JP2010164355A - Stimulus-value direct reading instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stimulus-value direct reading instrument capable of obtaining a tristimulus value as an accurate measurement value while greatly reducing work for setting color correction coefficients corresponding to new light sources. <P>SOLUTION: The tristimulus-value direct reading instrument 10 which includes: three light reception sections 12; and a correction value computation section (26) for obtaining tristimulus values by correcting respective actually measured values, further includes: a color correction coefficient calculation section (27) for obtaining a color correction coefficient K; and a storage means (25) for storing reference spectral radiation energy characteristics S, spectral responsivity characteristics R, a color-matching function T, and a color correction coefficient K. The color correction coefficient calculation section (27) obtains a reference tristimulus value by integrating the product of the color-matching function T and the reference spectral radiation energy characteristics S for the wavelength of visible regions, obtains a predicted tristimulus value by integrating the product of the respective spectral responsivity characteristics R and the reference spectral radiation energy characteristics S for the wavelength of visible regions, and obtains the color correction coefficient K for each stimulus value by dividing the predicted tristimulus value by the reference tristimulus value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical measurement device using a stimulus value direct reading method.

  Conventionally, in order to inspect the quality of a display image in an image forming apparatus such as a projector, an optical measurement device using a tristimulus value direct reading method that is inexpensive and has a short measurement time (hereinafter referred to as a tristimulus value direct reading type measuring instrument) has been used. It has been. This tristimulus value direct-reading type measuring instrument is a light source (image in the above example) that is measured by three sensors (stimulus value light receiving units) having the same sensitivity as the so-called color matching function corresponding to the human eye. The tristimulus value is directly measured by measuring the forming device. Each of these three stimulus value light receiving parts is composed of an optical filter and a light receiving element, and the sensitivity (spectral responsivity characteristic) for each wavelength when the light transmitted through the optical filter is received by the light receiving element is Each is set to match the color matching function for each corresponding stimulus value.

  However, it is difficult to design the optical filter and the light receiving element so that the spectral response characteristics of the three stimulus value light receiving units having the above-described configuration completely coincide with the color matching function. For this reason, the measured value obtained by the tristimulus value direct reading type measuring instrument is based on the measured value obtained by the spectroscopic type instrument conforming to the color matching function (hereinafter referred to as the reference measured value) as a spectral response characteristic. And an error occurs due to the difference between the color matching functions. As a method of eliminating such an error in the actual measurement value, it is known to correct the actual measurement value obtained by the tristimulus value direct reading type measuring instrument using the reference measurement value (see, for example, Patent Document 1).

  In this correction method, the correction light source (reference image forming apparatus) is measured with the tristimulus value direct reading measuring instrument and the spectroscopic measuring instrument to be corrected, and measured by the tristimulus value direct reading measuring instrument. A color correction coefficient (color conversion parameter) for matching the value with the reference measurement value obtained by the spectroscopic measuring instrument is obtained and stored. Then, when actually measuring the light source (image forming apparatus in the above example) with the tristimulus value direct reading type measuring instrument, the measured value of the tristimulus value direct reading type measuring instrument is corrected with the color correction coefficient, and the corrected actual measured value is obtained. Output as tristimulus values as measured values.

JP 2007-322203 A

  However, since the correction method described above uses a color correction coefficient obtained with reference to the light source for correction (reference image forming apparatus), the spectral shape (spectral radiant energy characteristic) of the light source for correction is used. Effective only when measuring light sources with equal spectral shape (can be accurately corrected). For this reason, it is necessary to use a color correction coefficient corresponding to a spectrum shape every time a light source having a different spectrum shape (an image forming apparatus of a different type in the above example) is a measurement target.

  Here, since the spectrum shape of the light source is different every time the type and model of the light source (image forming apparatus in the above example) are different, it is possible to prepare data corresponding to all types and models of the light source in advance. Since it is impossible, it is necessary for the user himself / herself to obtain an appropriate color correction coefficient by measurement according to the type and model of the light source. Then, for example, when inspecting the quality of display images of 100 types of image forming apparatuses with a single tristimulus value direct reading type measuring instrument, the user can use the tristimulus value direct reading type measuring instrument and the spectroscopic type measuring instrument. In this case, 100 types of image forming apparatuses (or light sources for correction corresponding thereto) are measured 100 times each, for a total of 200 times, and color correction coefficients corresponding to 100 types of image forming apparatuses (spectral shapes thereof) are not obtained. Don't be. Further, as the color correction coefficient, since data is required for each of the tristimulus values, the user needs to manage a total of 600 data, and 300 colors based on the 600 data. It is necessary to obtain correction coefficients and manage each color correction coefficient together with the correspondence relationships of 100 types of image forming apparatuses.

  Even if a lot of data is managed in this way, each time a new type or type of image forming apparatus is added as a display image quality inspection target, a color correction coefficient corresponding to the image forming apparatus is obtained. Work is required, and it is necessary to add a plurality of new data relating to the color correction coefficient to the management items.

  Furthermore, in reality, when the number of image forming apparatuses to be inspected is large, it is assumed that the user inspects the quality of the display image by using a plurality of the same type of tristimulus value direct reading type measuring instruments. Even if it is the same type, each tristimulus value direct-reading type measuring instrument has instrumental differences (for example, differences in spectral response characteristics based on individual differences in three stimulus value light receiving units, that is, optical filters and light receiving elements) In order to obtain an accurate tristimulus value, it is necessary to manage each data by obtaining a color correction coefficient corresponding to the image forming apparatus to be inspected for each tristimulus value direct reading type measuring instrument to be used.

  The present invention has been made in view of the above circumstances, and it is possible to obtain tristimulus values as accurate measurement values while greatly reducing the work for setting a color correction coefficient corresponding to a new light source. An object of the present invention is to provide a stimulus value direct-reading type measuring instrument.

  According to the first aspect of the present invention, the light receiving unit having a predetermined spectral response characteristic for measuring the tristimulus value of the object to be measured, and the actual value acquired by the light receiving unit that measured the object to be measured are colored. A correction value calculation unit that obtains the tristimulus values obtained by correcting each actual measurement value by multiplying by a correction coefficient, and a reference spectral radiant energy that stores a reference spectral radiant energy characteristic of a reference measured object serving as a reference for the measured object Characteristic storage means, spectral response characteristic storage means for storing the spectral response characteristics of the light receiving unit, color matching function storage means for storing color matching functions, color matching function storage means, spectral response characteristics A color correction coefficient calculation unit that obtains the color correction coefficient based on each characteristic stored in the storage unit and the reference spectral radiant energy distribution characteristic storage unit, and the color correction coefficient obtained by the color correction coefficient calculation unit Color correction coefficient storage means, and the color correction coefficient calculation unit obtains a reference tristimulus value by integrating a product of the color matching function and the reference spectral radiant energy characteristic with respect to a wavelength in a visible region, The product of the spectral response characteristic and the reference spectral radiant energy characteristic is integrated with respect to the wavelength in the visible region to obtain a predicted tristimulus value to be obtained when the reference spectral radiant energy characteristic is measured by the light receiving unit, and the prediction The color correction coefficient for each stimulus value is obtained by dividing the tristimulus value by the reference tristimulus value.

  The invention according to claim 2 is the stimulus value direct-reading type measuring instrument according to claim 1, wherein the reference spectral radiant energy characteristic storage means is inputted through the reference spectral radiant energy characteristic input means. Spectral radiant energy characteristic data can be stored.

  The invention according to claim 3 is the stimulus value direct reading type measuring instrument according to claim 1, wherein the reference spectral radiant energy characteristic storage means stores the reference spectral radiant energy characteristic measured by the spectroscopic measuring instrument. Data can be acquired and stored.

