JP4925747B2 - Light irradiation system - Google Patents

Description

  The present invention relates to a light irradiation system having a plurality of LEDs used for, for example, product inspection.

  Conventionally, as shown in Patent Document 1, a light irradiation system for illuminating a product or the like (hereinafter also referred to as a workpiece) with a large number of LEDs has been developed for surface inspection and the like. As the circuit configuration, for example, several LEDs are connected in series with a current limiting resistor or a constant current driving circuit interposed between the voltage line and the common line, and a plurality of the LED series circuits are connected in parallel. It is trying to do.

  By the way, a typical example of a failure in such a system is LED blown. If a part of the LED is blown out, the illuminance may change and the inspection may fail, and if the piece is particularly short-circuited, an extra current will flow through the other LEDs, causing chaining. It is necessary to detect this broken piece failure at an early stage in order to cause a broken piece.

However, due to the configuration of this system, it is difficult to detect LED defects visually. Because
(1) Even if one or two of the LEDs are not lit, the brightness does not change so that it can be easily discerned visually. (2) The light irradiation surface is placed close to the workpiece. Therefore, it is not possible to confirm that the LED is out of sight directly. (3) If the LED is covered with a light diffusing plate or the like, the LED may be out of direct sight.

  Therefore, recently, a system equipped with a function for automatically discriminating balls has been developed. For example, the current or voltage flowing through the LED is constantly monitored, and when the value changes suddenly, it is not automatically determined as a failure, or it is not a lighting-related device. In some cases, the radiant heat emitted from the LED is measured for each of the plurality, and when the radiant heat weakens, it is automatically determined as a failure.

  However, when the dimming function that allows the user to arbitrarily set the light intensity is added, the above-described configuration causes the current, voltage, or heat dissipation to fluctuate during dimming, and this is erroneously determined as a failure. End up.

However, in order to avoid this, adding a function that cancels the failure determination function during dimming adds complexity to the configuration, and this time when a light break occurs during dimming (actually, the environment When dimming, etc., when the light changes, ball breakage etc. is likely to occur).
Japanese Patent Laid-Open No. 10-21729 JP 2005-259724 A

  Therefore, the present invention is intended to solve such problems and provide a light irradiation system or an LED abnormality detection device for the light irradiation system that can automatically determine the failure of an LED with a simple configuration and surely.

The light irradiation system according to the present invention includes an LED series circuit interposed between a voltage line and a common line, and the LED series circuit comprising a plurality of LED series circuit elements each including a plurality of LEDs. , It is determined whether the ratio of the voltages applied to each LED series circuit element matches the ratio of the number of LEDs included in each LED series circuit element within a predetermined range, and the determination result is output. And a judgment circuit to perform.

  According to such a configuration, if a short circuit or disconnection failure occurs in one of the LEDs constituting the LED series circuit, the voltage ratio acting on each LED series circuit element becomes the ratio of the number of LEDs. Since they do not match, an abnormality can be detected by the decision circuit. In addition, since the voltage ratio and the ratio of the number of LEDs, which are the basis for determining the abnormality, do not depend on the absolute voltage value or current value, even if the voltage or current varies or is changing due to the dimming function. However, it is always possible to reliably detect the abnormality without adding another circuit. Further, since the voltage or the like of each LED series circuit element is monitored instead of each LED, the configuration can be simplified as much as possible by appropriately setting the number of LEDs included in the LED series circuit element. .

  If the number of LEDs included in a single LED series circuit element is set too large, such as several tens, even if one of them is short-circuited, the rate of change in the voltage that acts is small, which may lead to a misjudgment. Arise. Therefore, the number is preferably several at most (about 9 or less). Conversely, the number of LEDs included in each LED series circuit element is a number according to the total number of LEDs included in the LED series circuit. Divide it into pieces.

  Practically, the LED series circuit is divided into two LED series circuit elements, that is, a voltage side LED series circuit element composed of one or a plurality of LEDs continuous from the voltage line side, and a common side LED series circuit element composed of other LEDs. It is desirable to divide into

  An abnormality output circuit that outputs an indication that an abnormality has occurred in the LED when it is determined by the determination circuit that it does not match is further provided, and depending on the output of the abnormality output circuit, the entire system or a part of the operation It is preferable to be configured to notify that an abnormality has occurred by automatically stopping or turning on the lamp.

  In order to simplify the circuit configuration, it is desirable to set the number of LEDs included in each LED series circuit element to be the same. In the determination circuit, it is only necessary to determine whether or not the voltage applied to each LED series circuit element is matched within a predetermined range. For example, the circuit configuration can be simplified such that substantially only a comparator is required. Can be

The present invention also provides a plurality of light emitting circuits each including a plurality of LED series circuits and a current control circuit for controlling a current to the LED series circuits interposed between the voltage line and the common line in parallel. A judgment circuit for judging whether the ratio of the voltages acting on the series circuit matches the ratio of the number of LEDs constituting each LED series circuit within a predetermined range, and outputting the judgment result; This is a light irradiation system.

