JP2012048854A - Led lighting electric power supply unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve dimming under constant-current control without manually adjusting an LED illumination fixture having various constitution, for example, differing in number of LED elements or the like.SOLUTION: When a "setting mode" is specified, a specified voltage is applied to the LED lighting fixture as a load without performing the constant-current control to light the fixture (S3), and an output current is detected (S4-S6) at the point of time when a detection standby time passes after the start of the lighting and then current variation due to a rise in temperature ceases. A current value thereof is a maximum current value depending upon a configuration, such as the number of elements, of the LED lighting fixture, so a coefficient for control which determines output during 100% dimming is calculated based upon the current value and stored (S7, S8). For 0-100% dimming under the constant-current control, the stored coefficient for control is used to determine a maximum current corresponding to the output during the 100% dimming, and a constant current corresponding to a light quantity setting is supplied to the LED lighting fixture, which is continuously lighted.

Description

  The present invention relates to an LED lighting power supply device for driving an LED lighting fixture using a plurality of LEDs (light emitting diodes), and in particular, an LED lighting fixture used in an inspection line for product appearance inspection or sorting inspection in a factory or the like. It is related with the LED illumination power supply device suitable for lighting-driving.

  For product appearance inspection and sorting inspection at factories, products that move at high speed on the line are photographed, and image processing is performed on the resulting images to detect product defects and products. An inspection device for determining the shape is used. In such inspection apparatuses, various types of lighting fixtures are used to illuminate the product to be photographed. However, in recent years, LED lighting fixtures using LEDs as light sources have been rapidly used due to advantages such as long life and power saving. Is going on.

  In general, PWM (pulse width modulation) control and constant current control are known as lighting driving methods for LED lighting fixtures. In PWM control, dimming can be performed by varying the pulse width of the rectangular wave driving voltage supplied to the LED lighting apparatus. On the other hand, in the constant current control, dimming can be performed by changing the current value of the direct current supplied to the LED lighting apparatus. Conventionally, PWM control is widely used in the above-described power supply device for lighting and driving the LED lighting fixture for inspection (see Patent Documents 1 and 2). The main reason is as follows.

  The LED lighting fixture for inspection is different from the general LED lighting fixture for home use, and the range of the characteristics of the LED used is wide, and the number of LEDs used varies even if the fixture has the same rated voltage specification. When performing constant current control, it is necessary to adjust the current value supplied from the power supply according to the configuration such as the number and characteristics of the LEDs mounted on the LED lighting fixture used. Adjustment is very cumbersome when the instruments to be used are various. On the other hand, in PWM control, the voltage applied to the LED lighting fixture may be constant regardless of the configuration of the fixture, and because it can respond to the difference in the configuration of the fixture by simple control of the pulse width and can also perform dimming, Troublesome manual adjustment is not necessary and cost is advantageous.

  However, in the case of PWM control, although the LED is very fast, the LED repeats blinking, so that a period during which the product to be inspected is illuminated and a period during which the product is not illuminated are generated. In recent years, in response to a demand for high-speed inspection, imaging in an inspection apparatus has become increasingly faster, and if this happens, the effect of lighting blinking may appear in the captured image. In order to avoid such an influence, it is necessary to continuously turn on the LED lighting apparatus using constant current control instead of PWM control.

JP 2009-300871 A JP 2010-153151 A

  The present invention has been made in view of the above-mentioned problems. For example, in an LED illumination power supply device that lights and drives an LED lighting fixture for inspection used in an inspection apparatus by constant current control, the number and characteristics of LEDs are different. The main purpose is to realize high versatility for the LED lighting apparatus to be used by eliminating the need for complicated manual adjustment for such LED lighting apparatus.

In order to solve the above problems, the present invention is an LED lighting power supply apparatus that drives and lights an LED lighting apparatus using a plurality of LEDs by constant current control.
a) current detection means for detecting a current flowing through the lighting fixture in a state where a predetermined constant voltage is applied to the LED lighting fixture connected as a load;
b) Constant current control information acquisition means for creating and storing control information for setting the maximum output current during dimming by constant current control based on the current value detected by the current detection means;
c) A maximum output current corresponding to 100% dimming is set using the control information stored by the constant current control information acquisition means, and 0-100% dimming is supported according to an external dimming instruction. Constant current supply means for outputting a constant current,
It is characterized by having.