  A fourth aspect of the present invention is the stimulus value direct-reading type measuring instrument according to any one of the first to third aspects, wherein the light receiving unit is an optical device that allows light in a predetermined wavelength region to pass therethrough. A filter and a light receiving element that receives light that has passed through the optical filter, and the spectral responsivity characteristics of the light receiving unit in a state where the optical filter and the light receiving element are assembled as the light receiving unit. It is obtained by actually measuring the output with respect to the amount of received light.

  According to a fifth aspect of the present invention, there is provided a light receiving unit having a predetermined spectral response characteristic for measuring the tristimulus value of the object to be measured, and a color obtained by measuring the measured value obtained by the light receiving unit that has measured the object to be measured. A correction value calculation unit that obtains the tristimulus values obtained by multiplying each actual measurement value by multiplying a correction coefficient, a color correction coefficient storage unit that stores the color correction coefficient, and the spectral response characteristic of the light receiving unit A stimulus value direct reading type measuring instrument comprising: a spectral response characteristic storage means for calculating a product of a reference spectral radiant energy characteristic and a color matching function of a reference measurement object serving as a reference for the measurement object in a visible region. The reference tristimulus value is obtained by integrating with respect to the wavelength, and the product of the spectral response characteristic and the reference spectral radiant energy characteristic is integrated with respect to the wavelength in the visible region to measure the reference spectral radiant energy characteristic with the light receiving unit. Then, a predicted tristimulus value to be obtained is obtained, the color correction coefficient is obtained by dividing the predicted tristimulus value by the reference tristimulus value, and the color correction coefficient is stored in the color correction coefficient storage means. A correction coefficient calculation unit is provided.

  According to a sixth aspect of the present invention, a light receiving unit having a predetermined spectral responsivity characteristic for measuring the tristimulus value of the object to be measured, and an actual value acquired by the light receiving unit that has measured the object to be measured are colored. A correction value calculation unit that obtains the tristimulus values obtained by correcting each actual measurement value by multiplying by a correction coefficient, and a reference spectral radiant energy that stores a reference spectral radiant energy characteristic of a reference measured object serving as a reference for the measured object Characteristic storage means, spectral response characteristic storage means for storing the spectral response characteristics of the light receiving unit, color matching function storage means for storing color matching functions, color matching function storage means, spectral response characteristics A color correction coefficient calculation unit that obtains the color correction coefficient based on each characteristic stored in the storage unit and the reference spectral radiant energy distribution characteristic storage unit, and the color correction coefficient obtained by the color correction coefficient calculation unit Color correction coefficient storage means, and the color correction coefficient calculation unit obtains a reference tristimulus value by integrating a product of the color matching function and the reference spectral radiant energy characteristic with respect to a wavelength in a visible region, The product of the spectral response characteristic and the reference spectral radiant energy characteristic is integrated with respect to the wavelength in the visible region to obtain a predicted tristimulus value to be obtained when the reference spectral radiant energy characteristic is measured by the light receiving unit, and the prediction The color correction coefficient is obtained by dividing a tristimulus value by the reference tristimulus value.

  The invention according to claim 7 is an actual measurement value acquisition step of acquiring an actual measurement value before correction by measuring an object to be measured with a light receiving unit having a predetermined spectral response characteristic, and the acquired by the light receiving unit. A measurement calculation step of obtaining the tristimulus value by correcting the actual measurement value by multiplying the actual measurement value by a color correction coefficient, and a stimulus value direct-reading measurement method, the reference being a reference for the object to be measured A standard tristimulus value is obtained by integrating the product of the standard spectral radiant energy characteristic of the object to be measured and the color matching function with respect to the wavelength in the visible region, and the product of the spectral response characteristic and the standard spectral radiant energy characteristic is visible. The predicted tristimulus value to be obtained by measuring the reference spectral radiant energy characteristic with the light receiving unit is obtained by integrating the wavelength of the region, and the predicted tristimulus value is divided by the reference tristimulus value. And obtaining the color correction coefficient by.

  According to the stimulus value direct-reading type measuring instrument of the present invention, the color correction coefficient is obtained based on the color matching function, the spectral response characteristic of the light receiving unit, and the reference spectral radiant energy characteristic of the reference measurement object. When a light source having a different color is used as the object to be measured, the color correction coefficient can be obtained if the reference spectral radiant energy characteristic of the object to be measured is known. Therefore, the object to be measured is measured for calculating the color correction coefficient. Work can be eliminated.

  In addition, since the predicted tristimulus value is obtained from the spectral responsivity characteristic and the reference spectral radiant energy characteristic in the light receiving unit, the predicted tristimulus value is obtained from a light source (measured object) having the reference spectral radiant energy characteristic. It becomes equal to the actual measurement value as the stimulus value obtained by measurement by the light receiving unit. For this reason, the color correction coefficient for each stimulus value obtained by dividing the predicted tristimulus value by the reference tristimulus value is determined by measuring the light source (measurement object) having the reference spectral radiant energy characteristic used for the calculation. As long as the measured value obtained by measuring with the light receiving unit can be appropriately corrected, a corrected measured value, that is, an accurate stimulus value can be obtained.

  In addition to the above-described configuration, it is assumed that the reference spectral radiant energy characteristic storage unit can store the reference spectral radiant energy characteristic data input via the reference spectral radiant energy characteristic input unit. By simply inputting the reference spectral radiant energy characteristic data with the energy characteristic input means, the color correction coefficient can be obtained based on the reference spectral radiant energy characteristic data, and a new light source (measurement object) can be measured. can do. For this reason, for example, if data of a reference spectral radiant energy characteristic as a design value set in a new light source (measurement object) is input, the tristimulus values of the new light source (measurement object) are appropriately set. Can be measured.

  In addition to the above-described configuration, the reference spectral radiant energy characteristic storage means can acquire and store data of the reference spectral radiant energy characteristic measured by the spectroscopic measuring instrument. The color correction coefficient can be obtained based on the data of the reference spectral radiant energy characteristic obtained by the measurement only by measuring the measured object) with the spectroscopic measuring instrument. For this reason, a new light source (measurement object) can be set as a measurement target, and the tristimulus values of the new light source (measurement object) can be appropriately measured.

  In addition to the configuration described above, the light receiving unit includes an optical filter that allows transmission of light in a predetermined wavelength region, and a light receiving element that receives light that has passed through the optical filter, and the spectral response characteristic is: When the optical filter and the light receiving element are assembled as the light receiving unit, the optical filter and the light receiving element are respectively obtained by actually measuring the output with respect to the amount of light received by the light receiving unit. Since the color correction coefficient is obtained by using the spectral response characteristic obtained by actually measuring the light receiving unit in the assembled state, the actual measurement value by the light receiving unit can be corrected more appropriately, and more appropriate tristimulus A value can be obtained.

It is explanatory drawing which shows schematic structure of the tristimulus value direct reading type measuring device which is an example of the stimulation value direct reading type measuring device which concerns on this invention. It is a graph which shows the color matching function T of a 2 degree visual field, and an example of the spectral response characteristic in each stimulus value light-receiving part of a tristimulus value direct-reading type measuring device. It is a graph which shows the standard spectral radiant energy characteristic of color LCD as an example of a light source. It is a graph which shows the reference | standard spectral radiant energy characteristic of the display apparatus which uses three color LED as a light source as another example of a light source. It is a flowchart for demonstrating the process of calculating | requiring a color correction coefficient. It is explanatory drawing which shows schematic structure of the tristimulus value direct-reading type measurement system which concerns on this invention. It is a flowchart which shows the flow of a measurement in a tristimulus value direct-reading type measurement system. It is explanatory drawing which shows a mode that the test | inspection of the quality of the display image of a several image forming apparatus is performed, (a) shows the case where the tristimulus value direct reading type measuring device which concerns on this invention is used, (b) is The case where the conventional tristimulus value direct reading type measuring device is used is shown.

