WO2017038675A1

WO2017038675A1 - Two-dimensional color measurement device and two-dimensional color measurement method

Info

Publication number: WO2017038675A1
Application number: PCT/JP2016/074958
Authority: WO
Inventors: 滋人大森
Original assignee: コニカミノルタ株式会社
Priority date: 2015-09-02
Filing date: 2016-08-26
Publication date: 2017-03-09
Also published as: JP6915539B2; JPWO2017038675A1

Abstract

A first optical sensor captures an image with a two-dimensional region in an object to be measured as the measurement range thereof. A second optical sensor outputs a signal indicating the brightness of a spot region included in the two-dimensional region. A second measurement unit measures the flicker period of the object to be measured using the second optical sensor. With the reciprocal of a frame rate as a frame time, a setting unit sets the frame rate at which a value obtained by multiplying the flicker period by an integer of 1 or more is defined as the frame time when an exposure time is longer than or equal to the flicker period, and sets the frame rate at which a value obtained by dividing the flicker period by an integer greater than 1 is defined as the frame time when the exposure time is shorter than the flicker period. A first measurement unit measures a characteristic relating to the color of the two-dimensional region using the first optical sensor under the set frame rate.

Description

Two-dimensional color measuring device and two-dimensional color measuring method

The present invention relates to a technique for measuring characteristics related to the color of a screen of a liquid crystal display, for example.

A two-dimensional colorimeter is a device that measures a surface, that is, a two-dimensional region. Two-dimensional colorimeters are applied in various industrial fields, and are used, for example, for measuring the chromaticity distribution of the screen of a liquid crystal display.

As a two-dimensional colorimeter, for example, Patent Document 1 discloses a beam splitter that divides light from a measurement object into two parts, an imaging unit that receives one of the two divided lights, and the other of the two divided lights. The tristimulus value is calculated using the spectroscopic sensor and the spectral distribution of the measurement point measured by the spectroscopic sensor, and the tristimulus value and the data of each pixel in the measurement region imaged by the imaging unit are used. A two-dimensional colorimeter including a calculation unit that calculates a tristimulus value of each pixel is disclosed.

The liquid crystal display is driven by alternating current because the life of the liquid crystal display is shortened when driven by direct current. In AC driving, the polarity is reversed for each frame. There are a line inversion driving method and a dot inversion driving method as AC driving methods for liquid crystal displays.

The line inversion driving method is a method of inverting the polarity of the pixel for each horizontal line. This method is often used for small liquid crystal displays. The dot inversion driving method is a method of inverting the polarity of pixels adjacent in the vertical direction and the polarity of pixels adjacent in the horizontal direction. This method is often used for large liquid crystal displays.

15 and 16 are explanatory diagrams for explaining the change of the polarity of the frame in a state where the same screen is continuously displayed on the liquid crystal display. Frames with positive polarity and frames with negative polarity appear alternately. As shown in FIG. 15, when the reference potential (Vcom) and the amplitude center of the waveform of the polarity change are equal, the absolute value of the level of the video signal is equal between the positive polarity frame and the negative polarity frame.

On the other hand, as shown in FIG. 16, when the reference potential and the amplitude center of the waveform of the polarity change are different, the absolute value of the video signal level is different between the positive polarity frame and the negative polarity frame. . In this case, the video signal changes at a half frequency of the frame frequency. For example, when the frame frequency is 60 Hz, the change frequency of the video signal is 30 Hz. Since 30 Hz is lower than the maximum frequency that the human eye can respond to, it is recognized as flicker (flickering of the screen). When flicker occurs, the screen becomes difficult to see. For this reason, the manufacturing process of the liquid crystal display includes a flicker inspection process.

As an apparatus capable of inspecting flicker, for example, Patent Document 2 generates a plurality of image data related to an image captured in step (a) and a step (a) of capturing an image displayed on a display device for a predetermined time. Step (b), step (c) for dividing each of the plurality of image data obtained in step (b) into a plurality of minute regions, and each of the divided minute regions for the predetermined A step (d) for obtaining a luminance change amount based on a luminance transition in time, and a step (e) for mapping the luminance change amount for a predetermined frequency in association with the image to generate mapping data. A luminance information processing method is disclosed.

As a result of the flicker inspection, the reference potential is adjusted for the liquid crystal display in which flicker occurs. It is difficult to adjust the reference potential so that the reference potential matches the amplitude center of the waveform of the polarity change, and an error inevitably occurs. For this reason, flicker can be reduced, but it is difficult to eliminate it completely.

However, even if the flicker can be reduced, if the flicker is generated, the measurement accuracy of the characteristics relating to the color of the liquid crystal display is lowered.

Japanese Patent No. 3246021 Japanese Patent Laid-Open No. 2003-254860

An object of the present invention is to provide a two-dimensional colorimetry apparatus and a two-dimensional colorimetry method that can reduce the influence of flicker in the measurement of color-related characteristics using an optical sensor having a two-dimensional region as a measurement range. And

A two-dimensional colorimetric apparatus according to a first aspect of the present invention that achieves the above object includes a first optical sensor, a second optical sensor, a first measurement unit, a second measurement unit, and a setting unit. Prepare. The first optical sensor captures an image of a two-dimensional region in the measurement target as a measurement range, and outputs a signal indicating the color of each pixel for the captured image of the two-dimensional region. The second optical sensor outputs a signal indicating the brightness of the spot region, with a spot region included in the two-dimensional region and narrower than the two-dimensional region as a measurement range. The first measurement unit measures characteristics regarding the color of the two-dimensional region using the first optical sensor under a predetermined exposure time and a predetermined frame rate. The second measurement unit uses the second optical sensor to measure a flicker cycle that is a cycle of flicker generated in the measurement target. The setting unit sets the frame rate with a frame time that is a value obtained by multiplying the flicker cycle by an integer of 1 or more when the reciprocal of the frame rate is a frame time and the exposure time is the flicker cycle or more; When the exposure time is shorter than the flicker cycle, the frame rate is set such that a value obtained by dividing the flicker cycle by an integer greater than 1 is the frame time. The first measuring unit measures characteristics relating to the color of the two-dimensional region under the frame rate set by the setting unit.

