Display light measurement device, light measurement method, and program

Abstract

The present invention comprises: optical sensors (41)-(43); integrating circuits (51)-(53) that each have an integrating capacitor and accumulate electric charges outputted from the optical sensors; a monitoring means (7) that, before receiving a measurement execution instruction, monitors an output value of the amount of light entering the optical sensors; and a control means (7) that sets, on the basis of the output value of the amount of entering light monitored by the monitoring means, a postponement time by which the start of measurement is to be delayed.

Description

Display light measurement device, light measurement method, and program

[0001] The present invention relates to a display light measurement device, a measurement method, and a program for measuring the luminance, color, etc. of a display.

[0002] A known example of such an optical measurement device is a display color analyzer (one example is the CA-410 manufactured by Konica Minolta, Inc.) Such a display color analyzer has an internal light sensor equivalent to a spectral responsivity and acquires stimulus values.

[0003] There are two main methods for acquiring stimulus values: the sequential acquisition method, which acquires instantaneous values, and the integral acquisition method, which acquires integrated values ​​over a set period of time. The sequential acquisition method excels at high speed, but integrating circuits are preferred and widely used as a means of measuring a wide range of luminance from low to high while achieving a high S / N ratio. In particular, in recent years, advances in technology to reduce dark current and circuit noise have made it possible for integrating circuits to integrate for long periods of time. As they will be able to handle weaker photocurrents, further improvements in low-luminance performance are expected.

[0004] Patent Document 1 discloses a photodetector that includes the above-mentioned integrating circuit and has a wide dynamic range and an improved S / N ratio.

[0005] Furthermore, Patent Document 2 discloses a photodetector capable of measuring brightness over a wide range and with a high S / N ratio without increasing costs.

[0006] JP 2005-321313 A International Publication No. 2018-198674 A

[0007] In an optical measurement device equipped with an integrating circuit, a reset operation is required to transition an integrating capacitor in the integrating circuit to a reference potential before measurement is performed.

[0008] When using a light measurement device equipped with an integrating circuit to measure immediately after dimming the brightness of the display being measured, the integrating operation will begin before the integrating capacitor has reached the reference potential (a charge signal remains). If a low-luminance measurement is performed in this state, a slight error will occur in the light output value due to the slight residual charge.

[0009] Conventionally, in display measurement, there is a limit to the low brightness performance that can be expressed, so errors due to this slight residual charge do not pose a problem.

[0010] However, in recent years, the dynamic range of brightness that displays can display has expanded both in high and low brightness. As a result, the range of brightness from high to low will also become wider in measurements, and errors due to this slight residual charge will no longer be negligible, creating a problem.

[0011] An object of the present invention is to provide a display light measurement device, a measurement method, and a program that can suppress a decrease in measurement accuracy due to residual charge remaining in an integration capacitor of an integration circuit.

[0012] The above object is achieved by the following means: (1) A display light measurement device comprising: an optical sensor; an integrating circuit having an integrating capacitor and accumulating charge output from the optical sensor; monitoring means for monitoring an output value of the amount of light incident on the optical sensor before receiving a measurement execution command; and control means for setting a delay time for delaying the start of measurement based on the output value of the amount of incident light monitored by the monitoring means. (2) The display light measurement device according to the preceding paragraph 1, in which the control means sets the delay time when the output value of the amount of incident light monitored by the monitoring means exceeds a threshold. (3) The display light measurement device according to the preceding paragraph 1 or 2, in which the control means adjusts the delay time based on the output value of the amount of incident light. (4) The display light measurement device according to the preceding paragraph 1 or 2, in which the control means adjusts the delay time based on a photometric value after receiving a measurement execution command. (5) The display light measurement device according to the preceding paragraph 1 or 2, in which the output value of the amount of incident light monitored by the monitoring means is stored for a certain period of time. (6) The display light measurement device according to the preceding paragraph 4, wherein the photometric value after receiving a measurement command is a photometric value in a preliminary measurement performed with the capacity of the integrating capacitor at its maximum. (7) The display light measurement device according to the preceding paragraph 4, wherein the control means determines whether or not there is a residual charge in the integrating capacitor after a main measurement performed upon receiving a measurement execution command. (8) The display light measurement device according to the preceding paragraph 1 or 2, wherein the capacity of the integrating capacitor is maximized except for the period during which the measurement execution command is received and measurement is being performed. (9) The display light measurement device according to the preceding paragraph 2, wherein the monitoring means monitors the output value of the incident light amount by setting the exposure time of the optical sensor to a range of 1 / 120 to 1 / 10 seconds. (10) The display light measurement device according to the preceding paragraph 1 or 2, wherein the user can select whether or not to set the postponement time. (11) A display light measurement method, comprising: a display light measurement device comprising: a light sensor; and an integrating circuit having an integrating capacitor and accumulating an electric charge output from the light sensor; monitoring an output value of the amount of light incident on the light sensor before receiving a measurement execution command; and setting a delay time for delaying the start of measurement based on the output value of the monitored amount of incident light.(12) The display light measurement method according to the preceding paragraph 11, in which the postponement time is set when the output value of the monitored incident light amount exceeds a threshold. (13) The display light measurement method according to the preceding paragraph 11 or 12, in which the postponement time is adjusted based on the output value of the incident light amount. (14) The display light measurement method according to the preceding paragraph 11 or 12, in which the postponement time is adjusted based on a photometric value after receiving a measurement execution command. (15) A program for causing a computer of a display light measurement device comprising: a photosensor; and an integrating circuit having an integrating capacitor and configured to accumulate charge output from the photosensor: monitoring the output value of the incident light amount to the photosensor before receiving a measurement execution command; and setting a postponement time for delaying the start of measurement based on the monitored output value of the incident light amount. (16) The program according to the preceding paragraph 15, in which the program causes the computer to set the postponement time when the output value of the monitored incident light amount exceeds a threshold. (17) The program according to the preceding paragraph 15 or 16, in which the program causes the computer to adjust the postponement time based on the output value of the incident light amount. (18) The program according to the preceding paragraph 15 or 16, which causes the computer to adjust the postponement time based on a photometric value after receiving a measurement execution command.