  Embodiments of a stimulus value direct reading measuring instrument according to the present invention will be described below with reference to the drawings.

  FIG. 1 is an explanatory diagram showing a schematic configuration of a tristimulus value direct reading type measuring instrument 10 which is an example of a stimulation value direct reading type measuring instrument according to the present invention. FIG. 2 is a graph showing the color matching function T of the 2 ° visual field and an example of the spectral response characteristic R in each light receiving unit 12 of the tristimulus value direct reading type measuring instrument 10. FIG. 3 is a graph showing a reference spectral radiant energy characteristic S of a color LCD as an example of a measurement object, and FIG. 4 is a reference spectrum of a display device using three color LEDs as a light source as another example of the measurement object. It is a graph which shows the radiant energy characteristic S. In FIGS. 3 and 4, X (red), Y (green), and Z (blue) are standardized by their maximum values. FIG. 5 is a flowchart for explaining the process of obtaining the color correction coefficient K.

  The tristimulus value direct-reading-type measuring instrument 10 measures characteristics (for example, luminance, illuminance, chromaticity, color difference, etc.) of a light source that is a measurement target (object to be measured). For example, liquid crystal as an image forming apparatus The display characteristics of the panel (color LCD) are measured.

  As shown in FIG. 1, the tristimulus value direct reading type measuring instrument 10 includes a measurement optical system 11, three light receiving units 12, three amplification circuits 13, three A-D conversion circuits 14, a data processing unit 15, and a control unit. 16, an operation unit 17, and a display unit 18.

  The control unit 16 comprehensively controls the measurement optical system 11, each amplification circuit 13, each AD conversion circuit 14, the data processing unit 15, and the display unit 18. The operation performed on the operation unit 17 is executed via the control unit 16. The operations performed on the operation unit 17 include setting (switching) of an object to be measured, input of a reference spectral radiant energy characteristic S (see FIGS. 3 and 4) described later, setting of a color correction coefficient K described later and measurement start. This is an operation for using the tristimulus value direct reading type measuring instrument 10 such as. The display unit 18 displays a display for assisting the operation by the operation unit 17 and a tristimulus value (a corrected tristimulus value (Xo, Yo, Zo) described later) as a measurement result.

  The measurement optical system 11 includes an objective lens 19, a depolarizer 20, an optical shutter 21, and a three-branch optical system 22 housed in a not-shown casing, and passes through the objective lens 19 and the depolarizer 20. The incident light is divided into three equal parts by the three-branch optical system 22 and guided to the three light receiving units 12. Although not shown, the optical shutter 21 is held in an optical path between the depolarizer 20 and the three-branch optical system 22 by a driving mechanism so that the optical shutter 21 can be freely inserted and removed. A housing (not shown) that accommodates the measurement optical system 11 has a cylindrical shape made of a material having excellent light shielding properties and plays a role of shielding external light.

  The three light receiving sections 12 to which light is guided by the measurement optical system 11 have spectral response characteristics corresponding to different stimulus values so as to measure the tristimulus values of the object to be measured, and measure the object to be measured. By doing this, it is possible to acquire the actual measurement value before correction. Each of the three light receiving units 12 is configured by combining a spectral sensitivity correction filter 23 and a light receiving element 24. Each spectral sensitivity correction filter 23 is an optical filter having sensitivity in each wavelength region of X (red), Y (green), and Z (blue), and the three light receiving units 12 have spectral values corresponding to different stimulation values. Responsiveness (characteristic).

  The spectral response (characteristic) indicates the ratio of the intensity of a signal output to the amount of received light for each wavelength in each light receiving unit 12, and the spectral transmission characteristic and the light receiving element in the spectral sensitivity correction filter 23. 24 depending on the spectral sensitivity characteristics. Each light receiving unit 12 is set to a spectral response characteristic R (see FIG. 2) that is substantially equal to the color matching function T (see FIG. 2) at the corresponding stimulus value. The tristimulus values of light can be obtained when each light receiving element 24 receives the transmitted light flux. Note that the color matching function T is a sensitivity curve (characteristic) of a spectral stimulus value, which is the sensitivity of the eye to the equal energy spectrum defined by CIE (Commission Internationale de l'Eclairage). As shown in FIG. It can be expressed by the magnitude of each spectral response.

  As shown in FIG. 1, when the light is guided by the measurement optical system 11, the three light receiving units 12 output a signal having an intensity corresponding to its own spectral sensitivity characteristic to the corresponding amplification circuit 13. . The signal output from each light receiving unit 12 is appropriately amplified by the amplifier circuit 13, then converted from analog to digital by the corresponding AD conversion circuit 14, and output to the data processing unit 15. .

  The data processing unit 15 includes a memory 25, a correction value calculation circuit 26, and a color correction coefficient calculation circuit 27.

  The memory 25 stores the spectral response (spectral response characteristic R) of each light receiving unit 12 obtained by actual measurement in a state where the three light receiving units 12 described above are assembled as the tristimulus value direct-reading measuring instrument 10 ( Memory). For this reason, the memory 25 functions as a spectral response characteristic storage unit. A method of actually measuring the spectral response (spectral response characteristic R) will be described later.

  In this embodiment, the memory 25 stores a reference spectral radiant energy characteristic S (to be described for each stimulus value, Sx (λ), Sy (λ), Sz (λ)) and a color to be described later. Correction coefficient K (Kx, Ky, Kz when indicated for each stimulus value) and color matching function T (x (λ), y (λ), z (λ as shown later when indicated for each stimulus value) )) Is stored. The memory 25 can be composed of, for example, a RAM or a ROM. In this embodiment, the stored reference spectral radiant energy characteristic S and color correction coefficient K are rewritable, so that the memory 25 can be rewritten. Consists of media. Note that storage and rewriting in the memory 25 are performed under the control of the control unit 16.

  The correction value calculation circuit 26 can acquire the measurement signal M (actual measurement value) acquired by each light receiving unit 12 and output from the A-D conversion circuit 14, and color correction stored in the memory 25 as will be described later. The coefficient K can be read out. The correction value calculation circuit 26 corrects the measurement signal M, which is an actual measurement value, by multiplying the measurement signal M by the color correction coefficient K to obtain tristimulus values (Xo, Yo, Zo) as output values. For this reason, the correction value calculation circuit 26 corrects each actual measurement value by multiplying each actual measurement value acquired by each light receiving unit 12 by a color correction coefficient set for the stimulus value corresponding to each actual measurement value. Thus, it functions as a correction value calculation unit for obtaining tristimulus values. In the tristimulus value direct reading type measuring instrument 10, the tristimulus values (Xo, Yo, Zo) corrected by the correction value calculation circuit 26 are output as measured tristimulus values.

  The color correction coefficient calculation circuit 27 calculates the color correction coefficient K used in the correction value calculation circuit 26. Although a method for obtaining the color correction coefficient K in the color correction coefficient calculation circuit 27 will be described later, the color correction coefficient calculation circuit 27 functions as a color correction coefficient calculation unit. The color correction coefficient calculation circuit 27 stores the obtained color correction coefficient K in the memory 25. Therefore, the memory 25 functions as a color correction coefficient storage unit that stores the color correction coefficient K.

  Further, the reference spectral radiant energy characteristic S (see FIGS. 3 and 4) stored in the memory 25 is used for each stimulus in the image forming apparatus serving as a reference in the light source (image forming apparatus 28 (see FIG. 6)) to be measured. It shows the intensity distribution for each wavelength when the value is displayed, and has Sx (λ), Sy (λ), and Sz (λ) corresponding to the three stimulus values. The intensity in the reference spectral radiant energy characteristic S differs depending on the type of characteristic of the light source to be measured (for example, luminance, illuminance, chromaticity, color difference, etc.). For example, when measuring luminance as a characteristic Is the intensity of radiance, and when measuring illuminance as a characteristic, it is the intensity of irradiance. As described above, in this specification, the spectral radiance characteristic, the spectral irradiance characteristic, and the like are collectively referred to as the reference spectral radiant energy characteristic S.

