Light irradiation system

Abstract

When powering multiple light irradiation units independently from a single power supply unit, this not only promotes higher speed and brightness for each light irradiation unit but also enables highly accurate synchronized emission in each unit. [Solution] The power supply unit 1 includes a power supply circuit 11 that supplies power for light emission to each light irradiation unit 2 via a power supply terminal 1a, and a pulse generation circuit 12 that intermittently generates pulse signals and transmits the pulse signals to each light irradiation unit 2 via a signal output terminal 1b. The light irradiation unit includes a light source body 21, a power receiving terminal 2a connected to the power supply terminal 1a via a power cable 4, an input terminal 2b connected to the signal output terminal 1b via a signal cable 5, and a control unit 22 that counts the pulse signals input from the input terminal 2b and controls the current supplied from the power receiving terminal 2a to the light source body 21 in synchronization with the pulse signals received at a predetermined count.

Description

Technical Field

[0001] The present invention relates to a light irradiation system and the like used in a surface inspection system of a workpiece and the like.

Background Art

[0002] A conventional light irradiation system of this type is composed of a light irradiation unit that irradiates a workpiece with inspection light and a power supply unit that controls the light emission mode of this light irradiation unit. More specifically, a current for driving the light irradiation unit is supplied from the power supply unit, and inspection light with an intensity corresponding to the supplied current is irradiated from the light irradiation unit onto the workpiece. On the other hand, recently, there has been an increasing demand for higher brightness and higher speed in this type of light irradiation system. Furthermore, for example, in a system such as an inspection system (Patent Document 1) using the photometric stereo method, inspection light is irradiated onto a workpiece from different directions by switching a plurality of light irradiation units, and this is imaged to perform an appearance analysis of the product. In such a system, each light irradiation unit is required not only to have higher brightness and higher speed but also to more precisely control the light emission timing.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, if the power supply unit and the light irradiation unit are connected by a power cable, as in conventional systems, and the drive current flowing through that power cable is controlled by a control circuit such as a switching element installed on the power supply unit side, the impedance of the power cable not only hinders the increase in speed and brightness, but variations in impedance caused by differences in the length and wiring of the power cables from the power supply unit to each light irradiation unit can also disrupt the synchronization of light emission.

[0005] This invention was made to solve these problems, and its main objective is not only to promote high speed and high brightness of each light irradiation unit when power is supplied from a single power supply unit to make multiple light irradiation units emit light independently, but also to enable highly accurate synchronized emission of light irradiation in each light irradiation unit. [Means for solving the problem]

[0006] In other words, the light irradiation system according to the present invention is A light irradiation system comprising a plurality of light irradiation units that irradiate a workpiece with inspection light, and a power supply unit that supplies power to these light irradiation units and controls their light emission patterns, The aforementioned power supply unit It comprises a power supply terminal, a power supply circuit that supplies power for light emission to each of the light irradiation units via the power supply terminal, a signal output terminal, and a pulse generation circuit that intermittently generates pulse signals and transmits the pulse signals to each of the light irradiation units via the signal output terminal. The light irradiation unit, The device is characterized by comprising a light source, a power receiving terminal connected to the power supply terminal of the power supply unit via a power cable, an input terminal connected to the signal output terminal via a signal cable, and a control unit that counts pulse signals input from the input terminal and controls the current supplied to the light source from the power receiving terminal in synchronization with the pulse signals received at a predetermined count.

[0007] With this configuration, each light irradiation unit is equipped with a control unit that controls the current flowing through the light source, which allows for faster operation and higher brightness compared to control from the power supply unit. Furthermore, by transmitting pulse signals from the power supply unit via low-impedance signal cables and controlling the light emission timing of each light irradiation unit with these pulse signals, time differences and delays can be significantly reduced, improving the synchronization of light emission. Moreover, while the power supply unit only needs to transmit pulse signals, the light irradiation unit only needs to count the pulse signals and synchronize the light emission of the light source with the pulse signals at a predetermined count, eliminating the need for complex calculations and minimizing delays caused by such calculations. In this respect as well, it further promotes faster operation and improved synchronization.

