Optical measurement device, optical measurement method, data processing device, and program

Abstract

To provide a light measuring device, a light measuring method, a data processing device and a program with which it is possible to generate data of stimulus values with the time response of eyes taken into account, in which waveform distortion is suppressed, to make satisfactory flicker measurement possible, and also possible to respond to measurement objects having a nonperiodic emission waveform.SOLUTION: The present invention comprises: stimulus value acquisition means 20 for receiving light from a measurement object and successively acquiring intensity equivalent to a stimulus value at a given time interval; responsiveness characteristic acquisition means 32 for acquiring an impulse response characteristic from storage means 31 that stores impulse response characteristics equivalent to visual sense stimulus responses; and digital filtering means 32 for applying digital filtering to the acquired successive data of stimulus value intensity by acquired impulse response characteristics and generating data in which the visual sense stimulus response is superimposed.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an optical measurement device, an optical measurement method, a data processing device, and a program suitable for measuring flicker and the like of a measurement object such as a display. [Background technology]

[0002] As display functions and performance improve, light emission waveforms are becoming more complex. For example, in the case of OLED (Organic Light-Emitting Diode) displays, light emission control that combines not only amplitude modulation but also pulse width modulation for gradation control is adopted to achieve faithful color reproduction, and light emission with high amplitude and complex waveforms is becoming common.

[0003] Moreover, in recent years, displays with a variable refresh rate (VRR) function have been developed. In these displays, the refresh rate switches dynamically and aperiodically, making the emission waveform increasingly complex; for example, a transient response is observed in the emission waveform starting from the switching point.

[0004] As light emission waveforms become more complex, flicker (visible flickering) has become evident, which has become an issue for display quality.

[0005] As an optical measurement device for measuring the basic performance of a measurement target such as a display, for example, a display color analyzer (one example is the CA-410 manufactured by Konica Minolta, Inc.) is known. Such a display color analyzer has an internal optical sensor and can measure not only color and brightness, but also optical waveforms and flicker.

[0006] There are two main methods for acquiring the amount of light from a measurement target: the sequential acquisition method, which acquires an instantaneous value, and the integral acquisition method, which acquires an integral value over a set period of time. The sequential acquisition method excels in high speed, while the integral method excels in low luminance measurement performance.

[0007] The JEITA method is a common method for measuring flicker that occurs in displays, etc. However, although this method can effectively measure simple light emission waveforms such as liquid crystal (LCD), it is not suitable for complex waveforms, as the measured values ​​do not match with visual observation.

[0008] As a measurement method for dealing with complicated light emission waveforms, there is a method defined in the IEC standard "62341-6-3" (Non-Patent Document 1).

[0009] This standard derives a stimulus value that takes into account the temporal response of the eye by convolving the acquired continuous stimulus value with the temporal contrast sensitivity function (TCSF), which indicates the sensitivity characteristics of the eye to the light emission frequency, and then derives a flicker index from that stimulus value.

[0010] The specific processing procedure is as follows. (1) Continuously acquire the stimulus values ​​of the illuminated display. (2) The acquired data is subjected to a discrete Fourier transform (DFT) to convert it into a frequency spectrum. (3) The obtained frequency spectrum is convoluted with the TCSF to superimpose the eye characteristics. (4) An inverse Fourier transform (iDFT) process is performed to generate a stimulus value superimposed with TCSF. (5) Calculate the maximum value (Max) - minimum value (Min) / average value (Ave) of the stimulus value data on which TCSF is superimposed, and use the amount of flicker as an index. [Prior art documents] [Patent documents]

[0011] [Non-Patent Document 1] IEC standard “62341-6-3” Summary of the Invention [Problem to be solved by the invention]

[0012] However, the digital Fourier transform (DFT, iDFT) is a calculation that assumes that the input waveform has periodicity and is synchronized. The use of this digital Fourier transform in flicker measurement techniques has the following problems:

[0013] That is, for example, if the measurement time does not match (is not an integer multiple of) the period of the emitted light waveform (for example, the Vsync period), the light intensity values ​​at the leading and trailing ends of the acquired waveform will not match.

[0014] The frequency spectrum of such a waveform contains many spurious frequency components (=1 / measurement time × n, that is, the frequency with the measurement time as one period and its harmonics) that do not actually exist.

[0015] The superimposed waveform of this frequency spectrum has the problem that the leading and trailing ends are significantly distorted, resulting in large errors in the flicker value and measurements that lack reproducibility.

[0016] As a countermeasure, a method has been proposed in which the leading and trailing ends of acquired data are deleted to ensure synchronization. However, this method is not only time-consuming, but also has the risk of not being able to acquire data for the desired measurement time due to data deletion, making it inconvenient for flicker measurement. In addition, it cannot handle non-periodic emission waveforms, such as those of displays with the aforementioned VRR function.

