JP7466227B1 - Light source - Google Patents

Abstract

[Problem] To provide a light source device capable of accurately controlling the illuminance of light. [Solution] The device includes a CPU 50 capable of driving LEDs 34, 36, 38 and determining the illuminance of light emitted from the LEDs 34, 36, 38 based on the detection results of optical sensors 42G, 42G, 42B, and the CPU 50 creates a calibration value table prior to operation, sequentially causes the LEDs 34, 36, 38 of each color to emit light when creating the calibration value table, and determines calibration values for the LEDs 34, 36, 38 of each color based on the detection results of the optical sensors 42G, 42G, 42B during operation, when a drop in illuminance of a predetermined amount or more is detected based on the detection results of at least one optical sensor unit, calculates target values for driving the LEDs 34, 36, 38 based on the calibration values, and drives the LEDs 34, 36, 38 based on the target values. [Selected Figure] Figure 4

Description

The present invention relates to a light source device that can be used for product inspection, etc.

Patent Document 1 (see paragraph 0035, etc.) below discloses that in a display device, the light emission intensity of an LED chip is feedback-controlled for each emitted color using a control signal.

Japanese Patent No. 4753661

Incidentally, some light source devices that provide illumination for inspection generate inspection light by mixing light from multiple color light sources. Even for these types of light source devices, it is desirable to be able to accurately control the illuminance of the light.

Therefore, the present invention aims to provide a light source device that can accurately control the illuminance of light.

The light source device according to the present invention is characterized by:
A plurality of light source units that emit light of different colors;
A plurality of light sensor units provided to detect the illuminance of light of each color;
a control unit that drives the light source unit and determines the illuminance of the light emitted from the light source unit based on the detection result of the optical sensor unit;
The control unit is
A calibration table is created prior to operation.
When creating the calibration value table, the light source units for the respective colors are sequentially caused to emit light, and a calibration value for the light source unit for each color is defined based on a detection result of the optical sensor unit;
During operation, when a decrease in illuminance of a predetermined amount or more is detected based on a detection result of at least one of the optical sensor units,
Calculating a target value for driving the light source unit based on the calibration value;
Driving the light source unit based on the target value;
the optical sensor unit is also capable of detecting the illuminance of the light source unit of a color not associated with the optical sensor unit;
When creating the calibration value table, the control unit
The calibration value is defined based on the detection result of the optical sensor unit corresponding to the light source unit that has emitted light and the detection result of the optical sensor unit corresponding to the light source unit that has not emitted light .

The present invention provides a light source device that can accurately control the illuminance of light.

1 is a perspective view of a light source device according to an embodiment of the invention. FIG. FIG. 2 is a plan view illustrating a schematic internal configuration of a light source device. FIG. 2 is a block diagram illustrating a schematic configuration of a control circuit. 1 is a graph illustrating a concept of feedback control. 10 is a flowchart illustrating an example of a calibration process. 11 is a diagram showing an example of a calibration value table. FIG. 13 is an explanatory diagram illustrating a schematic diagram of a modified example relating to leakage light detection.

<First embodiment>
The light source device according to the first embodiment is
A plurality of light source units (such as R-LED 34, G-LED 36, and B-LED 38) that emit light of different colors (such as red, green, and blue),
A plurality of optical sensor units (optical sensors 42R, 42G, 42B, etc.) provided for detecting the illuminance of light of each color;
a control unit (such as a CPU 50) that drives the light source unit and is capable of determining the illuminance of the light emitted from the light source unit based on the detection result of the light sensor unit;
The control unit is
A calibration table is created prior to operation.
When creating the calibration value table, the light source units for the respective colors are sequentially caused to emit light, and a calibration value for the light source unit for each color is defined based on a detection result of the optical sensor unit;
During operation, when a decrease in illuminance of a predetermined amount or more (e.g., a decrease in illuminance of more than 3%) is detected based on the detection result of at least one of the optical sensor units,
Calculating a target value for driving the light source unit based on the calibration value;
The light source unit is driven based on the target value.

<Second embodiment>
The light source device of the second embodiment is the same as that of the first embodiment,
The optical sensor unit is also capable of detecting the illuminance of the light source unit of a color that is not associated with the optical sensor unit.

<Third embodiment>
The light source device of the third embodiment is the same as that of the second embodiment,
When creating the calibration value table, the control unit
The calibration value is determined based on the detection result of the optical sensor unit (such as optical sensor 42R) corresponding to the light source unit (such as R-LED 34) that emits light and the detection result of the optical sensor unit (such as optical sensor 42G) corresponding to the light source unit (such as G-LED 36) that does not emit light.

<Fourth embodiment>
The light source device of the fourth embodiment is the same as that of the third embodiment,
During the operation, a user can select one of a plurality of dimming values (such as “1023”, “1001”, …, “101”, “1”, “0”, etc.) for setting the illuminance of the light source unit;
The calibration value table is created by:
The light source unit is caused to emit light for each dimming value.

<<<<<Present Embodiment>>>>>
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this specification and the drawings, components with the same reference numerals have substantially the same structure or function.

<<<Outline of Light Source Device 100>>>
The light source device 100 can be used for industrial purposes such as product inspection. The light source device 100 emits inspection light, and the inspection light is irradiated onto an object to be inspected via a light guide using an optical fiber, for example. The light source device 100 illuminates the object to be inspected, allowing defects such as scratches on the object to be confirmed by image processing or visual inspection.

<<<Overall configuration of light source device 100>>>
The overall configuration of the light source device 100 will be described with reference to Figures 1 to 4. Figure 1 shows the light source device 100 as viewed obliquely from the front, and Figure 2 shows the light source device 100 as viewed from the rear. The X, Y and Z axes in Figure 1 are perpendicular to each other, and the X axis direction coincides with the width direction of the light source device 100. The Y axis direction coincides with the height direction of the light source device 100, and the Z axis direction coincides with the depth direction of the light source device 100.

