Display light measuring apparatus, light measuring method, and program

Abstract

To provide a display light measuring apparatus and a measuring method capable of suppressing deterioration of zero calibration accuracy due to residual charges of the integration capacitor of an integration circuit, and a program.SOLUTION: A display light measuring apparatus includes: optical sensors 41 to 43; integration circuits 51 to 53 having integration capacitors, the integration circuits accumulating electric charges output from the optical sensors; light shielding means 91 for shielding incident light to the optical sensors; calibration means 7 for acquiring a dark-time output value as the output value of a quantity of incident light on the optical sensors, in a state where the incident light to the optical sensors is shielded by the light shielding means, and for performing zero calibration on the basis of the acquired dark-time output value; and control means 7 for setting a postponement time for delaying acquisition of the dark-time output value.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[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. [Background technology]

[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 optical 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 luminance over a wide range and with a high S / N ratio without increasing costs.

[0006] Meanwhile, zero calibration is a method for suppressing measurement errors caused by the dark current of the optical sensor and the offset of the circuit.

[0007] Zero calibration is a process in which an output value (zero calibration value) is prepared when the index value should be set to zero, and the zero calibration value is subtracted from the output value (obtained when the optical path is open) during optical measurement.

[0008] The zero calibration value is generated from the dark output value, which is the output value acquired when the optical path to the optical sensor is closed and light is blocked. The dark output value is acquired under conditions that allow the generation of a zero calibration value that corresponds to the photometric conditions used during light measurement (for example, integration time and capacity of the integration circuit (circuit gain)).

[0009] For example, in the case of a system with multiple circuit gains, a zero calibration value corresponding to each circuit gain is required, so the dark output value to be acquired will naturally be acquired under multiple conditions. Basically, the dark output is acquired for each circuit gain, but if it can be made common across multiple circuit gains, the number of acquisition conditions can be reduced.

[0010] The integration time is similar to the circuit gain, and must be acquired under conditions that allow for the generation of a zero calibration value that corresponds to the photometric conditions during light measurement. The photometric conditions do not necessarily have to be the same.

[0011] There are two main types of timing for acquiring the dark output value for zero calibration. The first is a method in which the dark output value is acquired for each optical measurement (immediate type). The second is a method in which the dark output value is acquired and stored in advance before measurement is performed (advance type).

[0012] Immediate zero calibration is performed consecutively with the optical measurement, either immediately before or immediately after the optical measurement. When performed immediately after the optical measurement, the photometric conditions used in the optical measurement are known, so there is an advantage that the dark output value only needs to be obtained under one condition (the same conditions as the optical measurement performed immediately before).

[0013] Pre-calibration of the zero point calibration type is generally performed at the following times (1) to (3): (1) at startup, (2) when the temperature sensor output value exceeds the allowable range based on the previous zero calibration (this is done to reduce drift errors), (3) when requested by the user, etc. Since the photometric conditions during light measurement are unknown, it is common to obtain all dark output values ​​in advance for multiple major conditions. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-321313 [Patent Document 2] International Publication No. 2018-198674 Summary of the Invention [Problem to be solved by the invention]

[0015] 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.

[0016] When zero calibration is performed using an optical measurement device equipped with an integrating circuit while the display being measured is on, the integration operation will begin before the integrating capacitor reaches the reference potential (a charge signal remains). If zero calibration is performed in this state, the acquired dark output value will have an error due to the slight remaining charge (residual charge). As a result, a slight error will occur when measurements in the low luminance range are performed using the above zero calibration value.

[0017] 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.

[0018] However, in recent years, the dynamic range of brightness that displays can express has expanded both in the high- and low-luminance ranges, which has led to a problem in that errors caused by this slight residual charge that occurs when zero calibration is performed in the high-luminance range cannot be ignored.