[0013] According to the display light measurement device and light measurement method of the present invention, the output value of the incident light amount to the optical sensor is monitored before receiving a measurement execution command, and a delay time for delaying the start of measurement is set based on the monitored output value of the incident light amount. As a result, the residual charge in the integrating capacitor can be reduced within the delay time, and a decrease in measurement accuracy due to the residual charge can be suppressed.

[0014] According to the program of the present invention, the output value of the amount of light incident on the optical sensor can be monitored before starting measurement upon receiving a measurement command, and the computer of the display light measurement device can be made to execute a process of setting a delay time to delay the start of measurement based on the output value of the amount of incident light that has been monitored.

[0015] 1 is a block diagram showing the configuration of a display light measurement device 1 according to an embodiment of the present invention. FIG. 1 is a state transition diagram of a display light measurement device. FIG. 2 is a flowchart showing the operation of a display light measurement device in a standby state according to embodiment 1. FIG. 3 is a flowchart showing the operation of a display light measurement device according to embodiment 1 when performing measurement. FIG. 4 is an example of a timing chart of the operation of a display light measurement device according to embodiment 1. FIG. 5 is an example of a timing chart of the operation of a display light measurement device according to embodiment 2. FIG. 6 is a table showing a history of standby light intensity values ​​in embodiment 2. FIG. 7 is a lookup table for determining a requested postponement time in embodiment 2. FIG. 7 is an example of a timing chart of the operation of a display light measurement device according to embodiment 3. FIG. 8 is a table showing a history of standby light intensity values ​​in embodiment 3. FIG. 9 is a flowchart showing the operation of a display light measurement device according to embodiment 3 during measurement. FIG. 10 is a lookup table for determining a requested postponement time in embodiment 3. FIG. 11 is an example of a timing chart of the operation of a display light measurement device according to embodiment 4. FIG. 12 is a flowchart showing the operation of a display light measurement device according to embodiment 4 during measurement.

[0016] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0017] FIG. 1 is a block diagram showing the configuration of a display light measurement device 1 according to an embodiment of the present invention.

[0018] The display light measurement device 1 includes a focusing unit 2, an optical path branching unit 3, three optical sensors 41 to 43, three current integration circuits 51 to 53, three A / D converters 61 to 63, a control unit 7, and a memory unit 8.

[0019] The light collecting unit 2 is made up of a collecting lens etc. and collects light emitted from a display which is the object to be measured. The light path branching unit 3 branches the light path of the light collected by the light collecting unit 2 into three.

[0020] Optical sensors 41 to 43 receive light from each of the three optical paths branched by optical path branching unit 3. Optical sensors 41 to 43 may be of a tristimulus value direct reading type or a spectral type. The stimulus values ​​to be converted include, for example, luminance, chromaticity (xy), and tristimulus values ​​represented by XYZ.

[0021] The current integration circuits 51 to 53 accumulate the electric charge output from each of the optical sensors 41 to 43 in an integration capacitor, and output an output value according to the amount of accumulated electric charge. In this embodiment, each of the current integration circuits 51 to 53 has a plurality of selectable gains. In other words, the capacitance of the integration capacitor can be changed to a plurality of values.

[0022] A / D converters 61 to 63 convert the output values ​​of the current integration circuits 51 to 53 into digital signals.

[0023] The optical sensors 41 to 43, the current integration circuits 51 to 53, and parts of the A / D converters 61 to 63 form an analog circuit section.