[0017] Furthermore, as a countermeasure different from synchronization, a method using a window function that converts the data ends to the same value has been disclosed. In this method, the acquired waveform is first multiplied by the window function, and then the TCSF is superimposed on the waveform in a similar manner, and finally the desired waveform is created by dividing the window function. However, this method also has the problem that the error at the time of waveform acquisition is expanded when the window function is divided, and as a result, the waveform is significantly distorted, causing a large error in the flicker value.

[0018] This invention has been made in consideration of the above technical background, and aims to provide an optical measurement device, an optical measurement method, a data processing device, and a program that can generate data with suppressed waveform distortion while still being stimulus value data that takes into account the time response of the eye, thereby enabling good flicker measurement and being compatible with measurement objects having non-periodic light emission waveforms. [Means for solving the problem]

[0019] The above object can be achieved by the following means: (1) a stimulus value acquisition means for receiving light from a measurement object and continuously acquiring an intensity corresponding to a stimulus value at a constant time interval; a response characteristic acquisition means for acquiring an impulse response characteristic corresponding to a visual stimulus response from a storage means for storing the impulse response characteristic; a digital filter processing means for performing digital filtering on the continuous data of the stimulus value intensity acquired by the stimulus value acquisition means, using the impulse response characteristic acquired by the response characteristic acquisition means, to generate data on which the visual stimulus response is superimposed; a derivation means for deriving a flicker index from the data generated by the digital filter processing means; An optical measurement device equipped with (2) a stimulus value acquisition means for receiving light from a measurement object and continuously acquiring an intensity corresponding to a stimulus value at regular time intervals; A conversion means for converting the frequency characteristic of the eye stored in the storage means into an impulse response characteristic corresponding to a visual stimulus response; a digital filter processing means for performing digital filtering on the continuous data of the stimulus value intensity acquired by the stimulus value acquisition means using the impulse response characteristic converted by the conversion means to generate data on which the visual stimulus response is superimposed; a derivation means for deriving a flicker index from the data generated by the digital filter processing means; An optical measurement device equipped with (3) The frequency characteristics include phase characteristics. before Item 3. An optical measurement device according to item 2. (4) The optical measurement device according to any one of items 1 to 3 above, wherein the impulse response in the impulse response characteristic is 0.5 seconds or less. (5) The derivation means is generated by the digital filter processing means The above At multiple times in the data, the time is shorter than the measurement time length. The above Deriving the Flicker Index Before Item 4. The optical measurement device according to any one of Items 1 to 3. (6) The optical measurement device according to any one of items 1 to 5 above, wherein the constant time interval when the stimulus value acquisition means acquires the intensity corresponding to the stimulus value is a time interval of 6 kHz or less. (7) The optical measurement device according to any one of the preceding paragraphs 1 to 6, wherein the stimulus value acquisition means acquires an intensity equivalent to the stimulus value by an integration method. (8) The optical measurement device according to any one of the preceding paragraphs 1 to 6, wherein a plurality of the impulse response characteristics exist. (9) An optical measurement device according to any one of the preceding paragraphs 1 to 8, comprising at least a Fourier transform means, and capable of measuring flicker using the Fourier transform means. (10) a stimulus value acquisition step of receiving light from a measurement object and continuously acquiring an intensity corresponding to a stimulus value at a constant time interval; a response characteristic acquisition step of acquiring an impulse response characteristic from a storage means that stores the impulse response characteristic corresponding to a visual stimulus response; a digital filter processing step of performing digital filtering on the continuous data of the stimulus value intensity acquired in the stimulus value acquisition step using the impulse response characteristic acquired in the response characteristic acquisition step to generate data on which the visual stimulus response is superimposed; a derivation step of deriving a flicker index from the data generated by the digital filtering step; An optical measurement method comprising: (11) a stimulus value acquisition step of receiving light from a measurement object and continuously acquiring an intensity corresponding to a stimulus value at a constant time interval; A conversion step of converting the frequency characteristics of the eye stored in the storage means into impulse response characteristics corresponding to a visual stimulus response; a digital filter processing step of performing digital filtering on the continuous data of the stimulus value intensity acquired in the stimulus value acquisition step using the impulse response characteristic converted in the conversion step to generate data on which the visual stimulus response is superimposed; a derivation step of deriving a flicker index from the data generated by the digital filtering step; An optical measurement method comprising: (12) The optical measurement method according to the preceding paragraph 10 or 11, wherein the impulse response in the impulse response characteristic is 0.5 seconds or less. (13) In the deriving step, The digital filtering step generates The above At multiple times in the data, the time is shorter than the measurement time length. The above Deriving the Flicker Index Before Item 13. The optical measurement method according to any one of items 10 to 12. (14) a receiving means for receiving continuous data of the stimulus value intensity obtained by receiving light from a measurement object and continuously acquiring the intensity corresponding to the stimulus value at a constant time interval; a response characteristic acquisition means for acquiring an impulse response characteristic corresponding to a visual stimulus response from a storage means for storing the impulse response characteristic; a digital filter processing means for performing digital filtering on the continuous data of the stimulus value intensity received by the receiving means, using the impulse response characteristic acquired by the response characteristic acquiring means, to generate data on which the visual stimulus response is superimposed; a derivation means for deriving a flicker index from the data generated by the digital filter processing means; A data processing device comprising: (15) a receiving means for receiving continuous data of a stimulus value intensity obtained by receiving light from a measurement object and continuously acquiring an intensity corresponding to the stimulus value at a constant time interval; A conversion means for converting the frequency characteristic of the eye stored in the storage means into an impulse response characteristic corresponding to a visual stimulus response; a digital filter processing means for performing digital filtering on the continuous data of the stimulus value intensity received by the receiving means using the impulse response characteristic converted by the converting means to generate data on which the visual stimulus response is superimposed; a derivation means for deriving a flicker index from the data generated by the digital filter processing means; A data processing device comprising: (16) The data processing device according to claim 14 or 15, wherein the impulse response in the impulse response characteristic is 0.5 seconds or less. (17) The derivation means is generated by the digital filter processing means The above At multiple times in the data, the time is shorter than the measurement time length. The above Deriving the Flicker Index Before 17. A data processing device according to any one of items 14 to 16. (18) a receiving step of receiving continuous data of the stimulus value intensity obtained by receiving light from the measurement object and continuously acquiring the intensity corresponding to the stimulus value at a constant time interval; a response characteristic acquisition step of acquiring an impulse response characteristic from a storage means that stores the impulse response characteristic corresponding to a visual stimulus response; a digital filter processing step of performing digital filtering on the continuous data of the stimulus value intensity received in the receiving step using the impulse response characteristic acquired in the response characteristic acquiring step to generate data on which the visual stimulus response is superimposed; a derivation step of deriving a flicker index from the data generated by the digital filtering step; A program for causing a computer to execute the following. (19) a receiving step of receiving continuous data of the stimulus value intensity obtained by receiving light from the measurement object and continuously acquiring the intensity corresponding to the stimulus value at a constant time interval; a conversion receiving step of converting the frequency characteristic of the eye stored in the storage means into an impulse response characteristic corresponding to a visual stimulus response; a digital filter processing step of performing digital filtering on the continuous data of the stimulus value intensity received in the receiving step using the impulse response characteristic converted in the converting step to generate data on which the visual stimulus response is superimposed; a derivation step of deriving a flicker index from the data generated by the digital filtering step; A program for causing a computer to execute the following. (20) The program according to claim 18 or 19, wherein the impulse response in the impulse response characteristic is 0.5 seconds or less. (twenty one) In the deriving step, The digital filtering step generates The above At multiple times in the data, the time is shorter than the measurement time length. The above Deriving the Flicker Index process The computer Real 21. The program according to any one of items 18 to 20, which causes the program to be executed. Effect of the Invention

