 ... Bit shift Department.

Claims (3)

In a lighting control system that dims lighting equipment according to the surrounding illuminance,
An illuminance sensor that outputs a current according to the illuminance of light detected from the periphery;
An A / D conversion circuit that converts a current input from the illuminance sensor into a digital signal;
An excess or deficiency of a gain is determined based on a level of the digital signal converted by the A / D conversion circuit and a preset reference value, and the A / D conversion circuit is determined in accordance with the determined excess or deficiency of the gain. Gain switching means for controlling the signal amplification degree of the A / D conversion circuit so as to switch the signal amplification degree of 1 / n or n times; and a digital signal input from the A / D conversion circuit; Dimming means for dimming the lighting fixture based on the signal amplification switched by the gain switching means;
A lighting control system comprising: The lighting control system according to claim 1,
The A / D conversion circuit comprises:
A voltage conversion element that converts a current signal input from the illuminance sensor into a voltage;
A current mirror circuit interposed and connected between the voltage conversion element and the illuminance sensor;
A lighting control system comprising: In a lighting system that dims lighting equipment according to the surrounding illuminance,
An illuminance sensor that outputs a current according to the illuminance of light detected from the periphery;
An A / D conversion circuit that converts a current output from the illuminance sensor into a digital signal;
The level of the digital signal converted by the A / D conversion circuit is compared with a preset target reference value to determine whether the gain of the digital signal is excessive or insufficient. A bit shift unit that shifts a read bit of a digital signal input from the A / D conversion circuit so as to switch a signal amplification degree of the A / D conversion circuit to 1 / n or n times;
A lighting control system for controlling light control of the lighting apparatus by reading data from the digital signal with the read bit shifted by the bit shift means.

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