The above and other objects, features and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings.

It is a block diagram which shows the structure of the two-dimensional colorimetric apparatus which concerns on this embodiment. It is a schematic diagram which shows the structure of the light-receiving part which concerns on a 1st modification. It is a schematic diagram which shows the structure of the light-receiving part which concerns on a 2nd modification. It is explanatory drawing explaining the functional block of a control processing part. It is a graph which shows an example of the luminance signal output from the spot area | region colorimetric sensor. It is explanatory drawing explaining a series of processes for calculating | requiring Vmax and Vmin of a luminance signal using a contrast system. It is a flowchart explaining operation | movement of the two-dimensional colorimetric apparatus which concerns on this embodiment. It is a flowchart explaining operation | movement of the two-dimensional colorimetric apparatus which concerns on this embodiment. FIG. 6 is a schematic diagram showing a first example of the relationship between the exposure time, flicker cycle, and frame time when the initial value of the exposure time is equal to or greater than the flicker cycle. It is a schematic diagram showing a second example of the relationship between the exposure time, flicker cycle and frame time when the initial value of the exposure time is equal to or greater than the flicker cycle. It is a schematic diagram showing a third example of the relationship between the exposure time, flicker cycle and frame time when the initial value of the exposure time is equal to or greater than the flicker cycle. It is a schematic diagram showing a first example of the relationship between the exposure time, the flicker cycle, and the frame time when the initial value of the exposure time is smaller than the flicker cycle. It is a schematic diagram showing a second example of the relationship between the exposure time, flicker cycle and frame time when the initial value of the exposure time is smaller than the flicker cycle. In FIG. 13, it is a schematic diagram which shows the case where the phase of a frame is shifted. It is explanatory drawing explaining the change of the polarity of a flame | frame, when a reference potential and the amplitude center of the waveform of a polarity change are equal. It is explanatory drawing explaining the change of the polarity of a flame | frame, when a reference potential differs from the amplitude center of the waveform of a polarity change.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of a two-dimensional colorimetric apparatus 1 according to the present embodiment. The two-dimensional colorimetric device 1 is a two-dimensional colorimeter that measures a light source color, and includes a light receiving unit 2 and a main body unit 3.

The measurement object 4 of the two-dimensional colorimetric device 1 is a light emitter such as a liquid crystal display screen. A characteristic (for example, chromaticity) regarding the color of the measuring object 4 and the luminance of the measuring object 4 are measured by the two-dimensional colorimetric device 1.

The light receiving unit 2 includes an optical lens 5, a beam splitter 6, a two-dimensional area colorimetric sensor 7, and a spot area colorimetric sensor 8. In the present embodiment, the two-dimensional area colorimetric sensor 7 is a first optical sensor, and the spot area colorimetric sensor 8 is a second optical sensor.

The optical lens 5 focuses the light L from the measurement object 4. The beam splitter 6 (an example of a light splitting unit) splits the focused light L into two. More specifically, the beam splitter 6 transmits part of the focused light L and reflects the rest. The transmitted light is referred to as light L1, and the reflected light is referred to as light L2. The beam splitter 6 transmits, for example, 10 percent of the focused light L and reflects 90 percent.

A two-dimensional colorimetric sensor 7 is disposed in the optical path of the light L1. The two-dimensional area colorimetric sensor 7 includes a two-dimensional image sensor (not shown), and receives the light L1 to thereby detect a two-dimensional area (for example, the entire screen of the liquid crystal display or a part of the screen) in the measurement object 4. The light source color is imaged, and a signal indicating the color of each pixel is output for the captured image of the two-dimensional region. Each pixel refers to each pixel of the two-dimensional image sensor. In this embodiment, the X, Y, and Z signals in the XYZ color system are described as examples of signals indicating the color of each pixel. However, any signal indicating the color of each pixel may be used (for example, an R signal). , G signal, B signal). The Y signal is a luminance signal and indicates the luminance of each pixel of the image in the two-dimensional area. The two-dimensional image sensor is, for example, a CCD, and is an optical sensor having a two-dimensional region as a measurement range.

A spot area colorimetric sensor 8 is disposed in the optical path of the light L2. The spot area colorimetric sensor 8 uses a spot area (for example, one point in the entire screen of the liquid crystal display) included in the two-dimensional area of the measurement object 4 imaged by the two-dimensional area colorimetry sensor 7 as a measurement range. The spot area has an angle of view of, for example, 0.1 to 3 degrees and is narrower than the two-dimensional area.

The spot area colorimetric sensor 8 includes three photodiodes, and outputs X, Y, and Z signals of the XYZ color system indicating the light source color of the spot area by receiving the light L2. The Y signal is a luminance signal and indicates the luminance of the spot area.

There are a first modification and a second modification in the light receiving section. FIG. 2 is a schematic diagram illustrating a configuration of the light receiving unit 2a according to the first modification. The two-dimensional area colorimetric sensor 7 is disposed on the optical axis of the optical lens 5. The spot area colorimetric sensor 8 is disposed at a position where light L that has passed through the optical lens 5 can be received from a location other than the optical axis of the optical lens 5.

FIG. 3 is a schematic diagram showing a configuration of the light receiving unit 2b according to the second modification. The two-dimensional area colorimetric sensor 7 is disposed on the optical axis of the optical lens 5. The spot area colorimetric sensor 8 is disposed at a position where the component reflected by the light receiving surface 70 of the two-dimensional area colorimetric sensor 7 in the light L can be received. According to the first modification and the second modification, the light L from the measuring object 4 is supplied to the two-dimensional area colorimetric sensor 7 and the spot area colorimetric sensor 8 without providing the beam splitter 6 (FIG. 1). Light can be received.

