KR102426522B1 - optical instrumentation - Google Patents

Abstract

The range of luminance that can be measured by the optical measuring device is expanded without complicating the optical measuring device. In an optical measuring device, an optical sensor receives light from a display, outputs a photocurrent corresponding to the light, and an integrator temporally continuously integrates the photocurrent to output an integration signal. The required precision for the measured value, the estimated luminance of the light, and the period of time change of the luminance and chromaticity of the light are obtained. The exposure time is determined from the required precision and the estimated luminance. The integration time is determined such that the integrator is not saturated and the exposure time is a common multiple of the period and integration time. the exposure period consists of at least one integration period, the length of the exposure period becomes the determined exposure time, each length of the at least one integration period becomes the determined integration time, and the integrator generates a photocurrent in the at least one integration period The integrator is controlled to integrate and output at least one integration signal, respectively. A measurement value is calculated from the at least one integral signal.

Description

optical instrumentation

The present invention relates to an optical measuring device.

In the optical measuring device for measuring the luminance and chromaticity of a display, the optical sensor receives light from the display and outputs a photocurrent according to the received light, the integrator integrates the output photocurrent to output an integration signal, The measured value is measured from the integral signal output from the calculation unit. However, there is a restriction on the integration time indicating the length of the integration period during which the integrator integrates the optical signal.

The luminance and chromaticity of the display, including transient response, change periodically with time. For this reason, the measurement of the luminance and chromaticity of the display must be performed in synchronization with the periodic time changes of the luminance and chromaticity of the display. Accordingly, the integration time is limited to an integer multiple of the period of the temporal change of the luminance and chromaticity of the display.

The period of time change of the luminance and chromaticity of the display corresponds to the reciprocal of the frame rate or the length of the vertical sync (Vsync) period. For this reason, the integration time is limited to the reciprocal of the frame rate or an integer multiple of the length of the Vsync period. However, in a liquid crystal display (LCD) in which inversion driving is performed to prevent ghosting, flicker occurs in principle. For this reason, when the optical measuring device measures the luminance and chromaticity of LCD, in order to measure the luminance and chromaticity accurately without being affected by flicker, the period of time change of the luminance and chromaticity is twice the reciprocal of the frame rate or It is considered to be twice the length of the Vsync period, and the integration time is limited to an integer multiple of that period.

In the optical measurement device, in order to expand the range of luminance that can be measured, a plurality of gains can be selected in the integrator, and when exposure is not appropriate exposure, the selected gain is changed. For example, when exposure is over or under than appropriate exposure, gain down or gain up is implemented, respectively. The technique described in Patent Document 1, as an example, makes it possible to measure a wide range of luminance from low luminance to high luminance while realizing a high S/N ratio.

Further, in other optical measurement devices, in order to expand the range of the luminance that can be measured, a light-sensitive filter (ND filter) can be inserted into the optical path of the light incident on the optical sensor, so that the exposure is appropriate. In the case of being over, the photosensitive filter is inserted into the optical path and the amount of light incident on the optical sensor is reduced.

Japanese Laid-Open Patent Publication No. 2005-321313

However, in the conventional optical measuring device, in order to expand the range of luminance that can be measured, it is necessary to select a plurality of gains in the integrating circuit, and to form a photosensitive mechanism (ND mechanism) for inserting the ND filter. There were problems such as For this reason, in order to correct the fluctuation|variation of the environment in which measurement is performed, individual deviation of a measurement object, etc., many correction values and calculations are needed, and the storage capacity for it is needed. For example, a large number of offset/gain corrections, environmental correction values, and the like respectively corresponding to a large number of gains are required.

In particular, when the optical measuring device measures the luminance and chromaticity of the display, since the integration time is limited as described above, the appropriate exposure changes according to the length of the Vsync period and the saturation value for the luminance changes. For this reason, the number of necessary gains increases, and the load applied to an optical measuring apparatus becomes large.