  The reference spectral radiant energy characteristic S is obtained by measuring a reference light source (image forming apparatus 28 (see FIG. 6)) itself, which is manufactured as a reference device, with a spectroscopic measuring instrument (not shown). be able to. In the present embodiment, the tristimulus value direct reading type measuring instrument 10 has a terminal for connecting a spectroscopic measuring instrument (not shown) although not shown in the figure, and the object to be measured is connected to the spectroscopic measuring instrument. When the (light source serving as the reference) is measured, the tristimulus value direct-reading measuring instrument 10 (the memory 25) directly acquires the data of the reference spectral radiant energy characteristic S as the measurement result.

  Further, as the reference spectral radiant energy characteristic S, a set value (so-called design value) set in advance as a value for displaying tristimulus values in the image forming apparatus 28 (see FIG. 6) to be measured can be used. Such a design value is easy to obtain, and can be surely obtained particularly in the case of inspection of the quality of the display image in the manufactured image forming apparatus.

  Since the reference spectral radiant energy characteristic S varies depending on the type and model of the measurement target, it is necessary to acquire data corresponding to a new measurement target every time the measurement target is changed. In the present embodiment, the reference spectral radiant energy characteristic S is configured to be stored in the memory 25 when data as a preset design value is input via the operation unit 17. Therefore, the memory 25 functions as a reference spectral radiant energy characteristic storage unit that stores the reference spectral radiant energy characteristic S. The operation unit 17 also functions as a reference spectral radiant energy characteristic input unit for inputting data of the reference spectral radiant energy characteristic S.

  Further, the color matching functions T (x (λ), y (λ), z (λ)) stored in the memory 25 are determined by the CIE as described above, and are constant regardless of changes in the measurement target. Since it is a value, it is stored in the memory 25 in advance in the process of manufacturing the tristimulus value direct-reading measuring instrument 10 as a product.

  In the tristimulus value direct-reading type measuring instrument 10 of the present embodiment, as the color matching function T, the color matching function for the 2 ° field of view and the color matching function for the 10 ° field of view are stored in the memory 25 and can be switched according to the application. It is possible. Therefore, the memory 25 functions as a color matching function storage unit that stores the color matching functions x (λ), y (λ), and z (λ). Note that the tristimulus value direct-reading measuring instrument 10 of this embodiment is provided with a function of changing the color matching function T stored in the memory 25 and a function of returning the changed value to the original value. Yes. By changing the color matching function T, reference tristimulus values Xs, Ys, and Zs, which will be described later, can be adjusted. For example, the eye sensitivity curve (characteristic) that serves as a reference when examining the characteristics of the light source Can be unique.

  Next, spectral response characteristics R (Rx (λ), Ry (λ), Rz (λ)) (see FIG. 2) stored in the memory 25 will be described.

  As shown in FIG. 2, the spectral response characteristics Rx (λ), Ry (λ), and Rz (λ) indicate the ratio of the intensity of the signal output with respect to the amount of received light for each wavelength in each light receiving unit 12. It depends on the spectral transmission characteristic in the spectral sensitivity correction filter 23 and the spectral sensitivity characteristic in the light receiving element 24. Here, since it is difficult to manufacture the spectral sensitivity correction filter 23 having the spectral transmission characteristic that matches the design value and to manufacture the light receiving element 24 having the spectral sensitivity characteristic that matches the design value, It is difficult to completely match the spectral response characteristics Rx (λ), Ry (λ), and Rz (λ) of the unit 12 with the color matching functions x (λ), y (λ), and z (λ). Further, the spectral sensitivity correction filter 23 and the light receiving element 24 have manufacturing errors, and an assembly error in a state where the tristimulus value direct-reading measuring instrument 10 is assembled may occur. For this reason, even if it is the same setting, a difference will arise in the actual spectral response characteristic R between each manufactured tristimulus value direct-reading type measuring instrument 10.

  For this reason, in the tristimulus value direct-reading measuring instrument 10 according to the present invention, in the state where the three light receiving parts 12 having the spectral sensitivity correction filter 23 and the light receiving element 24 are assembled, the spectral response characteristics in the respective light receiving parts 12. Rx (λ), Ry (λ), and Rz (λ) are acquired by actual measurement, and the data is stored in the memory 25. This measurement is performed as follows.

  By measuring light of a single wavelength having a predetermined intensity with the manufactured tristimulus value direct-reading type measuring instrument 10, it is possible to obtain output values from the three light receiving units 12 corresponding to the predetermined intensity at the wavelength. it can. In this measurement, the wavelength of single-wavelength light having a predetermined intensity is appropriately changed to a plurality of arbitrary values in the visible region (for example, a range of 380 nm to 780 nm) (for example, the wavelength of the light to be measured is 380 nm). To increase by 5 nm.) Thereby, in the visible region, it is possible to obtain data of fluctuations in output values from the three light receiving units 12 with respect to the wavelength. This tristimulus value direct-reading-type measuring instrument 10 (the three light receiving units 12) has a specific spectral response characteristic Rx (λ) indicating the ratio of the intensity of the output signal to the amount of received light for each wavelength, Ry (λ) and Rz (λ). The spectral response characteristics Rx (λ), Ry (λ), and Rz (λ) measured in this way are measured in the tristimulus value direct reading type measuring instrument 10 before the tristimulus value direct reading type measuring instrument 10 is shipped. Each is stored in the memory 25 as unique data.

  Next, how to obtain the color correction coefficient K in the color correction coefficient calculation circuit 27 of the tristimulus value direct-reading measuring instrument 10 according to the present invention will be described with reference to the flowchart of FIG.

  First, reference spectral radiant energy characteristics Sx (λ), Sy (λ), and Sz (λ) data are acquired and stored in the memory 25 (step S1). In this embodiment, as described above, the acquisition of the data of the reference spectral radiant energy characteristics Sx (λ), Sy (λ), and Sz (λ) is performed by the light source (the image forming apparatus 28 (see FIG. 6). )) As preset values (reference spectral radiant energy characteristics Sx (λ), Sy (λ), Sz (λ)) are input via the operation unit 17.

  The color correction coefficient calculation circuit 27 includes reference spectral radiant energy characteristics Sx (λ), Sy (λ), Sz (λ) stored in the memory 25 and color matching functions x (λ), y (λ), z ( λ) and reference tristimulus values Xs, Ys, Zs are obtained by the following equation (1) (step S2). In the following equation (1), km is a proportionality coefficient determined so that the tristimulus value Ys matches the side light amount.

  The reference tristimulus values Xs, Ys, and Zs are obtained from a light source (in this embodiment, the image forming apparatus 28 (see FIG. 6)) having reference spectral radiant energy characteristics Sx (λ), Sy (λ), and Sz (λ). The tristimulus values themselves in the emitted light, that is, the reference spectral radiant energy characteristics Sx (λ), Sy (λ), and Sz (λ) themselves are represented by tristimulus values. In other words, the reference tristimulus values Xs, Ys, and Zs are obtained by converting the reference spectral radiant energy characteristics Sx (λ), Sy (λ), and Sz (λ) into color matching functions x (λ), y (λ), and z ( It is a value weighted for each wavelength according to λ).

  The color correction coefficient calculation circuit 27 includes reference spectral radiant energy characteristics Sx (λ), Sy (λ), Sz (λ) stored in the memory 25 and spectral response characteristics Rx (λ), Ry (λ), Rz. From (λ), predicted tristimulus values Xi, Yi, Zi are obtained by the following equation (2) (step S3). In the following equation (2), km is a proportionality coefficient determined so that the tristimulus value Yi matches the side light amount.