  Even in such a parallel circuit configuration, the same effect as described above can be obtained by applying the essential part of the present invention in which abnormality detection is performed by comparing the voltage ratio with the ratio of the number of LEDs. it can. That is, if a short circuit or disconnection failure occurs in one of the LEDs constituting the LED series circuit, the voltage ratio acting on each LED series circuit will not match the ratio of the number of LEDs. Anomaly detection can be performed. In addition, since the voltage ratio and the ratio of the number of LEDs, which are the basis for determining the abnormality, do not depend on the absolute voltage value or current value, even if the voltage or current varies or is changing due to the dimming function. However, it is always possible to reliably detect the abnormality without adding another circuit. In addition, since the voltage of each LED series circuit is monitored, not each LED, the configuration can be simplified as much as possible by appropriately setting the number of LEDs included in the LED series circuit.

As a configuration in which a part necessary only for LED abnormality detection is cut out and used as an LED abnormality detection device, an LED series circuit interposed between a voltage line and a common line includes a plurality of LEDs each including a plurality of LEDs . The ratio of the voltages acting on each LED series circuit element when the LED series circuit element is assumed to match the ratio of the number of LEDs included in each LED series circuit element within a predetermined range. A judgment circuit for judging whether or not the judgment result is output, and an abnormality output circuit for outputting that an abnormality has occurred in the LED when it is judged that the judgment circuit does not agree with the judgment circuit. You can list what you have.

As another example, an abnormality of an LED in a configuration in which a plurality of light emitting circuits composed of a plurality of LED series circuits and a current control circuit for controlling a current to the LED series circuits are interposed in parallel between a voltage line and a common line. LED abnormality detection device for detecting the LED, wherein the ratio of the voltages acting on each LED series circuit matches the ratio of the number of LEDs constituting each LED series circuit within a predetermined range. A judgment circuit for judging whether or not the judgment result is output, and an abnormality output circuit for outputting that an abnormality has occurred in the LED when it is judged that the judgment circuit does not agree with the judgment circuit. You can list what you have.

  According to the present invention having such a configuration, abnormality detection is performed by comparing a voltage ratio acting on a plurality of LED series circuits (elements) with a ratio of the number of LEDs included in each LED series circuit (element). Therefore, even if the absolute voltage value or current value fluctuates or is in the middle of fluctuation due to the dimming function, etc., it is possible to detect the abnormality with a simple configuration without adding a separate circuit. Can be performed reliably.

  An embodiment of the present invention will be described below with reference to the drawings.

<First Embodiment>
FIG. 1 is a schematic diagram showing the entire light irradiation system 100 according to the present embodiment. The light irradiation system 100 includes a lighting device 1, a power supply device 2 that is separated from the lighting device 1, connected by an electric cable 4, and a light control device housed in the same housing as the power supply device 2. 3 is provided.

  First, a simple structure of the lighting device 1 will be described. As shown in FIGS. 1 to 3, for example, the illuminating device 1 is a disk-shaped device in which a large number of LEDs 11 are laid concentrically on the bottom surface and the bottom surface emits light. In order to detect the mark, the bottom is brought close to the work and illuminated. An observation hole H is penetrated through the center of the illumination device 1, and the surface of the workpiece illuminated through the observation hole H can be imaged or visually observed.

  Next, the electrical circuit configuration (see FIG. 4) of the entire light irradiation system will be described together with the description of the power supply device 2 and the light control device 3. Note that the electric circuit configuration of FIG. 4 is a schematic one for facilitating understanding of the characteristics and properties of the light irradiation system 100, and the actual electric circuit configuration can be made different from this. Needless to say.

  The power supply device 2 is a constant voltage direct current type that outputs a constant voltage between the voltage line L + and the common line L−.

  Between the voltage line L + and the common line L-, a plurality of LED series circuits 13 in which several (5 to 9) LEDs 11 are arranged in series are connected in parallel. Each LED series circuit 13 is further connected with a current limiting resistor 8. Further, between the LED series circuit 13 and the common line L-, for example, a dimming circuit (PWM controller) 7 for performing dimming by PWM control is provided.

  In this embodiment, however, the voltage measuring circuit 4 that measures the voltage acting on each LED series circuit element 12 obtained by dividing the LED series circuit 13 into two parts, and the ratio of each measured voltage is the LED series circuit. It is determined whether or not the ratio of the number of LEDs included in each element 12 matches within a predetermined range, and when the determination circuit 5 that outputs the determination result and the determination circuit 5 determines that they do not match , And an abnormality output circuit 6 that outputs that an abnormality has occurred in the LED 11.