Referring to FIG. 1, the main body unit 3 includes a control processing unit 9, an input unit 10, and an output unit 11.

The control processing unit 9 is a microcomputer realized by an AD conversion circuit, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), etc., and has functions as shown in FIG. As a block, a two-dimensional area luminance / chromaticity calculation unit 21, a spot area luminance / chromaticity calculation unit 22, a luminance calibration unit 23, a chromaticity calibration unit 24, a flicker measurement unit 25, and a setting unit 26 are provided. Details of these blocks will be described later.

The input unit 10 is a device for inputting commands (commands), data, and the like from the outside to the two-dimensional colorimetric device 1, and is, for example, a touch panel or a keyboard. Alternatively, the input unit 10 includes an interface unit (such as a USB terminal) for inputting commands, data, and the like set by an external controller (such as a personal computer) to the two-dimensional colorimetric device 1 according to the measurement object 4 and measurement conditions. The device used may be used. The output unit 11 is a device for outputting the command and data input from the input unit 10 and the calculation result of the control processing unit 9. For example, the output unit 11 is a display device such as an LCD (liquid crystal display) or an organic EL display. Or, for example, a printing apparatus such as a printer.

Referring to FIGS. 1 and 4, the two-dimensional area luminance / chromaticity calculation unit 21 (an example of a first measurement unit) is a two-dimensional area colorimetric sensor under a predetermined exposure time and a predetermined frame rate. The chromaticity of the two-dimensional region of the measuring object 4 is calculated using the X signal, Y signal, and Z signal output from 7. The spot area luminance / chromaticity calculation unit 22 (an example of a third measurement unit) calculates the chromaticity of the spot area using the X signal, the Y signal, and the Z signal output from the spot area colorimetric sensor 8. .

The brightness calibrating unit 23 uses the brightness of the spot area calculated by the spot area brightness / chromaticity calculation unit 22 for each pixel of the image of the two-dimensional area calculated by the 2D area brightness / chromaticity calculation unit 21. , Calibrate the brightness. Thereby, the brightness | luminance of a two-dimensional area | region can be measured with high precision.

The chromaticity calibration unit 24 (an example of a calibration unit) uses the chromaticity of the spot region calculated by the spot region luminance / chromaticity calculation unit 22 and uses the two-dimensional region luminance / chromaticity calculation unit 21 to calculate The chromaticity is calibrated for each pixel of the image in the dimension area. Thereby, the chromaticity of the two-dimensional region can be measured with higher accuracy. A process similar to this process is described in detail in Patent Document 1 described above.

The flicker measurement unit 25 (an example of a second measurement unit) measures flicker generated in the measurement target 4. Flicker is measured using a luminance signal (Y signal) output from the spot area colorimetric sensor 8. As a flicker measuring method, there are a contrast method and a JEITA (Japan Electronics and Information Technologies Association) method. The flicker measuring unit 25 measures flicker by the contrast method, but may measure flicker by the JEITA method.

FIG. 5 is a graph showing an example of the luminance signal output from the spot area colorimetric sensor 8. The horizontal axis represents time, and the vertical axis represents the luminance signal. The luminance signal can be seen as an AC component stacked on a DC component. The waveform of the luminance signal has a sine curve shape. When the maximum value of the luminance signal is Vmax and the minimum value is Vmin, Vmax and Vmin are alternately repeated.

The flicker value by the contrast method is defined by the following equation.
Flicker value = AC component / DC component = (Vmax−Vmin) / {(Vmax + Vmin) / 2} × 100

The flicker measuring unit 25 calculates an index value indicating the flicker cycle and the flicker size. The flicker cycle is a cycle of the luminance signal, and a value obtained by doubling these time intervals T1 between the adjacent Vmax and Vmin is the flicker cycle.

The index value indicating the flicker size is Vmax−Vmin. The flicker value may be used as an index value.

Thus, the flicker cycle and the index value are calculated based on Vmax and Vmin. The flicker measurement unit 25 obtains Vmax and Vmin as follows using a contrast method. FIG. 6 is an explanatory diagram for explaining a series of processes for obtaining these. The flicker measurement unit 25 uses a low-pass filter having frequency characteristics shown in (B) for the analog luminance signal output from the spot area colorimetric sensor 8 shown in (A), and is included in this luminance signal. Remove harmonic components. This low pass filter cuts frequencies greater than 60 Hz. (C) shows the luminance signal after the harmonic component is removed.

The flicker measuring unit 25 samples the luminance signal shown in (C) with a sampling period T2 as shown in (D) and converts the luminance signal from an analog signal to digital as shown in (E). Convert to signal. The sampling frequency is set higher than the frame rate when the characteristics relating to the color of the two-dimensional region are measured by the two-dimensional region colorimetric sensor 7. In (E), the sampling frequency and the sampling period T2 are set so that the black circles correspond to digital values and the digital values are several hundred.

Among the digital values in the sampling period T2, the maximum value is V1max and the minimum value is V1min. The flicker measurement unit 25 determines V1max and V1min, and calculates a time interval T1 between time t1 indicating V1max and time t2 indicating V1min.

The flicker measuring unit 25 processes the digital value of the sampling period T2 shown in (E) with a digital low-pass filter having frequency characteristics shown in (F). The frequency characteristics of this low-pass filter are the same as the frequency characteristics shown in (B). The flicker measuring section 25 attenuates the luminance signal by processing the luminance signal with a low-pass filter having the frequency characteristics shown in FIG. Therefore, the flicker measuring unit 25 restores attenuation by processing the digital value of the sampling period T2 shown in (E) with a low-pass filter having the frequency characteristics shown in (F).

V1max and V1min after processing by this low-pass filter are Vmax and Vmin, respectively.