[0019] 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 the accuracy of zero calibration due to residual charge in the integration capacitor of an integration circuit. [Means for solving the problem]

[0020] The above object can be achieved by the following means: (1) an optical sensor; an integration circuit having an integration capacitor for accumulating the charge output from the photosensor; a light blocking means capable of blocking incident light to the optical sensor; a calibration means for acquiring a dark output value, which is an output value of the amount of light incident on the optical sensor, in a state in which the incident light on the optical sensor is blocked by the light blocking means, and for performing zero calibration based on the acquired dark output value; a control means for setting a delay time for delaying acquisition of the dark output value; A display light measurement device comprising: (2) a monitoring means for monitoring an output value of the amount of light incident on the optical sensor before the zero calibration is performed by the calibration 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 the preceding paragraph 1 or 2, wherein the control means adjusts the delay time based on the output value of the incident light amount monitored by the monitoring means. (4) A display light measurement device as described in paragraph 1 or 2 above, in which if the light blocking means has already blocked the incident light to the optical sensor when the calibration means receives a command to perform zero calibration, the control means does not set the postponement time. (5) Equipped with dimming means; A display light measurement device as described in paragraph 1 or 2 above, wherein if the dimming means is dimming the light incident on the optical sensor when the calibration means receives a command to perform zero calibration, the control means does not set the postponement time. (6) The display light measuring device according to the preceding paragraph 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. (7) A display light measurement device according to the preceding paragraph 1 or 2, which maximizes the capacitance of the integrating capacitor except for a period during which a measurement execution command is received and measurement is being executed. (8) The display light measuring device according to the preceding paragraph 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. (9) A display light measurement device according to the preceding paragraph 1 or 2, in which the user can select whether or not to set the postponement time. (10) an optical sensor; an integration circuit having an integration capacitor for accumulating the charge output from the photosensor; a light blocking means capable of blocking incident light to the optical sensor; A display light measurement device comprising: a dark output value, which is an output value of the amount of light incident on the optical sensor, is acquired in a state in which the incident light on the optical sensor is blocked by the light blocking means, and zero calibration is performed based on the acquired dark output value; setting a delay time for delaying acquisition of the dark output value; A display light measurement method comprising: (11) A display light measurement method as described in the preceding paragraph 10, in which the output value of the amount of incident light to the optical sensor is monitored before zero calibration is performed, and the postponement time is set when the output value of the monitored amount of incident light exceeds a threshold value. (12) The display light measurement method according to the preceding paragraph 10 or 11, wherein the delay time is adjusted based on the output value of the monitored incident light amount. (13) an optical sensor; an integration circuit having an integration capacitor for accumulating the charge output from the photosensor; a light blocking means capable of blocking incident light to the optical sensor; A computer of a display light measurement device equipped with a dark output value, which is an output value of the amount of light incident on the optical sensor, is acquired in a state in which the incident light on the optical sensor is blocked by the light blocking means, and zero calibration is performed based on the acquired dark output value; setting a delay time for delaying acquisition of the dark output value; A program for executing a process. (14) The program according to the preceding paragraph 13, which monitors the output value of the amount of light incident on the optical sensor before zero calibration is performed, and causes the computer to execute a process of setting the postponement time if the output value of the monitored amount of incident light exceeds a threshold value. (15) The program according to the preceding paragraph 13 or 14, which causes the computer to execute a process of adjusting the postponement time based on the output value of the monitored incident light amount. [Effects of the Invention]

[0021] According to the display light measurement device and light measurement method of the present invention, a dark output value, which is an output value of the amount of light incident on the light sensor, is acquired while the light incident on the light sensor is blocked by a light blocking means, and zero calibration is performed based on the acquired dark output value. During this zero calibration, a delay time is set to delay the acquisition of the dark output value. This allows the residual charge in the integrating capacitor to be reduced within the delay time. As a result, high-precision zero calibration can be performed even when zero calibration is performed in the high-luminance range, maintaining low-luminance performance and eliminating the limitation on the luminance value during zero calibration.

