JP2006235891A - Reference voltage setting device and lighting system using the device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To set a voltage corresponding to the rated current of a load circuit as a reference voltage and control a load current within a range posing no adverse effects to a life characteristic and the like according to the reference voltage. <P>SOLUTION: A lighting system comprises: the load circuit connecting in series a lighting head 3, a switching element Q1 and a current detection resistor Rs; a reference voltage setting circuit 4 for holding as a reference voltage Vref a voltage Vs corresponding to a load current detected by the current detection resistor when a rated voltage is applied to the load circuit and the switching element is switched on; and a current control circuit 8 for controlling the switching element such that the detected voltage Vs has a constant relationship with the reference voltage Vref when a predetermined voltage is applied to the load circuit. The reference voltage setting circuit and the current control circuit cooperate in limiting the current flowing through the lighting head within a controlled range. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

    The present invention relates to a reference voltage setting device applied to a system / device for performing visual inspection, positioning, etc. of a product by processing image data from, for example, general illumination, display display or CCD (charge coupled device), and the device. The present invention relates to an improvement of the used lighting device.

In general, when performing surface inspection of a product or positioning of an assembly part in a manufacturing process, an illumination device is used to capture image information from the product or the assembly part. For example, when surface inspection of a product is performed, the surface state of the product to be inspected is obtained by irradiating the product to be inspected with light from an illumination device, imaging the product to be inspected with a CCD, and comparing the image data with reference data. (Scratches, deformation, etc.) are inspected.

An illumination device applied to such an application is configured by connecting an illumination head in which a large number of light emitting diodes (LEDs) are connected in series or in parallel to a power supply device that outputs a voltage of 12 to 25 V, for example. Yes.
In this apparatus, when an AC power supply is connected to the power supply apparatus, a predetermined voltage is applied to the illumination head, and each light emitting diode emits light to illuminate a product to be inspected.
By the way, it is known that a light emitting diode constituting an illumination head affects characteristics such as brightness and life depending on a current flowing therethrough. For example, the brightness increases when the amount of current supplied to the light emitting diode is greater than an appropriate value (for example, a rated value), and conversely decreases when the amount is less than the appropriate value. In addition, the greater the energization amount is, the more likely it is to be damaged, and there is a concern about adverse effects on the service life. Accordingly, it is required to set the energization amount of the light emitting diode during operation to an appropriate current range.

  For example, Japanese Patent Laid-Open No. 2004-299102 proposes an illumination device for dealing with such a case. As shown in FIG. 5, the lighting device connects a plurality of light emitting diodes F and a current detection resistor Rs in series, and has four terminals Ta and Tb at both ends of the circuit and the current detection resistor Rs. , Tc, Td, a power supply unit NU that outputs a voltage (for example, 12 to 25 V) sufficient to turn on the lighting head H and a reference voltage corresponding to the rated current of the lighting head H, current And a power supply device B having a control circuit IC. The current control circuit IC includes an operational amplifier OP, a transistor TR, a resistor, and the like.

This lighting device operates as follows. First, when the transistor TR is turned on, the load current Io flows from the power supply unit NU to the lighting head H, and the voltage Vs (= Io · Rs) is generated at the terminals Tb and Tc of the current detection resistor Rs. This detection voltage Vs is compared with the reference voltage Vref by the operational amplifier OP of the current control circuit IC, and when the detection voltage Vs becomes equal to the reference voltage Vref, a rated current flows. When the current Io flowing through the illumination head H is large, the detection voltage Vs becomes high. Therefore, the current control circuit IC operates such that the detection voltage Vs is lowered and equal to the reference voltage Vref. Therefore, the load current Io is reduced, and control is performed so that an appropriate current (rated current) flows. Further, when the detection voltage Vs is lower than the reference voltage Vref, control is performed so that an appropriate current flows through the reverse operation.
Therefore, according to this lighting device, even if the output voltage of the power supply unit NU fluctuates, the lighting head H is controlled so that an appropriate current always flows. The surface condition of the inspection product can be inspected with high accuracy, and the life of the light emitting diode can be extended.

By the way, although this lighting device is suitable for inspection in a state where the product to be inspected is stationary, accurate image data cannot be obtained in, for example, surface inspection of the product to be inspected in a moving state, and high-precision inspection is performed. Becomes difficult.
Therefore, in order to solve such a problem, an excessive current compared to the rated current is instantaneously supplied to the lighting head H to cause the light emitting diode F to emit light in a stroboscopic manner. However, although the light-emitting diode F has an adverse effect on the life if the current-carrying amount is less than the allowable current, it is difficult to always set the current-carrying amount below the allowable current, and the adverse effect on the life characteristics cannot be ignored. There is a problem.
Moreover, in this lighting device, if the lighting head H has a current detection terminal, the current amount can be controlled to an appropriate current as described above, but a normal lighting head has only two terminals. There is also a problem that such an illumination head cannot be applied.
Therefore, an object of the present invention is to set a voltage corresponding to an appropriate current (for example, a rated current) of a load circuit as a reference voltage, and within a range in which the load current is not adversely affected by the reference voltage based on the reference voltage. A reference voltage setting device that can be controlled and a lighting device using the device.

  Therefore, in order to achieve the above-described object, the present invention provides a load circuit in which at least a load, a switching element, and a current detection resistor are connected in series, and a current detection when a predetermined voltage is applied to the load circuit. And a reference voltage setting circuit having a function of holding a voltage corresponding to a load current detected by a resistor as a reference voltage.

  According to a second aspect of the present invention, there is provided a reference voltage setting device comprising a power supply device that outputs a predetermined voltage, and at least a load, a switching element, and a current detection resistor connected in series to the output side of the power supply device. And a reference voltage setting circuit that holds, as a reference voltage, a voltage corresponding to a load current detected by a current detection resistor of the load circuit when the switching element is turned on, the reference voltage setting circuit Is an AND circuit having at least three input terminals, an electronic volume output so that the output voltage is sequentially increased based on an output signal of the AND circuit, a detection voltage by the current detection resistor, and an output voltage of the electronic volume. And a comparator that detects that the output voltage of the electronic volume has become substantially equal to the detection voltage (reference voltage). The path is turned on when a clock signal, a high level output signal of the comparator, and a set signal are input to the three input terminals, and the electronic volume is operated based on the output signal, and the output voltage is the detected voltage. When the substantially equal voltage is reached, the output signal of the comparator becomes low level to stop the operation of the AND circuit, and the output voltage of the electronic volume is held as a reference voltage.