The light source device 100 includes a housing 10 made of an aluminum alloy. The housing 10 is box-shaped and has a front surface, a back surface, a top surface, a bottom surface, a left side surface, and a right side surface. The housing 10 is constructed by combining multiple sheet metal parts, and houses various components of the light source device 100. The housing 10 has a structure that allows a portion of it to be removed to expose the inside of the light source device 100.

<<Front Configuration of Housing 10>>
The front portion 11 of the housing 10 is provided with a display unit 12, a contrast adjustment screw 13, an adapter for attaching a light guide 14, a power lamp 15, an error lamp 16, an operation knob 17, an ON/OFF button 18, a MENU button (hereinafter referred to as the “menu button”) 19, and a power switch 20.

The display unit 12 has a display screen such as liquid crystal, and displays the status of the light source device 100, a setting screen, an error display screen, etc. The contrast adjustment screw 13 is used to adjust the visibility of the screen of the display unit 12. The light guide attachment adapter 14 is used to attach the light guide 21 used in the examination.

The power lamp 15 lights up when the power supply of the light source device 100 is ON. The error lamp 16 lights up or blinks when an error occurs in the light source device 100. The operation knob 17 can detect rotation or pressing operations by the user. The ON/OFF button 18 is a button that is enabled during manual control, and is used to switch the test light on and off.

The menu button 19 is a button used to display a menu screen on the display unit 12. When the user presses the menu button 19 for a predetermined period of time (e.g., about 4 seconds) or more, the menu screen is displayed. If the menu button 19 is not operated for the predetermined period of time, an operation screen is displayed on the display unit 12.

<<Rear Configuration of Housing 10>>
The rear portion 22 of the housing 10 is provided with four general-purpose cooling fan exhaust holes 23, a monitor terminal block 24, an AC inlet 25, an insulator 26, a trigger input connector 27, a LAN connector 28, and a power supply cooling fan exhaust hole 29.

The general-purpose cooling fan exhaust hole 23 is used for exhausting the fan that exhausts heat inside the housing 10. The monitor terminal block 24 is used for connecting an external monitor device. The AC inlet 25 is used for connecting to an AC power source for power supply. The insulator 26 provides electrical insulation between the light source device 100 and the ground surface and provides anti-slip properties. The power supply cooling fan exhaust hole 29 is used for exhausting the fan that exhausts heat inside the housing 10, especially the power supply.

The trigger input connector 27 is used to connect a specified communication cable (here, RS-232C). The LAN connector 28 is used to connect an Ethernet cable.

<<Internal configuration of housing 10>>
As shown in FIG. 3, three light source units 30R, 30G, and 30B, two dichroic mirrors (a first dichroic mirror 32 and a second dichroic mirror 33), and the like are provided inside the housing 10.

Light source unit 30R is equipped with a red-emitting LED module (hereinafter referred to as "R-LED") 34. Light source unit 30G is equipped with a green-emitting LED module (hereinafter referred to as "G-LED") 36, and light source unit 30B is equipped with a blue-emitting LED module (hereinafter referred to as "B-LED") 38.

The light source units 30R, 30G, and 30B have lens units 40R, 40G, and 40B, and optical sensors 42R, 42G, and 42B, etc. The light source units 30R, 30G, and 30B are equipped with heat sinks (which may be heat pipes) 44R, 44G, and 44B, and other heat sinks.

Light source unit 30R emits red light 46R. Light source unit 30G emits green light 46G. Light source unit 30B emits blue light 46B. Light source units 30R, 30G, and 30B emit light 46R, 46G, and 46B in different directions.

Light 46R, 46G, 46B from light source units 30R, 30G, 30B is guided in the same direction by first dichroic mirror 32 and second dichroic mirror 33, where it overlaps and the three colors are mixed. Both the light before being mixed and the light after being mixed can be called "LED light" or "light source light". Both the light 46R, 46G, 46B before being mixed and the light after being mixed are "inspection light". Light of only one of the colors or light formed by mixing two colors may be used as the illumination light for inspection.

The first dichroic mirror 32 reflects the red light 46R and transmits the green light 46G and blue light 46B. The second dichroic mirror 33 reflects the blue light 46B and transmits the green light 46G. The mixed light passes through the exit lens system 47 and the exit section 48.

The exit section 48 is a space surrounded by the light guide attachment adapter 14. The light passing through the exit section 48 is guided to the outside of the housing 10 via the light guide 21 attached to the light guide attachment adapter 14.

The light source device 100 also includes a cooling fan 49 (Figure 2), a filter changer 80, and the like within the housing 10. An optical filter or a neutral density filter 90 can be attached to the filter changer 80. The filter changer 80 can rotate to position the optical filter or neutral density filter 90 in the path of the mixed light or outside the path. The filter changer 80, the optical filter, and the neutral density filter 90 will be described later.

<<Basic configuration of control circuit>>
4 shows a schematic configuration of a control circuit provided in the light source device 100. As described above, the light source device 100 is provided with the R-LED 34 for red, the G-LED 36 for green, and the B-LED 38 for blue. The R-LED 34, G-LED 36, and B-LED 38 are electrically connected in parallel.

Power is supplied to the R-LED 34, G-LED 36, and B-LED 38 from the power supply 52 under the control of the CPU 50. Constant current circuits 54R, 54G, and 54B are connected to the LEDs 34, 36, and 38 of each color.

Each constant current circuit 54R, 54G, 54B is provided with a DA converter (digital-analog converter) 56R, 56G, 56B, an operational amplifier 58R, 58G, 58B, a transistor 60R, 60G, 60B, a resistor 62R, 62G, 62B, and an AD converter (analog-digital converter) 64R, 64G, 64B, etc. In this embodiment, FETs (field effect transistors) are used as the transistors 60R, 60G, 60B.