[0022] According to the program of the present invention, the computer of the display light measurement device can be made to execute the following processes: when the incident light to the light sensor is blocked by the shading means, a dark output value, which is the output value of the amount of light incident to the light sensor, is acquired; zero calibration is performed based on the acquired dark output value; and a delay time is set to delay the acquisition of the dark output value. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a block diagram showing the configuration of a display light measurement device 1 according to an embodiment of the present invention. [Figure 2] FIG. 2 is a state transition diagram of the display light measurement device according to the first embodiment. [Figure 3] 10 is a flowchart showing an operation in a standby state of the display light measurement device according to the first embodiment. [Figure 4]10 is a flowchart showing the operation of the display light measurement device according to the first embodiment at the time of zero calibration. [Figure 5] 1 is a flowchart showing the operation of the display light measurement device according to the first embodiment when performing measurement. [Figure 6] 6A to 6C are examples of timing charts of the operation of the display light measurement device according to the first embodiment. [Figure 7] 10 is a table showing a history of standby light intensity values ​​in the second embodiment. [Figure 8] 10 is a lookup table for determining a request postponement time in the second embodiment. [Figure 9] FIG. 11 is a state transition diagram of a display light measurement device according to a third embodiment. [Figure 10] 10 is an example of a timing chart of the operation of the display light measurement device according to the third embodiment. [Figure 11] 10 is a flowchart showing an operation at the time of zero calibration of a display light measurement device according to another embodiment. [Figure 12] 10 is an example of a timing chart of the operation of a display light measurement device according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0025] FIG. 1 is a block diagram showing the configuration of a display light measurement device 1 according to an embodiment of the present invention.

[0026] The display light measurement device 1 includes a focusing unit 2, a shading means 91, a dimming means 92, 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.

[0027] The light collecting unit 2 is made up of a collecting lens and the like, and collects light emitted from a display, which is the object to be measured.

[0028] The light blocking means 91 is a member that blocks incident light to the optical sensors 41 to 43 during zero calibration, and is provided so as to be able to open and close the incident light path to the optical sensors 41 to 43. In this embodiment, a shutter is used as the light blocking means 91, for example.

[0029] The light-reducing means 92 is a member that limits the amount of light incident on the optical sensors 41 to 43 in order to expand the measurement brightness range, and is provided so as to be insertable into and removable from the incident light path to the optical sensors 41 to 43. In this embodiment, for example, an ND filter is used as the light-reducing means 92. However, there is also a case where the light-reducing means 92 is not provided.

[0030] The optical path branching unit 3 branches the optical path of the light condensed by the light condensing unit 2 into three.

[0031] The optical sensors 41 to 43 receive light along each of the three optical paths branched by the optical path branching unit 3. The optical sensors 41 to 43 may be of a tristimulus value direct reading type or a spectroscopic type.

[0032] The current integration circuits 51 to 53 accumulate the electric charges output from the optical sensors 41 to 43 in their respective integration capacitors, 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.

[0033] A / D converters 61 to 63 convert the output values ​​of the current integration circuits 51 to 53 into digital signals.

[0034] 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.

[0035] The control unit 7 comprehensively controls the entire display light measurement device 1. For example, it calculates stimulus values ​​based on the output signal values ​​of each A / D converter 61-63, or communicates with an external device (not shown) such as a personal computer. The calculated stimulus values ​​include, for example, luminance, chromaticity (xy), and tristimulus values ​​represented by XYZ. In this embodiment, the control unit 7 also performs zero calibration. Zero calibration is performed by the control unit 7 acquiring dark output values, which are output values ​​of the amount of light incident on the optical sensors 41-43, while the light blocking means 91 blocks light incident on the optical sensors 41-43. The control unit 7 then calibrates the measurement values ​​based on the acquired dark output values.

[0036] Furthermore, the control unit 7 monitors the output values ​​of the incident light amount to the optical sensors 41 to 43 before zero calibration is performed, based on the output values ​​of the current integration circuits 51 to 53. In the following description, the output values ​​of the incident light amount monitored before zero calibration is performed are also referred to as standby light amount values, and monitoring the standby light amount values ​​is also referred to as light amount monitoring.

[0037] Furthermore, the control unit 7 compares the standby light intensity value obtained by the light intensity monitor with a preset threshold value, and if the standby light intensity value is greater than the threshold value, it sets a residue flag. The residue flag is a flag indicating that there is residual charge in the integrating capacitors of the current integration circuits 51 to 53 that reduces the accuracy of zero calibration. Furthermore, during zero calibration, the control unit 7 sets a delay time based on the standby light intensity value to delay the acquisition of the dark output value. These points will be described later.