  According to a third aspect of the present invention, there is provided a reference voltage setting device, wherein a power supply device that outputs a predetermined voltage, and at least a load, a switching element, and a current detection resistor are connected in series to the output side of the power supply device. A reference voltage setting circuit that holds a voltage corresponding to the load current detected by the current detection resistor of the load circuit when the switching element is turned on, and a reset signal to the reference voltage setting circuit. A reset signal generation circuit for supplying, and a set signal generation circuit for supplying a set signal to the reference voltage setting circuit, wherein the reference voltage setting circuit includes at least three input terminals, and an output of the AND circuit The electronic volume that is output so that the output voltage is sequentially increased based on the signal, and the detection voltage by the current detection resistor and the output voltage of the electronic volume are compared. The electronic volume is composed of a comparator that detects that the output voltage of the electronic volume is substantially equal to the detection voltage (reference voltage). The electronic volume is reset by a reset signal from the reset signal generation circuit, and the AND circuit is When the clock signal, the high level output signal of the comparator, and the set signal from the set signal generation circuit are input to the two input terminals, the electronic volume is activated based on the output signal, and the output voltage is When a voltage substantially equal to the detection voltage is reached, the output signal of the comparator becomes low level to stop the operation of the AND circuit, and the output voltage of the electronic volume is held as a reference voltage.

    According to a fourth aspect of the present invention, in the reference voltage setting device, the reference voltage setting circuit is configured to sequentially increase the output voltage based on an AND circuit having at least three input terminals and an output signal of the AND circuit. A comparator for detecting that the output voltage of the electronic volume is substantially equal to the detected voltage (reference voltage) by comparing the electronic volume output to the voltage detected by the current detection resistor and the output voltage of the electronic volume. And a voltage changing circuit for relatively changing the output voltage of the electronic volume held as the reference voltage by using a voltage distribution circuit including a variable resistor. The fifth invention is characterized in that the reset signal generation is performed. The circuit is characterized in that the reset signal is generated only for a certain period. According to a sixth aspect of the invention, the set signal generating circuit In the seventh aspect, the switching element of the load circuit is based on the set signal from the set signal generating circuit. According to an eighth aspect of the invention, the power supply device outputs a rated voltage for the load based on a set signal from the set signal generation circuit, and the set signal is stopped. The ninth invention is characterized in that a voltage higher than the rated voltage is output, and the ninth invention is characterized in that the load is composed of at least a plurality of light emitting elements such as light emitting diodes.

    A tenth aspect of the present invention is an illumination device, and is a load circuit comprising at least an illumination head mainly composed of a light emitting element such as a light emitting diode, a switching element, and a current detection resistor connected in series. A reference voltage setting circuit having a function of applying a predetermined voltage to the load circuit and holding a voltage corresponding to the load current detected by the current detection resistor as a reference voltage when the switching element is turned on, and the load circuit When a predetermined voltage or a different voltage other than the predetermined voltage is applied to the switching element, the switching element is set so that the detection voltage at the current detection resistor has a certain relationship with the reference voltage held in the reference voltage setting circuit. A current control circuit for controlling, and the current flowing through the lighting head is limited within a controlled range by the cooperative action of the reference voltage setting circuit and the current control circuit. Characterized in that it was.

    An eleventh aspect of the present invention is an illumination device, wherein a power supply device that outputs at least a predetermined voltage, and at least an illumination head, a switching element, and a current detection resistor are connected in series to the output side of the power supply device. A reference voltage setting circuit for applying a predetermined voltage to the load circuit and holding a voltage corresponding to the load current detected by the current detection resistor as a reference voltage when the switching element is turned on, and a load When a predetermined voltage or a different voltage other than the predetermined voltage is applied to the circuit, the switching element so that the detection voltage at the current detection resistor has a certain relationship with the reference voltage held in the reference voltage setting circuit And a current control circuit that controls the load current to a desired current amount by controlling the reference voltage setting circuit, and the reference voltage setting circuit has at least three input terminals. And the electronic volume output so that the output voltage is sequentially increased based on the output signal of the AND circuit, the detected voltage by the current detection resistor and the output voltage of the electronic volume are compared, and the output voltage of the electronic volume is detected voltage The AND circuit is turned on when a clock signal, a high-level output signal of the comparator, and a set signal are input to the three input terminals, respectively. At the same time, the electronic volume is operated based on the output signal, and when the output voltage reaches a voltage substantially equal to the detection voltage, the output signal of the comparator becomes a low level to stop the operation of the AND circuit. The output voltage is held as a reference voltage, and the load circuit has a predetermined voltage or a different voltage other than the predetermined voltage. When pressure is applied, and controls the detection voltage by the current detecting resistor to have a certain relation to the reference voltage.

    According to a twelfth aspect of the present invention, there is provided a lighting device comprising: a power supply device that outputs at least a predetermined voltage; and at least an illumination head, a switching element, and a current detection resistor connected in series to the output side of the power supply device. A reference voltage setting circuit for applying a predetermined voltage to the load circuit and holding a voltage corresponding to the load current detected by the current detection resistor as a reference voltage when the switching element is turned on, and a reference A gain changing circuit that outputs an output signal having a predetermined magnification with respect to a reference voltage held in the voltage setting circuit, and a current when a predetermined voltage or a different voltage other than the predetermined voltage is applied to the load circuit. A current control circuit that controls the load current to a desired amount of current by controlling the switching element so that the detection voltage at the detection resistor is substantially equal to the output voltage of the gain changing circuit; The reference voltage setting circuit includes an AND circuit having at least three input terminals, an electronic volume output so that an output voltage is sequentially increased based on an output signal of the AND circuit, and detection by a current detection resistor Comparing the voltage with the output voltage of the electronic volume, it is composed of a comparator that detects that the output voltage of the electronic volume is almost equal to the detected voltage, and the AND circuit has a clock signal at each of the three input terminals. When the high level output signal of the comparator and the set signal are input, the electronic volume is activated based on the output signal, and when the output voltage reaches a voltage almost equal to the detection voltage, When the output signal of the comparator goes low, the AND circuit stops operating and the output voltage of the electronic volume This is held as a reference voltage, and when a predetermined voltage or a different voltage other than the predetermined voltage is applied to the load circuit, the detection voltage at the current detection resistor is controlled to be substantially equal to the output voltage of the gain changing circuit. It is characterized by that.

    According to a thirteenth aspect of the present invention, there is provided a lighting device comprising: a power supply device that outputs at least a predetermined voltage; and at least an illumination head, a switching element, and a current detection resistor connected in series to the output side of the power supply device. A reference voltage setting circuit for applying a predetermined voltage to the load circuit and holding a voltage corresponding to the load current detected by the current detection resistor as a reference voltage when the switching element is turned on, and a reference A reset signal generation circuit for supplying a reset signal to the voltage setting circuit, a set signal generation circuit for supplying a set signal to the reference voltage setting circuit, and an output having a predetermined magnification with respect to the reference voltage held in the reference voltage setting circuit When the voltage change circuit that outputs a signal and the load circuit is applied with a predetermined voltage or a different voltage other than the predetermined voltage, the detection voltage at the current detection resistor is gained. And a current control circuit for controlling the load current to a desired current amount by controlling the switching element so as to be substantially equal to the output voltage of the further circuit, wherein the reference voltage setting circuit includes at least three input terminals. The AND circuit, the electronic volume output so that the output voltage is sequentially increased based on the output signal of the AND circuit, the detected voltage by the current detection resistor and the output voltage of the electronic volume are compared, and the output voltage of the electronic volume The electronic volume is reset by the reset signal from the reset signal generating circuit, and the AND circuit has a clock signal and a comparator at the three input terminals, respectively. The high level output signal and the set signal from the set signal generation circuit are input. The electronic volume is activated based on the output signal, and when the output voltage reaches a voltage almost equal to the detection voltage, the AND circuit is stopped by the comparator output signal becoming low level. The output voltage of the electronic volume is held as a reference voltage, and when a predetermined voltage or a different voltage other than the predetermined voltage is applied to the load circuit, the detected voltage at the current detection resistor is output from the gain changing circuit. It is characterized by controlling so that it may become substantially equal.

