JP5592769B2 - Lighting device - Google Patents

Lighting device Download PDF

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JP5592769B2
JP5592769B2 JP2010272939A JP2010272939A JP5592769B2 JP 5592769 B2 JP5592769 B2 JP 5592769B2 JP 2010272939 A JP2010272939 A JP 2010272939A JP 2010272939 A JP2010272939 A JP 2010272939A JP 5592769 B2 JP5592769 B2 JP 5592769B2
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voltage
led
unit
power supply
control signal
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JP2012123988A (en
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孚 出島
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株式会社アイテックシステム
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02BCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00Energy efficient lighting technologies
    • Y02B20/40Control techniques providing energy savings
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02BCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00Energy efficient lighting technologies
    • Y02B20/40Control techniques providing energy savings
    • Y02B20/42Control techniques providing energy savings based on timing means or schedule

Description

  The present invention relates to an illumination device for illuminating an inspection object and a reading object in, for example, an inspection process and a reading process.

  In general, as this type of lighting device, a plurality of LEDs and a constant current circuit connected in series and connected in parallel to each other, a power supply unit that supplies power to each LED unit, Based on the detection means for detecting the voltage drop of the constant current circuit of each LED unit and the lowest voltage drop among the voltage drops of the constant current circuit of each LED unit, the supply voltage supplied from the power supply unit to each LED unit is calculated. A device provided with control means for feedback control is known (for example, see Patent Document 1).

JP 2006-278304 A

  By the way, in the inspection process and reading process in which image processing is performed, the LED lighting apparatus with constant current control as described above is often preferred over the LED lighting apparatus that performs PWM (pulse width modulation) control. One reason for this is that in the case of PWM control, the lighting device is repeatedly turned on and off within a very short time. Recently, however, speeding up of the inspection process and the reading process has been demanded. Since the shutter speed of the imaging device to be used is also increased, it can be mentioned that ON / OFF of the illumination device by PWM control has come to affect the contrast of the imaging data of the imaging device.

  The constant current control LED lighting device is used, for example, to illuminate a long product conveyed in the longitudinal direction at a predetermined position, or a product conveyed by a belt conveyor or the like at a predetermined position. Used for lighting. And the product of an illumination position is imaged with an imaging device, and image processing is carried out, thereby inspecting the presence or absence of scratches on the surface of the long product and inspecting the product on the belt conveyor.

  In recent years, the accuracy of product inspection has been improved, and as shown in FIG. 9, for example, in the inspection process of a long plate-shaped product W, for a scratch K <b> 1 extending in the longitudinal direction of the surface thereof. The inspection is performed using the first illumination device 111 that irradiates light from the oblique direction of the width direction of the plate-like product W and the first imaging device 121 that images the illumination position from directly above the plate-like product W. For the scratches K2 extending in the width direction of the plate-like product W, the second illumination device 112 that irradiates light from an oblique direction of the longitudinal direction of the plate-like product W, and the illumination position of the plate-like product W are true. Inspection is performed using the second imaging device 122 that images from above, and the first imaging device 121 and the second imaging device 122 are arranged in the longitudinal direction of the plate-like member W so that the lights of the illumination devices 111 and 112 do not interfere with each other. They are placed apart in the direction.

  Also, as shown in FIG. 10, for example, in the process in which the product P is placed and transported on the belt conveyor CV, it is not necessary to turn on the illumination device 113 until the product comes under the imaging device 123. The illumination device 113 is turned on / off. Here, in the LED lighting device using the constant current circuit as described above, when the lighting device is turned off, the voltage is not applied to the LED unit, and the voltage applied to the constant current circuit is once lost, and the lighting device is turned on. As a result, the voltage is again applied to the LED unit, and the voltage is also applied to the constant current circuit, so that the constant current control by the constant current circuit is performed again. However, since it is known that the feedback control by the constant current circuit is not stable for a while after the lighting device is turned on again, in the case of a lighting device that repeats ON / OFF, usually the feedback control is not performed.