[0020] According to the inventions described in the preceding paragraphs (1), (10) and (14), light from a measurement object is received, and the intensity corresponding to the stimulus value is continuously acquired at a fixed time interval, and the continuous data of the acquired stimulus value intensity is subjected to digital filter processing using the impulse response characteristics acquired from the storage means, and data on which the visual stimulus response is superimposed is generated. Therefore, although the generated data is stimulus value data that takes into account the time response of the eye, no distortion of the waveform occurs because the data is not digitally Fourier transformed, and therefore good flicker measurement can be performed based on this data. Moreover, since there is no need to delete a part of the waveform to remove the distortion, it can also be used for measurement objects having non-periodic emission waveforms.

[0021] According to the inventions described in the preceding paragraphs (2), (11) and (15), light from a measurement object is received, and the intensity corresponding to the stimulus value is continuously acquired at a fixed time interval, and the continuous data of the acquired stimulus value intensity is digitally filtered using the impulse response characteristic corresponding to the visual stimulus response converted from the frequency characteristic of the eye stored in the storage means, to generate data on which the visual stimulus response is superimposed. Therefore, although the generated data is stimulus value data that takes into account the time response of the eye, no distortion of the waveform occurs because the data is not digitally Fourier transformed, and therefore good flicker measurement can be performed based on this data. Moreover, since there is no need to delete a part of the waveform to remove the distortion, it can also be used for measurement objects having non-periodic emission waveforms.

[0022] According to the invention described in the preceding paragraph (3), since the frequency characteristic includes the phase characteristic, it is possible to reduce errors in the impulse response.

[0023] According to the inventions described in the preceding paragraphs (4), (12) and (16), the impulse response in the impulse response characteristic is 0.5 seconds or less, so that the invalid period of data during digital filter processing can be reduced, and the measurement time can be shortened.

[0024] According to the inventions described in the preceding paragraphs (5), (13) and (17), a flicker index is derived for a time shorter than the measurement time length at multiple time points in the data generated by the digital filter processing, so that the change in flicker intensity over time can be measured.

[0025] According to the invention described in the preceding paragraph (6), the constant time interval for acquiring the intensity corresponding to the stimulation value is 6 kHz or less, so that high-precision measurement without waveform distortion can be performed by low-speed control.

[0026] According to the invention described in the preceding paragraph (7), the intensity corresponding to the stimulus value is acquired by an integral method, and the acquisition process is not performed at a high speed, so that the S / N ratio can be improved and highly accurate measurements can be performed.