    According to a fourteenth aspect of the present invention, in the lighting device, the reference voltage setting circuit outputs an AND circuit having at least three input terminals and an output voltage that is sequentially increased based on an output signal of the AND circuit. A comparator that detects that the output voltage of the electronic volume is substantially equal to the detected voltage (reference voltage) by comparing the detected voltage of the electronic volume with the voltage detected by the current detection resistor and the output voltage of the electronic volume. According to a fifteenth aspect of the present invention, there is provided a reference voltage setting circuit comprising: a voltage changing circuit that relatively changes an output voltage of the electronic volume held as a voltage by using a voltage distribution circuit including a variable resistor. The voltage changing circuit is configured to be able to contact and separate from the electronic volume using a switch.

    According to a sixteenth aspect of the present invention, in the lighting device, the reset signal generating circuit is configured such that the reset signal is generated only for a predetermined period. The seventeenth aspect of the present invention is the reset signal generating circuit. Is composed of at least an inverter, a time constant circuit composed of a resistor and a capacitor, and a switch connected in parallel to the capacitor of the time constant circuit. By turning on the switch for a certain period, a high level reset signal is output from the inverter. Is output in accordance with the ON period of the switch. According to an eighteenth aspect of the invention, the set signal generation circuit is configured such that the set signal is generated only for a certain period after the reset signal generation period. It is characterized by comprising.

    Furthermore, a nineteenth aspect of the present invention is a lighting device, wherein the switching element of the load circuit is configured to be turned on by a set signal from the set signal generation circuit and a control signal corresponding to the operation pattern of the lighting head. According to a twentieth aspect of the invention, the power supply device outputs a predetermined voltage (for example, a rated voltage of the lighting head) in response to a set signal from the set signal generation circuit, and other than the predetermined voltage by stopping the set signal. Are different from each other (for example, a voltage higher than the rated voltage), and the gain changing circuit includes at least an operational amplifier and two resistors Ra and Rb for determining gain. And a predetermined magnification (Ra /) with respect to the reference voltage held in the reference voltage setting circuit by turning the switch on and off. Characterized in that it is configured to output a b + 1) output signal having a.

As described above, according to the reference voltage setting device of the present invention, even if the terminal for detecting the voltage corresponding to the current is not installed in the lighting head, if the rated voltage is known, the load circuit can be used. A voltage corresponding to the rated current can be detected by applying the rated voltage, and a reference voltage can be set and held based on the detected voltage. For this reason, when applied to a lighting device, the lighting head can be turned on with a predetermined current.
According to the lighting device of the present invention including the reference voltage setting device, the load current flowing in the load circuit is controlled by the current control circuit so that the detection voltage at the current detection resistor has a predetermined relationship with the reference voltage. Therefore, the current amount is set so as not to adversely affect the lifetime.
In particular, if a gain change circuit is connected between the reference voltage setting circuit and the current control circuit, the reference voltage of the reference voltage setting circuit changes the voltage value applied to the current control circuit according to the gain value of the gain change circuit. . For this reason, the current control circuit operates so that the voltage detected by the current detection resistor is approximately equal to the output voltage of the gain change circuit, so that the load current of the load circuit is changed to the reference voltage changed according to the gain value. Controlled by the corresponding current. Accordingly, the gain value of the gain changing circuit is set so that its output voltage does not adversely affect the lifetime characteristics of the light emitting element in the lighting head, so that the lighting head can be lit in various operation patterns. it can.
Furthermore, if a voltage change circuit is added to the reference voltage setting circuit, the reference voltage can be changed by the voltage distribution ratio of the voltage change circuit, so that the current range is such that the additional circuit including the lighting head does not adversely affect the life characteristics. Thus, an appropriate load current can be passed. Therefore, it is possible to illuminate various lighting heads.

Next, the Example regarding the illuminating device containing the reference voltage setting apparatus concerning this invention is described with reference to FIGS.
In the figure, reference numeral 1 denotes a power supply device for a lighting device. For example, an AC power supply is connected to the input side via a power switch SW, and three terminals T1, T2, and T3 are provided on the output side. ing. The power supply device 1 outputs a predetermined voltage (for example, a voltage of 12V, a rated voltage of an illumination head described later) Vo to the terminals T1 and T2 during a period in which a set signal described later is applied to the terminal T3, for example. When the set signal is not applied, a different voltage (for example, a voltage of 24 to 36 V) other than a predetermined voltage is output. Reference numeral 2 denotes a control power supply device, which is configured such that a drive voltage Vcc of about 5 V, for example, is output from the output side and supplied to various circuits to be described later. Reference numeral 3 denotes an illumination head, which is configured, for example, by connecting a plurality of series circuits of a light emitting element 3a such as a plurality of light emitting diodes and a protective resistor 3b in parallel. In addition, the connection of the light emitting element 3a can employ | adopt an appropriate connection form according to a use, such as connecting in parallel other than series connection. The lighting head 3 forms a load circuit by being connected in series with the switching element Q1 and the current detection resistor Rs, and is connected to the terminals T1 and T2 of the power supply device 1. The switching element Q1 may be any element as long as the element operates linearly, but a transistor or a field effect transistor (FET) is preferable.

    Reference numeral 4 denotes a reference voltage setting circuit, for example, an AND circuit AND having three input terminals, an electronic volume MR having a function of sequentially increasing an output voltage based on count-up by an output signal of the AND circuit AND, The comparator CMP for comparing the output voltage Vref of the volume MR with the detection voltage Vs by the current detection resistor Rs to detect that the output voltage Vref is substantially equal to the detection voltage Vs, and the switch S1 at the volume portion of the electronic volume MR. And a voltage changing circuit connected through the circuit. In the illustrated example, the electronic volume MR is configured such that the output voltage Vref is sequentially increased by changing the resistance value of the variable resistor based on the count up by the output signal from the AND circuit AND. In the above AND circuit AND, the first input terminal has a clock signal, the second input terminal has an output signal of the comparator CMP, and the third input terminal has a set signal from a set signal generation circuit described later. It is configured to be entered. The electronic volume MR is provided with a reset terminal Re, and a reset signal from a reset signal generating circuit described later is applied to this terminal so that the output voltage Vref is reset to 0 volts. In addition, a switch S1 is provided between the electronic volume MR and the voltage changing circuit, the drive voltage Vcc is applied to the contact on the A side thereof, and the voltage changing circuit is connected to the contact on the B side. Has been. This circuit is composed of, for example, an operational amplifier OP3 and a variable resistor VR as a voltage distribution circuit. A drive voltage Vcc is applied to the variable resistor VR, and its slider is a positive input terminal of the operational amplifier OP3. (Normal phase input terminal). The negative input terminal (reverse phase input terminal) of the operational amplifier OP3 is connected to the output side of the operational amplifier OP3 and to the contact on the B side.