  In addition, several tens to hundreds of LED units that are formed by connecting a plurality of LEDs and a constant current circuit in series and connected in parallel to each other are often used. In this case, when the lighting device is repeatedly turned on and off as described above, the supply voltage supplied from the power supply unit is supplied to each LED unit without feedback control. It is preferable to set the supply voltage of the power supply unit so that the circuit operates and has the lowest voltage. For example, as shown in FIG. 11, a plurality of LED units CON (1) to CON (n) that are formed by connecting a plurality of LEDs and a constant current circuit 130 in series and connected in parallel to each other, and each LED unit CON ( A description will be given of the case of a lighting device including the power supply unit 140 that supplies power to 1) to CON (n). When the operating voltage of each LED is 4V and the minimum operating voltage of the constant current circuit 130 is 3V, if there is no variation of each component and the resistance values of all the wirings are 0, each LED unit CON ( The operating voltage of 1) to CON (n) is 15V. However, the LED has a large variation in operating voltage. In this example, the LED usually has a variation of about ± 10% with respect to 4V. Moreover, the length of the conducting wire between the power supply unit 140 and each of the LED units CON (1) to CON (n) varies, and a voltage drop of several volts may occur in this portion. For this reason, when installing such an illuminating device in an inspection process or a reading process, the voltage Vc (1) at the connection point between each LED and the constant current circuit 130 in each LED unit CON (1) to CON (n). ˜Vc (n) is measured, and the supply voltage of the power supply unit 140 is set according to the minimum voltage.

  Therefore, if the measurement is not performed correctly, the constant current circuit 130 does not operate normally, but if the number of LED units CON (1) to CON (n) is large, the possibility increases. It is not preferable for improving accuracy. Moreover, when there are many LED units CON (1) -CON (n), installation of an illuminating device takes time.

  The present invention relates to an LED lighting device having a plurality of LED units each of which an LED and a constant current circuit are connected in series, improving the light irradiation performance while saving power, and facilitating the installation work. The purpose is to plan.

  The present invention is an LED lighting device having a plurality of LEDs, wherein a power supply unit whose supply voltage is controlled based on a voltage control signal, and each one or a plurality of LEDs and a constant current circuit are connected in series. A plurality of LED units each supplied with power from the power supply unit, and a comparison voltage generated at a connection point between the LED and the constant current circuit in each LED unit is detected, and the lowest of the comparison voltages of the LED units A power supply unit that detects a comparison voltage and a voltage control signal for raising or lowering a supply voltage from the power supply unit based on a detection result by the detection unit so that the detection result becomes a predetermined set voltage. When the detection result reaches the predetermined set voltage, the feedback means supplies the power supply unit with the feedback means. A storage means for storing the voltage control signal being stored, a steady control means for supplying the voltage control signal stored in the storage means to the power supply unit, and a trigger switch, and when the trigger switch is operated, the detection The feedback means operates until the result reaches the predetermined set voltage, and the steady control means operates while the feedback means is not operating.

  Thus, when the trigger switch is operated, the feedback means operates until the detection result by the detection means reaches a predetermined set voltage, and the steady control means operates while the feedback means is not operating, and the storage means Since the voltage control signal stored in is supplied to the power supply unit, for example, even if there are hundreds of LED units, when the trigger switch is operated, the LED means The comparison voltage at the connection point with the constant current circuit is detected and the lowest comparison voltage among the comparison voltages of the LED units is detected, so that the detection result of the detection means becomes a predetermined set voltage by the feedback means. A voltage control signal for increasing or decreasing the supply voltage from the power supply unit is supplied to the power supply unit. When the detection result reaches a predetermined set voltage, the voltage control signal supplied from the feedback means to the power supply unit at that time is stored in the storage means, and thereafter the voltage control signal stored in the storage means by the steady control means. A signal is supplied to the power supply unit.