Between the CPU 50 and each of the constant current circuits 54R, 54G, and 54B, an FPGA (Field-Programmable Gate Array) 66 is provided. In this embodiment, the FPGA 66 functions to relay signals from the CPU 50 to each of the constant current circuits 54R, 54G, and 54B. Although not shown in the figure, the control circuit also includes various storage means such as RAM and ROM, and an interface circuit used for inputting and outputting signals.

A signal indicating a digital value (DAC value) is input from the CPU 50 to the DA converters 56R, 56G, 56B of each constant current circuit 54R, 54G, 54B via the FPGA 66. This digital value (DAC value) is used to control the current flowing through the LEDs 34, 36, 38 of each color. Note that the FPGA 66 may be omitted, and a signal indicating a digital value (DAC value) may be input from the CPU 50 to the DA converters 56R, 56G, 56B without going through the FPGA 66.

DA converters 56R, 56G, 56B convert the digital value (DAC value) signal input from CPU 50 into an analog signal. The output signals of DA converters 56R, 56G, 56B are input to the positive feedback terminals (not shown) of operational amplifiers 58R, 58G, 58B. Although not shown, one terminal of resistors 62R, 62G, 62B is connected to the terminals (e.g., source terminals) of transistors 60R, 60G, 60B and the negative feedback terminals of operational amplifiers 58R, 58G, 58B.

Transistors 60R, 60G, and 60B perform switching operations based on signals input from operational amplifiers 58R, 58G, and 58B. As transistors 60R, 60G, and 60B switch, current flows through LEDs 34, 36, and 38.

The value of the current flowing through LEDs 34, 36, and 38 corresponds to the ratio of the voltage value of the output signal from DA converters 56R, 56G, and 56B to the resistance value of resistors 62R, 62G, and 62B. When current flows through LEDs 34, 36, and 38, LEDs 34, 36, and 38 emit light. The value of the current supplied to LEDs 34, 36, and 38 is input to CPU 50 via AD converters 64R, 64G, and 64B.

The illuminance of the light emitted from the LEDs 34, 36, and 38 is detected by the optical sensors 42R, 42G, and 42B. The optical sensors 42R, 42G, and 42B mainly detect the light from the LEDs (corresponding LEDs) 34, 36, and 38 that are arranged in close proximity. The detection results of the optical sensors 42R, 42G, and 42B are input to the CPU 50.

<<Dimming function>>
The light source device 100 of the present embodiment has a dimming function that allows a user to set the brightness of light of each color while checking the display unit 12 or via an external connection device (not shown) such as a computer device.

The digital value (DAC value) output from the CPU 50 to each constant current circuit 54R, 54G, 54B may differ for each color depending on the dimming value (LS) preset by the user, the target illuminance, etc. Dimming is performed for each color (each wavelength). The range in which dimming can be performed (dimming range) is 1024 steps from 0 to 1023 for each color.

The dimming status is represented by a dimming value (an integer between 0 and 1023). The dimming value can be displayed on the display unit 12. The dimming value is displayed for each color. The dimming value can be displayed as a number between 0 and 1023, or as a percentage.

When the dimming value is displayed as a percentage, a calculation is performed with 1023, which is the dimmable range according to the dimming value, as the denominator and the dimming value set by the user as the numerator. The dimming percentage is converted to a value in 1% increments, for example, and displayed on the display unit 12.

In addition, in the light source device 100 of this embodiment, in addition to 1024 levels of dimming (10-bit dimming), 256 levels (0 to 255) of dimming (8-bit dimming) are possible. The user can switch between these 1024 levels of dimming and 256 levels of dimming depending on the settings.

<<Dimming range switching function>>
The light source device 100 of the present embodiment has a dimming range switching function. The dimming range switching function switches the dimming mode between HIGH resolution (HIGH resolution mode) and LOW resolution (LOW resolution mode). The dimming mode can be switched by the user while checking the display unit 12 or via an external connection device (not shown) such as a computer device.

When switching the dimming range, the dimming range of the constant current circuits 54R, 54G, and 54B is set. When the dimming range is HIGH resolution, dimming is possible within a range of 0 to 100% of the maximum value (maximum light intensity), and when the dimming range is LOW resolution, dimming is possible within a range of 0 to 60% of the maximum value (maximum light intensity). With HIGH resolution, 100% of the maximum light intensity corresponds to the maximum dimming value, and with LOW resolution, 60% of the maximum light intensity corresponds to the maximum dimming value. However, the illuminance of the emitted light changes depending on the combination with the feedback (hereinafter referred to as "FB") function described below.

<<Overview of Facebook Function>>
The light source device 100 of this embodiment has an FB function. The FB function is a function for correcting aging deterioration (also called time deterioration, illuminance aging deterioration, illuminance aging deterioration, etc.) caused by the accumulation of the lighting time of the LEDs 34, 36, 38 by the FB control of the CPU 50. In the FB control, the output of the LEDs 34, 36, 38 of each color is corrected so that the received light amount (PDS) of the optical sensors 42R, 42G, 42B becomes a value according to the calibration value (TBL). The calibration value (TBL) will be described later. Here, the value of the "received light amount (PDS)" and the value of the "illuminance" are not strictly the same, but there is a relationship between the two that makes them proportional to each other and almost the same.

The graph in Figure 5 conceptually illustrates FB control. In Figure 5, the horizontal axis indicates the time during which the LED is stably emitting light (light emission time) using a logarithmic scale. The vertical axis indicates the relative intensity (unit: %) of the brightness of the light output by the LED. The relative intensity (%) is the ratio of the brightness at that time to the brightness (intensity) of the LED in the past, which serves as a reference time. An example of the reference time in the past is a timing when the cumulative light emission time of the LED was around 0 hours.

When FB control is not performed, as shown by curve A (dashed line) in Figure 5, the relative intensity gradually decreases as the LED stabilization time increases. In the example of Figure 5, the relative intensity (%) decreases gently until the LED stabilization time reaches about 30,000 hours. After that, the decrease in relative intensity (%) becomes more rapid than before.

