KR20190133030A - Optical measuring device - Google Patents

Abstract

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

Description

Optical measuring device

The present invention relates to an optical measuring device.

In the optical measuring device for measuring the brightness and chromaticity of the display, an optical sensor receives light from the display and outputs a light current according to the received light, integrates the light current outputted by the integrator, and outputs an integrated signal, The calculation unit measures the measured value from the output integrated signal. However, there is a limitation in the integration time indicating the length of the integration period in which the integrator integrates the optical signal.

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

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

In the optical measuring device, in order to expand the range of the luminance that can be measured, a plurality of gains can be selected in the integrator, and when the exposure is not an appropriate exposure, the selected gain is changed. For example, when exposure is more or less than appropriate exposure, gain down or gain up is performed, respectively. As an example, the technique of patent document 1 makes it possible to measure the range of the wide brightness | luminance from low brightness to high brightness, realizing a high S / N ratio.

In another optical measuring device, a photosensitive filter (ND filter) can be inserted into an optical path of light incident on an optical sensor in order to expand the range of luminance that can be measured. If it is more over, the photosensitive filter is inserted into the optical path to reduce the amount of light incident on the optical sensor.

Japanese Laid-Open Patent Publication 2005-321313

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

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

It is also possible to enlarge the range of luminance which can be measured by a few gains by increasing the gain pitch indicating the difference between two adjacent gains in the selectable few gains. However, when the gain pitch is made large, the problem arises that the measurement conditions under which the exposure becomes less than the appropriate exposure occur at the selected gain.

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

In the optical measuring device, an optical sensor receives light from a display, outputs a photocurrent according to the light, and an integrator integrates the photocurrent continuously in time to output an integrated signal.

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

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

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

The measured value is calculated from at least one integrated signal.

According to the invention described below, the range of luminance that the optical measuring device can measure can be enlarged without complicating the optical measuring device.

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

1 is a block diagram showing an optical measuring device according to a first embodiment.
It is a flowchart which shows the flow of a measurement in the optical measuring device of 1st Embodiment.
FIG. 3 is a diagram showing a lookup table (LUT) for determining the exposure time from the required S / N ratio and the estimated luminance in the optical measuring device of the first embodiment.
4 is a diagram showing a lookup table (LUT) for determining the integration time from the required S / N ratio, the vertical synchronization (Vsync) frequency, and the estimated luminance in the optical measuring device of the first embodiment.
FIG. 5 is a timing chart showing an example of a time change in the state of the integrator included in the display and the integrator provided in the optical measuring device of the first embodiment.
FIG. 6 is a timing chart showing an example of a time-dependent change in the state of an integrator included in the display and the integrator provided in the optical measuring device of the first embodiment.
FIG. 7 is a timing chart showing an example of time variation of the state of the integrator included in the optical measuring device and the optical measuring device according to the first embodiment. FIG.

1 optical measuring device

1 is a block diagram showing an optical measuring device according to a first embodiment. It is a flowchart which shows the flow of a measurement in the optical measuring device of 1st Embodiment.

The optical measuring device 1000 shown in FIG. 1 measures the brightness and chromaticity of a display, and includes an optical sensor 1020, an integrator 1021, a control unit 1022, and a peripheral portion 1023. The optical measuring device 1000 may be provided with a structure other than these structures.

In the optical measuring device 1000, the optical sensor 1020 receives the light from the display and outputs a photocurrent corresponding to the received light. Integrator 1021 also integrates the output photocurrent, and outputs an integrated signal corresponding to the amount of charge accumulated by the integration. The control unit 1022 also calculates a measured value from the output integrated signal.

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

The integration circuits 1040 and 1041 integrate the photocurrent. The switches 1042 and 1043 switch the integration circuit for integrating the photocurrent under the control by the control unit 1022 between the integration circuit 1040 and the integration circuit 1041. For this reason, the integrator 1021 can integrate the light current without interrupting it continuously in time.

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

The control unit 1022 is a computer that operates in accordance with the installed program. The control unit 1022 is a computer that operates according to the installed program, and the required precision acquisition unit 1060, the estimated luminance acquisition unit 1061, the period acquisition unit 1062, the exposure time determination unit 1063, and the integral time determination A unit 1064, an integrator control unit 1065, and a calculation unit 1066 are provided. Hardware which does not execute a program may be in charge of all or part of the process which a computer handles.