  For this reason, if the predetermined set voltage is set to a voltage required for the constant current circuit to operate, for example, 3 V, the LED unit of each LED unit is installed in the inspection process or the reading process. Even if there is a variation in the operating voltage of the LED or a voltage drop due to the lead wire between the power supply source and each LED unit, even if the size of the variation is unknown, each LED can be operated simply by operating the trigger switch. A voltage control signal corresponding to a supply voltage necessary for operating the constant current circuit of the unit is stored by the storage means, and thereafter, the voltage control signal is supplied to the power supply unit by the steady control means.

  Accordingly, by appropriately setting the predetermined set voltage, it is possible to efficiently save power, and it can be easily installed in the inspection process and the reading process. Furthermore, once the trigger switch is operated and the voltage control signal is stored by the storage means, the voltage control signal stored by the storage means is then used to operate the constant current circuit and supply a voltage that is not unnecessarily high. Supplied to each LED unit. Therefore, even when the lighting device is repeatedly turned on and off, a voltage which is necessary for operation and is not unnecessarily high is applied to the constant current circuit of each LED unit as soon as it is turned on. That is, the light irradiation performance can be improved while saving power.

  The lighting device of the present invention can improve the light irradiation performance while saving power, and can facilitate the installation work.

1 is a schematic configuration diagram showing a lighting device according to a first embodiment of the present invention. Schematic configuration diagram showing the lighting device Flow chart showing operation of control unit Installation example of lighting equipment in inspection process Schematic which shows the modification of an illuminating device Flow chart showing operation of control unit Schematic which shows the modification of the illuminating device of 2nd Embodiment of this invention. Flow chart showing operation of control unit Schematic of inspection process for inspecting long plate products Schematic of the inspection process for inspecting products on the conveyor Schematic showing a conventional lighting device Bottom view of lighting device

  A lighting device according to a first embodiment of the present invention will be described with reference to FIGS.

  The lighting device 1 includes a plurality of LEDs and a constant current circuit 10 connected in series, a plurality of LED units CON connected in parallel to each other, and a power supply unit for supplying power to each LED unit CON. 20 and a minimum voltage detection circuit 30 for detecting a comparison voltage at a connection point between the plurality of LEDs and the constant current circuit 10 in each LED unit CON and detecting the lowest comparison voltage among the comparison voltages of each LED unit CON; Based on the detection result by the minimum voltage detection circuit 30, the supply voltage from the power supply unit 20 is set so that the detection result becomes a predetermined set voltage Vb (the set voltage Vb may be within a predetermined voltage range). A feedback circuit 40 for performing feedback control for supplying a voltage control signal for raising or lowering to the power supply unit 20; When the output result becomes the predetermined set voltage Vb, a storage unit 50 comprising an EEPROM (Electronically Erasable and Programmable Read Only Memory) for storing a voltage control signal supplied from the feedback circuit 40 to the power supply unit 20 at that time. And a control unit 60 including a known computer having a CPU, ROM, RAM, and the like, a trigger switch 70 connected to the control unit 60, and a changeover switch 80. In the illuminating device 1 of this embodiment, each LED is a high-brightness type LED called a power LED, and hundreds of LED units CON are provided. Moreover, the illuminating device 1 of this embodiment is arrange | positioned above the elongate plate-shaped product conveyed, for example in a longitudinal direction, and illuminates the upper surface of the conveyed plate-shaped product, The illumination part is predetermined. The image is picked up by the image pickup apparatus.

  The power supply unit 20 is connected to an AC power supply (not shown), for example, and supplies DC power using AC power from the AC power supply. In the power supply unit 20, the potential of the plus side terminal 20a is controlled by a voltage control signal inputted to the external terminal 20c, and the minus side terminal 20b is grounded.

