Stimulus value direct-reading colorimeter

Abstract

The present invention is provided with: a plurality of color sensing units (51)-(54) that comprise a plurality of color filters (511)-(541) and a plurality of light-receiving sensors (512)-(542) for receiving light which has passed through the color filters (511)-(541); a plurality of signal processing circuits (61)-(64) that respectively correspond to the plurality of color sensing units (51)-(54) and have a function for integrating signals input thereto from the color sensing units (51)-(54); and a computation unit (7) that computes outputs from the signal processing circuits (61)-(64). Among the plurality of color sensing units (51)-(54), color sensing units that have spectral sensitivities corresponding to the X component, the Y component, and the Z component of a color-matching function are included, and there are a plurality of second color sensing units (52), (53) that have a spectral sensitivity corresponding to the Y component. Signals from the second color sensing units (52), (53) are processed by the corresponding signal processing circuits (62), (63) and added by the computation unit (7).

Description

Direct-reading stimulus colorimeter

[0001] This invention relates to a stimulus value direct reading colorimeter.

[0002] The direct-reading stimulus colorimeter includes multiple color sensing units. Each color sensing unit has a color filter and a light-receiving sensor that receives light transmitted through the color filter. Each of the multiple color sensing units has a spectral sensitivity corresponding to the X component, the Y component, and the Z component of the color matching function.

[0003] As is well known, rod sensitivity is higher than cone sensitivity, so differences in luminance are more noticeable than differences in chromaticity at low luminance. Therefore, in direct-reading stimulus colorimeters, luminance measurement performance should be prioritized over chromaticity measurement performance in the low luminance range. In other words, the spectral sensitivity corresponding to the Y component of the color-matching function should be higher than the spectral sensitivity corresponding to the X component and the spectral sensitivity corresponding to the Z component.

[0004] Therefore, in order to increase the spectral sensitivity corresponding to the Y component, it is conceivable to add a color sensing unit having a spectral sensitivity corresponding to the Y component.

[0005] In Patent Document 1, in the third mode of the second embodiment, the output of the light-receiving sensor 6b for Y-value detection and the output of the light-receiving sensor 6d for flicker measurement are added together and input to an amplifier (integrator) 7b of the Y-value detection circuit. In other words, in Patent Document 1, a color sensing unit having spectral sensitivity corresponding to the Y component is added in the amount of the light-receiving sensor 6d for flicker measurement. As a result, the spectral sensitivity corresponding to the Y component of the color matching function is higher than the spectral sensitivity corresponding to the X component and the spectral sensitivity corresponding to the Z component.

[0006] Patent No. 6794995

[0007] However, in the technology described in Patent Document 1, the output of the light-receiving sensor 6b for detecting the Y value and the output of the light-receiving sensor 6d for measuring flicker are input to the integrator 7b of the Y-value detection circuit. In other words, the outputs of both light-receiving sensors are added together before being input to the integrator 7b of the Y-value detection circuit, which has the following drawbacks:

[0008] That is, in low-brightness areas, where weak light is to be detected, it is better to keep the wiring from the light-receiving sensor to the integrator short. The reason for this is that long wiring increases the risk of increased parasitic capacitance and crosstalk, and there is also the risk of leakage due to the effects of humidity. These become noise components, which in turn reduce measurement accuracy.

[0009] However, when the outputs of multiple light-receiving sensors are added before being input to an integrator (amplifier), as in the technology described in Patent Document 1, the output of each light-receiving sensor must be switched, which inevitably leads to long wiring and the generation of noise components. Furthermore, the switching of the output of each light-receiving sensor also introduces noise caused by the circuitry. This results in an increase in noise compared to when the output of the light-receiving sensor is directly input to the integrator.

[0010] An object of the present invention is to provide a stimulus value direct reading colorimeter that suppresses noise even when it has a plurality of color sensing units having spectral sensitivity corresponding to the Y component.