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 on a hardware switch included 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 the acquisition of the measurement conditions, the required precision acquisition unit 1060 acquires the required S / N ratio for the measured value. The request precision acquiring unit 1060 corresponds to the designated mode by accepting designations of one mode included in three modes of high precision mode, standard mode, and high speed mode respectively corresponding to three required S / N ratios. Obtain the required S / N ratio. The acquisition method of the required S / N ratio may be changed. For example, the request precision acquiring unit 1060 accepts designation of one precision range included in a plurality of precision ranges respectively corresponding to a plurality of request S / N ratios, thereby requesting S / corresponding to the specified precision range. You may acquire N ratio. The precision range is, for example, “…”. % Below","… % To… Up to% "and the like. Request accuracy other than the required S / N ratio may be obtained.

In the acquisition of the measurement conditions, the period acquisition unit 1062 acquires the Vsync time which is the length of the vertical synchronization (Vsync) period corresponding to the period of the time change of the brightness and chromaticity of the display. The Vsync time is obtained from an 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 obtained from the obtained Vsync frequency. The acquisition method of the Vsync time may be changed. For example, the Vsync signal may be input to the period acquisition unit 1062, and the Vsync time may be acquired from the Vsync signal input to the period acquisition unit 1062. When the luminance and chromaticity of the liquid crystal display on which the inversion driving is performed are measured, instead of the Vsync time, twice the time of the Vsync time as the period of the time change of the luminance and chromaticity of the liquid crystal display is obtained.

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

In obtaining the estimated luminance, the integrator control unit 1065 controls the integrator 1021. The control is implemented such that the integrator 1021 integrates the photocurrent in the initial integration period preceding the plurality of integration periods described later to output the initial integration signal. In addition, the estimated luminance obtaining unit 1061 acquires the estimated luminance of the light from the display from the initial integrated signal. The initial integration period may be short. The acquisition method of the estimated luminance may be changed. An example thereof will be described later.

In subsequent step S103, measurement conditions are determined.

In the determination of the measurement conditions, the exposure time determining unit 1063 determines the exposure time from the obtained required S / N ratio and the estimated luminance. The exposure time can be changed in accordance with 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 the lookup table (LUT). This function is a function represented by Formula (1), for example. F (required S / N ratio, estimated luminance) contained in Formula (1) is an integer. The LUT is a lookup table for determining the exposure time from, for example, the required S / N ratio and the estimated luminance shown in FIG. 3.

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

In addition, in the acquisition of measurement conditions, the integration time determining unit 1064 is the maximum desaturation integral, which is the upper limit of an appropriate integration time that can ensure the S / N ratio without integrating the integrator 1021 from the acquired approximation luminance. Determine the time. In addition, the integration time determination unit 1064 determines the integration time and the number of iterations so that the integration time is shorter than the determined maximum desaturation integration time, and the determined exposure time is a multiple of the obtained Vsync time and integration time. Thereby, the integral time at which the integrator 1021 is not saturated and the exposure time is a common multiple of the Vsync time and the integration time is determined.

The integration time is preferably the longest one that satisfies the conditions described above, which satisfy the formulas (2) and (3). Moreover, the common multiple is preferably the minimum common multiple. These increase the charge accumulated in the integrator 1021 within the range where the integrator 1021 is not saturated, and the S / N ratio is improved.

Number of repetitions = Int (exposure time / maximum unsaturation integration time) + 1. (2)

Integral time = exposure time / repetition number. (3)

The determination of the exposure time, the determination of the maximum unsaturation integration time and the determination of the integration time are performed in a separate step, but may be performed in the same step. For example, the integration time may be directly determined by the LUT that determines the integration time from the required S / N ratio, the Vsync frequency, and the estimated luminance, so as to satisfy the above-described conditions.

In subsequent step S104, measurement is performed.

In the measurement, the integrator control unit 1065 controls the integrator 1021. The control includes an exposure period consisting of a plurality of integration periods, the number of repetition periods of which the number of integration periods is determined, the exposure time of which the length of the exposure period is determined, and the integration time of each length of the plurality of integration periods is determined. Then, the integrator 1021 is implemented to integrate the photocurrent in the plurality of integration periods and output the plurality of integrated signals, respectively. Thereby, measurement by the determined measurement conditions is performed.

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

In the calculation and output of the measured values, the calculation unit 1066 acquires a plurality of integrated signal values representing the magnitudes of the plurality of output integrated signals, respectively, and converts the average values of the obtained plurality of integrated signal values into values per unit time. It calculates, and calculates the measured value of brightness | luminance and chromaticity by performing the calculation process required for the value obtained by conversion. In this way, measured values of luminance and chromaticity are calculated from the plurality of integrated signals. The calculation method of the measured value of brightness | luminance and chromaticity may be changed. In addition, the calculating unit 1066 outputs the calculated values of the calculated luminance and chromaticity.