[0024] The control unit 7 performs overall control of the display light measurement device 1. For example, it calculates stimulus values ​​based on the output signal values ​​of the A / D converters 61-63, or communicates with an external device (not shown), such as a personal computer. In this embodiment, the control unit 7 monitors the output values ​​of the incident light intensity of the optical sensors 41-43 based on the output values ​​of the current integration circuits 51-53 before starting measurement upon receiving a measurement execution command from an external device, i.e., during standby. In the following description, the output value of the incident light intensity monitored during standby is also referred to as the standby light intensity value, and monitoring the standby light intensity value is also referred to as light intensity monitoring. The control unit 7 also compares the standby light intensity value obtained by the light intensity monitor with a preset threshold, and if the standby light intensity value is greater than the threshold, it sets a residue flag. The residue flag indicates the presence of residual charge in the integrating capacitors of the current integration circuits 51-53, which reduces measurement accuracy. The control unit 7 also performs processing such as setting a delay time to delay the start of measurement. These points will be discussed later.

[0025] Furthermore, the control unit 7 has a timer function. This timer function is used to periodically acquire the output value of the amount of light incident on the optical sensor even during standby, and is also used to manage the time until measurement starts.

[0026] The control unit 7 is configured by a computer including a hardware processor such as a CPU, a ROM, and the like.

[0027] The memory unit 8 accumulates and stores a history of standby light intensity values ​​for the optical sensors 41 to 43, which were monitored before measurement began. The memory unit 8 also stores a lookup table for determining the time required to eliminate residual charge in the integrating capacitor based on the standby light intensity value, i.e., the aforementioned postponement time. The memory unit 8 also stores programs and other data.

[0028] 2 is a state transition diagram of the display light measurement device 1. In FIG. 2, when the power is turned on, the display light measurement device 1 performs a startup process in step S01. Next, in step S02, the display light measurement device 1 enters a standby state until it receives a measurement execution command. When the display light measurement device 1 receives the measurement execution command, it performs measurement in step S03. After completing the measurement, the display light measurement device 1 returns to step S02 and enters a standby state again, and thereafter repeats the standby of step S02 and the measurement of step S03. When the user turns off the power, it transitions to a sleep state. [Embodiment 1] Next, embodiment 1 of the display light measurement device 1 will be described with reference to the flowcharts of FIGS. 3 and 4 and an example of a timing chart of FIG. 5. The operations shown in the flowcharts from FIG. 3 onwards are executed by the processor of the control unit 7 of the display light measurement device 1 operating in accordance with an operation program.

[0029] The flowchart in Figure 3 shows the operation in standby mode, and the flowchart in Figure 4 shows the operation during measurement. (Operation in Standby Mode) In step S11 in Figure 3, the control unit 7 sets the gain of each current integration circuit 51-53. While the control unit 7 monitors the light intensity during standby mode, the gain of the current integration circuits 51-53 is set to minimum (the capacitance value of the integration capacitor is set to maximum) to avoid malfunction of the light intensity monitor due to exposure to high luminance. If the control unit 7 has sufficient computing power, it may also control the gain of the current integration circuits 51-53 in real time. By using variable gain, the accuracy of the light intensity monitor can be improved.

[0030] Next, in step S12, the control unit 7 sets the photometric conditions (exposure time, integration time, number of integrations, and monitor cycle) for the light quantity monitor. In this embodiment, the settings are as follows.

[0031] Integration time: 20 msec Exposure time: 100 msec (the output of the current integration circuit is integrated five times) Light intensity monitor cycle: 200 msec Increasing the exposure time improves the accuracy of the light intensity monitor, but reduces the response to the amount of exposed light, making it unsuitable for determining residual charge. On the other hand, making the exposure time too short improves response, but only picks up a portion of the light emission waveform, reducing accuracy. Taking these factors into consideration, the appropriate range for exposure time is 1 / 120 to 1 / 10 seconds. In this embodiment, 100 msec, a nearly common multiple, was selected to ensure synchronization with both the universal standards NTSC and PAL.

[0032] If the period of the vertical synchronization signal (Vsync) of the display to be measured is known, that value may be acquired and used to determine the exposure time. For example, this may be the case when the user has already set the frequency of the vertical synchronization signal. To improve the accuracy of the light intensity monitor, it is recommended that the exposure time be a natural number multiple of the period of the vertical synchronization signal.

[0033] The integration time is the exposure time divided by a natural number (the number of divisions is the number of integrations). Taking into account the S / N ratio of the photometric value, it is preferable to make the integration time longer, assuming conditions to avoid saturation. In this example, 20 msec was selected, but this is not limiting.