It is also possible to expand the range of the luminance that can be measured with a small number of gains by increasing the gain pitch representing the difference between two adjacent gains in the selectable few gains. However, when the gain pitch is made large, the problem that the measurement conditions under which exposure becomes under than appropriate exposure in the selected gain generate|occur|produces arises.

The invention described below aims to solve this problem. A solution to the problem described below is to expand the range of luminance that the optical measurement device can measure without complicating the optical measurement device.

In an optical measuring device, an optical sensor receives light from a display, outputs a photocurrent corresponding to the light, and an integrator temporally continuously integrates the photocurrent to output an integration signal.

The required precision for the measured value, the estimated luminance of the light, and the period of time change of the luminance and chromaticity of the light are obtained.

The exposure time is determined from the required precision and the estimated luminance. The integration time is determined such that the integrator is not saturated and the exposure time is a common multiple of the period and integration time.

the exposure period consists of at least one integration period, the length of the exposure period becomes the determined exposure time, each length of the at least one integration period becomes the determined integration time, and the integrator generates a photocurrent in the at least one integration period The integrator is controlled to integrate and output at least one integration signal, respectively.

A measurement value is calculated from the at least one integral signal.

According to the invention described below, the range of luminance that can be measured by the optical measuring device can be expanded without complicating the optical measuring device.

The object, characteristic, aspect, and advantage of this invention become clearer with the following detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows the optical measurement apparatus of 1st Embodiment.
Fig. 2 is a flowchart showing a flow of measurement in the optical measurement device according to the first embodiment.
Fig. 3 is a diagram showing a look-up table (LUT) for determining an exposure time from a required S/N ratio and an estimated luminance in the optical measurement apparatus of the first embodiment.
Fig. 4 is a diagram showing a look-up table (LUT) for determining an integration time from a requested S/N ratio, a vertical synchronization (Vsync) frequency, and an estimated luminance in the optical measuring apparatus of the first embodiment.
Fig. 5 is a timing chart showing an example of temporal changes in the states of a display to be measured by the optical measuring device of the first embodiment and an integrator provided in the optical measuring device.
Fig. 6 is a timing chart showing an example of temporal change in states of a display to be measured by the optical measuring device of the first embodiment and an integrator provided in the optical measuring device.
Fig. 7 is a timing chart showing an example of temporal change in the state of the optical measuring device according to the first embodiment and an integrator provided in the optical measuring device.

1 Optical instrumentation

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows the optical measurement apparatus of 1st Embodiment. Fig. 2 is a flowchart showing a flow of measurement in the optical measuring device according to the first embodiment.

The optical measurement device 1000 shown in FIG. 1 measures the luminance and chromaticity of a display, and includes an optical sensor 1020 , an integrator 1021 , a control unit 1022 , and a peripheral part 1023 . The optical measurement device 1000 may include structures other than these structures.

In the optical measurement device 1000 , the optical sensor 1020 receives light from the display and outputs a photocurrent corresponding to the received light. Further, the integrator 1021 integrates the output photocurrent, and outputs an integration signal according to the amount of electric charge accumulated by the integration. Moreover, the control part 1022 calculates a measured value from the output integral signal.

The integrator 1021 includes an integrator circuit 1040 , an integrator circuit 1041 , a switch 1042 , and a switch 1043 .

The integrating circuits 1040 and 1041 integrate the photocurrent. The switches 1042 and 1043 switch the integrating circuit that integrates the photocurrent between the integrating circuit 1040 and the integrating circuit 1041 according to the control by the control unit 1022 . For this reason, the integrator 1021 can integrate the photocurrent continuously without interruption in time.

The integrator 1021 may have a plurality of selectable gains. Thereby, the range of the luminance that can be measured is further expanded.