    Reference numeral 5 denotes a reset signal generation circuit, which is composed of, for example, an inverter INV1, a time constant circuit including a resistor R1 and a capacitor C1, a switch S3 connected in parallel to the capacitor C1, and a diode D1 connected in parallel to the resistor R1. The input side of the inverter INV1 is connected to the connection point between the resistor R1 and the capacitor C1, and the output side is connected to the reset terminal Re of the counter in the electronic volume MR. Note that the switch S3 is configured to be open in the normal state. Reference numeral 6 denotes a set signal generation circuit, which includes, for example, an inverter INV2, a time constant circuit composed of a resistor R2 and a capacitor C2, and a diode D2 connected in parallel to the resistor R2. The input side of the inverter INV2 is a resistor. At the connection point between R2 and capacitor C2, the output side is connected to the third input terminal of the AND circuit AND in the reference voltage setting circuit 4, the terminal T3 of the power supply device 1, and the first input terminal of the OR gate described later. Yes. The output side of the inverter INV1 is also connected to the capacitor C2 in the set signal generation circuit 6.

OR is an OR gate, and is configured such that a set signal from the set signal generating circuit 6 is applied to a first input terminal of the OR gate, and a light emitting element 3a in the lighting head 3 is applied to a second input terminal. A control signal (not shown) according to the operation pattern (lighting pattern) is applied. The output side of the OR gate OR is connected to a control unit (for example, a base) of the switching element Q1 via a resistor R3, and is also connected to a current control circuit described later. Reference numeral 7 denotes a gain changing circuit, which includes, for example, an operational amplifier OP1, resistors Ra and Rb, and a switch S2. An output signal (reference voltage Vref) of the electronic volume MR is applied to the positive input terminal of the operational amplifier OP1. The connection points of the resistors Ra and Rb are connected to the negative input terminal.
The gain Av in the circuit 7 is expressed by (Av = Ra / Rb + 1), and is 1 or more when the switch S2 is on, and 1 when the switch S2 is off. For example, when the resistance ratio between the resistors Ra and Rb is set to 4: 1 and the switch S2 is on, the gain Av is five times. The output signal of the operational amplifier OP1 in the gain changing circuit 7 is configured to be given to a current control circuit described later.

    Reference numeral 8 denotes a current control circuit, which includes, for example, an operational amplifier OP2, a resistor R4, and a switching element Q2 such as a transistor. In particular, the output signal Vf of the operational amplifier OP1 in the gain changing circuit 7 is applied to the negative input terminal of the operational amplifier OP2, and the detection voltage Vs of the current detection resistor Rs is applied to the positive input terminal. It is configured. A resistor R4 is connected between the output side of the operational amplifier OP2 and the control unit (for example, base) of the switching element Q2. A control unit (for example, a base) of the switching element Q1 is connected to, for example, the collector of the switching element Q2.

    Next, the reference voltage setting function in the lighting device configured as described above will be described with reference to FIGS. First, in FIG. 1, when the switch S1 is connected to the A side and the power switch SW is closed, power is supplied from the AC power source to the power source devices 1 and 2, and a predetermined voltage is output from each power source device. The The capacitor C1 of the time constant circuit in the reset signal generating circuit 5 starts to be charged by the drive voltage Vcc. However, since the signal level is low in the initial stage, the output side of the inverter INV1 is as shown in FIG. In addition, a high level H reset signal is output and applied to the reset terminal Re of the counter in the electronic volume MR. As a result, the counter is reset and the output voltage Vref of the variable resistor is reset to 0 volts. When the potential of the capacitor C1 of the time constant circuit in the reset signal generation circuit 5 becomes high, the input side of the inverter INV1 becomes a high level, so that the output side is at a low level L as shown in FIG. Become. As a result, the input side of the inverter INV2 in the set signal generation circuit 6 is at a low level, so that a high level H set signal is output from the output side as shown in FIG. This is applied to the terminal T3, the third input terminal of the AND circuit AND, and the first input terminal of the OR gate OR. Note that a predetermined clock signal is given to the first input terminal of the AND circuit AND in connection with the power-on.

    When the set signal is applied to the terminal T3 of the power supply device 1 in this way, a predetermined voltage (for example, rated voltage) Vo is output to the output terminals T1 and T2 as shown in FIG. The When the set signal is applied to the first input terminal of the OR gate OR, the OR gate OR is turned on, and the output signal is applied to the control unit (for example, base) of the switching element Q2 via the resistor R3. As a result, the switching element Q1 is turned on, and when a predetermined voltage Vo is applied from the power supply device 1, a load current Io flows through the lighting head 3, the switching element Q1, and the current detection resistor Rs. This load current Io generates a voltage Vs (= Io · Rs) in the current detection resistor Rs, and this detection voltage Vs is applied to the positive input terminal of the comparator CMP in the reference voltage setting circuit 4.

    On the other hand, since a high level signal is output from the output side of the comparator CMP in the reference voltage setting circuit 4 when the set signal is output from the set signal generation circuit 6, the three input terminals of the AND circuit AND. Is given a high level signal, the AND circuit AND is turned on. Based on the output signal from the AND circuit AND, the counter in the electronic volume MR is counted up, and the output voltage Vref of the variable resistor is also increased sequentially. This output voltage Vref is input to the negative input terminal of the comparator CMP and is compared with the current detection voltage Vs. The comparator CMP operates so that the output voltage Vref of the electronic volume MR is substantially equal to the detection voltage Vs. If possible, it is recommended to set the operation so that the output voltage Vref is slightly higher than the detection voltage Vs. When the output voltage Vref and the detection voltage Vs are substantially equal, the output signal of the comparator CMP becomes a low level, and the AND circuit AND is turned off, and the output voltage Vref becomes the detection voltage Vs by stopping the counter operation of the electronic volume MR. It is held at approximately the same voltage. The set signal from the set signal generation circuit 6 becomes a low level L after a certain period as shown in FIG. 3C due to the potential rise of the capacitor C2 in the time constant circuit. At the same time, the first input terminal of the OR gate OR also goes low, so that the switching element Q1 is turned off, the lighting head 3 stops the light emission operation, and the load current does not flow. Therefore, as described above, the output voltage Vref of the electronic volume MR is held in the reference voltage setting circuit 4 as a reference voltage with a value substantially equal to the detection voltage Vs corresponding to the load current Io. In particular, if the output voltage Vo of the power supply device 1 is set to a rated voltage for the lighting head 3 in advance, the load current Io that flows during the operation of the lighting head 3 is considered to be the rated current. For this reason, the reference voltage Vref held by the reference voltage setting circuit 4 can be handled as a voltage corresponding to the rated current (Io).