In contrast, when feedback control is performed, the relative intensity gradually decreases even as the LED stabilization time increases, as shown by curve B (solid line) in Figure 5. In the example of Figure 5, the relative intensity (%) remains at 100% until the LED stabilization time reaches a predetermined time (30,000 hours in this case).

As mentioned above, Figure 5 shows only a concept of feedback control of illuminance, and even when feedback control is performed, the intensity at the start of use (when the cumulative light emission time is 0 hours) is not always guaranteed. However, by performing feedback control, the decrease in intensity can be kept within a specified amount (e.g. 3%).

The feedback control is executed when the decrease in relative intensity exceeds a predetermined amount (e.g., 3%). In the feedback control, the correction of the output of the corresponding LEDs 34, 36, 38 is repeated until the decrease in intensity reaches (returns to) within the predetermined amount (e.g., 3%). The correction of the output is stopped when the value calculated by the following formula (1) becomes 0.97 or more, which is a decrease of 3%.
Current light receiving amount (PDS)/calibration value (TBL) ... formula (1)

Of these, the denominator "current amount of received light (PDS)" is a value indicating the measurement result by the optical sensors 42R, 42G, and 42B at that time. The denominator "calibration value (TBL)" is the value of the amount of received light obtained during calibration of the light source device 100. For example, correction begins when the value calculated by formula (1) falls below 0.97, and correction stops when it returns to 0.97 or greater.

Calibration is performed after the user of the light source device 100 has attached peripheral devices such as the light guide 21 and prepared the installation environment (usage environment). Since the illuminance of the illumination light may change depending on the characteristics of the light guide 21 and other items actually used, calibration is performed for each user's installation environment.

Calibration is performed before the user operates the light source device 100 for a desired purpose such as inspection (before actual operation). As will be described in detail later, calibration is performed for each color. In calibration, after a waiting period until the illuminance stabilizes at the maximum dimming value, the dimming value is gradually reduced to obtain a calibration value.

Note that, below, the light source unit that emits light (here, the LED) can be referred to as the "light-emitting light source unit", and the light source unit that does not emit light can be referred to as the "non-light-emitting light source unit". Also, the light sensor unit associated with the light-emitting light source unit can be referred to as the "light sensor unit for the light-emitting light source unit", and the light sensor unit associated with the non-light-emitting light source unit can be referred to as the "light sensor unit for the non-light-emitting light source unit".

<<Calibration process>>
6 shows an outline of the calibration process (calibration process) performed by the light source device 100. The calibration process starts when the user operates the menu button 19 or the operation knob 17 in a predetermined procedure after turning on the power.

Specifically, prior to the calibration process in FIG. 6, the user operates the power switch 20 while pressing the menu button 19 (FIG. 1) to turn on the power. Although not shown, after the initial screen is displayed, when the user removes his or her finger from the menu button 19 and releases it, the light source device 100 starts up in the user maintenance mode.

In the user maintenance mode, a password entry screen is displayed on the display unit 12. The user operates the operation knob 17 to select numbers and inputs the defined number combination as a password. When the password has been entered and an input completion operation is performed, the display on the display unit 12 switches to a menu screen. The menu screen displays a calibration item, and when the operation knob 17 is pressed with the calibration item selected, the screen display transitions to the calibration screen.

When the operation knob 17 is pressed while the calibration screen is displayed, the calibration process shown in FIG. 6 is started. The calibration process is performed for each of the two resolution levels (HIGH/LOW). In the example of FIG. 6, the resolution is first set to HIGH (S (step) 11). Furthermore, the dimming value (LS) is set to 0 (zero) for each of the RGB colors (S12).

Next, it is determined whether calibration for R (red) has been completed (S13). If calibration has not been completed (if the determination result in S13 is NO), the R-LED 34 (Figures 3 and 4) is turned on (S14).

If the determination result in S13 above is YES, it is determined whether calibration of G-LED36 is complete (S15). If calibration is not complete (if S15 is NO), G-LED36 is turned on (S16). If the determination result in S15 is YES, B-LED38 is turned on (S17).

The LS (dimming value) for the lit LED (LEDs 34, 36, and 38 that are lit) is set to "1023" (S18), and the process of waiting for stable illuminance continues for a predetermined time (here, 10 minutes) (S19). The process of waiting for stable illuminance is a process for waiting for the illuminance of the lit LED to stabilize.

When the illuminance stabilization waiting process (S19) is completed, the illuminance measurement results at HIGH resolution for the lit LEDs are obtained and the measurement results are saved (stored) (S20). In the measurement of illuminance in S20, the measurement results are saved not only of the light sensor corresponding to the lit LED (e.g., light sensor 42R) but also of the light sensors corresponding to the unlit LEDs (e.g., light sensors 42G, 42B).

In measuring illuminance (S20), the light detected by the light sensor corresponding to the off LED is leakage light occurring inside the housing 10. The leakage light is light that leaks into the housing 10 from the lit LED (LED package) or the light source unit of that LED (light source units 30R, 30G, 30B). The path of the leakage light is unknown, but it is thought that some of the leakage light directly enters the light sensor, and some of it is reflected inside the housing 10 and enters the light sensors 42R, 42G, 42B.

For example, when only the R-LED 34 is on, the light from the R-LED 34 is detected as leak light by the optical sensor 42G corresponding to the unlit G-LED 36 and the optical sensor 42B corresponding to the B-LED 38. The optical sensors 42R, 42G, 42B for each color are disposed in positions suitable for detecting the LEDs 34, 36, 38 of the corresponding color (e.g., positions near the LEDs 34, 36, 38).