[0038] Furthermore, the control unit 7 has a timer function. This timer function is used to automatically (periodically) acquire the output values ​​of the amounts of light incident on the optical sensors 41 to 43 even during standby. Furthermore, it is used to manage the time from the start of zero calibration to the acquisition of the dark output values.

[0039] The control unit 7 is configured by a computer equipped with a hardware processor such as a CPU, a ROM, and the like.

[0040] The memory unit 8 accumulates and stores a history of standby light intensity values ​​for the optical sensors 41 to 43 that were monitored for light intensity before zero calibration was performed. 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 delay time. The memory unit 8 also stores programs and other data. [Embodiment 1] Next, a first embodiment of the display light measurement device 1 will be described with reference to the state transition diagram of the display light measurement device 1 in FIG. 2, the flowcharts in FIGS. 3 to 5, and an example of a timing chart in FIGS. 6A to 6C.

[0041] This embodiment 1 is applied to a method (pre-type) in which dark output values ​​for zero calibration are acquired and stored in advance before measurement is performed. As described above, the dark output values ​​are output values ​​acquired in a light-blocking state in which the optical paths of the optical sensors 41 to 43 are closed.

[0042] 2, when the power is turned on, the display light measurement device 1 performs a startup process in step S01. When the display light measurement device 1 receives a zero calibration execution command, it performs zero calibration in step S02.

[0043] After the zero calibration is completed, the display light measurement device 1 goes into a standby state in step S03. When a zero calibration execution command is received in the standby state, the display light measurement device 1 returns to step S02 and performs the zero calibration.

[0044] When a measurement execution command is received in the standby state, the display light measurement device 1 performs measurement in step S04. After the measurement is completed, the display light measurement device 1 returns to step S03 and enters standby state again, and thereafter repeats the standby state of step S03, zero calibration of step S02 as needed, and measurement of step S04. When the user turns off the power, the device transitions to the stopped state.

[0045] The flowchart in Fig. 3 shows the operation in standby state, the flowchart in Fig. 4 shows the operation during zero calibration, and the flowchart in Fig. 5 shows the operation during measurement. 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 the operating program.

[0046] FIG. 6A shows a timing chart in a standby state, FIG. 6B shows a timing chart during zero calibration, and FIG. 6C shows a timing chart during measurement. (Startup process) The startup process is the same as that of a conventional display light measurement device, so a description thereof will be omitted. After the startup process is complete, the operation of the display light measurement device 1 is the same as that in the standby state described below, and light intensity monitoring is performed. (Operation in standby mode) In step S31 of FIG. 3, the control unit 7 sets the gain of each of the current integration circuits 51 to 53. During standby, the control unit 7 monitors the light intensity, but to avoid malfunction of the light intensity monitor due to exposure to high luminance, the gain of the current integration circuits 51 to 53 is set to minimum (the capacitance value of the integration capacitor is set to maximum). If the control unit 7 has sufficient computing power, the control unit 7 may control the gain of the current integration circuits 51 to 53 in real time. By using variable gain, the accuracy of the light intensity monitor can be improved.

[0047] Next, in step S32, 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.

[0048] Integration time: 20msec Exposure time: 100 msec (current integration circuit output is integrated 5 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, if the exposure time is too short, the response improves, but only a portion of the light emission waveform is picked up, 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, which is a nearly common multiple, was selected to ensure synchronization with both the universal standards NTSC and PAL.

[0049] 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 best to set the exposure time to a natural number multiple of the period of the vertical synchronization signal.

[0050] 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 limited to this.

[0051] Considering the response to the amount of exposed light, it is more appropriate to have a shorter light intensity monitor period. However, a shorter period places a burden on the control unit 7. Taking this into consideration, a period 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 of the 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 period shorter than the exposure time.