As described above, the flicker measuring unit 25 samples the luminance signal output from the spot area colorimetric sensor 8 for a predetermined period, and among the values obtained by sampling, the maximum value Vmax and the minimum value Vmin are obtained. To decide. This means the maximum value and the minimum value determined by the contrast method, which is one of the flicker value calculation methods. Since the flicker value can be measured at high speed according to the contrast method, the flicker measuring unit 25 using the contrast method can improve the speed at which the flicker period is measured, and as a result, the two-dimensional colorimetric device 1. Accordingly, the time required for measuring the color characteristics of the two-dimensional region can be shortened.

The two-dimensional area colorimetric sensor 7 includes a two-dimensional image sensor such as a CCD, and measurement using the two-dimensional image sensor has a low frame rate. Accordingly, when flicker is measured using the two-dimensional area colorimetric sensor 7, the measurement time becomes long because the sampling frequency (= frame rate) is low. The flicker measurement unit 25 measures flicker using the spot area colorimetric sensor 8 that measures the brightness of the spot area. Therefore, the sampling frequency of the signal output from the spot area colorimetric sensor 8 (signal indicating the brightness of the spot area) is measured using the two-dimensional area colorimetric sensor 7 (measurement of characteristics relating to the color of the two-dimensional area). Since it can be higher than the frame rate, the time required for measuring the flicker period can be shortened. Therefore, in the two-dimensional colorimetric apparatus 1, the time required for measuring the color characteristics of the two-dimensional region can be shortened.

The setting unit 26 shown in FIG. 4 will be described. The reciprocal of the frame rate when the luminance and chromaticity of the measuring object 4 is measured by the two-dimensional area luminance / chromaticity calculator 21 is defined as a frame time. The setting unit 26 sets the flicker cycle when the exposure time when measuring the luminance and chromaticity of the measurement target 4 by the two-dimensional area luminance / chromaticity calculating unit 21 is equal to or longer than the flicker cycle calculated by the flicker measuring unit 25. A frame rate is set with a value obtained by multiplying an integer of 1 or more as a frame time. When the exposure time is shorter than the flicker cycle, a frame rate with a value obtained by dividing the flicker cycle by an integer greater than 1 is set.

The operation of the two-dimensional colorimetric apparatus 1 according to this embodiment will be described. 7 and 8 are flowcharts for explaining the operation. 4 and 7, the operator operates the input unit 10 (FIG. 1) to input the exposure time and the frame rate. Thus, the control processing unit 9 stores the input exposure time and frame rate as the initial value of the exposure time and the initial value of the frame rate (step S1). Note that the control processing unit 9 may calculate and store the initial value of the exposure time and the initial value of the frame rate based on the brightness around the measurement object 4.

When the operator inputs an instruction to start measurement by operating the input unit 10, the spot area colorimetric sensor 8 (an example of the second optical sensor) is used for the spot area of the measurement object 4 (for example, a screen of a liquid crystal display). Light from one point), and outputs an X signal, a Y signal, and a Z signal indicating the color of the spot area (step S2).

The flicker measuring unit 25 (an example of a second measuring unit) uses an Y signal (luminance signal) in step S2 to indicate an index value indicating the flicker size of the flicker generated in the measurement target 4, and A flicker cycle is calculated (step S3). The index value is a difference between the maximum value Vmax and the minimum value Vmin described in FIG.

The two-dimensional area luminance / chromaticity calculation unit 21 (an example of a first measurement unit) determines whether or not the index value calculated in step S3 exceeds a predetermined value (step S4).

When the two-dimensional area luminance / chromaticity calculation unit 21 determines that the index value is equal to or smaller than a predetermined value (No in step S4), that is, the size of the flicker generated in the measurement target 4 is the measurement target. In the case where the measurement of the luminance and chromaticity of the four two-dimensional area is not affected, the luminance and chromaticity of the two-dimensional area are measured by a normal method. More specifically, the two-dimensional area luminance / chromaticity calculation unit 21 uses the two-dimensional area colorimetric sensor 7 (first optical sensor) under the initial exposure time value and the initial frame rate value stored in step S1. The chromaticity of each pixel is calculated for the image of the two-dimensional region of the measurement object 4 using the X signal, the Y signal, and the Z signal output from the example), and the Y signal is used to calculate the chromaticity of the measurement object 4. For the image in the two-dimensional area, the luminance of each pixel is calculated (step S5).

The spot area luminance / chromaticity calculation unit 22 (an example of a third measurement unit) uses the X signal, the Y signal, and the Z signal output from the spot area colorimetric sensor 8 described in step S2 to calculate the spot area. The chromaticity is calculated, and the luminance of the spot area is calculated using the Y signal (luminance signal). The luminance calibration unit 23 calibrates the luminance calculated in step S5 for each pixel of the image of the two-dimensional region of the measurement target 4 using the luminance of the spot region (step S6). The chromaticity calibration unit 24 calibrates the chromaticity calculated in step S5 for each pixel of the image of the two-dimensional region of the measurement target 4 using the chromaticity of the spot region (step S6).

The output unit 11 displays the brightness and chromaticity calibrated in step S6 (step S7). Thereby, the operation of the two-dimensional colorimetric apparatus 1 is completed.

When the two-dimensional area luminance / chromaticity calculation unit 21 determines that the index value exceeds a predetermined value (Yes in step S4), that is, the size of the flicker generated in the measurement object 4 is If the measurement of the luminance and chromaticity of the two-dimensional area of the measuring object 4 is affected, the process proceeds to step S8. 4 and 8, in step S8, setting unit 26 determines whether or not the initial value of the exposure time stored in step S1 is equal to or greater than the flicker cycle measured in step S3.

When the setting unit 26 determines that the initial value of the exposure time is equal to or longer than the flicker cycle (Yes in step S8), the frame time is determined (step S9). The frame time is the reciprocal of the frame rate.