[0011] The above object is achieved by the following means: (1) A direct-reading stimulus colorimeter comprising: a plurality of color sensing units each having a plurality of color filters and a plurality of light-receiving sensors that receive light transmitted through each color filter; a plurality of signal processing circuits each corresponding to the plurality of color sensing units and having an integration function to which signals from each color sensing unit are input; and a calculation unit that calculates outputs from the plurality of signal processing circuits, wherein the plurality of color sensing units include a first color sensing unit having spectral sensitivity corresponding to the X component of a color matching function, a second color sensing unit having spectral sensitivity corresponding to the Y component, and a third color sensing unit having spectral sensitivity corresponding to the Z component, and wherein there are a plurality of second color sensing units, and wherein the signals from the plurality of second color sensing units are processed by the corresponding signal processing circuits and then added together in the calculation unit. (2) A direct-reading stimulus colorimeter according to the preceding paragraph 1, wherein the total area of ​​the plurality of light-receiving sensors that make up the plurality of second color sensing units is larger than the area of ​​each of the light-receiving sensors that make up the first color sensing unit and the third color sensing unit. (3) A direct stimulus reading colorimeter according to paragraph 1 or 2, in which one signal processing circuit includes an integrator, an A / D converter, and a filter, and the plurality of signal processing circuits are configured on a single semiconductor chip. (4) A direct stimulus reading colorimeter according to paragraph 1 or 2, in which a light guide section is provided for guiding light of the object to be measured to each of the plurality of color sensing sections. (5) A direct stimulus reading colorimeter according to paragraph 4, in which the light guide section is formed of an optical fiber. (6) A direct stimulus reading colorimeter according to paragraph 5, in which light incident on an incident area located at a point symmetrical about the optical axis on the incident surface of an optical fiber into which light from the object to be measured is incident is guided to each of the color sensing sections. (7) A direct stimulus reading colorimeter according to paragraph 5, in which the light receiving sensor is configured of a Si photodiode.

[0012] The direct-reading stimulus colorimeter according to the present invention includes a plurality of color sensing units each having a plurality of color filters and a plurality of light-receiving sensors that receive light transmitted through each color filter, a plurality of signal processing circuits each corresponding to the plurality of color sensing units and having an integration function to which signals from each color sensing unit are input, and a calculation unit that calculates outputs from the plurality of signal processing circuits. The plurality of color sensing units include a first color sensing unit having spectral sensitivity corresponding to the X component of a color matching function, a second color sensing unit having spectral sensitivity corresponding to the Y component, and a third color sensing unit having spectral sensitivity corresponding to the Z component. There are also a plurality of second color sensing units.

[0013] The signals from the multiple second color sensing units are then processed by their corresponding signal processing circuits and then added together in the calculation unit. In other words, the signals from the second color sensing units having spectral sensitivities corresponding to the Y component are not added together before being input to the integrator, as in the conventional method, but are input to the signal processing circuit, processed, and then added together in the calculation circuit. This eliminates the need for signal input switching when the signals from each second color sensing unit are input to the signal processing circuit, shortening the wiring between the second color sensing units and the signal processing circuit and suppressing noise components. Furthermore, circuit-related noise caused by input switching of signals from the second color sensing units is not generated. As a result, noise is suppressed, enabling highly accurate color measurement in low-brightness areas.

[0014] 1 is a block diagram showing the configuration of a color luminance meter, which is an example of a stimulus value direct-reading colorimeter according to an embodiment of the present invention. It is a diagram schematically showing the size of each light-receiving sensor of the first to third color sensing units. It is a front view of the incident surface of the fiber bundle, illustrating the relationship between light input to eight incident regions on the incident surface and light guided to the color sensing unit. It is also a front view of the incident surface of the fiber bundle, illustrating the relationship between light input to four incident regions on the incident surface and light guided to the color sensing unit. It is a diagram schematically showing a light beam with a circular cross section that leaves a point in the measured area and enters the incident surface of the fiber bundle. It is a diagram schematically showing a state in which, of the light beams emitted from the object to be measured, the light beam emitted upward is larger than the light beam emitted downward. It is a diagram for explaining the effect of providing multiple second color sensing units having spectral sensitivity corresponding to the Y component, illustrating the case where light is received without a condenser lens. It is a diagram for explaining the effect of providing multiple second color sensing units having spectral sensitivity corresponding to the Y component, illustrating the case where light is received with a condenser lens. FIG. 9 is a diagram for explaining a state in which the area of ​​the light receiving sensor in FIG. 8 is doubled.