  The constant current circuit 10 includes a first resistor 11 whose low voltage side is connected to the negative terminal 20 b of the power supply unit 20, a transistor 12, an operational amplifier 13, and a second resistor connected between the transistor 12 and the operational amplifier 13. It has a known configuration including a resistor 14 and a capacitor 15. A dimming voltage signal from a dimming volume (not shown) is input to the reference potential input terminal 13a of the operational amplifier 13, and the transistor 12 and the first resistor are input to the comparison potential input terminal 13b of the operational amplifier 13. 11 is input with a potential at a connection point with the terminal 11. The output terminal 13 c of the operational amplifier 13 is connected to the base of the transistor 12 through the second resistor 14. As a result, when the dimming volume is adjusted to increase the amount of current flowing through each LED unit CON, the potential input to the reference potential input terminal 13a of the operational amplifier 13 is increased, whereby the transistor 12 and the first resistor 11 increases, and the amount of current flowing through each LED unit CON increases. It should be noted that other configurations can be used as the constant current circuit 10.

  The minimum voltage detection circuit 30 is connected to a connection point between the plurality of LEDs and the constant current circuit 10 in each LED unit CON. Of the comparison voltages at the connection point between the LED of each LED unit CON and the constant current circuit 10 It is configured to detect the lowest comparison voltage.

  The feedback circuit 40 is configured to receive the minimum voltage detected by the minimum voltage detection circuit 30. Further, the feedback circuit 40 compares the lowest comparison voltage among the input comparison voltages of the LED units CON with the predetermined set voltage Vb, and according to the voltage difference between the predetermined set voltage Vb and the comparison voltage. The voltage is output as a voltage control signal VA. In the present embodiment, for example, a voltage control signal VA of + 1V to + 4V is output. The feedback circuit 40 outputs a voltage control signal VA to both the A / D converter 51 (analog / digital converter) and the changeover switch 80. In this embodiment, as an example, each LED unit CON has three LEDs, the catalog value of the voltage drop of each LED at 20 ° C. is 4V, and the minimum operating voltage of each constant current circuit 10 is the transistor 13 It is 2.5 V obtained by adding the operating voltage of about 2 V and the voltage drop of 0.5 V at the maximum current load of the first resistor R. For this reason, the predetermined set voltage Vb is preset to 3 V by adding a safety value. For example, when the minimum voltage input from the minimum voltage detection circuit 30 to the feedback circuit 40 is 5V, the feedback circuit 40 outputs a voltage control signal VA of 3V, for example, so as to converge the comparison voltage to 3V, and the minimum voltage When the minimum voltage input from the detection circuit 30 to the feedback circuit 40 becomes 3V, the voltage becomes stable. At this time, for example, a voltage control signal VA of 2.5V is output.

  The A / D converter 51 converts the output from the feedback circuit 40 into digital data and outputs the data to the storage unit 50. The storage unit 50 is connected to the control unit 60 and stores data output from the A / D converter 51 as a voltage control signal VD based on a command from the control unit 60. The storage unit 50 transmits the stored voltage control signal VD to the D / A converter 52 (digital / analog converter) based on a command from the control unit 60. The D / A converter 52 converts the voltage control signal VD from the storage unit 50 into analog data and outputs it to the changeover switch 80.

  The changeover switch 80 has a first input terminal 81, a second input terminal 82, and an output terminal 83. The changeover switch 80 is connected to the control unit 60, and based on a command from the control unit 60, the first input terminal 81 and the output terminal 83 are connected, or the second input terminal 82 and the output terminal 83 are connected. . The output of the D / A converter 52 is input to the first input terminal 81, the output of the feedback circuit 40 is input to the second input terminal 82, and the output of the output terminal 83 is input to the external terminal 20 c of the power supply unit 20. It has come to be.

  The trigger switch 70 is provided, for example, inside the box-type exterior of the lighting device 1 and is operated by inserting a thin stick from a small hole provided in the exterior.