The control unit 1022 is a computer operating in accordance with the installed program, and includes a required precision acquisition unit 1060, an approximate luminance acquisition unit 1061, a period acquisition unit 1062, an exposure time determination unit 1063, and an integration time determination unit. A unit 1064 , an integrator control unit 1065 , and an arithmetic unit 1066 are provided. Hardware that does not execute a program may bear all or part of the processing that the computer is responsible for.

The peripheral portion 1023 includes a display portion 1080 and an operation portion 1081 .

In the measurement, in response to the reception of the measurement command from the operator, steps S101 to S105 shown in FIG. 2 are executed.

In step S101, measurement conditions are acquired. The measurement conditions may be obtained from an operation with respect to a hardware switch provided in the operation unit 1081 , or may be obtained from an operation performed using the operation unit 1081 with respect to a graphical user interface (GUI) displayed on the display unit 1080 . .

In acquisition of measurement conditions, the required precision acquisition part 1060 acquires the requested|required S/N ratio with respect to a measured value. The required precision acquisition unit 1060 receives the designation of one mode included in three modes, a high-precision mode, a standard mode, and a high-speed mode, respectively corresponding to the three requested S/N ratios, thereby Obtain the requested S/N ratio. The method of obtaining the requested S/N ratio may be changed. For example, the requested precision acquisition unit 1060 receives the designation of one precision range included in the plurality of precision ranges respectively corresponding to the plurality of requested S/N ratios, and thus the requested S/N corresponding to the specified precision range. The N ratio may be obtained. The precision range is, for example, "... % below","… % at … %", etc. The required precision other than the requested S/N ratio may be acquired.

Further, in acquiring the measurement conditions, the period acquiring unit 1062 acquires the Vsync time, which is the length of the vertical synchronization (Vsync) period that coincides with the period of time changes in luminance and chromaticity of the display. The Vsync time is acquired from the operation performed using the operation unit 1081 with respect to the GUI displayed on the display unit 1080 . The Vsync frequency may be acquired, and the Vsync time may be acquired from the acquired Vsync frequency. The method of acquiring the Vsync time may be changed. For example, a Vsync signal may be input to the period acquiring unit 1062 and the period acquiring unit 1062 may acquire the Vsync time from the inputted Vsync signal. When the luminance and chromaticity of the liquid crystal display to which the inversion driving is performed are measured, instead of the Vsync time, a time twice the Vsync time, which coincides with the period of time change of the luminance and chromaticity of the liquid crystal display, is obtained.

In the subsequent step S102, the estimated luminance of the light from the display is acquired. Step S102 may be executed simultaneously with step S101.

In acquisition of the estimated luminance, the integrator control unit 1065 controls the integrator 1021 . Control is performed such that the integrator 1021 integrates the photocurrent in an initial integration period preceding a plurality of integration periods to be described later and outputs an initial integration signal. In addition, the estimated luminance acquisition unit 1061 acquires the estimated luminance of the light from the display from the initial integral signal. The initial integration period may be short. The method of acquiring the approximate luminance may be changed. An example thereof will be described later.

In subsequent step S103, measurement conditions are determined.

In determining the measurement conditions, the exposure time determining unit 1063 determines the exposure time from the acquired required S/N ratio and the estimated luminance. The exposure time can be changed according to the required S/N ratio. The exposure time may be determined by a function having the required S/N ratio and the estimated luminance as variables, or may be determined by a lookup table (LUT). The said function is a function represented by Formula (1), for example. f (requested S/N ratio, estimated luminance) contained in Formula (1) is an integer. The LUT is, for example, a lookup table for determining the exposure time from the required S/N ratio and the estimated luminance shown in FIG. 3 .