9, 10, and 11 are schematic diagrams illustrating a first example, a second example, and a third example of the relationship between the exposure time, the flicker cycle, and the frame time when the initial value of the exposure time is equal to or greater than the flicker cycle. It is. In these diagrams, the waveform of the graph indicates the waveform of the luminance signal, the horizontal axis of the graph indicates time, and the vertical axis of the graph indicates the value (voltage) of the luminance signal. The setting unit 26 determines a frame time that is a value obtained by multiplying the flicker cycle by an integer N1 of 1 or more. An example of this determination method will be described.

Referring to FIG. 9, when the initial value of the exposure time is a value obtained by multiplying the flicker cycle by an integer N1 of 1 or more, the setting unit 26 determines the initial value of the exposure time as the frame time. The integer N1 here is 3, for example.

Referring to FIG. 10 and FIG. 11, when the initial value of the exposure time is not a value obtained by multiplying the flicker cycle by an integer N1 of 1 or more, the setting unit 26 calculates a value obtained by adding the time d1 to the initial value of the exposure time. A time d1 that is a value obtained by multiplying the flicker cycle by an integer N1 of 1 or more is calculated, or a value obtained by subtracting the time d2 from the initial value of the exposure time is a value obtained by multiplying the flicker cycle by an integer of 1 or more. Time d2 is calculated. As the time d1, a value is selected so that the value obtained by adding the time d1 to the initial value of the exposure time does not cause excessive exposure. As the time d2, a value is set such that the value obtained by subtracting the time d2 from the initial value of the exposure time does not cause an underexposure.

The setting unit 26 is a value obtained by adding the calculated time d1 to the initial value of the exposure time as shown in FIG. 10, or a value obtained by subtracting the calculated time d2 from the initial value of the exposure time as shown in FIG. Is determined as a frame time.

The setting unit 26 sets a frame rate with the frame time determined in step S9 as the frame time (step S10). That is, the reciprocal of the frame time determined in step S9 is set as the frame rate.

The two-dimensional area luminance / chromaticity calculation unit 21 uses the frame time determined in step S9 as the exposure time, and the two-dimensional area colorimetric sensor 7 under the exposure time and the frame rate set in step S10. The chromaticity of each pixel is calculated for the image of the two-dimensional region of the measurement target 4 using the X signal, Y signal, and Z signal output from the signal, and the two-dimensional region of the measurement target 4 is calculated using the Y signal. For each of the images, the luminance of each pixel is calculated (step S11).

The spot area luminance / chromaticity calculation unit 22 calculates the chromaticity of the spot area using the X signal, Y signal, and Z signal output from the spot area colorimetric sensor 8 described in step S2, and generates a Y signal ( The brightness of the spot area is calculated using the brightness signal. The luminance calibration unit 23 calibrates the luminance calculated in step S11 for each pixel of the image of the two-dimensional region of the measurement target 4 using the luminance of the spot region (step S12). The chromaticity calibration unit 24 calibrates the chromaticity calculated in step S11 for each pixel of the image of the two-dimensional region of the measurement target 4 using the chromaticity of the spot region (step S12). Then, the process proceeds to step S7.

When the setting unit 26 determines that the initial value of the exposure time is smaller than the flicker cycle (No in step S8), the frame time is determined (step S13).

12 and 13 are schematic diagrams showing a first example and a second example of the relationship between the exposure time, flicker cycle, and frame time when the initial value of the exposure time is smaller than the flicker cycle. In these diagrams, the waveform of the graph indicates the waveform of the luminance signal, the horizontal axis of the graph indicates time, and the vertical axis of the graph indicates the value (voltage) of the luminance signal. The setting unit 26 determines a frame time that is a value obtained by dividing the flicker cycle by an integer N2 greater than 1. An example of this determination method will be described.

The setting unit 26 determines, as the frame time, a value obtained by dividing the flicker cycle by an integer N2 greater than 1 among the frame times equal to or greater than the initial value of the exposure time. A value that does not cause underexposure is selected for N2. Here, N2 is described as 3, for example.

FIG. 12 shows a case where the frame time determined by the setting unit 26 matches the initial value of the exposure time, and FIG. 13 shows a case where the frame time determined by the setting unit 26 becomes larger than the initial value of the exposure time. Yes.

The setting unit 26 sets a frame rate with the frame time determined in step S13 as the frame time (step S14). That is, the reciprocal of the frame time determined in step S13 is set as the frame rate.

The two-dimensional area luminance / chromaticity calculation unit 21 uses the initial value of the exposure time stored in step S1 as the exposure time, and measures the two-dimensional area under the exposure time and the frame rate set in step S14. Using the X signal, Y signal, and Z signal output from the color sensor 7, the chromaticity of each pixel is calculated for the image of the two-dimensional region of the measurement object 4, and the Y signal is used to calculate the chromaticity of the measurement object 4. For the image of the two-dimensional area, the luminance of each pixel is calculated (step S15).

The two-dimensional area luminance / chromaticity calculation unit 21 determines whether the frame time determined in step S13 is greater than or coincides with the exposure time (initial value of the exposure time) in step S15 (step S16). . When the two-dimensional area luminance / chromaticity calculation unit 21 determines that the frame time and the exposure time match as shown in FIG. 12 (No in step S16), the process proceeds to step S17.

The spot area luminance / chromaticity calculation unit 22 calculates the chromaticity of the spot area using the X signal, Y signal, and Z signal output from the spot area colorimetric sensor 8 described in step S2, and generates a Y signal ( The brightness of the spot area is calculated using the brightness signal. The luminance calibration unit 23 calibrates the luminance calculated in step S15 for each pixel of the image of the two-dimensional region of the measurement target 4 using the luminance of the spot region (step S17). The chromaticity calibration unit 24 calibrates the chromaticity calculated in step S15 for each pixel of the image of the two-dimensional region of the measurement target 4 using the chromaticity of the spot region (step S17). Then, the process proceeds to step S7.