  In the LED lighting power supply device according to the present invention, for example, when a predetermined command is given from the outside, the current detection means applies a prescribed constant voltage to the LED lighting fixture connected as a load to the device correspondingly. . This prescribed constant voltage depends on the voltage specification of the LED lighting fixture. In a normal LED lighting fixture, when a specified constant voltage is applied, a maximum current allowed to flow through the lighting fixture flows. Therefore, the current detection means detects the maximum current of the LED lighting fixture connected at that time. Can do. Usually, the maximum current depends on the number of LEDs (number of elements) used in the instrument, and the maximum current increases as the number of elements increases.

  The constant current control information acquisition means creates and stores control information for setting the maximum output current during dimming by constant current control based on the current value of the maximum current. For example, the reference current value Is can be determined in advance, and the ratio (Im / Is) between the current value Im detected by the current detection means and the reference current value Is can be used as control information.

  The constant current supply means sets a maximum output current corresponding to 100% dimming using the control information, and loads a constant current corresponding to 0 to 100% dimming according to an external dimming instruction, that is, LED It outputs to a lighting fixture and makes this fixture light continuously. In such constant current control, since control information stored in advance according to the number of elements of the LED lighting fixture as a load is used, the maximum current of the fixture is set to 100% regardless of the configuration of the LED lighting fixture. Dimming by constant current control with dimming is possible. Moreover, since acquisition of control information is performed automatically, a troublesome operation by an operator can be omitted.

  In the LED lighting power supply device according to the present invention, it is desirable to re-acquire control information when the LED lighting fixture as a load is replaced. Therefore, as one aspect of the LED lighting power supply device according to the present invention, when a predetermined command is given from the outside, the current detecting means applies a specified constant voltage to the LED lighting fixture and flows through the lighting fixture. The constant current control information acquisition means creates and stores control information for setting a maximum output current during dimming by constant current control based on the detected current value, and stores the predetermined information When the command is not given, the constant current supply means does not execute the current detection by the current detection means and the creation of the control information by the constant current control information acquisition means, and the constant current control using the control information by the constant current supply means. It is preferable to further include control means for controlling each means so as to perform light control.

  According to this configuration, when the LED lighting apparatus is replaced, a predetermined command is given from the outside, so that control information corresponding to the LED lighting apparatus connected at that time is automatically acquired again. can do.

  In the LED lighting power supply device according to the present invention, preferably, the current detection unit detects a current flowing through the lighting fixture when a predetermined time has elapsed from the start of applying a constant voltage to the LED lighting fixture. It may be configured. Here, the predetermined time is either a value determined in advance based on a state of change in current caused by a temperature rise when current is supplied to a general LED, or a value input and set from the outside. But you can.

  Generally, an LED generates heat as it is turned on, and the current increases as the temperature rises. On the other hand, if the predetermined time is appropriately set in the above configuration, the maximum current can be detected in a state where the temperature rise of each LED in the LED lighting fixture is suppressed and the change in current is also suppressed. Thereby, more accurate control information can be obtained corresponding to the LED lighting apparatus as the load, and the illuminance at the time of dimming by the constant current control becomes further accurate.

  According to the LED lighting power supply device according to the present invention, it is possible to realize good dimming by constant current control for LED lighting fixtures having various configurations such as the same voltage specifications and different numbers of LEDs. In addition, since it is not necessary to perform complicated adjustments or work by an operator in order to deal with variously configured LED lighting fixtures, a single power supply device can be used universally for the user, which is very convenient. .

The block block diagram of the LED illumination power supply device which is one Example of this invention. The control flowchart at the time of the initial setting in the LED illumination power supply device of a present Example. The figure which shows an example of the light control operation | movement by the initial setting and constant current control in the LED illumination power supply device of a present Example.

  Hereinafter, an inspection LED illumination power supply device according to an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a block diagram of the LED lighting power supply device for inspection of this embodiment.

  The inspection LED illumination power supply device 1 of the present embodiment drives and lights up the LED illumination fixture 2 for inspection in which about several tens to several hundreds of LEDs are used. Typical voltage specifications for LED lighting fixtures are + 12V, + 24V, + 48V, and the like. The LED lighting power supply device 1 for inspection according to the present embodiment includes, as main blocks, a constant current output unit 13 that supplies a driving current to the LED lighting device 2 that is a load, and a CPU that controls operation of the entire device including a CPU. Unit 10, an output control unit 11 that controls a current value output from the constant current output unit 13 under the control of the control unit 10, a current detection unit 14 that detects a current value flowing through the LED lighting fixture 2, Based on the detected current value, a coefficient calculation unit 15 that calculates a control coefficient corresponding to the control information in the present invention, and an instruction from an external computer or the like (not shown) that accepts or connects an operation by an operator And an input unit 16 for receiving.

  FIG. 2 is a control flowchart at the time of initial setting in the LED lighting power supply for inspection of this embodiment. With reference to FIG. 2 in addition to FIG. 1, the characteristic operation in the LED lighting power supply for inspection of this embodiment will be described in detail.