For this reason, optical sensors 42R, 42G, 42B detect the most light emitted from the LEDs 34, 36, 38 of the corresponding color. For example, when the R-LED 34 is lit, the measurement results by optical sensors 42G, 42B of non-corresponding colors (non-corresponding colors) are a few percent or less of the measurement results by optical sensor 42R of the corresponding color. This is also true for optical sensors 42R, 42B when G-LED 36 is lit, and for optical sensors 42R, 42G when B-LED 38 is lit.

As mentioned above, FB control is executed when the decrease in relative intensity exceeds a predetermined amount (e.g., 3%). For this reason, even if the measurement result decreases by, for example, 1%, it still accounts for a large proportion of the overall decrease in relative intensity. In other words, even if the measurement result value for a non-corresponding color is 1% of the overall relative intensity, this is equivalent to approximately 33% compared to the predetermined amount (3% in this case), which is the execution condition for FB control, and since this is a large proportion, it is important to take into account the measurement results for non-corresponding colors.

It is difficult to completely prevent the occurrence of leak light, and leak light can be detected without any special measures. However, it is also possible to adopt a structure suitable for detecting leak light, as shown in Figure 8, for example. Details of Figure 8 will be described later.

The measurement result saved in S20 (measurement and saving of illuminance) described above is the illuminance when LS (dimming value) is "1023" at HIGH resolution in the first stage of calibration. When the measurement result when LS = 1023 at HIGH resolution is obtained, the LED is turned off (S21), and the resolution is switched to LOW with LS = 1023 remaining (S22).

In the LOW resolution state, the LED to be measured is turned on based on the LS at that time (here, 1023) (S23). Then, for the turned-on LED, the illuminance measurement result at LOW resolution is obtained, and the measurement result is saved (stored) (S24).

In other words, in S24, immediately after the measurement result of LS=1023 at HIGH resolution is obtained in the illuminance measurement (S20), the measurement result of LS=1023 at LOW resolution for the R-LED34 is saved. After that, the LED is turned off (S25), and the resolution is switched to HIGH (S26).

It is determined whether LS has become "0" (S27), and if LS is not 0 (if S27 is NO), LS is changed to the next level value (S28). LS is changed in 13 levels for each color.

In this embodiment, LS is changed for 13 values out of the consecutive values from 0 to 1023: "0", "1", "101", "201", "301", "401", "501", "601", "701", "801", "901", "1001", and "1023" (S28). For each LS value, the processes of S20 to S28 are repeated, and measurement results are obtained in the order of HIGH resolution and LOW resolution.

After the illuminance is measured and stored at LS=1023 (S20, S24), LS is lowered by one step to LS=1001. Furthermore, for the same R-LED34, measurement results are obtained at LS=1001 in the order of HIGH resolution and LOW resolution (S20-S26), and then measurement results are obtained at LS=901 (S20-S26).

In this way, the LS is gradually decreased to "1023", "1001", "901", "801", "701", "601", etc., and similar processing is carried out (S20 to S26). When LS reaches "0" (YES in S27), it is determined whether processing for B-LED38 is complete (S29), and if not (NO in S29), processing proceeds to S13.

In S13, it is determined whether the processing for the R-LED34 has been completed as described above, and if it has not been completed (NO in S30), the R-LED34 is turned on (S14). Then, the processing from S18 onwards is executed.

If it is determined in S13 that the processing for R-LED34 is complete (YES in S13), it is determined whether or not the processing for G-LED36 is complete (S15), and if it is not complete (NO in S15), G-LED36 is turned on (S16). Then, the processing from S18 onwards is executed for G-LED36 in the same way as for R-LED34.

If it is determined in S15 that the process for G-LED36 is complete (YES in S15), B-LED38 is turned on (S17). Then, the process from S18 onwards is executed for B-LED38, just as in the case of R-LED34 and G-LED36.

In this way, the same process is repeated for R-LED34, G-LED36, and B-LED38 in that order. Then, when LS=0 is reached for B-LED38, a positive determination (YES determination) is made in S29, and the calibration ends.

<<Example of measurement results>>
The table in Fig. 7 shows an example of the measurement results obtained by calibration. The example in Fig. 7 shows the measurement results (received light amount (PDS)) of the optical sensors 42R, 42G, and 42B when the LEDs 34, 36, and 38 of each color are turned on as shown in the top row (head) of the table for each LS with the HIGH resolution and LOW resolution shown in the leftmost column (front side) of the table.

More specifically, in the columns to the right of HIGH resolution and LOW resolution, the LS values are shown from the top: "1023", "1001", "901", ..., "101", "1", "0". For each LS, the top of the table shows columns for "When R is lit", "When G is lit", and "When B is lit", and these columns are divided into "<R>PDS", "<G>PDS", and "<B>PDS".

Of these, "<R>PDS" indicates that it is the measurement result of the optical sensor 42R corresponding to the R-LED 34. "<G>PDS" indicates that it is the measurement result of the optical sensor 42G corresponding to the G-LED 36. "<B>PDS" indicates that it is the measurement result of the optical sensor 42B corresponding to the B-LED 38.

For example, in the "R on" column, for LS=1023 with HIGH resolution, the values of <R>PDS, <G>PDS, and <B>PDS are "53526," "651," and "420," respectively. These values indicate that when R-LED 34 is turned on with LS=1023 with HIGH resolution, the measurement result of the red optical sensor 42R is "53526," the measurement result of the green optical sensor 42G is "651," and the measurement result of the blue optical sensor 42B is "420."

Also, FIG. 7 shows that, for example, when the R-LED 34 is turned on with LS=1023 in LOW resolution, the measurement result of the red light sensor 42R is "32116", the measurement result of the green light sensor 42G is "391", and the measurement result of the blue light sensor 42B is "252".

Here, an example has been described in which the R-LED 34 is lit with LS=1023, but similar measurement results can be obtained by the optical sensors 42R, 42G, and 42B for each color when the R-LED 34 is lit with other LS. Similarly, similar measurement results can be obtained by the optical sensors 42R, 42G, and 42B for each color when the G-LED 36 and B-LED 38 are lit.