[0027] According to the invention described in the preceding paragraph (8), since there are a plurality of impulse response characteristics, it is possible to obtain data that matches the sensory characteristics.

[0028] According to the invention described in the preceding paragraph (9), it is also possible to carry out conventional flicker measurement using Fourier transform means.

[0029] According to the invention described in the preceding paragraph (18), it is possible to cause a computer to execute a process of receiving continuous data of stimulus value intensity obtained by receiving light from a measurement object and continuously acquiring an intensity corresponding to a stimulus value at a fixed time interval, acquiring an impulse response characteristic from a storage means that stores an impulse response characteristic corresponding to a visual stimulus response, and performing digital filtering on the received continuous data of stimulus value intensity using the acquired impulse response characteristic to generate data on which the visual stimulus response is superimposed.

[0030] According to the invention described in the preceding paragraph (19), a computer can be caused to execute a process of receiving continuous data of stimulus value intensity obtained by receiving light from a measurement object and continuously acquiring an intensity corresponding to the stimulus value at a fixed time interval, converting the frequency characteristic of the eye stored in the storage means into an impulse response characteristic corresponding to a visual stimulus response, performing digital filtering on the received continuous data of stimulus value intensity using the converted impulse response characteristic, and generating data on which the visual stimulus response is superimposed.

[0031] According to the invention described in the preceding paragraph (20), it is possible to cause a computer to execute a process of performing digital filtering using an impulse response characteristic with an impulse response of 0.5 seconds or less.

[0032] According to the invention described in the preceding paragraph (21), it is possible to cause a computer to execute a process of deriving a flicker index for a time shorter than the measurement time length at multiple time points of the data generated by the digital filter processing step. [Brief description of the drawings]

[0033] [Figure 1] 1 is a block diagram showing a functional configuration of an optical measurement device according to an embodiment of the present invention. [Diagram 2] 1 is a waveform diagram showing an example of an impulse response characteristic corresponding to a visual stimulus response. [Diagram 3] 11(A) to 11(D) are diagrams for explaining the measurement results of a light emission waveform in which a VRR display is modeled as a measurement object. [Figure 4] (A) is a waveform diagram of data obtained by digital filtering with superimposed stimulus values, and (B) is a graph showing fluctuations in flicker intensity. [Diagram 5] FIG. 13 is a block diagram showing a functional configuration of an optical measurement device according to another embodiment of the present invention. [Figure 6] 1A is a graph showing sensitivity characteristics in the frequency characteristics of the eye, and FIG. 1B is a graph showing an example of the frequency characteristics of the eye including phase characteristics. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. [First embodiment] <Configuration of optical measurement device> Fig. 1 is a block diagram showing a functional configuration of an optical measurement device 1 according to an embodiment of the present invention. As shown in Fig. 1, the optical measurement device 1 includes a measurement head 2 and a data processing device 3. The measurement head 2 includes an optical sensor 21 and an output unit 22 forming a stimulus value acquisition unit 20, and the data processing device 3 is configured by a personal computer (PC) and includes a response storage unit 31, a digital filter processing unit 32, and a flicker index derivation unit 33. Note that reference numeral 41 shown in Fig. 1 denotes an operation unit for operating the data processing device 3, and reference numeral 42 denotes a display unit for displaying the digital filter processing result by the digital filter processing unit 32, the flicker index derived by the flicker index derivation unit 33, and the like.

[0035] The optical sensor 21 is a light receiving sensor that receives light emitted from a measurement object 100 such as a display, and the stimulus value acquisition unit 20 has the function of continuously acquiring the output of the optical sensor 21 at regular time intervals using the output unit 22 and converting it into continuous data of stimulus value intensity.

[0036] The optical sensor 21 may be of a tristimulus value direct reading type or a spectroscopic type. The converted stimulus values ​​include, for example, luminance, chromaticity (xy), and tristimulus values ​​represented by XYZ. In the continuous data conversion of the stimulus values, a filter process may be performed to remove noise. For example, a moving average process using previous and following data may be applied.

[0037] In this embodiment, the output unit 22 acquires data from the optical sensor 21 by an integral method. The integral method has a superior S / N ratio, and therefore can improve measurement accuracy. On the other hand, the integral method has the disadvantage that the data acquisition speed cannot be increased like the sequential method, but this is not a problem in this embodiment for the reasons described below. Therefore, overall, the integral method is more preferable than the sequential method.

[0038] In this embodiment, the optical measurement device 1 is configured from the measurement head 2 and the data processing device 3, but the optical measurement device 1 may be a standalone device in which the measurement head 2 and the data processing device 3 are provided in the same device. <Necessity of high-speed sampling> The eye frequency response (TCSF) has almost no sensitivity in the high frequency range. Therefore, even if the emission waveform of the measurement object 100 is high speed and high frequency, flicker measurement does not require high speed to faithfully obtain the emission waveform (shape).