  The predicted tristimulus values Xi, Yi, and Zi are obtained from a light source (in this embodiment, the image forming apparatus 28 (see FIG. 6)) having reference spectral radiant energy characteristics Sx (λ), Sy (λ), and Sz (λ). When the emitted light is measured by the tristimulus value direct reading type measuring instrument 10 (three light receiving units 12 having spectral responsivity characteristics Rx (λ), Ry (λ), Rz (λ) used for calculation), It is a tristimulus value predicted to be obtained as a measurement result. In other words, the predicted tristimulus values Xi, Yi, Zi are the reference spectral radiant energy characteristics Sx (λ), Sy (λ), Sz (λ) and the spectral response characteristics Rx (λ), Ry (λ), Rz. It is a value weighted for each wavelength according to (λ).

  The color correction coefficient calculation circuit 27 obtains the color correction coefficients Kx, Ky, Kz from the reference tristimulus values Xs, Ys, Zs and the predicted tristimulus values Xi, Yi, Zi by the following equation (3) (step S4). ).

Kx = Xs / Xi
Ky = Ys / Yi (3)
Kz = Zs / Zi
As described above, the color correction coefficient calculation circuit 27 obtains the color correction coefficients Kx, Ky, and Kz and stores the color correction coefficients Kx, Ky, and Kz in the memory 25. In this embodiment, the color correction coefficients Kx, Ky, Kz are stored in the memory 25 in association with the corresponding light source (its reference spectral radiant energy characteristics Sx (λ), Sy (λ), Sz (λ)). ing. Thereby, when changing the measurement object, if the color correction coefficients Kx, Ky, Kz corresponding to the measurement object after the change have already been acquired, the step of recalculating the color correction coefficient (reference spectral radiant energy characteristic S) Can be eliminated.

  The color correction coefficients Kx, Ky, Kz obtained in this way are the reference spectral radiant energy characteristics Sx (λ, which are tristimulus values of the reference spectral radiant energy characteristics Sx (λ), Sy (λ), Sz (λ) themselves. ), Sy (λ), and Sz (λ) are the ratios of the measured values (tristimulus values) measured by the tristimulus value direct-reading measuring instrument 10, and by multiplying the measured values, It can be corrected to the correct tristimulus value of the light source. In the flowchart of FIG. 5 described above, the predicted tristimulus values Xi, Yi, Zi are obtained after obtaining the reference tristimulus values Xs, Ys, Zs. However, the order of obtaining them may be reversed. It is not limited to.

  The tristimulus value direct reading type measuring instrument 10 can be configured as a tristimulus value direct reading type measuring system 30 by connecting to a personal computer (hereinafter referred to as a PC 31) (see FIGS. 1 and 6). FIG. 6 is an explanatory diagram showing a schematic configuration of a tristimulus value direct reading measurement system 30 using the tristimulus value direct reading type measuring instrument 10.

  The tristimulus value direct-reading measurement system 30 uses the tristimulus value direct-reading type measuring instrument 10 as a measuring instrument under the control of the PC 31, and acquires the acquired data (tristimulus values (Xo, Yo, Zo as output values to be described later)). )) Is output to the PC 31.

  The PC 31 stores a dedicated application program for operating the tristimulus value direct-reading measurement system 30, that is, for operating the tristimulus value direct-reading type measuring instrument 10, and input means 32 composed of a keyboard or a mouse. A signal corresponding to the operation performed is output to the tristimulus value direct reading type measuring instrument 10. In addition, the display screen 33 of the PC 31 displays a display for assisting the operation of the tristimulus value direct-reading measuring instrument 10, a tristimulus value as a measurement result (tristimulus values (Xo, Yo, Zo)) and the like are displayed.

  Further, the PC 31 inputs the data of the reference spectral radiant energy characteristic S by operating the input means 32 and stores the data in the memory 25 (see FIG. 1) through the control unit 16 of the tristimulus value direct reading type measuring instrument 10. Can be made. For this reason, in the tristimulus value direct reading measurement system 30, the input unit 32 of the PC 31 functions as a reference spectral radiant energy characteristic input unit for inputting data of the reference spectral radiant energy characteristic S. In addition, the PC 31 performs operations such as calculation of the above-described color correction coefficient K (see the flowchart in FIG. 5), setting of a measurement target and measurement start described later (see the flowchart in FIG. 7) by the input unit 32. Can do.

  Further, the PC 31 can acquire data of the reference spectral radiant energy characteristics Sx (λ), Sy (λ), Sz (λ) necessary for obtaining the color correction coefficient K using a network line or the like. The acquired data can be stored in the memory 25 (see FIG. 1) through the control unit 16 of the tristimulus value direct reading type measuring instrument 10. Thereby, when measuring an object to be measured using a plurality of tristimulus value direct reading type measuring instruments 10, it is possible to reduce the work of inputting the data, and the data in each tristimulus value direct reading type measuring instrument 10. Can be easily shared. This is particularly effective when measuring an object to be measured at each of a plurality of factories using the tristimulus value direct-reading measuring instrument 10.

  Note that, when the tristimulus value direct reading type measuring instrument 10 is used alone and when the tristimulus value direct reading type measuring system 30 is configured, the operation unit 17 is used for various operations or the input means 32 of the PC 31 is used. The basic operations, functions, effects, and the like are the same except that they are used in different ways and whether the displayed portion is the display unit 18 or the display screen 33 of the PC 31 is different. Below, the correction | amendment in the correction value calculating circuit 26 of the tristimulus value direct reading type measuring device 10 which concerns on this invention is demonstrated using the flowchart of FIG. 7 which follows the flow of the measurement in the tristimulus value direct reading type | mold measurement system 30. FIG. In this flowchart, it is assumed that the image forming apparatus 28 (see FIG. 6) is selected as a measurement target, and the color correction coefficient K corresponding to the image forming apparatus 28 has already been obtained and stored in the memory 25 ( (See the flowchart in FIG. 5).

  The tristimulus value direct reading type measuring instrument 10 connected to the PC 31 is installed at a predetermined position by the user (step S10). Specifically, the tristimulus value direct-reading measuring instrument 10 is installed so that the objective lens 19 of the measurement optical system 11 faces the desired position (for example, the center) in the image forming apparatus 28 to be measured. (See FIG. 6).

  The tristimulus value direct reading type measuring instrument 10 is activated (step S11). This can be performed, for example, by operating a power switch (not shown) provided in the tristimulus value direct reading type measuring instrument 10.

  The application program stored in the PC 31 is activated (step S12). As a result, a display image for measurement by the tristimulus value direct reading measurement system 30 is displayed on the display screen 33 of the PC 31.

  The user sets the measurement target, that is, the setting that the image forming apparatus 28 (see FIG. 6) is the measurement target in this example (step S13). This measurement target setting is a setting for specifying a measurement target (corresponding color correction coefficient K) in a measurement to be performed in the future. In this embodiment, the user operates the input unit 32 while viewing the display screen 33 of the PC 31. To do. When the measurement target is set, a signal corresponding to this operation is output from the PC 31 to the control unit 16 (see FIGS. 1 and 6) of the data processing unit 15 of the tristimulus value direct reading type measuring instrument 10, The control unit 16 controls the correction value calculation circuit 26.

  Then, the correction value calculation circuit 26 reads the color correction coefficients Kx, Ky, Kz corresponding to the image forming apparatus 28 (see FIG. 6) selected from the memory 25 and corrects the color correction coefficients. Is set to be used (step S14). As a result, the tristimulus value direct reading type measuring instrument 10, that is, the tristimulus value direct reading type measurement system 30, can measure the image forming device 28 (the light source having the reference spectral radiant energy characteristic S equal to this). In the present embodiment, the control unit 16 outputs a signal indicating that the setting has been completed to the PC 31, and the PC 31 causes the display screen 33 to display that the image forming apparatus 28 can be measured.