[0052] 3, the control unit 7 performs photometry (integration) under the conditions determined in step S32. The control unit 7 repeatedly performs photometry by performing the following steps (1) to (3) until a measurement execution command is received. (1) As shown in the "integration circuit" section of the timing chart in Fig. 6A, the control unit 7 starts integration after resetting each of the current integration circuits 51 to 53. 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. 6A, the control unit 7 samples and holds the output values ​​of the current integration circuits 51 to 53 after a predetermined time (20 msec) has elapsed. (3) After completion, the process returns to (1), and the control unit 7 converts the values ​​held in (2) into digital data in the A / D converters 61 to 63 at the subsequent stage.

[0053] In this example, the current integration circuits 51-53 are operated even during standby periods when light intensity monitoring is not being performed. The operation of the current integration circuits 51-53 resets the integration capacitance, preventing the current integration circuits 51-53 from falling into an oversaturated state. This is to prevent the current integration circuits 51-53 from falling into an oversaturated state, as it takes time for them to return to an appropriate state. Note that the A / D conversion by each A / D converter 61-63 is performed by extracting only data relevant to light intensity monitoring, in order to reduce the load on the control unit 7.

[0054] In step S34 of FIG. 3, the control unit 7 performs residue flag processing (see the "Calculation (control unit)" item in the timing chart of FIG. 6A). Specifically, the control unit 7 first converts the data acquired in step S33 into a standby light intensity value. When exposure is divided into multiple times as in this embodiment, the control unit 7 performs conversion processing on a value obtained by averaging the data for each division. The conversion processing includes dark output correction, circuit gain calibration, and integral time normalization.

[0055] Next, the control unit 7 compares the obtained standby light intensity value with a threshold value to determine whether or not the intensity is at a level that would cause a decrease in the accuracy of zero calibration. If the standby light intensity value exceeds the threshold value, the control unit 7 sets a residue flag indicating that charge remains in the integration capacitors of the current integration circuits 51-53. This process is performed each time photometry is performed in step S33, 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 optical sensors 41-43 (XYZ) exceeds the threshold value, but this is not limiting. For example, it may be determined whether the standby light intensity value of only a specific optical sensor exceeds the threshold value. (Operation during zero calibration) When the control unit 7 receives a command to execute zero calibration, it checks whether the residue flag information is blank in step S21 of Fig. 4. The reason for this is that, for example, when zero calibration is executed immediately after startup, there may be cases where not even a single standby light intensity value is obtained by the light intensity monitor. If the information is blank, the light intensity monitor is executed once.

[0056] Next, in step S22, the control unit 7 closes the light blocking means (shutter) 91 to acquire the dark output value, thereby blocking the optical path to the optical sensors 41 to 43. In this embodiment, in order to reduce errors caused by leaking light, the light attenuating means 92 is also forcibly inserted into the optical path. However, the light attenuating means 92 does not have to be inserted into the optical path.

[0057] Next, in step S23, the control unit 7 determines whether or not a residue flag exists, i.e., whether the residue flag is set. If the residue flag is set (YES in step S23), the process proceeds to step S24, where the control unit 7 determines a delay time. The delay time is the time for delaying the start of acquisition of dark output values ​​for zero calibration in order to eliminate residual charge in the integration capacitor. In this embodiment, a fixed value of 2.16 seconds is used as the delay time to ensure the required accuracy at low brightness.

[0058] Next, the control unit 7 performs a postponement process in step S25. That is, the control unit 7 sets a postponement time and waits for the postponement time before acquiring the dark output value. After the postponement time has elapsed, the process proceeds to step S26. In this embodiment, even during the postponement time, the current integration circuits 51 to 53 perform an integration operation and reset to remove charge in order to reduce the residual charge in the integration capacitor (see the timing chart in FIG. 6B). 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.

[0059] If the residue flag is not set in step S23 (NO in step S23), the residual charge does not affect the accuracy of the zero calibration, and the process proceeds directly to step S26.

[0060] In step S26, the control unit 7 acquires dark output values ​​under a plurality of predetermined photometric conditions. In this embodiment, as shown by the timing chart in Fig. 6B, the control unit 7 acquires dark output values ​​four times under the condition of an exposure time of 1 / 30 [sec] (one integration time) while switching the gains of the current integration circuits 51 to 53.

[0061] In step S27, the control unit 7 performs arithmetic processing on the dark output value acquired in step S26 as necessary to generate a zero calibration value. One example of the arithmetic processing is normalization by integration time. The generated zero calibration value is stored in the memory unit 8 or the like.