Exposure time = Vsync time x f (requested S/N ratio, estimated luminance)... (One)

Moreover, in the acquisition of the measurement conditions, the integration time determining unit 1064 determines from the obtained estimated luminance that the integrator 1021 is not saturated and the S/N ratio is not saturated and the maximum unsaturated integral is the upper limit of the appropriate integration time. decide the time Further, the integration time determining unit 1064 determines the integration time and the number of repetitions so that the integration time is shorter than the determined maximum unsaturated integration time, and the determined exposure time is a common multiple of the acquired Vsync time and the integration time. Thereby, the integration time is determined at which the integrator 1021 is not saturated and the exposure time is a common multiple of the Vsync time and the integration time.

The integration time is preferably the longest which satisfies the above-mentioned conditions, which satisfy the formulas (2) and (3). In addition, the common multiple is preferably the least common multiple. Thereby, the electric charge accumulated in the integrator 1021 within a range in which the integrator 1021 is not saturated increases, and the S/N ratio is improved.

Number of repetitions = Int (exposure time/maximum non-saturation integral time) + 1 ... (2)

Integration time = exposure time/number of repetitions ... (3)

The determination of the exposure time, the determination of the maximum unsaturated integral time, and the determination of the integration time are performed in separate steps, but may be performed in the same step. For example, the integration time may be directly determined by the LUT which determines the integration time from the required S/N ratio, the Vsync frequency and the estimated luminance so as to satisfy the condition described above, shown in Fig. 4 .

In subsequent step S104, measurement is performed.

In measurement, the integrator control unit 1065 controls the integrator 1021 . The control is that the exposure period consists of a plurality of integration periods, the number of the plurality of integration periods becomes the determined number of repetitions, the length of the exposure period becomes the determined exposure time, and the integration time at which each length of the plurality of integration periods is determined. and the integrator 1021 integrates the photocurrent in a plurality of integration periods to output a plurality of integration signals, respectively. Thereby, measurement by the determined measurement conditions is performed.

In subsequent step S105, calculation and output of the measured value are performed.

In the calculation and output of the measured values, the calculating unit 1066 acquires a plurality of integral signal values each indicating the magnitudes of the outputted plurality of integral signals, and converts the average value of the obtained plurality of integral signal values to a value per unit time. It converts and performs necessary arithmetic processing on the value obtained by conversion, and calculates the measured values of luminance and chromaticity. Thereby, measured values of luminance and chromaticity are calculated from the plurality of integral signals. The calculation method of the measured values of luminance and chromaticity may be changed. In addition, the calculation unit 1066 outputs the calculated values of luminance and chromaticity.

According to such measurement in the optical measurement device of the first embodiment, the number of selectable gains can be reduced, the load applied to the optical measurement device can be reduced, and the optical measurement device can be simplified. For this reason, the range of luminance that can be measured by the optical measuring device can be expanded without complicating the optical measuring device.

2 Relationship between exposure time, integration time, and Vsync time under measurement conditions

5 and 6 are timing charts showing examples of temporal changes in the states of a display to be measured by the optical measuring device of the first embodiment and an integrator provided in the optical measuring device.

5 shows an example when the Vsync frequency of the display is high. 6 illustrates an example in which the Vsync frequency of the display is low.

In the example shown in Fig. 5, the exposure period 1100 having the exposure time necessary to secure the required S/N ratio is equally divided into eight Vsync periods 1120. The Vsync time is, for example, about 1 millisecond to 2 seconds. In addition, the exposure period 1100 is equally divided into five integration periods 1140 . For this reason, the exposure time is a common multiple of the integral time and the Vsync time. The integration time is shorter than the maximum unsaturated integration time.

In the example shown in Fig. 6, the exposure period 1160 having the exposure time required to secure the required S/N ratio is equally divided into four Vsync periods 1180. The Vsync time is, for example, about 1 millisecond to 2 seconds. In addition, the exposure period 1160 is equally divided into five integration periods 1200 . For this reason, the exposure time is a common multiple of the integral time and the Vsync time. The integration time is shorter than the maximum unsaturated integration time.

3 An example of how to obtain the estimated luminance

Fig. 7 is a timing chart showing an example of temporal change in the state of the optical measuring device according to the first embodiment and an integrator provided in the optical measuring device.