  The operation of the control unit 60 will be described below (see FIG. 3). Below, the case where the illuminating device 1 of this embodiment is installed in the inspection process of a plate-shaped product is demonstrated, for example. The control in FIG. 3 is performed, for example, by setting the supply voltage of the power supply unit 20 to 15 V as an initial voltage and setting the dimming volume to the maximum value. First, when the trigger switch 70 is operated (S1), as shown in FIG. 2, the second input terminal 82 and the output terminal 83 are connected in the changeover switch 80 (S2). As a result, the voltage control signal VA of the feedback circuit 40 is input to the external terminal 20 c of the power supply unit 20. For example, when the trigger switch 70 is operated and the detection result of the minimum voltage detection circuit 30 is 5V and is higher than 3V of the predetermined set voltage Vb, the voltage control signal VA from the feedback circuit 40 is the power The potential of the positive terminal 20a of the supply unit 20 is lowered. When the detection result of the lowest voltage detection circuit 30 is 3V and becomes equal to 3V of the predetermined set voltage Vb, the potential of the positive terminal 20a of the power supply unit 20 is stabilized. In the present embodiment, the potential of the positive terminal 20a of the power supply unit 20 is stabilized in about several hundred milliseconds after the trigger switch 70 is operated.

  Subsequently, when a predetermined time (for example, 1 second) elapses after the trigger switch 70 is operated (S3), the control unit 60 outputs from the feedback circuit 40 at that time and is converted into digital data by the A / D converter 51. The voltage control signal VD being stored is stored in the storage unit 50 (S4). Further, in the changeover switch 80, the first input terminal 82 and the output terminal 83 are connected (S5). Then, the storage unit 50 is caused to output the voltage control signal VD stored in step S4 (S6). As a result, the voltage control signal VD output from the storage unit 50 is converted into analog data by the D / A converter 52, and the voltage control signal VA is input to the external terminal 20 c of the power supply unit 20. That is, the voltage control signal VA when the potential of the positive terminal 20 a of the power supply unit 20 is stabilized by the feedback circuit 40 is continuously input to the external terminal 20 c of the power supply unit 20.

  Thus, according to the present embodiment, when the trigger switch 70 is operated, the feedback circuit 40 operates until the detection result by the minimum voltage detection circuit 30 reaches the predetermined set voltage Vb, and the feedback circuit 40 operates. In the switch 80, the first input terminal 81 and the output terminal 83 are connected in the changeover switch 80, and the voltage control signal VD stored in the storage unit 50 in the step S4 is converted into an analog signal. Input to the terminal 20c. For this reason, even when hundreds of LED units CON are provided, the feedback circuit 40 adjusts the supply voltage from the power supply unit 20 so that the minimum voltage detection circuit 30 becomes the predetermined set voltage Vb. The voltage control signal supplied from the feedback circuit 40 to the power supply unit 20 in the state adjusted as described above is stored in the storage unit 50, and thereafter, the voltage control signal stored in the storage unit 50 is stored in the power supply unit 20. To be supplied.

  For this reason, if the predetermined set voltage Vb is set to a voltage necessary for the constant current circuit 10 to operate, when the lighting device 1 is installed in an inspection process or a reading process, each LED unit CON Even if there is a variation in the LED operating voltage or a voltage drop due to the resistance of the conductor connecting the power supply source and each LED unit CON, the trigger switch 70 is only operated even if the variation is unknown. Thus, a voltage control signal corresponding to a supply voltage necessary for operating the constant current circuit 10 of each LED unit CON is stored in the storage unit 50, and thereafter, the voltage control signal stored in the storage unit 50 is supplied with power. Supplied to the unit 20.

  Therefore, by appropriately setting the predetermined set voltage Vb, it is possible to efficiently save power and suppress the heat generation of the constant current circuit. Furthermore, once the trigger switch 70 is operated and the voltage control signal is stored in the storage unit 50, the constant current circuit 10 is then activated by the voltage control signal stored in the storage unit 50 and is not unnecessarily high. A voltage is supplied from the power supply unit 20 to each LED unit CON. Therefore, even when the lighting device 1 is repeatedly turned on and off, a voltage that is necessary for operation and is not unnecessarily high is applied to each LED unit CON constant current circuit as soon as it is turned on. That is, the light irradiation performance can be improved while saving power.