[0062] In step S28, the control unit 7 opens the light blocking means 91 in preparation for measurement, and opens the optical paths to the optical sensors 41 to 43. (Operation when measurement is performed) When the control unit 7 receives the measurement execution command, it stops the light intensity monitor (discards the data if it is in the middle of the measurement) and performs the measurement according to the normal procedure in step S41 of Fig. 5. When performing the measurement, the control unit 7 performs gain switching of the current integration circuits 51 to 53 and derives the photometric conditions as necessary, and then performs the integration (measurement).

[0063] 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 accumulation). In step S42, the control unit 7 converts the output value acquired by the measurement in step S41 into a measurement index value (e.g., luminance value, chromaticity value). Specifically, the output value is subjected to zero calibration processing to calibrate offset errors, and then a normal output value conversion calculation process is performed to generate the target index value. After the calculation is completed, the display light measurement device 1 transitions to a standby state (step S03 in FIG. 2).

[0064] In this manner, in this first embodiment, a delay time is set before the start of acquisition of dark output values ​​in response to the reception of a command to execute zero calibration, and the start of acquisition of dark output values ​​is delayed. Therefore, within this delay time, residual charges remaining in the integrating capacitors of the current integrating circuits 51 to 53 are eliminated. Therefore, a reduction in the accuracy of zero calibration due to residual charges can be suppressed by a simple method. [Embodiment 2] This second embodiment is also applied to a method (advance type) in which the dark output value for zero calibration is acquired and stored in advance before measurement is performed.

[0065] In the first embodiment, a fixed value is used as the postponement time.

[0066] In contrast to this, in the second embodiment, the postponement time is adjusted according to the standby light amount value. (Operation in standby mode) The operation of the display light measurement device 1 in the standby state is the same as the operation example in the first embodiment shown in Fig. 3, except for the residue flag processing in step S34. Therefore, the operation will be described using the flowchart in Fig. 3.

[0067] In the residue flag processing in step S34, the control unit 7 converts the data acquired in step S33 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. Up to this point, it is the same as in the first embodiment.

[0068] The control unit 7 determines whether the standby light intensity value is at a level that will cause a decrease in the accuracy of zero calibration, 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.

[0069] In the example of FIG. 7, the standby light intensity value is acquired and stored every 0.2 seconds. Furthermore, 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, and 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. Furthermore, 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.

[0070] 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 value 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 a lookup table (LUT) that determines the postponement time, which will be described later. (Operation during zero calibration) The operation during zero calibration is the same as that in the first embodiment, except for the content of the process for determining the postponement time in step S24 in Fig. 4. Therefore, the operation will be described using the flowchart in Fig. 4.

[0071] When the control unit 7 receives the command to execute zero calibration, it stops the light intensity monitor (discards the data if it is in the middle of the process). The control unit 7 checks the residue flag information in step S21, closes the shutter in step S22, and then determines whether or not there is a residue flag, i.e., whether the residue flag is set, in step S23. If the residue flag is set (YES in step S21), the process proceeds to step S22.

[0072] 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 second embodiment, the control unit 7 determines the requested extension time from the LUT 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.

[0073] The LUT in FIG. 8 is set to a requested postponement time when the maximum value of the standby light intensity values ​​stored as a history is used as an input parameter. As described 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 requested 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 dissolving residual charge. Note that the method for determining the requested postponement time is not limited to this. For example, the amount of change in light intensity or the history shape may be added to the input parameters, or the requested postponement time may be determined based only on the most recent value without storing the standby light intensity history. The requested postponement time may also be derived from a calculation formula.

[0074] 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.

[0075] Deferral time = Request deferral time - Elapsed time = 1.63 seconds - 0.60 seconds = 1.03 seconds 4, the control unit 7 sets the determined postponement time and waits for the start of the dark output value acquisition operation. When the postponement time has elapsed, the processes of steps S24 and S25 are performed. The processes of steps S24 and S25 are the same as those in the first embodiment. (Operation when measurement is performed) The operation is the same as that of the first embodiment.