[0008] In order to streamline the wiring and prevent the wiring work from becoming complicated even if the number of light irradiation units increases, it is preferable that the light irradiation unit further has an output terminal connected to the input terminal, the signal output terminal of the power supply unit is connected via a signal cable to only the input terminal of one light irradiation unit, and the input terminals of other light irradiation units are further connected via signal cables to the output terminals of other light irradiation units in a daisy-chain configuration starting from the one light irradiation unit. To configure a workpiece inspection system by synchronizing the light emission operation of a light irradiation unit with imaging, it is preferable to further include an imaging unit that receives the pulse signal and, in synchronization with the pulse signal, images the workpiece irradiated with inspection light. [Effects of the Invention]

[0009] According to the present invention configured in this way, when power is supplied from a single power supply unit to make multiple light irradiation units emit light independently, it is possible to promote high speed and high brightness for each light irradiation unit, and to enable highly accurate synchronized emission of light in each light irradiation unit. [Brief explanation of the drawing]

[0010] [Figure 1] A schematic diagram showing the overall configuration of a light irradiation system according to one embodiment of the present invention. [Figure 2] A waveform diagram showing a group of pulse signals in the same embodiment. [Modes for carrying out the invention]

[0011] A light irradiation system 100 according to one embodiment of the present invention will be described below with reference to the drawings.

[0012] 1. Overview The light irradiation system 100 of this embodiment includes a plurality of light irradiation units 2 that irradiate the workpiece W with inspection light, and a power supply unit 1 that supplies power to these light irradiation units 2 and controls their light emission patterns.

[0013] 2. Power supply unit As shown in Figure 1, the power supply unit 1 comprises a power supply circuit 11 that supplies current for light emission to each of the light irradiation units 2, a pulse generation circuit 12, and a housing 13 that holds these components.

[0014] 2-1.Power supply circuit The power supply circuit 11 is a constant voltage source in this case, but is not limited to this. This power supply circuit 11 is connected to a power supply terminal 1a provided on the housing 13 of the power supply unit 1.

[0015] 2-2. Pulse Generation Circuit The pulse generation circuit 12 is configured using a controller such as a PC, PLC, or microcontroller, and generates a finite number of pulse signals at a constant period, as shown in Figure 2. The generated pulse signals are output from the signal output terminal 1b provided on the housing 13. When the above-mentioned finite number of pulse signals are defined as "a group of pulse signals", the first pulse signal in a group of pulse signals is generated starting from, for example, when a sensor or the like detects that a workpiece has been placed at the inspection position, and this detection signal is received by the pulse generation circuit 12, although not shown in the figure. In addition, the pulse generation circuit 12 may repeatedly generate the group of pulse signals.

[0016] 3. Light Irradiation Unit As shown in FIG. 1, this light irradiation unit 2 includes a light source body 21 that emits inspection light, a control unit 22, and a housing 23 that holds these components.

[0017] 3-1. Light Source Body Here, the light source body 21 is constituted by connecting a plurality of LEDs in series or in parallel. Note that the light source body 21 is not limited to being constituted by LEDs, and may also be constituted by an LD, an SLD, or the like.

[0018] 3-2. Control Unit The control unit 22 is composed of a control unit main body 221 and a drive circuit 222. The control unit main body 221 is an electronic circuit configured using a controller such as a PC, a PLC, or a microcomputer, and outputs a control signal to the drive circuit 222. More specifically, this control unit main body 221 receives a group of pulse signals generated by the power supply unit 1, and functions as a receiving unit that counts the number of received pulse signals, and an output unit that outputs the control signal triggered by the rising or falling of the received pulse signals at a predetermined count number. For example, the light irradiation unit 2 in which the count number is set to 2 outputs the control signal triggered by the second pulse signal.

[0019] The drive circuit 222 is an electric circuit composed of a switching element such as a FET or an amplification element, etc., amplifies the control signal, and causes a current corresponding to this control signal to flow through the light source body 21 to cause it to emit light.

[0020] The control signal here is, for example, a pulse waveform, and its waveform (duration and / or voltage) can be changed by an external input. This setting controls the drive circuit 222, which adjusts the current flowing through the light source 21, thereby setting the light emission intensity and duration for a single pulse signal.

[0021] 3-3. Enclosure The housing 23 is provided with a power receiving terminal 2a, an input terminal 2b, and an output terminal 2c. The power receiving terminal 2a is connected to the power supply terminal 1a of the power supply unit 1 via a power cable 4. The input terminal 2b is electrically connected to the signal output terminal 1b of the power supply unit 1. The output terminal 2c is connected to the input terminal 2b via an internal signal line 24 inside the housing 23.

[0022] 4. Wiring configuration As shown in Figure 1, in this embodiment, the signal output terminal 1b of the power supply unit 1 is connected via the signal cable 5 to only the input terminal 2b of one light irradiation unit 2(1), while the input terminals 2b of the other light irradiation units 2(2) to 2(4) are connected via the signal cable 5 to the output terminals 2c of other light irradiation units in a daisy-chain configuration starting from the one light irradiation unit 2(1).