According to such measurement in the optical measuring device of the first embodiment, the number of selectable gains can be reduced, the load on the optical measuring device can be reduced, and the optical measuring device can be simplified. For this reason, the range of the brightness which an optical measuring device can measure can be expanded, without complicating an optical measuring device.

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

Each of FIG. 5 and FIG. 6 is a timing chart which shows the example of the time-change of the display used as the object of measurement by the optical measuring device of 1st Embodiment, and the state of the integrator with which the said optical measuring device is equipped.

5 shows an example in the case where the Vsync frequency of the display is high. 6 shows an example in the case where the Vsync frequency of the display is low.

In the example shown in FIG. 5, the exposure period 1100 having the exposure time necessary for securing 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, exposure time becomes the common multiple of integration time and Vsync time. The integration time is shorter than the maximum unsaturation integration time.

In the example shown in FIG. 6, the exposure period 1160 having the exposure time necessary 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, exposure time becomes the common multiple of integration time and Vsync time. The integration time is shorter than the maximum unsaturation integration time.

Another example of how to obtain approximate luminance

FIG. 7 is a timing chart showing an example of time variation of the state of the integrator included in the optical measuring device and the optical measuring device according to the first embodiment. FIG.

As shown in FIG. 7A, the state of the optical measuring device 1000 changes from the standby state 1220 to the measurement state 1240 at timing T1 when the measurement command is received from the operator, and the exposure time has elapsed from the timing T1. The timing T2 changes from the measurement state 1240 to the standby state 1260.

As shown in FIG. 7B, the state of the integrator 1021 changes from the state 1280, which is performing the integral circuit reset operation to the timing T1, to the state 1300, which is performing the integration operation, and changes to the timing T2. It changes from the state 1300 which performs an integration operation to the state 1320 which performs an integration circuit reset operation. Therefore, the integrator 1021 is in states 1280 and 1320 in which the integrated circuit reset operation is performed when the optical measuring apparatus 1000 is in the standby states 1220 and 1260, respectively, and the optical measuring apparatus 1000 is in the measuring state. In the case of 1240, the state is 1300 in which the integral operation is performed.

The integrator 1021 can always integrate the optical signal even in the states 1280 and 1320 where the integral circuit reset operation is performed, and can output the integrated signal. For this reason, the integrator control unit 1065 controls the integrator 1021 so as to integrate the photocurrent in the standby integration period 1340 repeatedly arriving and output the standby integration signal, and the estimated luminance acquisition unit 1061 exposes the exposure. The estimated luminance may be obtained by considering the waiting-integration period immediately before the period as the initial integration period. As a result, the approximated luminance is acquired before timing T1 at which measurement is started, thereby reducing the time required for measurement. The length of the standby time integration period 1340 repeatedly arriving may be the shortest time that can be set.

Although this invention was demonstrated in detail, the above description is an illustration in all the aspects, Comprising: This invention is not limited to it. It is contemplated that a myriad of variations that are not illustrated may be assumed 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: approximated luminance acquisition unit
1062: cycle acquisition unit
1063: exposure time determining unit
1064: integral time determination unit
1065: integrator control unit
1066: calculation unit

Claims (6)

An optical sensor which receives light from the display and outputs a light current according to the light;
An integrator for integrating the photocurrent continuously and outputting an integrated signal in time;
A request precision acquiring unit for acquiring the required precision for the measured value;
An approximation luminance acquisition unit for acquiring an approximation luminance of the light;
A period acquiring unit for acquiring a period of time variation of the brightness and chromaticity of the light;
An exposure time determiner that determines an exposure time from the required precision and the estimated luminance;
An integration time determination unit for determining an integration time of the integrator so that the integrator is not saturated and the exposure time is a multiple of the period and the integration time;
An exposure period consists of at least one integration period, the length of the exposure period becomes the exposure time, the length of each of the at least one integration period becomes the integration time, and the integrator includes the at least one integration period An integrator controller for integrating the photocurrent to output at least one integrated signal to the integrator,
And an calculating unit for calculating the measured value from the at least one integrated signal. The method of claim 1,
The integrator control unit controls the integrator to output an initial integration signal by integrating the photocurrent in an initial integration period preceding the at least one integration period,
The estimated luminance acquisition unit obtains the estimated luminance from the initial integrated signal. The method of claim 2,
The integrator control unit controls the integrator to output the standby integration signal by integrating the photocurrent in a standby integration period that arrives repeatedly,
The initial integration period is an optical measurement device that is a standby time integration period that arrives immediately before the exposure period. The method according to any one of claims 1 to 3,
The common multiple is an optical multiple measurement device. The method according to any one of claims 1 to 4,
The exposure time can be changed according to the required precision. The method according to any one of claims 1 to 5,
The integrator has a plurality of selectable gains.

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