  For this reason, for example, as shown in FIG. 4, in the inspection process of the long plate-shaped product W, the scratches K <b> 1 extending in the longitudinal direction of the surface thereof are observed from an oblique direction in the width direction of the plate-shaped product W. Scratches extending in the width direction of the plate-like product W are inspected using the first illumination device 1 that irradiates light and the first imaging device 91 that images the illumination position from directly above the plate-like product W. For K2, a second illumination device 1 that irradiates light from an oblique direction of the longitudinal direction of the plate-like product W, and a second imaging device 92 that takes an image of the illumination position from directly above the plate-like product W. When the inspection is performed using the two, the positions of the two illumination devices can be brought close to each other. That is, when one lighting device 1 is turned on, the other lighting device 1 is turned off. When the other lighting device 1 is turned on, one lighting device 1 is turned off. The illumination does not interfere with each other, and each of the scratches K1 and K2 can be accurately inspected. Furthermore, each lighting device 1 is configured such that the constant current circuit 10 operates and a voltage that is not unnecessarily high is supplied from the power supply unit 20 to each LED unit CON by the control of FIG. Immediately after switching from the OFF state to the ON state, the constant current circuit 10 of each LED unit CON operates normally, and a desired light irradiation amount is obtained from each LED.

  Here, in each lighting device 1, when the second input terminal 82 and the output terminal 83 are always connected by the changeover switch 80, that is, in each lighting device 1, the potential of the positive terminal 20 a of the power supply unit 20 is It is assumed that feedback control is always performed by the feedback circuit 40. In this case, when the lighting device 1 is turned off, the voltage applied to the constant current circuit 10 becomes 0V, and when the lighting device 1 is turned on next time, the comparison point between the constant current circuit 10 and each LED is compared for a while. The potential is not stable, and therefore the feedback control by the feedback circuit 40 is not stable. Note that this unstable period is between several tens of milliseconds and several hundreds of milliseconds, so that it has not been regarded as a problem in the past. However, as shown in FIG. 4, when the two lighting devices 1 are brought close to each other and interference between the lighting devices is problematic, ON / OFF of each lighting device 1 is set to, for example, several milliseconds in order to further increase the inspection speed. When performed at intervals of ˜several tens of milliseconds, feedback control is not stable, and the light irradiation amount of each lighting device 1 is not stable. Therefore, the brightness of the image data of each of the image pickup apparatuses 91 and 92 is affected, which is not preferable for accurate inspection.

  On the other hand, in the lighting device 1 of this embodiment, the constant current circuit 10 of each LED unit CON operates normally immediately after switching from the OFF state to the ON state, and a desired light irradiation amount can be obtained from each LED. . For this reason, it is possible to arrange a plurality of illumination devices 1 so as to be close to each other, which is advantageous for space saving in an inspection process and a reading process. Moreover, the ON time of each illuminating device 1 can be shortened, and it is advantageous for the lifetime extension and power saving of LED. Furthermore, since the light irradiation amount of each illuminating device 1 is stable, it is advantageous in accurately performing inspection and reading.