[0039] Considering the load in the calculation process described below, it is preferable to have a small amount of data, and there is no need to make the data acquisition speed faster than necessary. Furthermore, unnecessary speed increases the amount of incident light and increases circuit noise, which leads to a deterioration of the S / N ratio and a loss of measurement accuracy.

[0040] An example of a data acquisition speed is shown below. In recent years, high-speed control displays with Vsync 240 Hz and the like have been released. If this is PWM driven, high-speed data acquisition of at least 24 kHz (100 data points per cycle) is required to acquire the waveform (shape). Furthermore, for a conventional Vsync 60 Hz display, high-speed data acquisition of at least 6 kHz is required. However, from the above perspective, when it comes to flicker measurement, there is no problem at all even if it is 6 kHz or less, and it is actually preferable.

[0041] In this embodiment, in view of the above, data is acquired at 1.5 kHz. The data acquisition speed may be changed according to the measurement target 100 and the driving conditions. For example, the speed may be set to low when the driving conditions are amplitude modulation driving, and high when the driving conditions are PWM modulation driving.

[0042] In the case of sequential data acquisition, when data is acquired at a high speed exceeding 6 kHz, it may be processed as is, or it may be thinned out or averaged to reduce the number of data items to be handled. <Response memory unit that stores impulse response characteristics> The data processing device 3 includes a response storage unit 31, and the response storage unit 31 stores impulse response characteristics corresponding to visual stimulus responses.

[0043] An example of an impulse response characteristic equivalent to a visual stimulus response is shown in Figure 2. The response period to be stored is sufficient if it is long enough for the eye response to converge. The eye response generally converges after 0.5 seconds.

[0044] The visual stimulus response, which is a sensory characteristic, is highly dependent on the individual (person), the environment, and the measurement target object 100. For this reason, a plurality of impulse response characteristics may be stored in the response storage unit 31, and different impulse response characteristics may be used according to the conditions. Also, the response storage unit 31 may be configured so that the user can store (register) the impulse response characteristics.

[0045] Examples of parameters on which the visual stimulus response depends include the measurement area of ​​the stimulus value acquisition unit 20, luminance, color, sex, age, ambient luminance, individual, etc. The impulse response characteristics may be selected by manual setting by the user, or may be automatically selected by the optical measurement device 1. For example, when using colors as parameters, automatic selection can be realized by utilizing the stimulus values ​​acquired for flicker measurement. As another example, a sensor may be provided in the optical measurement device 1 to automatically switch between the colors.

[0046] The response storage unit 31 does not have to be built in the data processing device 3, and may be located externally. In this case, impulse response data may be acquired from the external response storage unit 31 and processed. <Digital filter processing> The digital filter processing by the digital filter processing unit 32 is executed by a processor such as a CPU provided in the data processing device 3 operating in accordance with an operation program stored in a ROM or the like and loaded into a RAM.

[0047] The digital filter processing unit 32 receives the continuous data of stimulus value intensity acquired by the stimulus value acquisition unit 20, and acquires the impulse response characteristics from the response characteristic memory unit 31. The digital filter processing unit 32 applies digital filter processing to the received continuous data of stimulus value intensity using the acquired impulse response characteristics to generate data on which a visual stimulus response is superimposed (also referred to as superimposed stimulus value data in the following description).

[0048] To perform digital filter processing, at least stimulus value data for the impulse response period is required. Also, the beginning of the generated superimposed stimulus value data comes after the response period, and the period before that is an invalid period due to data loss. In order to reduce this period of missing data, in this embodiment, the impulse response period is set to 0.5 seconds or less, which is the period during which the eye response converges. Digital filter processing is performed using only the response portion of 0.5 seconds or less.

[0049] The timing of performing the digital filter processing is not limited, and may be after acquisition of consecutive stimulus values ​​has been completed, or the acquired stimulus values ​​may be processed sequentially even if acquisition of all data has not been completed. <Generation of superimposed stimulus value data and derivation of flicker index> As described above, the digital filter processing unit 32 generates and outputs data on which a visual stimulus response is superimposed. The flicker index derivation unit 33 derives a flicker index using this superimposed stimulus value data. The flicker index derivation process by the flicker index derivation unit 33 is also executed by the processor of the data processing device 3 operating in accordance with an operating program.

[0050] An example of derivation of a flicker index is given below.

[0051] In cases where the flicker intensity is static, such as when the light emission waveform is a periodic waveform, it is preferable to derive (maximum value (Max) - minimum value (Min) / average value (Ave)) for the entire time range of the superimposed stimulus value data and use this as the index value. More preferably, the time range for deriving the index value can be set under synchronous conditions, that is, to an integer multiple of the light emission period, in order to reduce measurement errors. Note that methods of synchronization include, but are not limited to, a method using an external synchronization signal or a method in which the user inputs a synchronization frequency.

[0052] On the other hand, there are cases where the Vsync frequency in a VRR display switches randomly. For example, some mobile devices operate at a low speed when displaying still images and at 60 Hz when displaying moving images or when the screen is touched to save power. In such cases where the flicker intensity fluctuates, it is preferable to generate a time-varying flicker intensity.