When the two-dimensional area luminance / chromaticity calculation unit 21 determines that the frame time is longer than the exposure time as shown in FIG. 13 (Yes in step S16), the process proceeds to step S18. As shown in FIG. 14, the two-dimensional area luminance / chromaticity calculation unit 21 shifts the phase of the frame by a value D obtained by subtracting the exposure time (initial value of the exposure time) from the frame time, and the exposure time in step S15. Using the X signal, Y signal, and Z signal output from the two-dimensional area colorimetric sensor 7 under the conditions of (exposure time initial value) and frame rate, The chromaticity of each pixel is calculated, and the luminance of each pixel is calculated for the image of the two-dimensional region of the measuring object 4 using the Y signal (step S18).

The two-dimensional area luminance / chromaticity calculation unit 21 calculates a value obtained by averaging the luminance calculated in step S15 and the luminance calculated in step S18 for each pixel of the image in the two-dimensional area. The luminance of each pixel of the image is set (step S19). The two-dimensional area luminance / chromaticity calculation unit 21 calculates a value obtained by averaging the chromaticity calculated in step S15 and the chromaticity calculated in step S18 for each pixel of the image in the two-dimensional area. The chromaticity of each pixel of the image of the dimension area is set (step S19).

The spot area luminance / chromaticity calculation unit 22 calculates the chromaticity of the spot area using the X signal, Y signal, and Z signal output from the spot area colorimetric sensor 8 described in step S2, and generates a Y signal ( The brightness of the spot area is calculated using the brightness signal. The luminance calibration unit 23 calibrates the luminance calculated in step S19 for each pixel of the image of the two-dimensional region of the measurement target 4 using the luminance of the spot region (step S20). The chromaticity calibration unit 24 calibrates the chromaticity calculated in step S19 for each pixel of the image of the two-dimensional region of the measurement target 4 using the chromaticity of the spot region (step S20). Then, the process proceeds to step S7.

When obtaining uniformity, after step S6, step S12, step S17, and step S20, the two-dimensional region luminance / chromaticity calculation unit 21 sets the screen size (for example, 2380 × 1200) of the measurement target 4 to, for example, , 7 × 5, and the uniformity is calculated.

The main effect of this embodiment will be described. The two-dimensional colorimetric apparatus 1 according to the present embodiment focuses on the case where the exposure time is longer than the flicker cycle (Yes in step S8) and the case where the exposure time is shorter than the flicker cycle (No in step S8). In the former case, the setting unit 26 sets a frame rate in which a value obtained by multiplying the flicker cycle by an integer of 1 or more is set as a frame time (step S9, FIG. 9 to FIG. 11). A frame rate is set in which a value obtained by dividing by a large integer is set as a frame time (step S13, FIG. 12, FIG. 13). If such a relationship is established between the frame time and the flicker cycle, the influence of flicker can be reduced. Therefore, according to the two-dimensional colorimetric apparatus 1 according to the present embodiment, the influence of flicker in the measurement of the color-related characteristics using the optical sensor (two-dimensional region colorimetric sensor 7) having the two-dimensional region as the measurement range. Can be reduced.

Further, according to the present embodiment, as shown in FIG. 13, when the initial value of the exposure time is shorter than the flicker cycle and shorter than the frame time at the frame rate set by the setting unit 26 (No in step S8). In step S16, the first measurement value is calculated by measuring the color characteristics of the two-dimensional area under the conditions of the initial value of the exposure time and the frame rate set by the setting unit 26 (step S15). ), The phase of the frame is shifted by a value D obtained by subtracting the exposure time from the frame time, and the color characteristics of the two-dimensional region are measured under the same conditions as described above to obtain the second A measurement value is calculated (step S18), and a value obtained by averaging the first measurement value and the second measurement value is calculated (step S19).

When the initial value of the exposure time is shorter than the flicker cycle and shorter than the frame time at the frame rate set by the setting unit 26 (No in step S8, Yes in step S16), only part of the flicker cycle is exposed. This is not done (FIG. 13), and the influence of flicker cannot be canceled only by the measured value (that is, the first measured value) at this time. Therefore, according to the present embodiment, the two-dimensional area luminance / chromaticity calculation unit 21 shifts the phase of the frame by a value D obtained by subtracting the exposure time from the frame time, as shown in FIG. Under the exposure time and frame rate when the value was obtained, the color characteristic of the measurement object 4 was measured to calculate the second measurement value, and the first measurement value and the second measurement value were averaged. Calculate the value. Thereby, luminance fluctuations within the frame time are canceled out, and the influence of flicker can be canceled.

As shown in FIG. 4, the two-dimensional colorimetric apparatus 1 according to the present embodiment includes the luminance calibration unit 23 and the chromaticity calibration unit 24, but may be configured without these components. In this aspect, instead of the spot area colorimetric sensor 8, an optical sensor (luminance sensor) capable of measuring the brightness of the spot area is provided.

(Summary of embodiment)
The two-dimensional colorimetric apparatus according to the first aspect of the present embodiment images a two-dimensional region in a measurement target as a measurement range, and outputs a signal indicating the color of each pixel for the imaged two-dimensional region. A first optical sensor, a second optical sensor that is included in the two-dimensional region and has a spot region narrower than the two-dimensional region as a measurement range, and outputs a signal indicating the luminance of the spot region; Under an exposure time and a predetermined frame rate, using the first optical sensor, a first measurement unit that measures characteristics related to the color of the two-dimensional region, and using the second optical sensor, A second measurement unit that measures a flicker period that is a flicker period generated in a measurement target; and a reciprocal of the frame rate as a frame time, and the exposure time is equal to or greater than the flicker period, When the frame rate is set to a value obtained by multiplying 1 by an integer of 1 or more and the exposure time is shorter than the flicker cycle, a value obtained by dividing the flicker cycle by an integer greater than 1 is set as the frame time. A setting unit configured to set the frame rate, and the first measurement unit measures characteristics relating to the color of the two-dimensional region under the frame rate set by the setting unit.