  Details each circuit

  The voltage measurement circuit 4 measures a voltage acting on each LED series circuit element 12 when one LED series circuit 13 is divided into two LED series circuit elements 12 including the same number of LEDs 11. is there. Here, the voltage acting on each LED series circuit element 12 is measured by analog using an operational amplifier or the like, and each analog signal is digitized by an AD converter and output. In addition, although the operational amplifier and AD converter which are components which comprise this voltage measurement circuit 4 are mounted in the illuminating device 1 side, the arrangement | positioning aspect is not restricted to this example.

  The determination circuit 5 is realized by arithmetic processing based on a predetermined program of the CPU, and each measurement voltage output from the AD converter is predetermined to the ratio of the number of LEDs included in each LED series circuit element 12. It is used to determine whether or not they match within the range. In this embodiment, as described above, since the number of LEDs 11 included in each LED series circuit element 12 is the same, the determination circuit 5 determines whether or not each measured voltage value matches within a predetermined range. It is doing so.

  The predetermined range is, for example, that when one of the LEDs 11 is short-circuited and the voltage fluctuates, it can be determined that the determination circuit 5 does not match, and the difference in voltage due to the variation in Vf of each LED is ignored and matched. It means the range that can be judged to be. If the number of LEDs included in the LED series circuit element 12 is too large, the predetermined range has to be reduced, and it becomes impossible to distinguish the LED 11 due to the difference in Vf between the LEDs 11 and the risk of misjudgment increases. The number of LEDs included in the LED series circuit element 12 is preferably several.

  The abnormal output circuit 6 is configured to turn on an abnormal lamp (not shown), sound an alarm, or turn off the LED 11 when an output signal indicating that they do not match is received from the determination circuit 5. is there.

  At this time, the LED series circuit 13 (or element 12) in which an abnormality has occurred may be specified. In this embodiment, an AD converter is provided for each LED series circuit element 12, and an output signal from the AD converter can be specified by an I / O port number on the CPU side. The LED series circuit 13 (or element 12) can be identified from the number of the I / O port that has received the signal.

  According to the above configuration, if a short circuit or disconnection failure occurs in one of the LEDs 11, the ratio of the voltages acting on each LED series circuit element 12 does not match the ratio of the number of LEDs. Therefore, the abnormality detection by the determination circuit 5 and the abnormality output circuit 6 can be performed.

  In addition, the basis for determining the abnormality is the ratio of the voltage ratio and the number of LEDs, both of which do not depend on the absolute voltage value or current value, so that the voltage or current acting on the LED 11 varies due to dimming. Even if it is in the middle of fluctuation, it is always possible to reliably detect the abnormality without adding a separate circuit.

  Further, since the voltage or the like of each LED series circuit element 12 is monitored instead of each LED 11, the configuration can be simplified as much as possible by appropriately setting the number of LEDs 11 included in the LED series circuit element 12. Can be

<Second Embodiment>
In this embodiment, as shown in FIG. 5, a configuration in which a current limiting circuit 9 (an FB constant current driving circuit, a current limiting resistor, etc.) is provided for each LED series circuit 13 connected in parallel will be described. . Components corresponding to the first embodiment are denoted by the same reference numerals. The LED series circuit 13 and the current limiting circuit 9 may be referred to as a light emitting circuit 14 as a unit.

  In this embodiment, the voltage measurement circuit 4 measures the voltage acting on each LED series circuit 13 and outputs the measurement result to the determination circuit 5.

  The determination circuit 5 determines whether each measurement voltage output from the voltage measurement circuit 4 matches the ratio of the number of LEDs 11 included in each LED series circuit 13 within a predetermined range. In this embodiment, since the number of LEDs 11 included in each LED series circuit 13 is the same, this determination circuit 5 determines whether or not each measured voltage value matches each other within a predetermined range.

  Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  Even in such a circuit configuration, the same effect as described above can be obtained by applying the essential part of the present invention in which abnormality detection is performed by comparing the voltage ratio with the ratio of the number of LEDs. .

<Other variations>
The present invention is not limited to the above embodiment. For example, the number of LEDs included in each LED series circuit (element) may not be the same number, and the LED series circuit may be divided into three or more LED series circuit elements.

  For example, in the case shown in FIG. 6, the ratio of the voltages acting on each LED series circuit element 12 (V1: V2: V3) is the ratio of the number of LEDs 11 included in each LED series circuit element 12 ( n: m: k) may be determined whether or not they match within a predetermined range.