[0076] According to this second embodiment, multiple standby light intensity values ​​for each monitored exposure are accumulated for a certain period of time, and the required postponement time is determined based on the accumulated standby light intensity values. Therefore, an appropriate postponement time is determined according to 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 postponement time even when the exposure light intensity (residual charge in the integrating capacitor) is small, resulting in wasted time. [Embodiment 3] This third embodiment is applied to a method (instant type) in which a dark output value is acquired for each optical measurement under the same photometric conditions as those of the optical measurement, consecutively.

[0077] A state transition diagram of the display light measurement device 1 in embodiment 3 is shown in Figure 9. In this embodiment 3, zero calibration is performed immediately after measurement in step S04. Zero calibration in step S02 may also be performed immediately before measurement in step S04. Figure 10 shows an example of a timing chart in embodiment 3. (Operation in standby mode) The operation of the display light measurement device 1 in the standby state is the same as that of the second embodiment, except for the following points.

[0078] That is, the control unit 7 acquires the standby light intensity value at regular time intervals. The control unit 7 stores, while updating, a history of the standby light intensity values ​​from the most recent value up to a predetermined period in the past in the storage unit 8. However, in this embodiment 3, the light intensity value acquired by the measurement performed immediately before the execution command of the zero calibration is also included in the same history as the standby light intensity value and is used to determine the request postponement time. (Operation during zero calibration) The operation of the display light measurement device 1 during zero calibration is the same as in the second embodiment except for the following points.

[0079] That is, in the process of determining the postponement time in step S24 of FIG. 4, as described above, the postponement time is determined while including the light intensity value obtained in the measurement performed immediately before the command to execute zero calibration in the same history as the standby light intensity value.

[0080] Moreover, since the third embodiment is a method applied to the immediate type, the control unit 7 acquires the dark output value only once under the same conditions as the immediately preceding optical measurement in the integration process of step 26. Therefore, also in the calculation process of step S27, a zero calibration value for one dark output value is generated. (Operation when measurement is performed) The operation is the same as that of the first embodiment.

[0081] In this embodiment 3, multiple monitored 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 from the immediately preceding light measurement. This allows for precise adjustment of the postponement time, preventing inconveniences such as setting an unnecessarily long postponement time when the light intensity is low, resulting in wasted time. [Other embodiments] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

[0082] For example, when a command to execute zero calibration is received, the light blocking means 91 and / or the light attenuating means 92 may be present in the optical path to the optical sensors 41 to 43. In this case, since the incident light is blocked or attenuated, the amount of light reaching the optical sensors 41 to 43 is extremely small, and residual charges in the current integration circuits 51 to 53 do not pose a problem. Therefore, steps S21 to S25 in Fig. 4 may be omitted, and there is no need to set a postponement time.

[0083] Furthermore, the light quantity monitoring is performed using at least one of the three optical sensors 41 to 43 for measurement, but a dedicated optical sensor for light quantity monitoring may also be provided.

[0084] In addition, the user may 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.

[0085] Furthermore, in the third embodiment, dark output values ​​for zero calibration were acquired immediately after optical measurement. However, dark output values ​​may be acquired immediately before optical measurement. In this case, if the measurement conditions for optical measurement are known, dark output values ​​are acquired under the same conditions as those measurement conditions. If the measurement conditions for optical measurement are unknown, dark output values ​​may be acquired under multiple conditions as in the first embodiment.

[0086] In yet another embodiment, the control unit 7 may execute a light intensity monitor process during the postponement time to directly measure the light intensity output value and determine the postponement time based on the measured value. This process is shown in the flowchart of FIG. 11 and the timing chart of FIG. 12.

[0087] As shown in the postponement processing of step S25 in FIG. 11, the control unit 7 monitors the light intensity value during the postponement time determined in step S24 in step S251, for example, under the conditions of an exposure time of 20 msec and one integration. In step S252, the control unit 7 determines whether or not there is residual charge in the current integration circuits 51-53 based on whether or not the standby light intensity value is within the allowable range. If there is residual charge in the current integration circuits 51-53 (YES in step S252), the control unit 7 repeats the light intensity value monitoring of step S251 and the determination of whether or not there is residual charge in step S252 until there is no residual charge. When there is no residual charge (NO in step S252), the postponement processing ends. The processing other than the postponement processing of step S25 shown in the flowchart of FIG. 11 is the same as the processing shown in the flowchart of FIG. 4.