As mentioned above, the reason that a measurement result can be obtained even with an optical sensor corresponding to an LED that is not lit (unlit) is because leakage light is detected. For example, when the R-LED 34 is lit at LOW resolution, the measurement result of red optical sensor 42R for leakage light is "32116", while the measurement result of optical sensor 42G is "391", which is a percentage of approximately 1.2% (=391/32116). The measurement result of optical sensor 42B is "252", which is a percentage of approximately 0.7% (=252/32116).

<<Example of target value calculation>>
The calibration process shown in Fig. 6 is executed, and a table (calibration value table) as shown in Fig. 7 is created. The values (calibration values) defined in the calibration value table are the values of the measurement results in the calibration. The calibration values in LS where no measurement is performed will be described later.

When the light source device 100 is used by a user for testing, the calibration values are the target values for the LEDs 34, 36, and 38 of each color to emit light at the set dimming value. Based on the target values, digital values (DAC values) for driving the LEDs 34, 36, and 38 of each color are determined. As described above, these digital values (DAC values) are the magnitude of the signals supplied from the CPU 50 to the DA converters 56R, 56G, and 56B to control the current flowing through the LEDs 34, 36, and 38 of each color. If the measurement result does not reach the target range (here, within 3%), the current value flowing through the LEDs 34, 36, and 38 is automatically adjusted little by little (by a set amount).

The target values are calculated as follows. For example, assume that the settings made by the user are HIGH resolution and LS = 501 for R-LED 34, LS = 301 for G-LED 36, and LS = 701 for B-LED 38.

In this case, the target value used to drive the R-LED 34 is "33837". This target value is the sum (32716 + 843 + 278 = 33837) of the <R>PDS value when R is lit in the HIGH resolution LS=501 column of the calibration value table shown in Figure 7, the <R>PDS value when G is lit in the HIGH resolution LS=301 column, and the <R>PDS value when B is lit in the HIGH resolution LS=701 column. In Figure 7, the columns of values related to the calculation of the target value for the R-LED 34 are surrounded by solid line frames.

The target value used to drive G-LED36 is "24749" (=482+24112+155), which is the sum of "482", the <G>PDS value when R is lit in the LS=501 column of HIGH resolution, "24112", the <G>PDS value when G is lit in the LS=301 column of HIGH resolution, and "155", the <G>PDS value when B is lit in the LS=701 column of HIGH resolution. In Figure 7, the columns of values related to the calculation of the target value of G-LED36 are surrounded by double-lined frames.

The target value used to drive B-LED38 is "25278" (=286+1221+23771), which is the sum of "286", the <B>PDS value when R is lit in the LS=501 column of HIGH resolution, "1221", the <B>PDS value when G is lit in the LS=301 column of HIGH resolution, and "23771", the <B>PDS value when B is lit in the LS=701 column of HIGH resolution. In FIG. 7, the columns of values related to the calculation of the target value of B-LED38 are surrounded by dashed lines.

As in these examples, the target value used to drive an LED of a target color (target color to be turned on) at a given dimming value is determined using (1) a calibration value for the light sensor corresponding to the LED to be turned on (target light source to be turned on) and (2) a dimming value set for an LED other than the target light source (target light source to be turned on) and a calibration value for the light sensor of the target color to be turned on in the target light source to be turned on.

When the intended lighting color is red, the intended lighting light source is R-LED 34. The intended non-lighting light sources are G-LED 36 and B-LED 38. When LS=501 with HIGH resolution is set as the predetermined dimming value for red as in the above example, in regard to item (1) above, the calibration value for the light sensor 42R corresponding to the intended lighting light source is "32716".

Furthermore, with regard to item (2) above, the dimming values set corresponding to the non-illuminated target light sources G-LED36 and B-LED38 are LS=301 for G-LED36 and LS=701 for B-LED38 in the above example.

Also, with regard to item (2) above, the calibration values for the light sensor 42R of the lighting target color (here, red) for these non-lighting target light sources are "843" for G-LED 36 and "278" for B-LED 38. These values are then summed up to calculate the target value of "33837" (=32716+843+278) as mentioned above.

The same applies to the case of LOW resolution. For example, assume that the settings made by the user are LOW resolution, and LS = 1023 for R-LED 34, LS = 101 for G-LED 36, and LS = 1 for B-LED 38.

In this case, the target value used to drive the R-LED34 is "32352" (=32116 + 225 + 11), which is the sum of the <R>PDS value when R is lit in the LOW resolution LS=1023 column, "32116", the <R>PDS value when G is lit in the LOW resolution LS=101 column, "225", and the <R>PDS value when B is lit in the LOW resolution LS=1 column, "11".

The target value used to drive G-LED36 is "6903" (=391+6507+5), which is the sum of the <G>PDS value when R is lit in the LOW resolution LS=1023 column, which is "391", the <G>PDS value when B is lit in the LOW resolution LS=101 column, which is "6507", and the <G>PDS value when G is lit in the LOW resolution LS=1 column, which is "5".

Furthermore, the target value used to drive B-LED56 is "1576" (=252+309+1015), which is the sum of the <B>PDS value when R is lit in the LOW resolution LS=1023 column, which is "252", the <B>PDS value when G is lit in the LOW resolution LS=101 column, which is "309", and the <B>PDS value when B is lit in the LOW resolution LS=1 column, which is "1015".

<<Calibration value interpolation>>
In the calibration value table shown in Fig. 7, only 13 dimming values (13 gradations, 13 points) are specified: "0", "1", "101", "201", "301", "401", "501", "601", "701", "801", "901", "1001", and "1023". In the calibration, the amount of received light of RGB is acquired for each of the 13 points, and the actual measured values are stored only for the 13 points. These 13 points are hereinafter referred to as "actual measured points".