  In each of the above embodiments, the voltage acting on the LED series circuit 13 (LED series circuit element 12) is measured via an operational amplifier that is a high input impedance element. In order to promote the implementation, a circuit configuration as shown in FIG. 7 may be used. In FIG. 7, resistors R1, R2 (R3, R4) are arranged in parallel with the LED series circuit 13 (LED series circuit element 12), and the voltage can be directly measured by a measurement circuit (for example, an AD converter). I can do it. In other words, the apparent impedance of the LED series circuit 13 (LED series circuit element 12) viewed from the measurement circuit side is lowered to enable measurement without the operational amplifier. Here, the resistor is divided into two (R1, R2 or R3, R4) so as to match the input voltage range of the AD converter, and the intermediate value is measured. Further, the voltage of the entire LED series circuit 13 and the voltage of the LED series circuit element 12 which is one component thereof are measured, and whether or not the voltage ratio matches the ratio of the number of LEDs, that is, here Whether or not it is 2: 1 is judged. However, in FIG. 7, parts corresponding to the first embodiment are given the same reference numerals.

  Furthermore, it is not always necessary to use a CPU for the circuit, and it may be configured by using analog / digital mixed components or analog-only discrete components.

  In addition, the present invention can be variously modified without departing from the spirit of the present invention, for example, by appropriately combining the configurations of the descriptions.

1 is an overall schematic configuration diagram showing an embodiment of a light irradiation system according to the present invention. The top view of the light control apparatus in the embodiment. The longitudinal cross-sectional view of the light control apparatus in the embodiment. The schematic circuit diagram of the light irradiation apparatus in the embodiment. The schematic circuit diagram of the light irradiation apparatus in 2nd Embodiment. The schematic partial circuit diagram which shows the modification of the light irradiation system concerning this invention. The schematic circuit diagram which shows the further another modification of the light irradiation system concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Illumination device 11 ... Light emitting diode (LED)
DESCRIPTION OF SYMBOLS 12 ... LED series circuit element 13 ... LED series circuit 2 ... Power supply 3 ... Light control device 5 ... Judgment circuit 6 ... Abnormal output circuit

Claims (10)

An LED series circuit interposed between the voltage line and the common line;
When the LED series circuit is composed of a plurality of LED series circuit elements each including a plurality of LEDs, the ratio of the voltages acting on each LED series circuit element is determined for each LED series circuit element. A light irradiation system comprising: a determination circuit configured to determine whether or not the ratio of the number of LEDs included is within a predetermined range. An LED series circuit interposed between the voltage line and the common line;
In the LED series circuit, the ratio of the voltages acting on the voltage side LED series circuit element composed of one or a plurality of LEDs continuous from the voltage line side and the common side LED series circuit element composed of other LEDs, A light irradiation system comprising: a determination circuit that determines whether or not a ratio of the number of LEDs included in each of the LED series circuit elements matches within a predetermined range and outputs the determination result.   3. The light irradiation system according to claim 1, further comprising an abnormality output circuit that outputs that an abnormality has occurred in the LED when it is determined by the determination circuit that they do not match. The number of LEDs included in each LED series circuit element is the same,
The light irradiation system according to any one of claims 1 to 3, wherein the determination circuit determines whether or not a voltage applied to each LED series circuit element is matched within a predetermined range.   The light irradiation system according to claim 1, wherein the number of LEDs included in the LED series circuit element is 5 or less. A plurality of light emitting circuits comprising a plurality of LED series circuits and a current control circuit for controlling a current to the LED series circuits interposed between the voltage line and the common line in parallel;
A determination circuit that determines whether the ratio of the voltages acting on each LED series circuit matches the ratio of the number of LEDs constituting each LED series circuit within a predetermined range, and outputs the determination result And a light irradiation system. The number of LEDs included in each LED series circuit is the same,
The light irradiation system according to claim 6, wherein the determination circuit determines whether a voltage applied to each LED series circuit is matched within a predetermined range.   The light irradiation system according to claim 6 or 7, wherein the number of LEDs included in the LED series circuit is 5 or less. When the LED series circuit interposed between the voltage line and the common line is composed of a plurality of LED series circuit elements each including a plurality of LEDs, the voltage acting on each LED series circuit element A determination circuit for determining whether the ratio matches a ratio of the number of LEDs included in each of the LED series circuit elements within a predetermined range and outputting the determination result;
An LED abnormality detection device comprising: an abnormality output circuit that outputs that an abnormality has occurred in the LED when it is determined by the determination circuit that they do not match. It is for detecting an abnormality in a plurality of light emitting circuits including a plurality of LED series circuits and a current control circuit for controlling a current to the LED series circuits interposed in parallel between the voltage line and the common line. And
Judgment whether or not the ratio of the voltages acting on each LED series circuit matches the ratio of the number of LEDs constituting each LED series circuit within a predetermined range, and outputting the judgment result Circuit,
An LED abnormality detection device comprising: an abnormality output circuit that outputs that an abnormality has occurred in the LED when it is determined by the determination circuit that they do not match.