The two-dimensional colorimetric apparatus according to the first aspect of the present embodiment focuses on the case where the exposure time is longer than the flicker cycle and the case where the exposure time is shorter than the flicker cycle. In the former case, the setting unit sets a frame rate in which a value obtained by multiplying the flicker cycle by an integer of 1 or more is used as a frame time. In the latter case, a value obtained by dividing the flicker cycle by an integer greater than 1 is used as the frame time. Set the frame rate. If such a relationship is established between the frame time and the flicker cycle, the influence of flicker can be reduced. Therefore, according to the two-dimensional colorimetric apparatus according to the first aspect of the present embodiment, the influence of flicker can be reduced in the measurement of the color-related characteristics using the optical sensor having the two-dimensional region as the measurement range. Each pixel refers to each pixel of the first optical sensor.

In the above configuration, the second measurement unit uses the second optical sensor to measure an index value indicating the size of flicker generated in the measurement target, and the first measurement unit includes the index value. If the value exceeds a predetermined value, a characteristic relating to the color of the two-dimensional area is measured under the frame rate set by the setting unit, and the index value is not more than a predetermined value. For example, the characteristics relating to the color of the two-dimensional region are measured under the frame rate determined in advance before the frame rate is set by the setting unit.

When the first measurement unit determines that the index value exceeds a predetermined value, that is, the flicker size generated in the measurement target is a characteristic measurement related to the color of the two-dimensional area of the measurement target. In the case of affecting the color, the characteristics relating to the color of the two-dimensional area are measured under the frame rate set by the setting unit. On the other hand, when the first measurement unit determines that the index value is equal to or smaller than a predetermined value, that is, the size of the flicker generated in the measurement object relates to the color of the two-dimensional area of the measurement object. When the measurement of the characteristics is not affected, the characteristics regarding the color of the two-dimensional area are measured at a predetermined frame rate. That is, the characteristics relating to the color of the two-dimensional region are measured by a normal method.

In the above configuration, the second measurement unit samples the signal indicating the brightness of the spot region output from the second optical sensor for a predetermined period, and outputs the maximum value from the values obtained by sampling. A value and a minimum value are determined, and twice the difference between the time indicating the maximum value and the time indicating the minimum value is set as the flicker cycle.

The second measurement unit samples a signal (a signal indicating the brightness of the spot area) output from the second optical sensor for a predetermined period, and calculates a maximum value and a minimum value from the values obtained by sampling. To decide. This means the maximum value and the minimum value determined by the contrast method, which is one of the flicker value calculation methods. According to the contrast method, the flicker value can be measured at high speed. Therefore, according to this configuration using the contrast method, the speed of measuring the flicker period can be improved, and as a result, the color characteristics of the two-dimensional region can be improved. The time required for measurement can be shortened.

In the above configuration, the second measurement unit samples a signal indicating the brightness of the spot area output from the second optical sensor at a sampling frequency higher than the frame rate.

The two-dimensional area colorimetric sensor includes a two-dimensional image sensor such as a CCD, and measurement using the two-dimensional image sensor has a low frame rate. Accordingly, when flicker is measured using a two-dimensional area colorimetric sensor, the sampling time (= frame rate) is low, so that the measurement time becomes long. According to this configuration, flicker is measured using the second optical sensor that measures the brightness of the spot area. Therefore, the frame rate of the measurement (measurement of the characteristics relating to the color of the two-dimensional area) using the sampling frequency of the signal (signal indicating the brightness of the spot area) output from the second optical sensor using the two-dimensional area colorimetric sensor. Since it can be made higher, the time required for measuring the flicker cycle can be shortened, and as a result, the time required for measuring the color characteristics of the two-dimensional region can be shortened.

In the above configuration, when the exposure time is shorter than the flicker cycle and shorter than the frame time at the frame rate set by the setting unit, the first measurement unit is configured to set the exposure time and the setting unit. The first measurement value is calculated by measuring the color characteristics of the two-dimensional region under the condition of the frame rate set by the step, and the phase of the frame is obtained by subtracting the exposure time from the frame time. The second measured value is calculated by measuring the color characteristics of the two-dimensional region under the above conditions, and the average value of the first measured value and the second measured value is calculated. To do.

When the exposure time is shorter than the flicker cycle and shorter than the frame time at the frame rate set by the setting unit, only a part of the flicker cycle is exposed, and the measured value at this time (that is, the first value) The flicker effect cannot be canceled only by the measured value. Therefore, according to this configuration, the first measurement unit shifts the phase of the frame by a value obtained by subtracting the exposure time from the frame time, and under the exposure time and the frame rate when the first measurement value is obtained. Then, the characteristics of the color to be measured are measured to calculate the second measurement value, and the average value of the first measurement value and the second measurement value is calculated. Thereby, luminance fluctuations within the frame time are canceled out, and the influence of flicker can be canceled.

In the above configuration, the second optical sensor outputs three signals indicating the tristimulus values of the spot region, and one of the three signals is a signal indicating the luminance of the spot region, Measured by the first measuring unit using the third measuring unit that measures the color-related characteristics of the spot region using the optical sensor of No. 2 and the value measured by the third measuring unit. A calibrating unit that calibrates the characteristic value relating to the color of each pixel in the two-dimensional region;

According to this configuration, the characteristics relating to the color of the two-dimensional region can be measured with higher accuracy.

In the above-described configuration, a light splitting unit that splits the light from the measurement target into two parts is further provided, and the first optical sensor is disposed in the optical path of the one split light, and the second optical sensor The sensor is arranged in the optical path of the other divided light.

According to this configuration, light from the measurement target can be sent to the first optical sensor and the second optical sensor using the light splitting unit.