  In the LED lighting power supply device 1 for inspection according to the present embodiment, the input unit 16 performs an initial setting for appropriately driving the LED lighting apparatus 2 connected to the device 1 in addition to the mode for performing normal lighting driving. “Setting mode” can be selected. When the apparatus 1 is turned on and starts operating, the control unit 10 first determines whether or not the “setting mode” is designated in the input unit 16 (step S1).

  If it is determined in step S1 that the “setting mode” is designated, the control unit 10 determines a detection waiting time (step S2). A value stored in advance in the control unit 10 may be used as the detection standby time, but an operator may appropriately set the detection standby time in the input unit 16. Next, the control unit 10 controls the constant current output unit 13 so as to apply a predetermined constant voltage to the load, that is, the LED lighting apparatus 2 via the output control unit 11 (step S3). The specified constant voltage at this time is assumed to correspond to the voltage specification of the LED lighting device 2. For example, in the case of an LED lighting fixture of + 12V specification (the voltage when used in PWM control is + 12V), the specified voltage is set to + 12V. At this time, the constant current control in the constant current output unit 13 is not executed, and the upper limit of the current supplied to the LED lighting device 2 is not substantially limited. As a result, the allowable maximum current determined by the number of elements of the fixture 2 and the LED characteristics is supplied from the constant current output unit 13 to the LED lighting fixture 2, and the LED lighting fixture 2 is lit.

  Simultaneously with the start of lighting, the control unit 10 starts timing by an internal timer (step S4), and repeatedly determines whether or not the timing has exceeded the detection standby time set in step S2 (step S5). And if detection waiting time passes, the electric current detection part 14 will detect the electric current which flows into the LED lighting fixture 2, ie, a maximum electric current, (step S6).

  As described above, when a driving current is supplied to each LED of the LED lighting device 2 and the LED is lit, the current gradually increases due to the influence of heat generated therewith. Therefore, even if the current detection unit 14 detects a current value in a state where the temperature of the LED immediately after the start of lighting is low, accuracy is lost. On the other hand, in the LED illumination power supply device 1 of the present embodiment, the current is detected after waiting for the detection waiting time to elapse from the lighting start time, that is, after the LED lighting apparatus 2 is continuously lit for that time. Therefore, it is possible to obtain a highly accurate current value in a state where the temperature of the LED is raised to some extent.

  In addition, when the current flowing through the LED increases due to temperature rise in a state where the maximum current or a current close thereto is continuously supplied, the approximate time required for the current increase to almost converge is obtained in advance by experiments. Can do. Therefore, the detection waiting time can be determined in advance based on such experiments. On the other hand, as described above, if the detection waiting time can be input and set from the input unit 16, even when using an LED lighting apparatus having a special configuration in which the temperature rise is extremely small or large, it is caused by temperature change. The influence of current increase / decrease can be accurately eliminated.

  As described above, the value of the current flowing through the LED lighting fixture 2 in a state where a predetermined constant voltage is applied depends on the number and characteristics of the LEDs used in the fixture 2. Therefore, the coefficient calculation unit 15 reads the current value detected by the current detection unit 14, and calculates a control coefficient so that the current value becomes the maximum output, that is, the output of 100% dimming (step S7).

An example of how to obtain the control coefficient will be described with reference to FIG.
Now, as shown in FIG. 3A, a certain LED lighting fixture a has a current value of 1 [A] in a state where a specified voltage + V (for example, +12 V) is applied, and another LED lighting fixture b has the same specified voltage. It is assumed that the current value with + V applied is 0.5 [A]. All of these current values are outputs at the time of 100% dimming, and a control coefficient is obtained from a ratio of an actually measured current value Im to a predetermined reference current Is. For example, here, the reference current Is is set to 1 [A], and the control coefficient is obtained from Im / Is. Therefore, the control coefficient for the LED lighting apparatus a is “1”, and the control coefficient for the LED lighting apparatus b is “0.5”. That is, this means that the current supplied to realize 100% dimming output needs to be ½ that of the LED lighting fixture a in the LED lighting fixture b. For example, if the current value in a state where the specified voltage + V is applied is 0.75 [A], the control coefficient for the LED lighting apparatus at that time is obtained as 0.75.

  As described above, the control coefficient calculated by the coefficient calculation unit 15 in the “setting mode” is stored in the coefficient storage unit 12 built in the output control unit 11 (step S8), and the operation of the “setting mode” is completed. To do. The processes in steps S1 to S8 after the “setting mode” is designated are all automatically performed, and there is no work / process that requires manual work such as an operator.