[0088] In addition, as yet another embodiment, the control unit 7 may execute the light amount monitoring process once at the beginning of the extension time, and determine the extension time again from the value obtained. [Explanation of symbols]

[0089] 1. Display light measurement device 2. Light collecting section 3 Optical path branching section 41~43 Optical sensor 51~53 Current integration circuit 61~63 A / D converter 7 Control Unit 8 Memory section 91 Shading means 92 Light reduction means

Claims

1. An optical sensor; an integration circuit having an integration capacitor for accumulating the charge output from the photosensor; a light blocking means capable of blocking incident light to the optical sensor; a calibration means for acquiring a dark output value, which is an output value of the amount of light incident on the optical sensor, in a state in which the light incident on the optical sensor is blocked by the light blocking means, and for performing zero calibration based on the acquired dark output value; a control means for setting a delay time for delaying acquisition of the dark output value; A display light measurement device comprising:

2. a monitoring means for monitoring an output value of the amount of light incident on the optical sensor before zero calibration is performed by the calibration 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. 3. The display light measurement device according to claim 1, wherein the control means adjusts the delay time based on the output value of the incident light amount monitored by the monitoring means.

4. 3. A display light measurement device according to claim 1, wherein when the calibration means receives a command to perform zero calibration, if the light blocking means has already blocked incident light to the optical sensor, the control means does not set the postponement time.

5. a dimming means; 3. A display light measurement device according to claim 1, wherein when the calibration means receives a command to perform zero calibration, if the dimming means is dimming the light incident on the optical sensor, the control means does not set the postponement time.

6. 3. The display light measuring device according to claim 1, wherein the output value of the incident light amount monitored by the monitoring means is stored for a certain period of time.

7. 3. The display light measurement device according to claim 1, wherein the capacitance of the integrating capacitor is maximized except for a period during which a measurement execution command is received and measurement is being executed.

8. 3. The display light measuring device according to claim 2, wherein the monitoring of the output value of the amount of incident light by the monitoring means is performed by setting the exposure time of the optical sensor in the range of 1 / 120 to 1 / 10 seconds.

9. 3. The display light measurement device according to claim 1, wherein a user can select whether or not to set the postponement time.

10. An optical sensor; an integration circuit having an integration capacitor for accumulating the charge output from the photosensor; a light blocking means capable of blocking incident light to the optical sensor; A display light measurement device comprising: a dark output value, which is an output value of the amount of light incident on the optical sensor, is acquired in a state in which the incident light on the optical sensor is blocked by the light blocking means, and zero calibration is performed based on the acquired dark output value; setting a delay time for delaying acquisition of the dark output value; A display light measurement method comprising:

11. The display light measurement method according to claim 10, wherein the output value of the incident light amount to the optical sensor is monitored before zero calibration is performed, and the postponement time is set when the output value of the monitored incident light amount exceeds a threshold value.

12. 12. The display light measurement method according to claim 10, wherein the delay time is adjusted based on the output value of the monitored amount of incident light.

13. An optical sensor; an integration circuit having an integration capacitor for accumulating the charge output from the photosensor; a light blocking means capable of blocking incident light to the optical sensor; A computer of a display light measurement device equipped with a dark output value, which is an output value of the amount of light incident on the optical sensor, is acquired in a state in which the incident light on the optical sensor is blocked by the light blocking means, and zero calibration is performed based on the acquired dark output value; setting a delay time for delaying acquisition of the dark output value; A program for executing a process.

14. The program according to claim 13, wherein the output value of the incident light amount to the optical sensor is monitored before zero calibration is performed, and when the output value of the monitored incident light amount exceeds a threshold value, the program causes the computer to execute a process of setting the postponement time.

15. 15. The program according to claim 13, which causes the computer to execute a process of adjusting the postponement time based on the output value of the monitored amount of incident light.

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