  In this embodiment, the changeover switch 80 can be omitted (see FIG. 5). The operation of the control unit 60 in this case will be described with reference to FIG. First, when the trigger switch 70 is operated (S11), the storage unit 50 is instructed to output the signal from the A / D converter 51 to the D / A converter 52 as it is (S12). Thereby, the potential of the positive terminal 20a of the power supply unit 20 is feedback controlled. Subsequently, when a predetermined time (for example, 1 second) elapses after the trigger switch S1 is operated (S13), the voltage control signal output from the feedback circuit 40 and converted into digital data by the A / D converter 51 at that time. The VD is stored in the storage unit 50 (S14). Then, the storage unit 50 is instructed to output the voltage control signal VD stored in step S14 (S15). Accordingly, the voltage control signal VD output from the storage unit 50 is converted into analog data by the D / A converter 52, and the voltage control signal VA is input to the external terminal 20 c of the power supply unit 20. That is, the voltage control signal VA when the potential of the positive terminal 20 a of the power supply unit 20 is stabilized by the feedback circuit 40 is continuously input to the external terminal 20 c of the power supply unit 20.

  A lighting device according to a second embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 7, the lighting device omits the feedback circuit 40 in the first embodiment, and a control unit 60 is provided between the A / D converter 51 and the D / A converter 52, and the control unit 60 has a storage unit. 50 is connected. The predetermined set voltage Vb is input to the control unit 60 via the AD converter 53.

  The operation of the control unit 60 in this case will be described with reference to FIG. The control in FIG. 8 is performed, for example, by setting the supply voltage of the power supply unit 20 to 15 V as the initial voltage and setting the dimming volume to the maximum value. At this time, a voltage control signal is output from the control unit 60 to the external terminal 20c of the power supply unit 20 via the D / A converter 52 so that the potential of the positive terminal 20a of the power supply unit 20 becomes 15V. It has become. First, when the trigger switch 70 is operated (S21), the voltage signal from the A / D converter 51 is compared with a predetermined set voltage Vb, and the voltage signal from the A / D converter 51 is compared with a predetermined set voltage Vb ( In this embodiment, the voltage range is a predetermined voltage range, for example, a voltage range of 3V ± 0.1V (S22), and the voltage signal from the A / D converter 51 is higher than the predetermined set voltage Vb. (S23) The voltage control signal output to the D / A converter 52 is lowered by a predetermined amount (for example, 0.05 V) (S24). On the other hand, if the voltage signal from the A / D converter 51 is lower than the predetermined set voltage Vb (S23), the voltage control signal output to the D / A converter 52 is increased by a predetermined amount (for example, 0.05V) ( S25). When a predetermined time (for example, 100 milliseconds) elapses (S26), step S22 is performed again, and steps S23 to S26 are repeated until the voltage signal from the A / D converter 51 reaches a predetermined set voltage Vb. When the voltage signal from the A / D converter 51 becomes a predetermined set voltage Vb in step S22, the voltage control data VD output to the D / A converter 52 at that time is stored in the storage unit 50 (S27). Then, the voltage control signal VD stored in the storage unit 50 in step S24 is output toward the D / A converter 52 (S28). As a result, the voltage control signal VD stored in the storage unit 50 is converted into analog data by the D / A converter 52, and the voltage control signal VA is input to the external terminal 20 c of the power supply unit 20.

  Thus, according to the present embodiment, when the trigger switch 70 is operated, steps S23 to S26 are repeated until the detection result by the minimum voltage detection circuit 30 reaches the predetermined set voltage Vb, and the feedback control is performed. While the feedback control is not being performed, the voltage control signal VD stored in the storage unit 50 in step S24 is analog-converted and input to the external terminal 20c of the power supply unit 20. For this reason, even when there are a large number of LED units CON, for example, a few hundred, for example, the supply voltage from the power supply unit 20 so that the output of the minimum voltage detection circuit 30 becomes the predetermined set voltage Vb by feedback control. In this state, the voltage control signal supplied from the feedback circuit 40 to the power supply unit 20 is stored in the storage unit 50. Thereafter, the voltage control signal stored in the storage unit 50 is It is supplied to the power supply unit 20.