Next, the operation of the lighting apparatus after setting the above-described reference voltage Vref will be described, particularly in the state where the switch S2 in the gain changing circuit 7 is opened and the gain of the circuit 7 is set to 1.
First, when the set signal from the set signal generation circuit 6 becomes low level, the output voltage of the power supply device 1 is automatically higher than a predetermined voltage (Vo) by the operation of the device, as shown in FIG. Become. On the other hand, in the reference voltage setting circuit 4, the output voltage of the electronic volume MR is also held at the reference voltage Vref by the OFF operation of the AND circuit AND. In this state, when a signal corresponding to the operation pattern (light emission pattern) of the lighting head 3 is input to the second input terminal of the OR gate OR, for example, a signal that is continuously lit for a certain period, the OR gate OR is turned on and switching is performed. The element Q1 is also turned on. As a result, the load current Io flows through the lighting head 3, the switching element Q1, and the current detection resistor Rs. However, since the output voltage of the power supply device 1 is higher than the predetermined voltage Vo, a large load current also flows. For this reason, the detection voltage Vs of the current detection resistor Rs also increases. This detection voltage Vs is applied to the plus input terminal of the operational amplifier OP2 in the current control circuit 8.

    On the other hand, since the gain change circuit 7 has the gain Av set to 1 time, the operational amplifier OP1 of the same circuit outputs the same voltage Vf as the reference voltage Vref held in the reference voltage setting circuit 4. . This output voltage Vf is applied to the negative input terminal of the operational amplifier OP2 in the current control circuit 8. The operational amplifier OP2 operates so that the detection voltage Vs at the current detection resistor Rs becomes substantially equal to the output voltage Vf of the gain changing circuit 7. Therefore, when the detection voltage Vs is higher than the output voltage Vf, the switching element Q2 is turned on by the output signal from the operational amplifier OP2, and at the same time, the switching element Q1 operates to decrease the load current Io. This series of operations is performed until the detection voltage Vs becomes substantially equal to the output voltage Vf, but is actually performed in a very short time. Therefore, the load current flowing through the illumination head 3 is controlled so that the detection voltage Vs by the current detection resistor Rs is equal to the output voltage Vf of the gain changing circuit 7, that is, the reference voltage Vref corresponding to the rated current. As a result, the lighting head 3 performs rated operation, and continues lighting at a constant brightness until the lighting signal to the second input terminal of the OR gate OR is stopped.

Next, an operation when the gain Av of the gain changing circuit 7 is set to 5 times will be described. It is assumed that the switch S2 of the circuit 7 is closed and the resistance ratio between the resistors Ra and Rb is set to 4: 1, for example.
First, when a lighting signal is applied to the second input terminal of the OR gate OR, the switching element Q1 is turned on, and a predetermined voltage (from the power supply device 1 is applied to the load circuit including the lighting head 3, the switching element Q1, and the current detection resistor Rs. For example, a voltage (for example, a voltage of about 24 to 36) higher than the rated voltage is applied, and a load current Io flows through the load circuit. As a result, a voltage of Io · Rs is generated in the current detection resistor Rs, and this detection voltage Vs is input to the positive input terminal of the operational amplifier OP2 in the current control circuit 8.
On the other hand, the operational amplifier OP1 of the gain changing circuit 7 outputs a signal Vf that is five times the reference voltage Vref. This output voltage Vf is input to the negative input terminal of the operational amplifier OP2 in the current control circuit 8, and is compared with the detection voltage Vs.
Since the operational amplifier OP2 operates so that the detection voltage Vs is substantially equal to the output voltage Vf of the gain changing circuit 7, the switching element Q1 is controlled so that the load current increases while the detection voltage Vs is lower than the output voltage Vf. Is done. Ultimately, the load current Io is controlled to be 5 times the rated current. Therefore, the lighting head 3 is turned on with high luminance. Such an excessive current is limitedly supplied in a short time, and the lighting head 3 is lit in a strobe manner. Usually, when the light-emitting element 3a constituting the illumination head 3 is a light-emitting diode, the amount of current applied to the light-emitting element 3 is allowed to be about five times the rated current. In particular, when applied to a system that inspects the surface state of a product to be inspected by a strobe lighting operation, accurate image data can be obtained. it can.

Next, in the state where the gain Av of the gain changing circuit 7 is set to 5 times as described above, the switch S1 in the reference voltage setting circuit 4 is switched from the A side to the B side, and the voltage changing circuit is connected to the electronic volume MR. The operation in this case will be described.
First, when the slider of the variable resistor VR in the voltage changing circuit is manually slid to the ground point, the distributed voltage of the slider becomes 0 volts, so that the reference held in the electronic volume MR is maintained. The voltage Vref is also 0 volts. For this reason, the output signal from the reference voltage setting circuit 4 is not applied to the gain changing circuit 7 (in other words, an output signal of 0 volts is output), and at the same time, from the operational amplifier OP1 of the gain changing circuit 7. The output signal Vf is not output (in other words, an output signal of 0 volts is output).
In this state, when a lighting signal is applied to the second input terminal of the OR gate OR, the switching element Q1 is turned on, a load current flows in the load circuit, and a voltage Vs is generated in the current detection resistor Rs. This detection voltage Vs is compared with the 0-volt output signal Vf from the operational amplifier OP1 in the operational amplifier OP2 of the current control circuit 8. As a result, the switching element Q2 is turned on by the output signal from the operational amplifier OP2, and based on this operation, the switching element Q1 is controlled so that the detection voltage Vs becomes 0 volts. Therefore, the operation of the switching element Q1 is stopped, and the lighting head 3 is also turned off. However, since this operation is performed in a very short time, the lighting head 3 is not substantially turned on.

Next, when the slider of the variable resistor VR in the voltage changing circuit is manually slid to the driving voltage Vcc point, the distribution voltage of the slider becomes the same voltage as the driving voltage Vcc. The reference voltage Vref held in the MR is output as it is. When this reference voltage Vref is applied to the gain change circuit 7, the operational amplifier OP1 of the gain change circuit 7 outputs an output signal Vf that is five times the reference voltage Vref. Therefore, if this state is maintained, the lighting device operates as described above.
Next, when the slider of the variable resistor VR in the voltage changing circuit is appropriately slid toward the ground point and stopped, the drive voltage Vcc is distributed according to the resistance ratio at the stop position. Since this distribution voltage is applied to the variable resistor in the electronic volume MR as a driving voltage for the variable resistance, the reference voltage Vref held in the electronic volume MR depends on the distribution voltage ratio (α) to the driving voltage Vcc. Decrease. The reference voltage (α · Vref) thus reduced is input to the gain changing circuit 7 and a signal five times the voltage is output to the current control circuit 8. The current control circuit 8 compares this input signal with the detection voltage Vs at the current detection resistor Rs, and operates so that the detection voltage Vs is substantially equal to the above-described input signal. In this way, the current flowing through the illumination head 3 is substantially determined by [rated current Io × (α · Vref) × gain Av]. Accordingly, by appropriately distributing the voltage by the variable resistor VR of the voltage changing circuit, a load current of 0 to 5 times the rated current can be passed through the illumination head 3, and various illuminations are possible depending on the amount of the current. Become.