[0034] Considering the response to the amount of exposure light, a shorter light intensity monitor cycle is more appropriate. However, a shorter cycle places a burden on the control unit 7. Taking this into consideration, a cycle of 200 msec was selected in this example. If the control unit 7 has sufficient computing power, a moving average process is performed on the integrated output value obtained by divided exposure (for example, the average value of the most recent five data points is used as the light intensity output value). This makes it possible to make the light intensity monitor cycle shorter than the exposure time.

[0035] In step S13 of FIG. 3, the control unit 7 performs photometry (integration) under the conditions determined in step S12. The control unit 7 repeatedly performs the following steps (1) to (3) until it receives a measurement execution command. (1) As shown in the "Integration Circuit" section of the timing chart in FIG. 5, the control unit 7 resets each of the current integration circuits 51 to 53 and then starts integration. Integration is performed five times over a predetermined time period (20 msec). (2) As shown in the "A / D Conversion" section of the timing chart in FIG. 5, the control unit 7 samples and holds the output values ​​of each of the current integration circuits 51 to 53 after the predetermined time period (20 msec) has elapsed. (3) After completion, the control unit 7 returns to step (1), and converts the values ​​held in step (2) into digital data using the downstream A / D converters 61 to 63.

[0036] In this example, the current integration circuits 51 to 53 are operated even during standby periods when light intensity monitoring is not being performed. The operation of the current integration circuits 51 to 53 resets the integral capacitance, preventing the current integration circuits 51 to 53 from falling into an oversaturated state. This is to prevent the current integration circuits 51 to 53 from falling into an oversaturated state, which would take time to return to an appropriate state. Note that the A / D conversion by each A / D converter 61 to 63 is performed by extracting only data relevant to the light intensity monitor, in order to reduce the load on the control unit 7.

[0037] In step S14 of Fig. 3, the control unit 7 performs residue flag processing (see the "Calculation (control unit)" item in the timing chart of Fig. 5). Specifically, the control unit 7 first converts the data acquired in step S13 into a standby light intensity value. In the case of multiple divided exposures as in this embodiment, the conversion process is performed on an average value of the data for each division. The conversion process includes dark output correction, circuit gain calibration, and integral time normalization.

[0038] Next, the control unit 7 compares the obtained standby light intensity value with a threshold value to determine whether it is at a level of intensity that would result in a decrease in measurement accuracy. If the standby light intensity value exceeds the threshold value, the control unit 7 sets a residue flag, indicating that charge remains in the integrating capacitors of the current integration circuits 51-53. This process is performed each time photometry is performed in step S13, and the residue flag is updated. Note that in this example, the residue flag is set when the standby light intensity value of any of the three XYZ optical sensors 41-43 exceeds the threshold value, but this is not limited to this. For example, it may be determined whether the standby light intensity value of only a specific optical sensor exceeds the threshold value. (Operation During Measurement Execution) When the control unit 7 receives a measurement execution command, it stops light intensity monitoring (discards data if it is in progress) and determines whether a residue flag exists, i.e., whether the residue flag is set, in step S21 of FIG. 4. If the residue flag is set (YES in step S21), the process proceeds to step S22, where the control unit 7 determines a delay time. The delay time is the time by which the start of measurement is delayed to eliminate residual charge in the integrating capacitors. In this embodiment, a fixed value of 2.16 seconds is used as the delay time in order to ensure the required accuracy at low brightness.

[0039] Next, the control unit 7 performs a postponement process in step S23. That is, the control unit 7 sets a postponement time and waits for the postponement time before performing the measurement. After the postponement time has elapsed, the process proceeds to step S24. In this embodiment, even during the postponement time, the current integration circuits 51 to 53 perform an integration operation and reset to remove the charge, with the aim of reducing the residual charge in the integration capacitor (see the timing chart in FIG. 5). Note that the integration time during the integration operation during the postponement time may be changed. For example, shortening the integration time can increase the number of resets of the current integration circuits 51 to 53. Furthermore, if extreme control is possible, it is also possible to continue sending reset commands and perform only the reset operation.

[0040] If the residue flag is not set in step S21 (NO in step S21), there is no influence of a decrease in accuracy due to residual charge, and the process proceeds directly to step S24.

[0041] In step S24, measurement is performed according to the normal measurement procedure. For example, gain switching and photometric conditions are derived as necessary, and then the main integration is performed. In this embodiment, it is assumed that a display with a Vsync frequency of 60 Hz is being measured, and the exposure time is set to 1 / 30 sec (1 integration). In step S25, the control unit 7 converts the output value acquired by the measurement in step S24 into a measurement index value (e.g., luminance value, chromaticity value) using normal conversion calculation processing. After conversion, the display light measurement device 1 transitions to a standby state (step S02 in FIG. 2).

[0042] In this manner, in the first embodiment, a delay time is set before the start of measurement in response to the reception of a measurement execution command, and the start of measurement is delayed, so that residual charges remaining in the integrating capacitors of the current integration circuits 51 to 53 are eliminated within this delay time. Therefore, a reduction in measurement accuracy due to residual charges can be suppressed by a simple method. [Embodiment 2] In the first embodiment, a fixed value was used as the delay time.