[0053] Specifically, for the superimposed stimulus value data, (Max-Min) / Ave is derived for a certain time width for each time, and the time change of the index value is generated. By using this time change data, it becomes possible to easily observe the extent to which the flicker intensity changes under certain circumstances. Note that it is desirable for the time width to be an integer multiple of the Vynsc cycle.

[0054] Figure 3 shows the measurement results of the emission waveform modeled on a VRR display as the measurement target 100. Figure 3(A) shows continuous data of stimulus value intensity acquired for the display. The drive frequency of this display changes from 60Hz to 24Hz to 60Hz. There is no change in gradation. The frequency of the continuous data of stimulus value intensity changes in response to the change in drive frequency.

[0055] Figure 3(B) is an enlarged view of the time around the timing when the drive frequency changes from 60 Hz to 24 Hz, and Figure 3(C) is an enlarged view of the time around the timing when the drive frequency changes from 24 Hz to 60 Hz.

[0056] Figure 3(D) shows the waveform of the impulse response used in the digital filter processing. The impulse response period is less than 0.5 seconds.

[0057] Figure 4 (A) shows the superimposed stimulus value data obtained by digital filtering. It is clear that no waveform distortion has occurred.

[0058] 4B is a graph showing the fluctuation of the flicker intensity. The derivation time of the flicker index value is set to 12 Hz.

[0059] The method for deriving the flicker index is not limited to the above method, and other methods of deriving the index, such as a method of deriving the index from an area ratio (Flicker Index according to the IES method), may also be used.

[0060] In this embodiment, the intensity corresponding to the stimulus value is continuously acquired at a constant time interval, and the continuous data of the acquired stimulus value intensity is subjected to digital filtering using the impulse response characteristics acquired from the response memory unit 31, generating data with the visual stimulus response superimposed thereon. Therefore, although the generated superimposed stimulus value data is stimulus value data that takes into account the time response of the eye, it is not digitally Fourier transformed, so no distortion of the waveform occurs, and therefore good flicker measurement can be performed based on this superimposed stimulus value data. Moreover, since it is not necessary to delete a part of the waveform to remove distortion, it can also be used for measurement objects 100 that have a non-periodic light emission waveform. [Second embodiment] In this embodiment, the impulse response is calculated using the TCSF. <Configuration of optical measurement device> Fig. 5 is a block diagram showing the functional configuration of the optical measurement device 1 according to the second embodiment of the present invention. As shown in Fig. 5, the optical measurement device 1 includes a stimulus value acquisition unit 20, a frequency characteristic storage unit 34, a conversion unit 35, a digital filter processing unit 32, and a flicker index derivation unit 33.

[0061] The stimulus value acquisition unit 20 has the same configuration as the stimulus value acquisition unit 20 of the first embodiment, and has the function of continuously acquiring the output of the optical sensor 21 at regular time intervals in the output unit 22 and converting it into continuous data of stimulus value intensity.

[0062] The characteristics of the eye have been widely studied, and many TCSFs have been reported for time responses. For example, the literature "De Lange, H. Journal of the Optical Society of America, 1958 48, 777-785" explains the differences for each brightness.

[0063] In order to utilize such research results, in this embodiment, the frequency characteristics of the eye, such as TCSF, are stored in the frequency characteristic storage unit 34. The conversion unit 35 converts the frequency characteristics into impulse response characteristics equivalent to visual stimulus response by performing inverse Fourier transform processing on the frequency characteristics.

[0064] The TCSF used in the IEC standard described in the prior art expresses only the sensitivity data of the eye's frequency characteristics as shown in Fig. 6(A). However, in order to accurately convert to impulse response characteristics, it is desirable for the frequency characteristics to include phase data. For this reason, in this embodiment, the frequency characteristics including the phase characteristics are stored in the frequency characteristics storage unit 34.

[0065] An example of the frequency characteristics of the eye including the phase characteristics is shown in Fig. 6(B). As in the first embodiment, a plurality of frequency characteristics of the eye may be stored in the frequency characteristics storage unit 34, and different frequency characteristics may be used according to the conditions. Also, the frequency characteristics may be configured so that the user can store (register) the frequency characteristics of the eye in the frequency characteristics storage unit 34, or an arbitrary frequency characteristic may be automatically selected.

[0066] The digital filter processing unit 32 performs digital filtering on the continuous data of the stimulus value intensity acquired by the stimulus value acquisition unit 20 using the impulse response characteristics converted from the frequency characteristics of the eye by the conversion unit 35, to generate superimposed stimulus value data. Except for the fact that the impulse response characteristics are generated by the conversion unit 35, the digital filter processing unit 32 performs the same operation as the digital filter processing unit 33 in the first embodiment.

[0067] The time data of the impulse response characteristics generated by the conversion unit 35 is often sufficiently longer than the response period of the eye (about 0.5 seconds). For example, when the frequency characteristics are stored in units of 0.1 Hz, the data of the impulse response characteristics generated by the inverse Fourier transform is 10 seconds.