[0023] For example, if the four light irradiation units shown in Figure 1 are designated as the first light irradiation unit 2(1) to the fourth light irradiation unit 2(4), then the input terminal 2b of the first light irradiation unit 2(1) is connected to the signal output terminal 1b of the power supply unit 1 via the signal cable 5. Furthermore, the input terminal 2b of the second light irradiation unit 2(2) is connected to the output terminal 2c of the first light irradiation unit 2(1), the input terminal 2b of the third light irradiation unit 2(3) is connected to the output terminal 2c of the second light irradiation unit 2(2), and the input terminal 2b of the fourth light irradiation unit 2(4) is connected to the output terminal 2c of the third light irradiation unit 2(3), all via the signal cable 5.

[0024] In this embodiment, a camera (imaging unit) 3 for imaging the workpiece is provided. This camera 3 is configured to receive the aforementioned pulse signal and to capture images of the workpiece W in synchronization with the light emission of each light irradiation device 2.

[0025] 5. Example of operation For example, in Figure 1, if the counts of each light irradiation unit 2 are set to 1, 2, 3, and 4 in a clockwise direction starting from the first light irradiation unit 2(1), then each light irradiation unit 2 will emit light (in this case, pulsed light emission) one after the other in a clockwise direction in synchronization with the pulse signal.

[0026] Furthermore, if the counts of each light irradiation unit 2 are set to 1, 2, 1, and 2 in a clockwise direction, then the first pulse signal will cause the two opposing light irradiation units 2(1) and 2(3) to emit light simultaneously, and the second pulse signal will cause the remaining two opposing light irradiation units 2(2) and 2(4) to emit light simultaneously. In addition, it is possible to make the emission interval of each light irradiation unit non-constant by, for example, setting the count of each light irradiation unit 2 to 1, 3, 4, and 7. The same can be achieved by generating the pulse signal at an irregular period instead of a fixed period.

[0027] 6. Effects With the above configuration, each light irradiation unit 2 is equipped with a control unit 22 that controls the current flowing to the light source 21, which makes it possible to accelerate light emission and increase brightness compared to controlling it on the power supply unit 1 side. Furthermore, since pulse signals are transmitted from the power supply unit 1 via a low-impedance signal cable 5, and the emission timing of each light irradiation unit 2 is controlled by this pulse signal, time differences and delays can be made very small, and the synchronization of light emission can be improved.

[0028] Furthermore, the power supply unit 1 only needs to transmit pulse signals, while the light irradiation unit 2 only needs to count the pulse signals and synchronize the light source 21 with the pulse signals at a predetermined count. This eliminates the need for complex calculations and virtually eliminates the delay caused by such calculations, thus promoting higher speed and improved synchronization.

[0029] Furthermore, since the light irradiation unit 2 is provided with an input terminal 2b and an output terminal 2c, and each light irradiation unit 2 is connected by a signal cable 5 in a daisy-chain configuration, the wiring can be streamlined, and the wiring work can be kept from becoming complicated even if the number of light irradiation units 2 increases.

[0030] However, the present invention is not limited to the embodiments described above. For example, signal cables may be wired from the power supply unit to each light irradiation unit. Furthermore, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from its spirit. [Explanation of symbols]

[0031] 100... Light irradiation system W...work 1. Power supply unit 11...Power supply circuit 12. Pulse generation circuit 1a... Power supply terminal 1b...Signal output terminal 2. Light irradiation unit 21...Light source 22.. Control Unit 2a... Power receiving terminal 2b... Input terminal 2c... Output terminal 4. Power Cables 5. Signal Cable

Claims

1. A light irradiation system comprising a plurality of light irradiation units that irradiate a workpiece with inspection light, and a power supply unit that supplies power to these light irradiation units and controls their light emission patterns, The aforementioned power supply unit is It comprises a power supply terminal, a power supply circuit that supplies power for light emission to each of the light irradiation units via the power supply terminal, a signal output terminal, and a pulse generation circuit that intermittently generates pulse signals and transmits the pulse signals to each of the light irradiation units via the signal output terminal. The aforementioned light irradiation unit is Light source and A power receiving terminal connected to the aforementioned power supply terminal via a power cable, An input terminal connected to the aforementioned signal output terminal via a signal cable, A light irradiation system characterized by comprising a control unit that counts pulse signals input from the input terminal and controls the current supplied to the light source from the power receiving terminal in synchronization with the pulse signals received at a predetermined count.

2. The light irradiation unit further comprises an output terminal connected to the input terminal, The signal output terminal of the power supply unit is connected via a signal cable to only one input terminal of the light irradiation unit. The light irradiation system according to claim 1, characterized in that the input terminals of other light irradiation units are connected to the output terminals of other light irradiation units in a daisy-chain configuration starting from the one light irradiation unit.

3. The light irradiation system according to claim 1 or 2, further comprising an imaging unit that receives the pulse signal and, in synchronization with the pulse signal, images a workpiece irradiated with inspection light.

Images