[0043] In contrast, in embodiment 2, the postponement time is adjusted according to the standby light intensity value. (Operation in standby state) The operation of the display light measurement device 1 in standby state is the same as the operation example in embodiment 1 shown in Figure 3, except for the residue flag processing in step S14. For this reason, the explanation will be given using the flowchart in Figure 3. An example of a timing chart is shown in Figure 6.

[0044] In the residue flag processing in step S14, the control unit 7 converts the data acquired in step S13 into a standby light intensity value. When exposure is performed in multiple divided steps as in the second embodiment, the conversion process is performed on an average value of the multiple data obtained in each exposure. The conversion process includes dark output correction, circuit gain calibration, and integral time normalization. Up to this point, the process is the same as in the first embodiment.

[0045] The control unit 7 determines whether the standby light intensity value is at a level that will cause a decrease in measurement accuracy, taking into account past standby light intensity values. Specifically, the control unit 7 stores a history of standby light intensity values ​​from the most recent to a predetermined period in the past in the storage unit 8, updating the history each time the standby light intensity value for each exposure is acquired. The history of standby light intensity values ​​stored in the storage unit 8 is shown in FIG. 7.

[0046] In the example shown in FIG. 7 , the standby light intensity value is acquired and stored every 0.2 seconds. In this embodiment, the standby light intensity value used as the basis for the calculation of the postponement process is 2132.5, which is the maximum standby light intensity value among the outputs of the XYZ optical sensors 41-43. However, this is not limited to this. For example, the standby light intensity value used as the basis for the calculation of the postponement process may be based on the standby light intensity value of only a specific optical sensor. In this embodiment, the history retention period is set to 2.2 seconds, based on the time required for the residual charge to dissipate when the measured brightness transitions from the highest measured brightness to the lowest measured brightness. The time required for the residual charge to dissipate is approximately equal to the maximum postponement time, which will be described later.

[0047] Furthermore, the control unit 7 determines whether the standby light intensity value exceeds a threshold value each time the standby light intensity value is acquired, and if a light intensity value exceeding the threshold value exists within the history retention period, it sets a residue flag indicating that charge remains in the integrating capacitors of the current integration circuits 51 to 53. Here, the threshold value is the minimum standby light intensity value at which a postponement time occurs, as determined by a lookup table (LUT) that determines the postponement time (described later). (Operation During Measurement) The operation during measurement is the same except for the content of the postponement time determination process in step S22. For this reason, the operation will be described using the flowchart of FIG. 4.

[0048] When the control unit 7 receives the measurement execution command, it stops the light quantity monitoring (discards the data if it is in the middle of the measurement), and in step S21, it determines whether or not there is a residue flag, i.e., whether the residue flag is set. If the residue flag is set (YES in step S21), the process proceeds to step S22.

[0049] In step S22, the control unit 7 determines the extension time. First, the control unit 7 determines the requested extension time based on the result of the residue flag processing described above. In this embodiment 2, the control unit 7 determines the requested extension time from the LUT shown in FIG. 8. As can be seen from the LUT in FIG. 8, the maximum extension time that can be set is 2.16 seconds. Therefore, the history retention time for the standby light intensity value shown in FIG. 7 is set to 2.20 seconds.

[0050] The LUT in FIG. 8 sets the required postponement time when the maximum value of the standby light intensity values ​​stored as history is used as an input parameter. As mentioned above, the maximum value of 2132.5 among the standby light intensity values ​​in the history shown in FIG. 7 is used as the standby light intensity value that serves as the basis for calculating the postponement process. Therefore, the LUT in FIG. 8 determines the required postponement time to be 1.63 seconds. In the LUT in FIG. 8, the postponement time is set longer as the standby light intensity value increases. This is because the larger the standby light intensity value, the more time is required for residual charge to dissipate. Note that the method for determining the required postponement time is not limited to this. For example, the amount of change in light intensity or the history shape may be taken into account as an input parameter, or the required postponement time may be determined based only on the most recent value without storing the standby light intensity history. The required postponement time may also be derived from a calculation formula.

[0051] After determining the requested postponement time, the control unit 7 derives the postponement time to actually wait until the start of measurement according to the following formula: Here, the elapsed time in the formula is 0.6 seconds (see FIG. 7) at the standby light intensity value (2132.5) used to derive the requested postponement time. Note that the determination of the elapsed time is not limited to this.

[0052] Postponement time = requested postponement time - elapsed time = 1.63 seconds - 0.60 seconds = 1.03 seconds. Then, in step S23 of Fig. 4, the control unit 7 sets the determined postponement time and waits for the start of measurement operation. When the postponement time has elapsed, the processes of steps S24 and S25 are performed.