The dimming value can range from 0 to 1023. A calibration value is determined for each dimming value, but for dimming values other than those at the actual measurement points, the calibration value is calculated and stored by linear interpolation (also called linear interpolation or first-order interpolation) using the actual measurement values. The calibration value can be calculated using the following formula (2).
Y=Y1+[(Y2-Y1)/(X2-X1)]×(X-X1) ... formula (2)
X: Any dimming value X1: An actual measurement point that is smaller than X and closest to X X2: An actual measurement point that is larger than X and closest to X Y: Calculated calibration value Y1: Calibrated value of an actual measurement value that is smaller than Y and closest to Y Y2: Calibrated value of an actual measurement value that is larger than Y and closest to Y

For example, when the R-LED 34 is turned on with HIGH resolution, if the dimming value is "750", the calibration value can be calculated from the above formula (2) as follows:
Y = 42425 + [(46734 - 42425) / (801 - 701)] x (750 - 701)
= [4309/100] x 49 = 42425 + 2111.41
= 44536.41
≒44536

This calculation of the calibration value is the same for any calibration value related to the dimming value other than the other actual measurement points at HIGH resolution. The same is also true for the calibration value of leakage light. Furthermore, the same is also true for any dimming value other than the actual measurement points at LOW resolution.

<<Other matters related to feedback control>>
When the illuminance of the illumination light is reduced and feedback control is being performed (during feedback control), the LED (error LED) of the error lamp 16 performs an alert operation to the effect that feedback control is in progress. An example of the alert operation in this case is blinking at a predetermined time interval (such as 1 second). When feedback control is not possible, the error lamp 16 performs an alert operation to the effect that feedback control is not permitted. An example of the alert operation in this case is blinking at a predetermined time interval (such as 0.2 seconds).

An example of a time when FB control is not permitted is when the light source device 100 is operating in a pulsed lighting mode in which the LEDs to be emitted (all or some of the LEDs 34, 36, and 38) blink intermittently (here, periodically) (a state in which they are pulse-driven).

In other words, the light source device 100 has multiple lighting modes, including the above-mentioned pulse lighting mode and constant lighting mode. The constant lighting mode is a state in which the LED that emits light continues to be lit continuously (a state in which it is driven to be constantly lit).

In the light source device 100 of this embodiment, the FB function is enabled when the lighting mode is set to the constant lighting mode. Even when the lighting mode is set, it is possible to set whether the FB function is enabled or disabled (setting the FB function ON/OFF). The lighting mode and the FB function ON/OFF can be set by the user while checking the display unit 12 or via an externally connected device (not shown) such as a computer device. When the FB function is set to ON, an icon to that effect is displayed on the display unit 12.

<<Modifications Related to Detection of Leakage Light>>
Fig. 8 shows a schematic diagram of a configuration (a modified example of the example shown in Fig. 3) for enabling more efficient detection of leak light. In the example shown in Fig. 8, an LED (here, an R-LED 34 is used as an example) is housed in a light-shielding case 82. The light-shielding case 82 is formed by processing a material such as an aluminum alloy. A light detection hole 84 is formed in the wall of the light-shielding case 82 so as to pass through it.

This light detection hole 84 is, for example, a perfect circular opening with a diameter of 1 mm or less to several mm. The light-shielding case 82 is fitted with a lens unit 40R. Light from the R-LED 34 is emitted to the outside (here, the light source unit 30R) via the lens unit 40R.

A light sensor of the corresponding color (here, light sensor 42R) is disposed on the outside of the light-shielding case 82. The light sensor 42R is disposed so as to face the light detection hole 84. The light sensor 42R measures (detects) the illuminance of the light from the R-LED 34 installed inside the light-shielding case 82 in a state narrowed by the light detection hole 84. This type of light detection structure is also used for LEDs of other colors (here, G-LED 36, B-LED 38).

Part of the light from the R-LED 34 passes through the light detection hole 84 as leak light and travels inside the housing 10 (Figure 3). Although not shown, part of the light from the other G-LED 36 and B-LED 38 also travels inside the housing 10 (Figure 3) as leak light. The leak light from the G-LED 36 and B-LED 38 is detected by the light sensor 42R provided on the outside of each light-shielding case 82.

By adopting such a light detection structure, the light sensors 42R, 42G, 42B (herein referred to as "light sensors 42R, etc.") are able to more reliably detect leaked light of non-compatible colors. In addition, because the light sensors 42R, etc. are disposed outside the light-shielding case 82, the sensitivity of the light sensors 42R, etc. can be adjusted by the light-shielding case 82 and the light detection hole 84. Furthermore, because the light from the LEDs 34, 36, and 38 passes through the light detection hole 84, the amount of leaked light can be narrowed down and suppressed. Furthermore, by suppressing the amount of leaked light, deterioration over time (deterioration over time) of the light sensors 42R, etc. can be suppressed.

<<<<Advantages of the Invention According to This Embodiment>>>
As described above, according to the light source device 100 of this embodiment, the LEDs 34, 36, 38 of each color are sequentially illuminated prior to operation of the light source device 100, and calibration values for the LEDs 34, 36, 38 of each color are defined based on the detection results of the optical sensors 42R, 42G, 42B. Furthermore, when the light source device 100 is operated, if a decrease in illuminance of a predetermined amount or more is detected based on the detection results of at least one of the optical sensors 42R, 42G, 42B, target values for driving the LEDs 34, 36, 38 are calculated based on the calibration values, and the LEDs 34, 36, 38 are driven based on the target values.

Therefore, it is possible to accurately correct the illuminance based on the situation before operation. Furthermore, feedback control can be performed for each color, which allows for more precise feedback control than, for example, when feedback control is performed by detecting mixed color light.

Furthermore, according to the light source device 100, the optical sensors 42R, 42G, and 42B can also detect the illuminance of the LEDs 34, 36, and 38 of colors that are not associated with each other. Therefore, it is possible to more accurately correct the illuminance, including leakage light.