  In this state, when an operation for starting measurement by the tristimulus value direct reading type measuring instrument 10 is performed on the input means 32 of the PC 31, the control unit 16 of the tristimulus value direct reading type measuring instrument 10 causes the image forming apparatus 28. In order to start the measurement, each part of the tristimulus value direct reading type measuring instrument 10 is driven and controlled (step S15). Then, in the tristimulus value direct-reading type measuring instrument 10, as described above, the three light receiving sections 12 acquire the light guided by the measurement optical system 11, and the output signals thereof are the three amplifier circuits 13 and the three A−. The measurement signal M (measured value) is passed through the D conversion circuit 14, and this measurement signal M is input to the correction value calculation circuit 26 of the data processing unit 15. Since the measurement signal M is output from each of the three light receiving units 12, the measurement signal M has Mx, My, and Mz corresponding to each stimulus value. This is an actual measurement value acquisition step.

  When the measurement signals Mx, My, and Mz are input, the correction value calculation circuit 26 corrects the measurement signals Mx, My, and Mz according to the following equation (4) using the set color correction coefficients Kx, Ky, and Kz. Thus, output values Xo, Yo, and Zo are obtained (step S16).

Xo = Kx × Mx
Yo = Ky / My (4)
Zo = Kz / Mz
This is a measurement calculation process.

  The correction value calculation circuit 26 outputs the corrected output values Xo, Yo, Zo as tristimulus values (Xo, Yo, Zo) as measurement results (step S17). In the present embodiment, the tristimulus values (Xo, Yo, Zo) output from the tristimulus value direct-reading measuring instrument 10 are transmitted to the PC 31, and the tristimulus values (Xo, Yo, Zo) of the measurement results are displayed on the display screen 33. ) Is displayed.

  As described above, when the tristimulus value direct-reading measuring instrument 10 is used alone, the operation of the input means 32 of the PC 31 is performed by the operation unit 17, and the display on the display screen 33 of the PC 31 is displayed. This is done on the display unit 18.

In the tristimulus value direct reading type measuring instrument 10 or the tristimulus value direct reading type measurement system 30 according to the present invention, the following effects (1) to (9) can be obtained.
(1) Since the color correction coefficient K is obtained based on the color matching function T, the spectral response characteristic R of the three stimulus value light receiving units, and the reference spectral radiant energy characteristic S of the reference measured object, the reference of the measured object Since the color correction coefficient K can be obtained as long as the spectral radiant energy characteristic S is known, the work of measuring the object to be measured by the tristimulus value direct reading type measuring instrument 10 for calculating the color correction coefficient K can be eliminated. In other words, as a preparatory work for the measurement, the user simply performs the input operation of the data of the reference spectral radiant energy characteristic S of the measurement target selected by the user, and the measurement is performed using the tristimulus value direct reading type measuring instrument 10. An accurate tristimulus value of the subject can be measured.
(2) Since the predicted tristimulus values Xi, Yi, Zi are obtained from the spectral responsivity characteristics R and the reference spectral radiant energy characteristics S in the three light receiving sections 12, the predicted tristimulus values Xi, Yi, Zi are obtained. Is equal to the actual measurement values as the three stimulus values obtained by measuring the light source (measurement object) having the reference spectral radiant energy characteristic S by the three light receiving units 12. Therefore, the color correction coefficient K for each stimulus value obtained by dividing the predicted tristimulus values Xi, Yi, Zi by the reference tristimulus values Xs, Ys, Zs is the reference spectral radiant energy characteristic used for the calculation. As long as the light source (measurement object) having S is a measurement object, each actual measurement value (measurement signal M) obtained by measurement by the three light receiving units 12 can be appropriately corrected, and each corrected actual measurement value can be corrected. That is, three accurate stimulus values (Xo, Yo, Zo) can be obtained.
(3) The color correction coefficient K can be obtained on the basis of the data of the reference spectral radiant energy characteristic S only by inputting the data of the reference spectral radiant energy characteristic S by the operation unit 17 or the input means 32 of the PC 31. A light source (object to be measured) having a reference spectral radiant energy characteristic S can be a measurement target. For this reason, for example, if data of the reference spectral radiant energy characteristic S as a design value set in the light source (measurement object) is input, the measurement object (the reference thereof) for calculating the color correction coefficient K is input. An appropriate color correction coefficient K corresponding to the object to be measured can be obtained without measuring the light source), and the tristimulus value of the object to be measured can be appropriately measured.
(4) Spectral response characteristic R obtained by actually measuring the three light receiving portions 12 in a state where the three spectral sensitivity correction filters 23 and the three light receiving elements 24 are assembled, that is, each tristimulus value direct reading type. Since the color correction coefficient K is obtained using the spectral response characteristics R unique to the three light receiving units 12 mounted on the measuring instrument 10, the actual measurement values (measurement signals M) acquired by the respective light receiving units 12 are more appropriate. Thus, a more appropriate tristimulus value can be obtained. In other words, the spectral response characteristic R used when obtaining the color correction coefficient K is obtained by actually measuring the three light receiving sections 12 in the state where the three spectral sensitivity correction filters 23 and the three light receiving elements 24 are assembled. Since it is obtained, it matches the actual measurement scene using the tristimulus value direct-reading type measuring instrument 10, so that the actual measurement value (measurement signal M) can be corrected more appropriately.
(5) Since the spectral responsivity characteristic R used when obtaining the color correction coefficient K is measured in advance and stored in the memory 25, it is easy to include the instrumental difference for each of the tristimulus value direct reading type measuring instruments 10. It can be corrected.
(6) A spectroscopic measuring instrument (not shown) is connected to the PC 31 as the tristimulus value direct reading type measuring instrument 10 or the tristimulus value direct reading type measuring system 30, and the spectroscopic measuring instrument (the reference and its object) The color correction coefficient K based on the reference spectral radiant energy characteristic S can be obtained by measuring the reference spectral radiant energy characteristic S of the light source (measured light source). ) Can be measured. For this reason, for example, even when the data of the reference spectral radiant energy characteristic S as the design value set in the light source (measurement object) cannot be obtained, appropriate color correction corresponding to the measurement object can be easily performed. The coefficient K can be obtained, and the tristimulus value of the object to be measured can be appropriately measured.
(7) In particular, in the tristimulus value direct-reading measurement system 30 according to the present invention, when the tristimulus value (Xo, Yo, Zo) as the measurement value is acquired by the tristimulus value direct-reading measuring instrument 10, Since the stimulus values (Xo, Yo, Zo) are output to the PC 31, management of each measurement value can be facilitated. This is more effective because the measurement results (acquired data) can be easily managed, particularly when measurement is performed for quality inspection of a large number of measurement objects.
(8) Further, in the tristimulus value direct-reading measurement system 30 according to the present invention, data of the reference spectral radiant energy characteristics Sx (λ), Sy (λ), and Sz (λ) is obtained by using a network line or the like in the PC 31. Since the data can be acquired, the input work of the data can be reduced, and the data can be easily shared. This is because, for example, when measurement is performed at a plurality of locations such as a plurality of factories, the same reference spectral radiant energy characteristics Sx (λ), Sy (λ) at all locations. , Sz (λ) data can be easily shared, which is particularly effective.
(9) Since the measurement for obtaining the color correction coefficient K is not required, the measurement can be performed more easily. This is due to the following. For example, when inspecting the quality of display images of 100 types of image forming apparatuses with a single tristimulus value direct reading type measuring instrument, in the conventional tristimulus value direct reading type measuring instrument, the user can directly read the tristimulus value direct reading type measuring instrument. 100 types of image forming apparatuses (or light sources for correction corresponding thereto) are measured 100 times with a measuring instrument and a spectroscopic measuring instrument for a total of 200 times, and 100 types of image forming apparatuses (reference spectral radiant energy thereof) are measured. It was necessary to obtain a color correction coefficient corresponding to the characteristic S (spectral shape). On the other hand, in the tristimulus value direct reading type measuring instrument 10 according to the present invention, the user acquires the reference spectral radiant energy characteristics S of 100 types of image forming apparatuses and obtains the corresponding setting (color correction coefficient K). And setting to use the color correction coefficient K), the measurement can be started. For this reason, the preparation work for performing the measurement can be greatly shortened, and the trouble of managing a lot of data relating to the preparation work can be saved. This is particularly effective in the following cases.