[0053] According to the second embodiment, multiple standby light intensity values ​​for each monitored exposure are accumulated for a certain period of time, and the required extension time is determined based on the accumulated standby light intensity values. Therefore, an appropriate extension time is determined based on the light intensity during exposure, i.e., the residual charge in the integrating capacitor. As a result, it is possible to avoid the inconvenience of setting an unnecessarily long extension time even when the exposure light intensity (residual charge in the integrating capacitor) is low, resulting in wasted time. [Embodiment 3] In the second embodiment, the extension time was set based on the standby light intensity values ​​acquired during standby. In contrast, in the third embodiment, the extension period is set taking into account not only the standby light intensity values ​​acquired during standby, but also the photometric value obtained during pre-measurement before measurement. An example timing chart is shown in FIG. 9. (Operation in Standby State) The operation of the display light measurement device 1 in standby state is the same as that in the second operation example. That is, the control unit 7 acquires standby light intensity values ​​at regular intervals. The control unit 7 stores a history of standby light intensity values, from the most recent to a predetermined period in the memory unit 8, updating the history. The history of standby light intensity values ​​stored in the memory unit 8 is shown in FIG. 10.

[0054] In the example of FIG. 10 , the standby light intensity value is acquired and stored every 0.2 seconds, as in the example of FIG. 7 . Furthermore, in this embodiment, the standby light intensity value used as the basis for calculating the postponement time is 2132.58, which is the maximum standby light intensity value among the outputs of the XYZ optical sensors 41-43. However, this is not limited to this, and for example, the standby light intensity value for only one of the optical sensors 41-43 may be used. Furthermore, in this embodiment, the history retention period is set to 7.2 seconds based on the time required for residual charge to dissipate when transitioning from the highest measured brightness to the lowest measured brightness. The time required for residual charge to dissipate is approximately equal to the maximum postponement time, which will be described later.

[0055] Furthermore, the control unit 7 determines whether the standby light intensity value exceeds a threshold value each time the standby light intensity value is acquired, and if there is a light intensity that exceeds the threshold value within the history retention period, it sets a residue flag indicating that charge remains in the integration capacitors of the current integration circuits 51 to 53. Here, the threshold value is set to the minimum standby light intensity value at which a postponement time occurs in the LUT that determines the postponement time, which will be described later. (Operation During Measurement) The operation during measurement is shown in the flowchart of FIG.

[0056] When the control unit 7 receives the measurement execution command, it stops the light intensity monitor (discards data if it is in the middle of measurement). Then, in step S41, a preliminary measurement is performed to obtain an approximate value of the incident light intensity at the time of measurement (see "Integration (Preliminary Measurement)" in the "state" section of the timing chart in FIG. 9). The preliminary measurement is performed under photometric conditions used in the high-luminance range to avoid remeasurement due to saturation. The photometric conditions are "circuit gain value: minimum, exposure time: 1 / 60 sec (1 Vsync period)," but are not limited to these.

[0057] In step S42, the control unit 7 determines whether or not a residue flag is set, i.e., whether or not the residue flag is set. If the residue flag is set (YES in step S42), the process proceeds to step S43.

[0058] In step S43, the control unit 7 determines the extension time. Specifically, the control unit 7 first determines the required extension time based on the standby light intensity value acquired in the residue flag processing described above and the photometric value obtained in the preliminary measurement (pre-photometric value). In this embodiment, the required extension time is determined from the LUT shown in FIG.

[0059] The LUT in Figure 12 sets the requested postponement time when the maximum value of the multiple standby light intensity values ​​stored as history (specified in the vertical column in Figure 12) and the pre-photometric value (specified in the horizontal column in Figure 12) are used as input parameters. As mentioned above, the maximum value in the standby light intensity value history shown in Figure 10 is 2132.58. Also, the pre-photometric value was greater than or equal to 0.0001 and less than 0.0002. Therefore, 1730166034176_0.5v@)4i is determined.

[0060] In the LUT of FIG. 12, the smaller the pre-photometric value, the longer the required postponement time is set. This is because the influence of residual charge increases when the light intensity at the time of measurement is low. Note that the method for determining the required postponement time is not limited to this. For example, the amount of change in light intensity and the history shape may be taken into account in the input parameters, or the required postponement time may be determined based only on the most recent standby light intensity value without accumulating a standby light intensity value history. As can be seen from the LUT of FIG. 12, the maximum configurable postponement time is 7.07 seconds. For this reason, the standby light intensity value history retention time shown in FIG. 10 is set to 7.20 seconds.

[0061] Once the requested postponement time is determined, the control unit 7 derives the actual waiting postponement time according to the following formula: Here, the elapsed time in the formula is 0.6 seconds (see FIG. 11) at the standby light intensity value (2132.58) used to derive the requested postponement time. Note that the determination of the elapsed time is not limited to this.