  For this reason, if the predetermined set voltage Vb is set to a voltage necessary for the constant current circuit 10 to operate, when the lighting device 1 is installed in an inspection process or a reading process, each LED unit CON Even if there is a variation in the operating voltage of the LED and a variation in the voltage drop due to the conductor between the power supply source and each LED unit CON, even if the size of the variation is unknown, just by operating the trigger switch 70, A voltage control signal corresponding to a supply voltage necessary for the constant current circuit 10 of each LED unit CON to operate is stored in the storage unit 50, and thereafter, the voltage control signal stored in the storage unit 50 is the power supply unit 20. To be supplied.

  Therefore, by appropriately setting the predetermined set voltage Vb, it is possible to efficiently save power, and it can be easily installed in the inspection process and the reading process. Further, once the trigger switch 70 is operated and the voltage control signal is stored in the storage unit 50, the constant current circuit 10 is activated and unnecessarily high by the voltage control signal stored in the storage unit 50 thereafter. No voltage is supplied from the power supply unit 20 to each LED unit CON. Therefore, even when the lighting device 1 is repeatedly turned on and off, a voltage that is necessary for operation and is not unnecessarily high is applied to each LED unit CON constant current circuit as soon as it is turned on. That is, the light irradiation performance can be improved while saving power.

  In the illumination device of each of the embodiments described above, the light irradiation amount of each LED is stabilized even when each LED unit CON is turned on / off at a high speed as described above. For this reason, as shown in FIG. 12, in the illuminating device 1 provided with the some LED arranged in the circumferential direction, each LED is lighted for every predetermined range of the circumferential direction, and ON / OFF of each LED is performed at high speed. It becomes possible. For example, in FIG. 12, after turning on only the LED arranged on one side with respect to the center line CL, it is possible to turn off only the LED arranged on the other side with respect to the center line CL and repeat this at high speed. It becomes. Thereby, when the inspection target product is arranged in the light irradiation direction of the lighting device 1 shown in FIG. 12, only a part of the product is irradiated with light, and only the range is inspected. It is possible to inspect only the range by irradiating light, and this can be performed at high speed. Furthermore, it is also possible to arrange a plurality of LEDs in a straight line direction, turn on each LED in a predetermined range in the juxtaposition direction, and perform ON / OFF at a high speed.

  DESCRIPTION OF SYMBOLS 1 ... Illuminating device, 10 ... Constant current circuit, 11 ... 1st resistance, 12 ... Transistor, 13 ... Operational amplifier, 14 ... 2nd resistance, 15 ... Capacitor, 20 ... Power supply part, 20a ... Positive side terminal, 20b ... Minus Side terminal, 20c ... external terminal, 30 ... minimum voltage detection circuit, 40 ... feedback circuit, 50 ... storage unit, 51 ... A / D converter, 52 ... D / A converter, 60 ... control unit, 70 ... trigger switch, 80 ... changeover switch, CON ... LED unit, Vb ... predetermined set voltage.

Claims (1)

  1. An LED lighting device comprising a plurality of LEDs,
    A power supply unit whose supply voltage is controlled based on a voltage control signal;
    Each of one or a plurality of LEDs and a constant current circuit are connected in series, and each of the plurality of LED units is supplied with power from a power supply unit,
    Detection means for detecting the voltage at the connection point between the LED and the constant current circuit in each LED unit as a comparison voltage, and detecting the lowest comparison voltage among the comparison voltages of each LED unit;
    Feedback means for supplying a voltage control signal for raising or lowering the supply voltage from the power supply unit to the power supply unit based on the detection result by the detection unit, so that the detection result becomes a predetermined set voltage;
    When the detection result is the predetermined set voltage, storage means for storing a voltage control signal supplied from the feedback means to the power supply unit at that time;
    Steady control means for supplying a voltage control signal stored in the storage means to the power supply unit;
    With trigger switch,
    An LED lighting apparatus configured such that when a trigger switch is operated, a feedback unit operates until the detection result reaches the predetermined set voltage, and a steady control unit operates while the feedback unit is not operating.
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JP2006303016A (en) * 2005-04-18 2006-11-02 Rohm Co Ltd Lighting device and display unit using the same
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