  FIG. 8 is an explanatory diagram showing a state in which the quality of display images of a plurality of image forming apparatuses 28 is being inspected. FIG. 8A shows a case where the tristimulus value direct reading type measuring instrument 10 according to the present invention is used. (B) has shown the case where the conventional tristimulus value direct-reading type measuring instrument 1 is used.

  As shown in FIG. 8, it is assumed that image forming apparatuses 28 of the same type (the same spectrum shape) are produced in five different factories F1 to F5. In this factory F1-F5, 10 tristimulus value direct-reading type measuring instruments (10 or 1) are provided.

  When inspecting the quality of the display image of each image forming apparatus 28 produced using the conventional tristimulus value direct-reading type measuring instrument 1, as shown in FIG. 8 (b), ten units of each factory F1 to F5 are used. It is necessary to collect all the tristimulus direct reading type measuring instruments in a single place (factory F3 in the illustrated example), and accordingly, all the image forming apparatuses 28 produced in the factories F1 to F5 are arranged. It was necessary to collect in a single place (factory F3 in the example shown). This is due to the following. Each of the ten tristimulus value direct reading type measuring instruments in each of the factories F1 to F5 has an instrumental difference. Therefore, in order to accurately inspect the quality of the display image of each image forming apparatus 28, the total number Therefore, it is necessary to obtain the color correction coefficient for (50 units). Here, in the conventional tristimulus value direct-reading type measuring instrument 1, it is necessary to measure the image forming apparatus 28 serving as a reference to obtain a color correction coefficient, but the measurement environment affects the measurement result. In order to obtain each color correction coefficient so as not to cause a difference in measured values (actually measured values after correction) among all (50 units) tristimulus value direct-reading-type measuring instruments 1, Therefore, it is necessary to obtain all the color correction coefficients. Further, the obtained color correction coefficient can be corrected accurately under the same environment as the measurement environment. For this reason, even if ten tristimulus direct-reading measuring instruments are provided in each of the factories F1 to F5, all the image forming apparatuses 28 produced in the factories F1 to F5 are displayed with high accuracy. In order to perform quality inspection, it was necessary to collect them in a single place (factory F3 in the illustrated example).

  On the other hand, when using the tristimulus value direct reading type measuring instrument 10 according to the present invention, as shown in FIG. 8 (a), ten tristimulus value direct reading type measuring instruments provided in each factory F1 to F5. 10 can be used to inspect the quality of the display image of each image forming apparatus 28. This is due to the following. In each of the ten tristimulus value direct-reading measuring instruments 10 in each of the factories F1 to F5, since there are instrumental differences, in order to accurately inspect the quality of the display image of each image forming apparatus 28, The fact that it is necessary to obtain the color correction coefficient K for all (50 units) is the same as the conventional tristimulus value direct reading type measuring instrument 1. Here, in the tristimulus value direct-reading type measuring instrument 10 according to the present invention, the color correction coefficient K can be obtained without measuring the image forming apparatus 28 serving as a reference for each, so that each factory F1 to F5 accurately. The color correction coefficient K can be obtained, and the conditions in the inspection preparation stage can be unified. Further, the obtained color correction coefficient K can be corrected accurately in each factory F1 to F5. For this reason, if ten tristimulus direct-reading measuring instruments 10 are provided in each of the factories F1 to F5, all the image forming apparatuses 28 produced in the factories F1 to F5 are connected to the factories F1 to F5. In F5, the quality of the display image can be inspected with high accuracy using the ten tristimulus value direct-reading measuring instruments 10.

  Further, when the tristimulus value direct reading type measurement system 30 according to the present invention is used, for example, the reference spectral radiant energy characteristic S as the design value of the image forming apparatus 28 at the factory F3 is measured by one tristimulus value direct reading type measurement. Assume that the data is input to the container 10 by the input means 32 of the PC 31. Then, in the factory F3, the reference spectral radiant energy characteristics S can be acquired without performing the input operation in all (10) tristimulus value direct reading type measuring instruments 10 by using a network line or the like. . Similarly, by using a network line or the like, the reference spectral radiant energy characteristics S can be acquired by all (40) tristimulus value direct-reading measuring instruments 10 in the factories F1, F2, F3, and F4. (See arrow D).

  Therefore, in the tristimulus value direct-reading measuring instrument 10 according to the present invention, the work for setting the color correction coefficient K corresponding to a new light source (object to be measured) is greatly reduced while the three measured values are accurate. Stimulus values can be obtained.

  In the embodiment described above, color matching function storage means for storing the color matching function T, reference spectral radiant energy characteristic storage means for storing the reference spectral radiant energy characteristic S, and color correction coefficient storage means for storing the color correction coefficient K. The tristimulus value direct reading type measuring system 10 provided with the memory 25 and the PC 31 constitutes the tristimulus value direct reading type measuring system 30. Since the reference spectral radiant energy characteristic storage means and the color correction coefficient storage means need only be included, for example, the PC 31 is provided with a color matching function storage means, a reference spectral radiant energy characteristic storage means, and a color correction coefficient storage means. However, the present invention is not limited to the above-described embodiments. In this case, for example, the application program for the tristimulus value direct reading measurement system 30 is provided with functions corresponding to the color matching function storage unit, the reference spectral radiant energy characteristic storage unit, and the color correction coefficient storage unit. can do. Since the spectral response characteristic R is unique to each tristimulus value direct reading type measuring instrument 10, the spectral response characteristic storage means is provided in each tristimulus value direct reading type measuring instrument 10. desirable.

  In the above-described embodiment, the tristimulus value direct reading type measuring instrument 10 provided with the correction value calculation circuit 26 as the correction value calculation unit and the color correction coefficient calculation circuit 27 as the color correction coefficient calculation unit and the PC 31 are used. The tristimulus value direct-reading measurement system 30 is configured. However, since the tristimulus value direct-reading measurement system only needs to have a correction value calculation unit and a color correction coefficient calculation unit, for example, correction to the PC 31 is performed. A value calculation unit and a color correction coefficient calculation unit may be provided, and the present invention is not limited to the above-described embodiment. In this case, for example, it can be realized by providing the application program for the tristimulus value direct-reading measurement system 30 with functions corresponding to the correction value calculation unit and the color correction coefficient calculation unit.

  Furthermore, in the above-described embodiment, in the tristimulus value direct reading type measuring instrument 10, the memory 25 stores color matching function storage means for storing the color matching function T and reference spectral radiant energy characteristic storage for storing the reference spectral radiant energy characteristic S. Means, a color correction coefficient storage means for storing the color correction coefficient K, and a spectral response characteristic storage means for storing the spectral response characteristic R, but these are not constituted by the same storage means (memory). However, the present invention is not limited to the above-described embodiments. For example, the spectral response characteristic R is fixed unique data in the tristimulus value direct-reading type measuring instrument 10, and the color matching function T is fixed data. The color function storage means may be constituted by a read-only medium such as a ROM, and the reference spectral radiant energy characteristic storage means and the color correction coefficient storage means may be constituted by a readable / writable medium such as a RAM.