[0062] Postponement Time = Requested Postponement Time - Elapsed Time = 30.5 seconds - 0.60 seconds = 2.45 seconds Next, in step S44, the control unit 7 determines whether the postponement time is ≦ 0 seconds. If the postponement time is ≦ 0 seconds (YES in step S44), it is determined that the accuracy error due to residual charge is within the allowable range, and measurement is immediately performed in step S46. On the other hand, if the postponement time is > 0 seconds (NO in step S44), in step S45, the control unit 7 waits for the postponement time before performing the measurement, and then performs the measurement in step S46. Note that if the residue flag is not set in step S42 (NO in step S42), the control unit 7 proceeds directly to step S46.

[0063] The processes of steps S46 and S47 in Fig. 11 are the same as the processes of steps S24 and S25 in Fig. 4. However, in step S46, the exposure time was set to 1 / 15 [sec] (1 accumulation) to improve measurement accuracy in low luminance areas.

[0064] In this embodiment 3, the monitored multiple standby light intensity values ​​are accumulated for a certain period of time, and the postponement time is determined based on the accumulated standby light intensity values ​​and the photometric value during preliminary measurement. This allows the postponement time to be finely adjusted, and it is possible to avoid the inconvenience of setting an unnecessarily long postponement time even when the light intensity is low, resulting in a waste of time. [Embodiment 4] In embodiment 3, preliminary measurement is performed during measurement, and the postponement time is determined based on the standby light intensity values ​​and the preliminary photometric values ​​monitored in the standby state.

[0065] In contrast, in the fourth embodiment, the postponement time is determined based on the light intensity value obtained by actual measurement, not pre-measurement, and the standby light intensity value monitored in standby state. An example of a timing chart is shown in FIG. 13. (Operation in standby state) This is the same as the operation in standby state in the third embodiment. That is, the control unit 7 acquires the standby light intensity value at regular intervals. The control unit 7 then updates and stores the history of standby light intensity values ​​from the most recent to a predetermined period in the memory unit 8. The history of standby light intensity values ​​stored in the memory unit 8 is the same as that shown in FIG. 10. Furthermore, the standby light intensity value used as the basis for calculating the postponement time is 2132.58, which is the maximum standby light intensity value among the outputs of the XYZ optical sensors 41 to 43.

[0066] Furthermore, the control unit 7 determines whether the standby light intensity value exceeds a threshold value each time the standby light intensity value is acquired, and if there is a light intensity that exceeds the threshold value within the history retention period, it sets a residue flag indicating that charge remains in the integration capacitors of the current integration circuits 51 to 53. Here, the threshold value is set to the minimum standby light intensity value at which a postponement time occurs in the LUT that determines the postponement time, which will be described later. (Operation During Measurement) The operation during measurement is shown in the flowchart of FIG.

[0067] When the control unit 7 receives the measurement execution command, it stops the light intensity monitoring (discards the data if it is in the middle of the measurement), and performs normal measurement processing in step S51 (see "Integration (measurement)" in the "state" section of the timing chart in Figure 13), thereby deriving the light intensity value.

[0068] In step S52, the control unit 7 determines whether or not a residue flag is present, i.e., whether the residue flag is set. If the residue flag is set (YES in step S52), the process proceeds to step S53, where the control unit 7 determines a postponement time. Specifically, the control unit 7 first determines a requested postponement time based on the standby light intensity value acquired in the above-described residue flag processing and the light intensity value at the time of measurement. In this embodiment, as in embodiment 3, the requested postponement time is determined from the LUT in FIG. 12. In this embodiment, because the display, which is the measurement object, was bright at the time of measurement, the control unit 7 determined the requested postponement time to be 3.05 seconds.

[0069] The method for determining the request postponement time is not limited to this. For example, the change in the amount of light intensity or the history shape may be taken into account in the input parameters, or the request postponement time may be determined only based on the most recent value without storing the history of standby light intensity values.

[0070] Once the requested postponement time is determined, the control unit 7 derives the actual postponement time according to the following formula: Here, the elapsed time in the formula is 0.6 seconds (see FIG. 11) at the light intensity value (2132.58) used to derive the requested postponement time. Note that the determination of the elapsed time is not limited to this.

[0071] Postponement time = requested postponement time - elapsed time = 30.5 seconds - 0.60 seconds = 2.45 seconds Next, in step S54, the control unit 7 determines whether the postponement time is ≦ 0 seconds. If the postponement time is ≦ 0 seconds (YES in step S54), it is determined that the accuracy error due to residual charge is within the allowable range, and the process proceeds to step S55.