In addition, a resetting method when it is necessary to reset the reference voltage Vref during the operation of the lighting device will be described.
First, the switch S1 of the reference voltage setting circuit 4 is switched to the A side. In this state, as shown in FIG. 4B, when the switch S3 of the reset signal generation circuit 5 is closed (turned on), the potential of the capacitor C1 in the time constant circuit becomes low level, so that the output side of the inverter INV1 From FIG. 4, a high level H reset signal is output as shown in FIG. The electronic volume MR is reset by this reset signal. Next, when the switch S3 of the reset signal generation circuit 5 is opened (turned off), the potential of the capacitor C1 in the time constant circuit rises, so that the output side of the inverter INV1 becomes the low level L. As a result, the output side of the inverter INV2 in the set signal generation circuit 6 becomes high level H as shown in FIG. 4D, and this set signal is supplied to the terminal T3 of the power supply device 1, and the third input terminal of the AND circuit AND. , Are simultaneously applied to the first input terminal of the OR gate OR. When this set signal is applied to the terminal T3, the output voltage of the power supply device 1 is changed from a high voltage (for example, 24-36V) to a predetermined voltage (for example, about 12V) as shown in FIG. The rated voltage is switched to Vo and applied to the load circuit. Further, when the AND circuit AND is turned on by applying the set signal, the electronic volume MR is sequentially increased in its output voltage (Vref) by counting up the counter. On the other hand, when the set signal is input to the OR gate OR, the switching element Q1 is turned on, and a load current (rated current) flows through the lighting head 3. This load current generates a voltage Vs in the current detection resistor Rs.
This detection voltage Vs is applied to the plus input terminal of the comparator CMP in the reference voltage setting circuit 4 and is compared with the output voltage (Vref) of the electronic volume MR. In this comparator CMP, at the moment when the output voltage (Vref) of the electronic volume MR is substantially equal to the detection voltage Vs, for example, Vref> Vs, the AND circuit AND stops operating because the output side of the comparator CMP becomes low level. The count up of the electronic volume MR is also stopped. Therefore, the output voltage of the electronic volume MR becomes a voltage corresponding to the load current (rated current) and is held as the reference voltage Vref. When the set signal becomes low level L as shown in FIG. 4D, the output voltage of the power supply device 1 is switched to a voltage higher than the predetermined voltage Vo, and the switching element Q1 is stopped by stopping the set signal to the OR gate OR. Is also turned off, and the lighting head 3 is also turned off.

    As described above, the reference voltage setting device used in the above-described illumination device according to the present invention includes at least a load circuit including the illumination head 3, the switching element Q1, and the current detection resistor Rs, an AND circuit AND, an electronic volume MR, and a comparator. The output voltage of the electronic volume MR is sequentially increased by the ON operation of the AND circuit AND, and at the same time, controlled by the comparator CMP so as to be substantially equal to the detection voltage Vs. When the AND circuit AND stops operating when it becomes substantially equal, and the increase in the output voltage of the electronic volume MR is also stopped based on this, the output voltage is used as a reference voltage Vref corresponding to a load current, for example, a rated current. It is held in the reference voltage setting circuit 4. Therefore, if this device is applied to a lighting device having a current control circuit 8, no matter what voltage is applied to the load circuit, the load circuit is controlled by the current control circuit 8 and is controlled by the reference voltage Vref. A fixed load current, for example, a rated current flows, and the lighting head 3 can be appropriately operated to emit light.

The lighting device according to the present invention includes at least a lighting circuit, a load circuit including a switching element Q1, a current detection resistor Rs, a reference voltage setting circuit 4, and a current control circuit 8. The load current flowing in the load circuit is controlled by the current control circuit 8 so that the detection voltage Vs at the current detection resistor Rs is substantially equal to the reference voltage Vref held in the reference voltage setting circuit 4. Accordingly, a load current corresponding to the reference voltage Vref flows through the illumination head 3, so that the illuminance of the illumination head 3 is stabilized and the inspection accuracy of the product to be inspected can be increased.
In particular, in this lighting device, since a voltage corresponding to a load current can be detected without incorporating a current detection resistor in the circuit of the lighting head 3, any lighting head having a known rated voltage can be used. The versatility of the apparatus can be improved. For example, the present invention can also be applied to an illumination head having four terminals disclosed in Japanese Patent Application Laid-Open No. 2004-299102.

In the illumination device according to the present invention, if the output signal (reference voltage Vref) of the electronic volume MR is supplied to the current control circuit 8 via the gain change circuit 7, the gain change circuit 7 An appropriate signal corresponding to the gain Av is output. Therefore, if the gain Av is set to 5 times, for example, the load current Io flowing through the load circuit becomes 5 times the rated current that is unlikely to adversely affect the life characteristics, and the lighting head 3 is lit with high brightness. become. In particular, by turning on the lighting head 3 in a stroboscopic manner, it is possible to further increase the inspection accuracy of the inspected product in a moving state.
If the gain Av of the gain changing circuit 7 can be switched between 1 and 5 times by the switch S2, for example, a desired lighting state can be obtained by appropriately switching the switch S2 according to the lighting mode of the lighting head 3. Can be.

Further, in the reference voltage setting circuit 4, the drive voltage Vcc is output to the contact A side via the switch S1 to the high voltage side (non-ground side) terminal of the variable resistor in the electronic volume MR, and the voltage change circuit output to the contact B side. When the switch S1 is connected to the contact B side, the voltage distributed to the high voltage side (non-ground side) terminal of the variable resistor in the electronic volume MR is distributed by the voltage changing circuit via the switch S1. Is supplied as a driving voltage, the reference voltage Vref held in the reference voltage setting circuit 4 (that is, the electronic volume MR) is changed according to the voltage distribution ratio α in the voltage changing circuit. Therefore, the load current Io of the load circuit is controlled based on the reference voltage (α · Vref) whose voltage has been changed. Therefore, since the load current of the load circuit can be changed to an appropriate amount of current by appropriately changing the voltage distribution ratio α to the drive voltage Vcc by the variable resistor VR in the voltage changing circuit, the lighting pattern of the lighting head 3 can be changed. In addition to the appearance inspection of the product to be inspected, it can be applied to various illuminations including display display.
In the voltage changing circuit, if the voltage distribution ratio α is 1 or more, that is, a voltage higher than the driving voltage Vcc by a predetermined magnification is applied to the variable resistor VR, the gain Av of the gain changing circuit 7 is set to 1. Even if it is set to double, the load current can be controlled to an appropriate amount of current according to α · Vref by changing the voltage distribution ratio by the variable resistor VR. Depending on the set value of the voltage distribution ratio α, the illumination head 3 can be caused to emit light in a strobe manner.
In particular, if the slider of the variable resistor VR in the voltage changing circuit is positioned on the drive voltage Vcc side, the drive voltage Vcc is applied to the slider, so that the switch S1 is connected to the A side. The same operation is performed. Therefore, the reference voltage Vref can be set in this state, and the switch S1 can be omitted depending on the case.