[0068] In the digital filter processing, as explained in the first embodiment, the impulse response period is directly related to the length of the invalid period of the superimposed stimulus value data. Therefore, in this embodiment, in order to suppress the invalid period, it is desirable to use only the first 0.5 seconds or less of the converted impulse response characteristic for the digital filter processing.

[0069] The flicker index derivation unit 33 derives a flicker index value from the superimposed stimulus value data, as in the first embodiment.

[0070] 5 receives a measurement command from a personal computer (PC) 5 and transmits the measurement results to the PC. The measurement results are superimposed stimulus value data and a flicker index value.

[0071] In addition, among the configuration of the optical measurement device 1 of the second embodiment shown in FIG. 5, the frequency characteristic storage unit 34, the conversion unit 35, the digital filter processing unit 32, and the flicker index derivation unit 33 may be provided in a PC 5 as a data processing device similarly to the first embodiment, and the processor in the PC 5 may operate according to an operating program to perform conversion processing of the frequency characteristic of the eye into an impulse response, generation of superimposed stimulus value data by digital filter processing, derivation of a flicker index value, etc.

[0072] Alternatively, the configuration of the optical measurement device 1 shown in FIG. 5 may be left as is, with the frequency characteristic storage unit 34, conversion unit 35, digital filter processing unit 32, and flicker index derivation unit 33 being provided within the PC 5.

[0073] Furthermore, the frequency characteristic storage unit 34 does not have to be built in the optical measurement device 1, and may be present externally. In this case, the frequency characteristic may be acquired from the external frequency characteristic storage unit 34 and processed. [Third embodiment] The optical measurement device 1 according to the first embodiment shown in FIG. 1 and the optical measurement device 1 according to the second embodiment shown in FIG. 5 may be equipped with a function capable of performing convolution of TCSF based on the conventional method defined in the IEC standard "62341-6-3". In the case of this conventional measurement method, since the convolution operation of TCSF is performed in frequency space, discrete Fourier transform (DFT) processing and inverse Fourier transform (iDFT) processing are required. Therefore, in order to have the functions of the conventional method as well, the optical measurement device 1 of the first embodiment requires a discrete Fourier transform (DFT) means and an inverse Fourier transform (iDFT) means. In the case of the second embodiment, the inverse Fourier transform (iDFT) can be performed by the conversion unit 35, so a discrete Fourier transform (DFT) means is required.

[0074] It is not necessary to switch between the conventional measurement method and the measurement method of this embodiment, and the data acquired by the stimulus value acquisition section 20 may be shared to enable simultaneous measurement.

[0075] However, the conventional measurement method has the advantage that no invalid periods occur, and is therefore beneficial in shortening the measurement time while ensuring measurement accuracy when performing synchronous measurement with a periodic light emission waveform. On the other hand, the measurement method of this embodiment, as described above, can achieve flicker measurement with a high degree of freedom in terms of measurement conditions and light emission waveforms. By incorporating both measurement methods, it becomes possible to use them according to the purpose, which increases convenience. [Explanation of symbols]

[0076] 1 Optical measurement device 2 Measuring head 3 Data Processing Device 20 Stimulus value acquisition section 21 Optical Sensor 22 Output section 31 Response memory section 32 Digital filter processing section 33 Flicker index derivation unit 34 Frequency characteristic memory section 35 Conversion unit 100 Measurement Object

Claims

1. a stimulus value acquiring means for receiving light from a measurement object and continuously acquiring an intensity corresponding to a stimulus value at a constant time interval; a response characteristic acquisition means for acquiring an impulse response characteristic corresponding to a visual stimulus response from a storage means for storing the impulse response characteristic; a digital filter processing means for performing digital filtering on the continuous data of the stimulus value intensity acquired by the stimulus value acquisition means, using the impulse response characteristic acquired by the response characteristic acquisition means, to generate data on which the visual stimulus response is superimposed; a derivation means for deriving a flicker index from the data generated by the digital filter processing means; An optical measurement device equipped with

2. a stimulus value acquiring means for receiving light from a measurement object and continuously acquiring an intensity corresponding to a stimulus value at a constant time interval; A conversion means for converting the frequency characteristic of the eye stored in the storage means into an impulse response characteristic corresponding to a visual stimulus response; a digital filter processing means for performing digital filtering on the continuous data of the stimulus value intensity acquired by the stimulus value acquisition means using the impulse response characteristic converted by the conversion means to generate data on which the visual stimulus response is superimposed; a derivation means for deriving a flicker index from the data generated by the digital filter processing means; An optical measurement device equipped with

3. The optical measurement device according to claim 2 , wherein the frequency characteristics include a phase characteristic.

4. 4. The optical measurement device according to claim 1, wherein the impulse response in the impulse response characteristic is 0.5 seconds or less.

5. An optical measurement device as described in any one of claims 1 to 3, wherein the derivation means derives the flicker index at a time shorter than the measurement time length at multiple time points of the data generated by the digital filter processing means.