  In the above-described embodiment, the tristimulus value direct reading type measuring instrument 10 acquires data of the reference spectral radiant energy characteristic S by an input operation performed on the operation unit 17 or from a connected spectroscopic measuring instrument (not shown). Although it was possible, it can be set as the structure which can be acquired by delivery of the data between other tristimulus value direct-reading type | mold measuring instruments 10, and is not limited to an above-described Example. In this case, for example, a configuration may be provided in which wireless communication means for data transfer between the two tristimulus value direct reading type measuring instruments 10 is provided, and data between the two tristimulus value direct reading type measuring instruments 10 may be provided. It may be configured to connect a cable for delivery.

  In the above-described embodiment, the tristimulus value direct reading type measuring instrument 10 that measures the tristimulus values (Xo, Yo, Zo) has been described as the stimulus value direct reading type measuring instrument according to the present invention. A stimulus value direct-reading type measuring instrument (for example, luminance meter or illuminance meter (in this case, only Y is used among tristimulus values)) for measuring one may be used, and is not limited to the above-described embodiment. Absent.

DESCRIPTION OF SYMBOLS 10 Tristimulus value direct-reading type measuring device 12 Light receiving part 17 Operation part (As a reference spectral radiant energy characteristic input means) 23 Spectral sensitivity correction filter (As an optical filter) 24 Light receiving element 25 (Color matching function storage means, reference spectral radiation) Memory 26 (as energy characteristic storage means, color correction coefficient storage means and spectral response characteristic storage means) 26 Correction value calculation circuit 27 (as correction value calculation section) Color correction coefficient calculation circuit 28 (as color correction coefficient calculation section) Image forming apparatus (as measured object) 30 Tristimulus value direct-reading measurement system 32 Input means (as reference spectral radiant energy characteristic input means) K Color correction coefficient M Measurement signal (as measured value) R Spectral response characteristics S standard spectral radiant energy characteristic T color matching function Xi, Yi, Zi predicted tristimulus value Xs, Ys, Zs standard tristimulus value Xo Yo, Zo (output value as a measured value) tristimulus values

Claims (7)

A light receiving unit having a predetermined spectral response characteristic to measure the tristimulus value of the object to be measured;
A correction value calculation unit for obtaining the tristimulus values obtained by correcting the actual measurement values obtained by multiplying the actual measurement values obtained by the light receiving unit that has measured the object to be measured by correcting the actual measurement values;
Reference spectral radiant energy characteristic storage means for storing a reference spectral radiant energy characteristic of a reference measured object serving as a reference for the measured object;
Spectral response characteristic storage means for storing the spectral response characteristic of the light receiving unit;
Color matching function storage means for storing color matching functions;
A color correction coefficient calculating unit for obtaining the color correction coefficient based on each characteristic stored in the color matching function storage means, the spectral response characteristic storage means, and the reference spectral radiant energy distribution characteristic storage means;
Color correction coefficient storage means for storing the color correction coefficient obtained by the color correction coefficient calculation unit,
The color correction coefficient calculation unit obtains a reference tristimulus value by integrating a product of the color matching function and the reference spectral radiant energy characteristic with respect to a wavelength in a visible region, and calculates the spectral responsivity characteristic and the reference spectral radiant energy. A predicted tristimulus value to be obtained by measuring the reference spectral radiant energy characteristic with the light receiving unit by integrating the product with the characteristic with respect to the wavelength in the visible region, and dividing the predicted tristimulus value by the reference tristimulus value A stimulus value direct-reading type measuring instrument that obtains the color correction coefficient for each stimulus value.   2. The stimulus value direct reading according to claim 1, wherein the reference spectral radiant energy characteristic storage unit is capable of storing data of the reference spectral radiant energy characteristic input via the reference spectral radiant energy characteristic input unit. Type measuring instrument.   2. The stimulus value direct reading type measurement according to claim 1, wherein the reference spectral radiant energy characteristic storage means can acquire and store data of the reference spectral radiant energy characteristic measured by a spectroscopic measuring instrument. vessel. The light receiving unit includes an optical filter that allows transmission of light in a predetermined wavelength region, and a light receiving element that receives light that has passed through the optical filter,
The spectral response characteristic is obtained by actually measuring an output with respect to a received light amount in the light receiving unit in a state where the optical filter and the light receiving element are assembled as the light receiving unit. The stimulus value direct reading type measuring instrument according to any one of claims 1 to 3. A light receiving unit having a predetermined spectral responsivity characteristic to measure the tristimulus value of the object to be measured, and each actual value obtained by multiplying the actual value acquired by the light receiving unit that measured the object to be measured by a color correction coefficient. A correction value calculation unit for obtaining the tristimulus values corrected values, a color correction coefficient storage unit for storing the color correction coefficient, a spectral response characteristic storage unit for storing the spectral response characteristic of the light receiving unit, A stimulus value direct reading type measuring instrument comprising:
A reference tristimulus value is obtained by integrating a product of a reference spectral radiant energy characteristic and a color matching function of a reference measurement object serving as a reference for the measurement object with respect to a wavelength in a visible region, and the spectral response characteristic and the reference By integrating the product of the spectral radiant energy characteristic with respect to the wavelength in the visible region, a predicted tristimulus value to be obtained when the reference spectral radiant energy characteristic is measured by the light receiving unit is obtained, and the predicted tristimulus value is obtained as the reference tristimulus value A stimulus value direct-reading type measuring instrument comprising: a color correction coefficient calculation unit that obtains the color correction coefficient by dividing by a value and stores the color correction coefficient in the color correction coefficient storage means. A light receiving unit having a predetermined spectral response characteristic to measure the tristimulus value of the object to be measured;
A correction value calculation unit for obtaining the tristimulus values obtained by correcting the actual measurement values obtained by multiplying the actual measurement values obtained by the light receiving unit that has measured the object to be measured by correcting the actual measurement values;
Reference spectral radiant energy characteristic storage means for storing a reference spectral radiant energy characteristic of a reference measured object serving as a reference for the measured object;
Spectral response characteristic storage means for storing the spectral response characteristic of the light receiving unit;
Color matching function storage means for storing color matching functions;
A color correction coefficient calculating unit for obtaining the color correction coefficient based on each characteristic stored in the color matching function storage means, the spectral response characteristic storage means, and the reference spectral radiant energy distribution characteristic storage means;
Color correction coefficient storage means for storing the color correction coefficient obtained by the color correction coefficient calculation unit,
The color correction coefficient calculation unit obtains a reference tristimulus value by integrating a product of the color matching function and the reference spectral radiant energy characteristic with respect to a wavelength in a visible region, and calculates the spectral responsivity characteristic and the reference spectral radiant energy. A predicted tristimulus value to be obtained by measuring the reference spectral radiant energy characteristic with the light receiving unit by integrating the product with the characteristic with respect to the wavelength in the visible region, and dividing the predicted tristimulus value by the reference tristimulus value A stimulus value direct-reading measurement system characterized in that the color correction coefficient is obtained by doing so. An actual measurement value acquisition step of acquiring an actual measurement value before correction by measuring an object to be measured with a light receiving unit having a predetermined spectral response characteristic;
A measurement calculation step for obtaining the tristimulus value by correcting the actual measurement value by multiplying the actual measurement value acquired by the light receiving unit by a color correction coefficient, and a stimulation value direct-reading measurement method comprising:
A reference tristimulus value is obtained by integrating a product of a reference spectral radiant energy characteristic and a color matching function of a reference measurement object serving as a reference for the measurement object with respect to a wavelength in a visible region, and the spectral response characteristic and the reference By integrating the product of the spectral radiant energy characteristic with respect to the wavelength in the visible region, a predicted tristimulus value to be obtained when the reference spectral radiant energy characteristic is measured by the light receiving unit is obtained, and the predicted tristimulus value is obtained as the reference tristimulus value. A stimulus value direct-reading type measuring method, wherein the color correction coefficient is obtained by dividing by a value.

Images