    The present invention is not limited to the above-described embodiment. For example, the power supply device for illumination is configured so that a predetermined voltage is output by applying a set signal, and a predetermined voltage and a predetermined voltage are set by a switch. The voltage can be switched to a voltage different from the above voltage, or the power supply for control can be incorporated in the power supply for lighting. Further, the reset signal generation circuit and the set signal generation circuit can generate a reset signal and a set signal by using an appropriate circuit other than the illustrated example. Further, the electronic volume in the reference voltage setting circuit is not limited to the illustrated circuit as long as it has a function of sequentially increasing the output voltage based on a signal input in the reset state. Further, the reference voltage held in the reference voltage setting circuit can be held using a semiconductor memory or the like in addition to the holding by the illustrated circuit. In the reference voltage setting circuit, the voltage changing circuit can be omitted depending on the application. The gain changing circuit only needs to have a gain changing function, and is not limited to the illustrated example. For example, a buffer can be inserted on the output side of the operational amplifier, and when the voltage changing circuit in the above-described reference voltage setting circuit is employed, the gain changing switch can be omitted. Furthermore, it is desirable that the predetermined voltage applied to the load circuit is the rated voltage of the lighting head, but it is set to an eye higher or lower than the rated voltage, and a reference voltage is set to the load current flowing at that time. It is also possible to do.

The electric circuit diagram of the illuminating device containing the reference voltage setting apparatus concerning this invention. FIG. 2 is a specific electric circuit diagram of the illumination head in FIG. 1. FIG. 2 is a timing chart of a reset signal and a set signal when a reference voltage is automatically set in association with an ON operation of a power switch in FIG. FIG. 2 is a timing chart of a reset signal and a set signal when a reference voltage is set by manually generating a reset signal with a power switch turned on in FIG. The electric circuit diagram of the conventional illuminating device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power supply device for illuminating devices 2 Power supply device for control 3 Lighting head 3a Light emitting element (light emitting diode)
4 Reference Voltage Setting Circuit 5 Reset Signal Generation Circuit 6 Reset Signal Generation Circuit 7 Gain Change Circuit 8 Current Control Circuit S1 to S3 Switch AND AND Circuit MR Electronic Volume CMP Comparator VR Variable Resistance OP1 to OP3 Operational Amplifier Q1 to Q2 Switching Element (Transistor)
OR OR gate INV1-INV2 Inverter R1-R4, Ra, Rb Resistor C1-C2 Capacitor

Claims (21)