  On the other hand, if it is determined in step S1 that the mode is not the “setting mode”, the LED lighting apparatus 2 is in a normal lighting mode, so the process proceeds from step S1 to S9, and normal constant current driving is executed. That is, the output control unit 11 controls the constant current output unit 13 so as to supply a constant current according to the instructed light amount setting (discrete setting or continuous setting in the range of 0 to 100% dimming), When a constant current is supplied from the output unit 13 to the LED lighting apparatus 2, the LED lighting apparatus 2 is lit at a constant light emission intensity. At this time, the output control unit 11 uses the control coefficient stored in the coefficient storage unit 12 for control.

  Specifically, the maximum current with respect to the maximum output (100% dimming) is obtained from the reference current Is × the control coefficient, and the current according to the light amount setting in the range of 0 to 100% with the maximum current determined as 100%. Determine. FIG. 3B is a diagram showing the relationship between the light amount setting and the current when the control coefficient is 0.5. When the control coefficient is 0.5, the maximum current is Is × 0.5 = 0.5 [A], and the dimming of 0 to 100% is in the range of 0 to 0.5 [A] as illustrated. This is realized by performing constant current control. When the control coefficient is 1, the maximum current is 1 [A], and 0 to 100% dimming is realized by performing constant current control in the range of 0 to 1 [A].

  As described above, in the LED lighting power supply device 1 for inspection according to the present embodiment, even if the configuration of the LED lighting apparatus 2 to be used, specifically, the number of elements and LED characteristics are various, the “setting mode” is executed. By calculating a control coefficient suitable for the LED lighting apparatus 2 connected at that time and storing it in the coefficient storage unit 12, accurate dimming according to the LED lighting apparatus 2 can be performed with constant current control. Can be realized.

  In step S3, it is necessary to apply a constant voltage defined to the connected LED lighting fixture 2. Since there are + 12V, + 24V, + 48V, etc. in addition to + 12V in the voltage specification of general LED lighting fixtures, it is preferable that the voltage specification can be set from the input unit 16.

  It should be noted that the above embodiment is merely an example of the present invention, and it is obvious that modifications, corrections and additions may be made as appropriate within the scope of the present invention and included in the scope of the claims of the present application.

  For example, in the above-described embodiment, the present invention is applied to a power supply device that drives an LED lighting fixture for an inspection apparatus. However, the LED illumination power supply device according to the present invention is not limited to an inspection use, but is used for various purposes. The present invention can be applied to a power supply device that drives Specifically, the LED lighting power supply device according to the present invention is useful if the LED lighting fixture has a predetermined input voltage specification. For example, when the LED lighting power supply device according to the present invention is used for general lighting or public lighting (for example, lighting in a tunnel, street light, stadium lighting, etc.) using such LED lighting fixtures, due to technological progress of LED elements in the future. LED lighting fixtures with a small number of elements and low drive current while maintaining illuminance are available on the market. Dimming control corresponding to the latest LED lighting apparatus can be performed without replacing the device itself.

DESCRIPTION OF SYMBOLS 1 ... LED illumination power supply device 10 for test | inspection ... Control part 11 ... Output control part 12 ... Coefficient memory | storage part 13 ... Constant current output part 14 ... Current detection part 15 ... Coefficient calculating part 16 ... Input part 2 ... LED lighting fixture

Claims (3)

In the LED lighting power supply device that drives the LED lighting fixture using a plurality of LEDs by constant current control,
a) current detection means for detecting a current flowing through the lighting fixture in a state where a predetermined constant voltage is applied to the LED lighting fixture connected as a load;
b) Constant current control information acquisition means for creating and storing control information for setting the maximum output current during dimming by constant current control based on the current value detected by the current detection means;
c) A maximum output current corresponding to 100% dimming is set using the control information stored by the constant current control information acquisition means, and 0-100% dimming is supported according to an external dimming instruction. Constant current supply means for outputting a constant current,
An LED illumination power supply device comprising: The LED illumination power supply device according to claim 1,
When a predetermined command is given from the outside, the current detection unit applies a predetermined constant voltage to the LED lighting fixture to detect a current flowing through the lighting fixture, and the constant current control information acquisition unit is detected. LED further comprising control means for controlling each of the means so as to create and store control information for setting a maximum output current at the time of dimming by constant current control based on the current value Lighting power supply. The LED illumination power supply device according to claim 1 or 2,
The said current detection means detects the electric current which flows into this lighting fixture when predetermined time passes since the time of starting application of the fixed voltage to LED lighting fixture, The LED lighting power supply device characterized by the above-mentioned.

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