6. 6. The optical measurement device according to claim 1, wherein the constant time interval when said stimulus value acquisition means acquires the intensity corresponding to the stimulus value is a time interval of 6 kHz or less.

7. 7. The optical measurement device according to claim 1, wherein the stimulus value acquisition means acquires an intensity corresponding to the stimulus value by an integration method.

8. 7. The optical measurement device according to claim 1, wherein a plurality of the impulse response characteristics exist.

9. 9. The optical measurement device according to claim 1, further comprising at least a Fourier transform means, and capable of measuring flicker using said Fourier transform means.

10. a stimulus value acquisition step of receiving light from a measurement object and continuously acquiring an intensity corresponding to a stimulus value at a constant time interval; a response characteristic acquisition step of acquiring an impulse response characteristic from a storage means that stores the impulse response characteristic corresponding to a visual stimulus response; a digital filter processing step of performing digital filtering on the continuous data of the stimulus value intensity acquired in the stimulus value acquisition step using the impulse response characteristic acquired in the response characteristic acquisition step to generate data on which the visual stimulus response is superimposed; a derivation step of deriving a flicker index from the data generated by the digital filtering step; An optical measurement method comprising:

11. a stimulus value acquisition step of receiving light from a measurement object and continuously acquiring an intensity corresponding to a stimulus value at a constant time interval; A conversion step of converting the frequency characteristics of the eye stored in the storage means into impulse response characteristics corresponding to a visual stimulus response; a digital filter processing step of performing digital filtering on the continuous data of the stimulus value intensity acquired in the stimulus value acquisition step using the impulse response characteristic converted in the conversion step to generate data on which the visual stimulus response is superimposed; a derivation step of deriving a flicker index from the data generated by the digital filtering step; An optical measurement method comprising:

12. 12. The optical measurement method according to claim 10, wherein the impulse response in the impulse response characteristic is 0.5 seconds or less.

13. An optical measurement method described in any of claims 10 to 12, wherein the derivation step derives the flicker index at multiple time points of the data generated by the digital filter processing step for a time shorter than the measurement time length.

14. a receiving means for receiving continuous data of the stimulus value intensity by receiving light from a measurement object and continuously acquiring the intensity corresponding to the stimulus value at a constant time interval; a response characteristic acquisition means for acquiring an impulse response characteristic corresponding to a visual stimulus response from a storage means for storing the impulse response characteristic; a digital filter processing means for performing digital filtering on the continuous data of the stimulus value intensity received by the receiving means, using the impulse response characteristic acquired by the response characteristic acquiring means, to generate data on which the visual stimulus response is superimposed; a derivation means for deriving a flicker index from the data generated by the digital filter processing means; A data processing device comprising:

15. a receiving means for receiving continuous data of the stimulus value intensity by receiving light from a measurement object and continuously acquiring the intensity corresponding to the stimulus value at a constant time interval; A conversion means for converting the frequency characteristic of the eye stored in the storage means into an impulse response characteristic corresponding to a visual stimulus response; a digital filter processing means for performing digital filtering on the continuous data of the stimulus value intensity received by the receiving means using the impulse response characteristic converted by the converting means to generate data on which the visual stimulus response is superimposed; a derivation means for deriving a flicker index from the data generated by the digital filter processing means; A data processing device comprising:

16. 16. A data processing apparatus according to claim 14, wherein the impulse response in the impulse response characteristic is 0.5 seconds or less.

17. A data processing device according to claim 14, wherein the derivation means derives the flicker index at a time shorter than a measurement time length at multiple time points of the data generated by the digital filter processing means.

18. a receiving step of receiving continuous data of the stimulus value intensity obtained by receiving light from the measurement object and continuously acquiring the intensity corresponding to the stimulus value at a constant time interval; a response characteristic acquisition step of acquiring an impulse response characteristic from a storage means that stores the impulse response characteristic corresponding to a visual stimulus response; a digital filter processing step of performing digital filtering on the continuous data of the stimulus value intensity received in the receiving step using the impulse response characteristic acquired in the response characteristic acquiring step to generate data on which the visual stimulus response is superimposed; a derivation step of deriving a flicker index from the data generated by the digital filtering step; A program for causing a computer to execute the following.

19. a receiving step of receiving continuous data of the stimulus value intensity obtained by receiving light from the measurement object and continuously acquiring the intensity corresponding to the stimulus value at a constant time interval; a conversion receiving step of converting the frequency characteristic of the eye stored in the storage means into an impulse response characteristic corresponding to a visual stimulus response; a digital filter processing step of performing digital filtering on the continuous data of the stimulus value intensity received in the receiving step using the impulse response characteristic converted in the converting step to generate data on which the visual stimulus response is superimposed; a derivation step of deriving a flicker index from the data generated by the digital filtering step; A program for causing a computer to execute the following.

20. 20. The program according to claim 18, wherein the impulse response in the impulse response characteristic is 0.5 seconds or less.

21. A program described in any of claims 18 to 20, wherein the derivation step causes the computer to execute a process of deriving the flicker index at multiple time points of the data generated by the digital filter processing step for a time shorter than the measurement time length.

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