A load circuit comprising at least a load, a switching element, and a current detection resistor connected in series, and a voltage corresponding to the load current detected by the current detection resistor when a predetermined voltage is applied to the load circuit is a reference voltage And a reference voltage setting circuit having a function of holding as a reference voltage setting device. A power supply device that outputs a predetermined voltage, a load circuit in which at least a load, a switching element, and a current detection resistor are connected in series on the output side of the power supply device, and a current detection resistor of the load circuit when the switching element is on And a reference voltage setting circuit for holding a voltage corresponding to the load current detected at the reference voltage as a reference voltage, the reference voltage setting circuit including an AND circuit having at least three input terminals, and an output signal of the AND circuit The electronic volume output so that the output voltage is sequentially increased based on the output voltage, and the voltage detected by the current detection resistor and the output voltage of the electronic volume are compared, and the output voltage of the electronic volume is substantially equal to the detected voltage (reference voltage ), And the AND circuit has a clock signal at three input terminals and a comparator When the level output signal and the set signal are input, it is turned on, and the electronic volume is activated based on the output signal. When the output voltage reaches a voltage almost equal to the detection voltage, the comparator output signal The reference voltage setting device stops the operation of the AND circuit when the signal becomes low level, and holds the output voltage of the electronic volume as a reference voltage. A power supply device that outputs a predetermined voltage, a load circuit in which at least a load, a switching element, and a current detection resistor are connected in series on the output side of the power supply device, and a current detection resistor of the load circuit when the switching element is on A reference voltage setting circuit that holds a voltage corresponding to the load current detected in step 1 as a reference voltage, a reset signal generation circuit that supplies a reset signal to the reference voltage setting circuit, and a set that supplies a set signal to the reference voltage setting circuit The reference voltage setting circuit includes an AND circuit having at least three input terminals, and an electronic volume output so that an output voltage is sequentially increased based on an output signal of the AND circuit, The voltage detected by the current detection resistor is compared with the output voltage of the electronic volume, and the output voltage of the electronic volume is approximately equal to the detected voltage ( The electronic volume is reset by the reset signal from the reset signal generation circuit, and the AND circuit outputs the clock signal to the three input terminals and the high level output of the comparator. When the electronic volume is activated based on the output signal and the output voltage reaches a voltage almost equal to the detection voltage, the comparator is activated. The reference voltage setting device is characterized in that the AND circuit is stopped when the output signal becomes low level and the output voltage of the electronic volume is held as a reference voltage. The reference voltage setting circuit includes at least an AND circuit having three input terminals, an electronic volume output so that an output voltage is sequentially increased based on an output signal of the AND circuit, a detection voltage and an electron detected by a current detection resistor. Comparing the output voltage of the volume and detecting that the output voltage of the electronic volume is almost equal to the detected voltage (reference voltage), and the variable voltage of the output voltage of the electronic volume held as the reference voltage 4. The reference voltage setting device according to claim 1, wherein the reference voltage setting device comprises a voltage changing circuit that relatively changes the voltage using a voltage distribution circuit including the voltage distributing circuit. 4. The reference voltage setting device according to claim 3, wherein the reset signal generation circuit is configured to generate a reset signal only for a certain period. 4. The reference voltage setting device according to claim 3, wherein the set signal generation circuit is configured to generate the set signal only for a certain period after the generation period of the reset signal. 4. The reference voltage setting device according to claim 3, wherein the switching element of the load circuit is configured to be turned on based on a set signal from a set signal generation circuit. The power supply device is configured to output a rated voltage for a load based on a set signal from a set signal generation circuit, and to output a voltage higher than the rated voltage when the set signal is stopped. The reference voltage setting device according to 2-3. The reference voltage setting device according to claim 1, wherein the load comprises at least a plurality of light emitting elements such as light emitting diodes. At least an illumination head composed mainly of light emitting elements such as light emitting diodes, a switching element, a load circuit formed by connecting current detection resistors in series, and a predetermined voltage is applied to the load circuit to turn on the switching element. Sometimes, a reference voltage setting circuit having a function of holding a voltage corresponding to the load current detected by the current detection resistor as a reference voltage, and a predetermined voltage or a different voltage other than the predetermined voltage is applied to the load circuit. And a current control circuit for controlling the switching element so that the detection voltage at the current detection resistor has a certain relationship with the reference voltage held in the reference voltage setting circuit, the reference voltage setting circuit, the current An illuminating device characterized in that the current flowing through the illuminating head is limited within a controlled range by the cooperative action of the control circuit. A power supply device that outputs at least a predetermined voltage, a load circuit in which at least an illumination head, a switching element, and a current detection resistor are connected in series on the output side of the power supply device, and a predetermined voltage is applied to the load circuit for switching. When the element is turned on, a reference voltage setting circuit that holds a voltage corresponding to the load current detected by the current detection resistor as a reference voltage, and a predetermined voltage or a different voltage other than the predetermined voltage is applied to the load circuit. Current control to control the load current to a desired amount of current by controlling the switching element so that the detection voltage at the current detection resistor has a certain relationship with the reference voltage held in the reference voltage setting circuit. The reference voltage setting circuit includes at least an AND circuit having three input terminals and an output voltage based on an output signal of the AND circuit. A comparator for detecting that the output voltage of the electronic volume is substantially equal to the detected voltage by comparing the detected voltage by the current detection resistor and the output voltage of the electronic volume, The AND circuit is turned on when the clock signal, the high level output signal of the comparator, and the set signal are input to the three input terminals, respectively, and the electronic volume is activated based on the output signal. When the output voltage reaches a voltage substantially equal to the detection voltage, the output signal of the comparator becomes low level, the AND circuit is stopped, the output voltage of the electronic volume is held as a reference voltage, and the load circuit When a predetermined voltage or a different voltage other than the predetermined voltage is applied, the detection current at the current detection resistor is Lighting device and controlling the desired load current by controlling the switching element so as to have a predetermined relationship with the reference voltage. A power supply device that outputs at least a predetermined voltage, a load circuit in which at least an illumination head, a switching element, and a current detection resistor are connected in series on the output side of the power supply device, and a predetermined voltage is applied to the load circuit for switching A reference voltage setting circuit that holds a voltage corresponding to a load current detected by a current detection resistor as a reference voltage when the element is turned on, and a predetermined magnification with respect to the reference voltage held in the reference voltage setting circuit When a predetermined voltage or a different voltage other than the predetermined voltage is applied to the gain change circuit that outputs the output signal and the load circuit, the detection voltage at the current detection resistor becomes substantially equal to the output voltage of the gain change circuit. And a current control circuit that controls the load current to a desired amount of current by controlling the switching element, and the reference voltage setting circuit includes at least three An AND circuit having an input terminal, an electronic volume output so that the output voltage is sequentially increased based on an output signal of the AND circuit, and a detection voltage by the current detection resistor and an output voltage of the electronic volume are compared, Comparing with the comparator which detects that the output voltage of the volume is almost equal to the detection voltage, the AND circuit inputs the clock signal, the high level output signal of the comparator, and the set signal to the three input terminals respectively. When the electronic volume is activated based on the output signal and the output voltage reaches a voltage substantially equal to the detection voltage, the output signal of the comparator becomes low level. The operation is stopped, the output voltage of the electronic volume is held as a reference voltage, and a predetermined voltage is supplied to the load circuit. Alternatively, when a different voltage other than a predetermined voltage is applied, the detection voltage at the current detection resistor is controlled to a desired load current by controlling the switching element so as to be approximately equal to the output voltage of the gain changing circuit. A lighting device characterized by that. A power supply device that outputs at least a predetermined voltage, a load circuit in which at least an illumination head, a switching element, and a current detection resistor are connected in series on the output side of the power supply device, and a predetermined voltage is applied to the load circuit for switching. A reference voltage setting circuit that holds a voltage corresponding to a load current detected by a current detection resistor as a reference voltage when the element is turned on, a reset signal generation circuit that supplies a reset signal to the reference voltage setting circuit, and a reference voltage A set signal generating circuit for supplying a set signal to the setting circuit; a gain changing circuit for outputting an output signal having a predetermined magnification with respect to the reference voltage held in the reference voltage setting circuit; and a predetermined voltage or a predetermined voltage for the load circuit When a different voltage other than the above voltage is applied, the detection voltage at the current detection resistor is switched so as to be approximately equal to the output voltage of the gain changing circuit. And a current control circuit that controls the load current to a desired amount of current by controlling the winding element, and the reference voltage setting circuit includes at least an AND circuit having three input terminals and an output signal of the AND circuit. Based on the comparison between the electronic volume that is output so that the output voltage is gradually increased based on the detected voltage by the current detection resistor and the output voltage of the electronic volume, the output voltage of the electronic volume is almost equal to the detected voltage. The electronic volume is reset by a reset signal from the reset signal generation circuit, and the AND circuit has a clock signal, a high-level output signal from the comparator, and a set signal generation circuit, respectively. Is turned on when the set signal from is input and based on the output signal When the electronic volume is activated and the output voltage reaches a voltage almost equal to the detection voltage, the output signal of the comparator becomes low level to stop the AND circuit operation and hold the output voltage of the electronic volume as the reference voltage. The switching element is controlled so that the detection voltage at the current detection resistor becomes substantially equal to the output voltage of the gain changing circuit when a predetermined voltage or a different voltage other than the predetermined voltage is applied to the load circuit. A lighting device characterized by controlling to a desired load current. The reference voltage setting circuit includes at least an AND circuit having three input terminals, an electronic volume output so that an output voltage is sequentially increased based on an output signal of the AND circuit, a detection voltage and an electron detected by a current detection resistor. Comparing the output voltage of the volume and detecting that the output voltage of the electronic volume is almost equal to the detection voltage (reference voltage), and the output voltage of the electronic volume held as the reference voltage is variable resistance The lighting device according to claim 10, wherein the lighting device is configured to be relatively changed using a voltage distribution circuit including a voltage distribution circuit. 15. The lighting device according to claim 14, wherein in the reference voltage setting circuit, the voltage changing circuit is configured to be able to contact and separate from the electronic volume using a switch. The lighting device according to claim 13, wherein the reset signal generation circuit is configured to generate the reset signal only for a certain period. The reset signal generating circuit is composed of at least an inverter, a time constant circuit composed of a resistor and a capacitor, and a switch connected in parallel to the capacitor of the time constant circuit. The lighting device according to claim 16, wherein a high-level reset signal is output according to an ON period of the switch. The lighting device according to claim 13, wherein the set signal generation circuit is configured such that the set signal is generated only for a certain period after the generation period of the reset signal. 14. The illumination according to claim 13, wherein the switching element of the load circuit is configured to be turned on by a set signal from the set signal generation circuit and a control signal corresponding to an operation pattern of the illumination head. apparatus. The power supply device outputs a predetermined voltage (for example, a rated voltage of the lighting head) by a set signal from the set signal generation circuit, and a different voltage other than the predetermined voltage (for example, a voltage higher than the rated voltage) by stopping the set signal. The illumination device according to claim 11, wherein the illumination device is configured to output the above. The gain changing circuit is composed of at least an operational amplifier, two resistors Ra and Rb for determining gain, and a switch, and a predetermined magnification (Ra) with respect to a reference voltage held in the reference voltage setting circuit by turning on and off the switch. The lighting device according to claim 12, wherein the lighting device is configured to output an output signal having / Rb + 1).

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