In addition, according to the light source device 100, when creating the calibration value table, the CPU 50 determines the calibration value based on the detection results of the optical sensors corresponding to the emitting LEDs and the detection results of the optical sensors corresponding to the non-emitting LEDs. Therefore, it is possible to perform more accurate correction of illuminance.

Furthermore, according to the light source device 100, during operation, the user can select one of multiple dimming values to specify the degree of illuminance of the LEDs 34, 36, and 38, and the calibration value table is created by making the LEDs 34, 36, and 38 emit light for each dimming value. Therefore, it is possible to correct the illuminance more accurately.

The number of light colors in the light source device 100 is not limited to three, but may be less than three or more than four.

<<<<Application of optical sensors 42R, 42G, and 42B>>>
<<Application Example 1>>
It is known that the optical sensors 42R, 42G, and 42B also deteriorate over time. For example, in the case of three colors, RGB, the optical sensor 42B provided for the B-LED 38 is the most susceptible to deterioration. For this reason, when comparing the three color optical sensors 42R, 42G, and 42B, the detection accuracy of the optical sensor 42B deteriorates the most quickly.

By utilizing this difference in the degree of deterioration, it is possible to identify optical sensors that have deteriorated relatively more. Specifically, the calibration values obtained during calibration are compared for each color with the measurement values of optical sensors 42R, 42G, and 42B during operation. When the measurement values have decreased compared to the calibration values, optical sensors whose degree of deterioration (e.g., the ratio to the calibration value) has reached a predetermined amount (e.g., several percent) or more are found.

Then, for example, the CPU 50 determines that the deterioration of the relevant optical sensor has progressed to a predetermined level or more, and displays, for example, on the display unit 12, that the optical sensor is more deteriorated than the other optical sensors. Furthermore, information to that effect can be output to an external device.

<<Application Example 2>>
As another application example, it is possible to provide a blue wavelength cut filter (long pass filter) in the optical system, which can suppress deterioration of the blue light sensor 42B.

<<Application Example 3>>
Another application example is providing an optical element using a blue-excited phosphor in an optical system. The blue-excited phosphor emits white light using a blue component as excitation light by yellow particles or a thin film, which is the complementary color of blue. When manufacturing the optical element, particles of the blue-excited phosphor are dispersed in a base material (transparent plate) or a thin film of the blue-excited phosphor is formed on the base material so that the blue component is not transmitted. An example of a blue-excited phosphor is Phoscera (registered trademark) by NTK Ceratec Co., Ltd.
<<Application Example 4>>
Another application example is to match the sensitivity with a camera used for inspection (inspection camera, not shown). For example, in an environment where the light source device 100 is used, an inspection camera is often used as a set. However, since the sensitivity of the optical sensors 42R, 42G, and 42B differs from the sensitivity of the camera, it may be necessary to take measures to deal with the difference in sensitivity.

For this reason, an optical filter (not shown) is added to the light source device 100 to change the sensitivity on the light source device 100 side. The optical filters are installed individually for the optical sensors 42R, 42G, 42B. The optical filters have characteristics that can eliminate the difference in sensitivity between the optical sensors 42R, 42G, 42B and the inspection camera. The difference in sensitivity between the optical sensors 42R, 42G, 42B and the inspection camera is confirmed in advance, and the confirmation results are used when selecting the optical filters.

<<Application Example 5>>
Also, a signal from an inspection camera or image information (e.g., average luminance value, etc.) acquired by the inspection camera can be input to the light source device 100. The signal from the inspection camera or image information acquired by the inspection camera is used in the light source device 100 to match the characteristics with the inspection camera. For example, a calibration sample is captured by the inspection camera to create a correction table. Calibration is not performed in real time but periodically (e.g., once a day).

Alternatively, as another method, during initial setup, an image of a calibration sample is captured in advance by an inspection camera. During subsequent calibrations, the percentage by which the output of the LEDs of each color was increased to make all colors the same brightness is saved (memorized), and the saved value is used as the correction value.

<<<<Details of this embodiment>>>>
As described above, the present invention has been described with reference to the present embodiment, but the description and drawings forming a part of this disclosure should not be understood as limiting the present invention. Thus, the present invention naturally includes various embodiments not described here.

10: Housing 21: Light guide 30R: Red light source unit 30G: Green light source unit 30B: Blue light source unit 32: First dichroic mirror 33: Second dichroic mirror 34: R-LED
36: G-LED
38: B-LED
42R: red light optical sensor 42G: green light optical sensor 42B: blue light optical sensor 46R: red light 46G: green light 46B: blue light 47: emission lens system 48: emission unit 50: CPU
100: Light source device

Claims (2)

A plurality of light source units that emit light of different colors;
A plurality of light sensor units provided to detect the illuminance of light of each color;
a control unit that drives the light source unit and determines the illuminance of the light emitted from the light source unit based on the detection result of the optical sensor unit;
The control unit is
A calibration table is created prior to operation.
When creating the calibration value table, the light source units for the respective colors are sequentially caused to emit light, and a calibration value for the light source unit for each color is defined based on a detection result of the optical sensor unit;
During operation, when a decrease in illuminance of a predetermined amount or more is detected based on a detection result of at least one of the optical sensor units,
Calculating a target value for driving the light source unit based on the calibration value;
Driving the light source unit based on the target value;
the optical sensor unit is also capable of detecting the illuminance of the light source unit of a color not associated with the optical sensor unit;
When creating the calibration value table, the control unit
A light source device that defines the calibration value based on a detection result of the optical sensor unit corresponding to the light source unit that has emitted light and a detection result of the optical sensor unit corresponding to the light source unit that has not emitted light . During the operation, a user can select one of a plurality of dimming values for setting the illuminance of the light source unit,
The calibration value table is created by:
The light source device according to claim 1 , wherein the light source unit is caused to emit light for each of the dimming values.