The two-dimensional colorimetric method according to the second aspect of the present embodiment images a two-dimensional region in a measurement target as a measurement range, and outputs a signal indicating the color of each pixel for the captured image of the two-dimensional region. A first optical sensor, and a second optical sensor that outputs a signal that indicates a brightness of the spot area, with a spot area that is included in the two-dimensional area and narrower than the two-dimensional area as a measurement range. A color measurement method using a two-dimensional color measurement device, wherein a first color sensor is used to measure a color-related characteristic of the two-dimensional region using the first optical sensor under a predetermined exposure time and a predetermined frame rate. A second step of measuring a flicker period, which is a flicker period generated in the measurement object, using the second optical sensor, and a reciprocal of the frame rate as a frame time. When the exposure time is equal to or longer than the flicker cycle, the frame rate is set to a value obtained by multiplying the flicker cycle by an integer equal to or greater than 1. When the exposure time is shorter than the flicker cycle, the flicker cycle is set to 1 A third step of setting the frame rate with the frame time being a value divided by a larger integer, wherein the first step is under the frame rate set by the third step. , Measuring the color-related characteristics of the two-dimensional region.

The two-dimensional color measurement method according to the second aspect of the present embodiment can reduce the influence of flicker for the same reason as the two-dimensional color measurement device according to the first aspect of the present embodiment.

This application is based on Japanese Patent Application No. 2015-172696 filed on September 2, 2015, the contents of which are included in this application.

In order to express the present invention, the present invention has been properly and fully described through the embodiments with reference to the drawings. However, those skilled in the art can easily change and / or improve the above-described embodiments. It should be recognized that this is possible. Therefore, unless the modifications or improvements implemented by those skilled in the art are at a level that departs from the scope of the claims recited in the claims, the modifications or improvements are not covered by the claims. To be construed as inclusive.

According to the present invention, a two-dimensional color measurement device and a two-dimensional color measurement method can be provided.

Claims

A first optical sensor that captures an image of a two-dimensional region in a measurement object as a measurement range, and outputs a signal indicating the color of each pixel for the captured image of the two-dimensional region;
A second optical sensor that is included in the two-dimensional area and has a spot area narrower than the two-dimensional area as a measurement range, and outputs a signal indicating the luminance of the spot area;
A first measurement unit that measures a color-related characteristic of the two-dimensional region using the first optical sensor under a predetermined exposure time and a predetermined frame rate;
A second measurement unit that measures a flicker period, which is a flicker period generated in the measurement object, using the second optical sensor;
The reciprocal of the frame rate is set as a frame time, and when the exposure time is equal to or longer than the flicker cycle, the frame rate is set as a frame time obtained by multiplying the flicker cycle by an integer of 1 or more, and the exposure time is A setting unit that sets the frame rate with the frame time being a value obtained by dividing the flicker period by an integer greater than 1 when the flicker period is shorter than the flicker period,
The first measurement unit is a two-dimensional colorimetry device that measures characteristics relating to colors of the two-dimensional region under the frame rate set by the setting unit.
The second measurement unit uses the second optical sensor to measure an index value indicating the size of flicker generated in the measurement target,
The first measurement unit, when the index value exceeds a predetermined value, measures a characteristic regarding the color of the two-dimensional region under the frame rate set by the setting unit, If the index value is equal to or less than a predetermined value, the characteristic relating to the color of the two-dimensional region is measured under the frame rate that is set in advance before the frame rate is set by the setting unit. Item 2. The two-dimensional colorimetric apparatus according to item 1.
The second measurement unit samples a signal indicating the brightness of the spot area output from the second optical sensor for a predetermined period, and the maximum value and the minimum value among the values obtained by sampling. The two-dimensional colorimetric apparatus according to claim 1, wherein the flicker cycle is twice the difference between the time indicating the maximum value and the time indicating the minimum value.
4. The two-dimensional colorimetric apparatus according to claim 3, wherein the second measurement unit samples a signal indicating the brightness of the spot region output from the second optical sensor at a sampling frequency higher than the frame rate. .
The first measurement unit is set by the exposure time and the setting unit when the exposure time is shorter than the flicker cycle and shorter than the frame time at the frame rate set by the setting unit. Under the condition of the frame rate, the color characteristic of the two-dimensional region is measured to calculate a first measurement value, the phase of the frame is shifted by a value obtained by subtracting the exposure time from the frame time, 2. A second measurement value is calculated by measuring a color characteristic of the two-dimensional region under a condition, and an average value of the first measurement value and the second measurement value is calculated. The two-dimensional colorimetric apparatus according to any one of 1 to 4.
The second optical sensor outputs three signals indicating tristimulus values of the spot area,
One of the three signals is a signal indicating the brightness of the spot area,
Using the second optical sensor, a third measurement unit that measures the characteristics of the spot area color;
A calibration unit that calibrates the value of the characteristic relating to the color of each pixel of the two-dimensional region measured by the first measurement unit using the value measured by the third measurement unit. The two-dimensional colorimetric apparatus according to any one of 1 to 5.
A light splitting unit that splits the light from the measurement object into two parts;
The first optical sensor is disposed in the optical path of the one of the two divided lights,
The two-dimensional colorimetric apparatus according to any one of claims 1 to 6, wherein the second optical sensor is disposed in an optical path of the other light divided into two.
A first optical sensor that outputs a signal indicating the color of each pixel for the image of the two-dimensional region that has been imaged as a measurement range, and is included in the two-dimensional region, and A colorimetric method using a two-dimensional colorimetric device comprising: a spot region narrower than the two-dimensional region as a measurement range; and a second optical sensor that outputs a signal indicating the luminance of the spot region,
A first step of measuring a color-related characteristic of the two-dimensional region using the first optical sensor under a predetermined exposure time and a predetermined frame rate;
A second step of measuring a flicker period, which is a flicker period generated in the measurement object, using the second optical sensor;
The reciprocal of the frame rate is set as a frame time, and when the exposure time is equal to or longer than the flicker cycle, the frame rate is set as a frame time obtained by multiplying the flicker cycle by an integer of 1 or more, and the exposure time is A third step of setting the frame rate with the frame time being a value obtained by dividing the flicker period by an integer greater than 1 when shorter than the flicker period,
The first step is a two-dimensional colorimetric method for measuring characteristics relating to the color of the two-dimensional region under the frame rate set in the third step.