As shown in Fig. 7(a) , the state of the optical measurement device 1000 changes from the standby state 1220 to the measurement state 1240 at the timing T1 when the measurement command is received from the operator, and the exposure time has elapsed from the timing T1 At timing T2, the measurement state 1240 changes to the standby state 1260.

Further, as shown in Fig. 7(b), the state of the integrator 1021 changes from the state 1280 in which the integrator circuit reset operation is performed at the timing T1 to the state 1300 in which the integrating operation is performed, and at the timing T2 It changes from the state 1300 in which the integration operation is being performed to the state 1320 in which the integration circuit reset operation is being performed. Accordingly, when the optical measurement device 1000 is in the standby state 1220 and 1260, the integrator 1021 is in the states 1280 and 1320 in which the integrator circuit reset operation is being performed, respectively, and the optical measurement device 1000 is in the measurement state. In the case of 1240, the state 1300 in which the integral operation is being performed is obtained.

The integrator 1021 can always integrate the optical signal even in the states 1280 and 1320 in which the integration circuit reset operation is being performed, and can output the integrated signal. For this reason, the integrator control unit 1065 controls the integrator 1021 to integrate the photocurrent in the repeatedly arriving standby integration period 1340 to output the standby integration signal, and the estimated luminance acquisition unit 1061 performs exposure The estimated luminance may be obtained by considering the standby integration period that arrived immediately before the period as the initial integration period. Thereby, since the estimated luminance is acquired before the timing T1 at which measurement is started, the time required for measurement is shortened. The length of the integral waiting time period 1340 that repeatedly arrives may be the shortest settable time.

Although this invention has been described in detail, the foregoing description, in all respects, is illustrative and not restrictive of the invention. It is to be understood that numerous modifications not illustrated can be made without departing from the scope of this invention.

1000: optical measuring device
1020: light sensor
1021 : Integrator
1022: control unit
1060: required precision acquisition unit
1061: approximate luminance acquisition unit
1062: cycle acquisition unit
1063: exposure time determining unit
1064: integral time determining unit
1065: integrator control unit
1066: arithmetic unit

Claims (6)

an optical sensor for receiving light from the display and outputting a photocurrent according to the light;
an integrator for outputting an integral signal by integrating the photocurrent continuously in time;
a required precision acquisition unit for acquiring the required precision for the measured value;
an approximate luminance acquisition unit for acquiring the approximate luminance of the light;
a period acquisition unit for acquiring a period of time change of the luminance and chromaticity of the light;
an exposure time determining unit for determining an exposure time from the required precision and the estimated luminance;
an integration time determining unit that determines an integration time of the integrator so that the integrator is not saturated and the exposure time is a common multiple of the period and the integration time;
an exposure period consists of at least one integration period, the length of the exposure period is the exposure time, each length of the at least one integration period is the integration time, and the integrator is the at least one integration period. an integrator control unit for controlling the integrator to output at least one integral signal by integrating the photocurrent into
and an arithmetic unit for calculating the measured value from the at least one integral signal. The method of claim 1,
The integrator control unit controls the integrator so that the integrator outputs an initial integration signal by integrating the photocurrent in an initial integration period preceding the at least one integration period;
and the estimated luminance acquiring unit acquires the estimated luminance from the initial integral signal. 3. The method of claim 2,
The integrator control unit controls the integrator to integrate the photocurrent in a standby integration period that repeatedly arrives to output an integration signal in standby,
The initial integration period is a standby integration period that arrives immediately before the exposure period. 4. The method according to any one of claims 1 to 3,
The common multiple is a least common multiple. 4. The method according to any one of claims 1 to 3,
The exposure time can be changed according to the required precision. 4. The method according to any one of claims 1 to 3,
The integrator is an optical measuring device having a plurality of selectable gains.

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