[0072] On the other hand, if the postponement time is greater than 0 seconds (NO in step S54), the control unit 7 waits until the postponement time has elapsed in step S56. Next, the control unit 7 performs remeasurement in step S57, and then returns to step S52, repeating steps S52 to S54, S56, and S57 until the postponement time becomes ≦0 seconds. If the postponement time becomes ≦0 seconds (YES in step S54), the process proceeds to step S55. Note that the timing chart in FIG. 13 shows the case where the remeasurement in step S57 is performed.

[0073] In step S55, the control unit 7 uses the most recent light intensity value acquired in step S51 or step S57 as measurement data to calculate measurement data.

[0074] If the residue flag is not set in step S52 (NO in step S52), the process proceeds directly to step S55.

[0075] According to the fourth embodiment, the postponement time is determined using data from the first measurement, so that pre-measurement is not necessary, and it is possible to further reduce wasted time. [Other Embodiments] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments.

[0076] For example, at least one of the three optical sensors 41 to 43 for measurement is used to monitor the amount of light in the standby state, but an optical sensor dedicated to monitoring the amount of light may also be provided.

[0077] The user may also be allowed to select whether to enable or disable the postponement time setting. For example, by enabling the postponement time setting only when high-precision measurement is required, measurement without postponement time will be performed as usual when the accuracy requirement is low, eliminating wasted time before the measurement starts.

[0078] This application claims priority from Japanese Patent Application No. 2024-15934, filed on February 5, 2024, the disclosure of which is incorporated herein by reference in its entirety.

[0079] The present invention can be used in a display light measurement device that measures the luminance, color, etc. of a display.

[0080] REFERENCE SIGNS LIST 1 Display light measurement device 2 Light collecting unit 3 Light path branching unit 41 to 43 Optical sensors 51 to 53 Current integration circuits 61 to 63 A / D converters 7 Control unit 8 Storage unit

Claims

1. A display light measurement device comprising: an optical sensor; an integrating circuit having an integrating capacitor and accumulating the charge output from said optical sensor; monitoring means for monitoring the output value of the amount of light incident on said optical sensor before receiving a measurement execution command; and control means for setting a delay time for delaying the start of measurement based on the output value of the amount of incident light monitored by said monitoring means.

2. The display light measurement device according to claim 1, wherein the control means sets the postponement time when the output value of the incident light amount monitored by the monitoring means exceeds a threshold value.

3. A display light measurement device according to claim 1 or 2, wherein the control means adjusts the delay time based on the output value of the amount of incident light.

4. A display light measurement device according to claim 1 or 2, wherein the control means adjusts the delay time based on the photometric value after receiving the measurement execution command.

5. A display light measurement device according to claim 1 or 2, wherein the output value of the incident light amount monitored by the monitoring means is stored for a certain period of time.

6. A display light measurement device according to claim 4, wherein the photometric value after receiving the measurement command is a photometric value obtained in a pre-measurement performed with the capacity of the integrating capacitor at its maximum.

7. The display light measurement device according to claim 4, wherein the control means determines whether or not there is a residual charge in the integrating capacitor after the main measurement is executed in response to the reception of a measurement execution command.

8. A display light measurement device according to claim 1 or 2, wherein the capacitance of the integrating capacitor is maximized except for the period when a measurement execution command is received and measurement is being executed.

9. A display light measurement device according to claim 2, wherein the monitoring means monitors the output value of the amount of incident light by setting the exposure time of the optical sensor in the range of 1 / 120 to 1 / 10 seconds.

10. A display light measurement device according to claim 1 or 2, wherein the user can select whether or not to set the postponement time.

11. A display light measurement method, comprising: a display light measurement device comprising: a light sensor; and an integrating circuit having an integrating capacitor for accumulating electric charge output from the light sensor; monitoring an output value of the amount of light incident on the light sensor before receiving a measurement execution command; and setting a delay time for delaying the start of measurement based on the output value of the monitored amount of incident light.

12. The display light measurement method according to claim 11, wherein the postponement time is set when the output value of the monitored incident light amount exceeds a threshold value.

13. The display light measurement method according to claim 11 or 12, wherein the delay time is adjusted based on the output value of the amount of incident light.

14. The display light measurement method according to claim 11 or 12, wherein the postponement time is adjusted based on a photometric value obtained after receiving a measurement execution command.

15. A program for causing a computer of a display light measurement device having an optical sensor and an integrating circuit having an integrating capacitor for accumulating the electric charge output from the optical sensor to monitor the output value of the amount of light incident on the optical sensor before receiving a measurement execution command, and to set a delay time for delaying the start of measurement based on the output value of the amount of incident light that has been monitored.

16. The program of claim 15, which causes the computer to set the postponement time when the output value of the monitored incident light amount exceeds a threshold value.

17. The program according to claim 15 or 16, which causes the computer to adjust the postponement time based on the output value of the amount of incident light.

18. The program according to claim 15 or 16, which causes the computer to adjust the postponement time based on a photometric value after receiving a measurement execution command.

Images