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0016] FIG. 1 is a block diagram showing the configuration of a color luminance meter 1, which is an example of a stimulus value direct reading color meter according to an embodiment of the present invention.

[0017] As shown in FIG. 1, the color luminance meter 1 includes an objective lens 2, a field stop 3, a fiber bundle 4, a plurality of (four in this example) color sensing units 51 to 54, four signal processing circuits 61 to 64, and a calculation unit 7.

[0018] The color sensing units 51 to 54 are provided with color filters 511 to 541 and light receiving sensors 512 to 542, respectively.

[0019] The color sensing unit 51 is a first color sensing unit, and includes a first color filter 511 and a first light-receiving sensor 512 that receives light that has passed through the first color filter 511. The first color sensing unit 51 has spectral sensitivity that corresponds to the X component of the color matching function.

[0020] The color sensing units 52 and 53 are second color sensing units, and each include a second color filter 521, 531, and a second light-receiving sensor 522, 532 that receives light that has passed through the second color filter 521, 531. The second color sensing units 52, 53 each have spectral sensitivity that corresponds to the Y component of the color matching function.

[0021] The color sensing unit 54 is a third color sensing unit, and includes a third color filter 541 and a third light-receiving sensor 542 that receives light that has passed through the third color filter 541. The third color sensing unit 54 has spectral sensitivity that corresponds to the Z component of the color matching function.

[0022] In this embodiment, sensors of approximately the same size are used for the light-receiving sensor 512 of the first color sensing unit 51, the light-receiving sensors 522 and 532 of the second color sensing units 52 and 53, and the light-receiving sensor 542 of the third color sensing unit 54, as schematically shown in Fig. 2. Therefore, the total area of ​​the light-receiving sensors 522 and 532 of the second color sensing units 52 and 53 is approximately twice the area of ​​each of the light-receiving sensor 512 of the first color sensing unit 51 or the light-receiving sensor 542 of the third color sensing unit 54.

[0023] In this embodiment, each of the light receiving sensors 512 to 542 is configured by a Si photodiode that has high light receiving sensitivity and a fast response time, but is not limited to a Si photodiode.

[0024] Furthermore, in the color sensing units 51 to 54, a condenser lens may be provided in front of each of the color filters 511 to 541.

[0025] Each of the signal processing circuits 61 to 64 includes an integrator 611 to 641, an A / D converter 612 to 642 that converts the analog signals from the integrators 611 to 641 into digital signals, and a filter 613 to 643 that removes noise contained in the signals from the A / D converters 612 to 642.

[0026] The four signal processing circuits 61 to 64 correspond to the first to third four color sensing units 51 to 54, and a signal from the light-receiving sensor 512 of the first color sensing unit 51 is input to an integrator 611 of the signal processing circuit 61. Signals from the light-receiving sensors 522 and 532 of the second color sensing units 52 and 53 are input to integrators 621 and 631 of the signal processing circuits 62 and 63, respectively. A signal from the light-receiving sensor 542 of the third color sensing unit 54 is input to an integrator 641 of the signal processing circuit 64.

[0027] The outputs of the four signal processing circuits 61 to 64 are input to the calculation unit 7 .

[0028] The calculation unit 7 is configured with a processor such as a CPU, and calculates measurement values ​​from the outputs of the signal processing circuits 61 to 64, and further controls the entire color luminance meter 1. For the two second color sensing units 52 and 53, the signals output from the signal processing circuits 62 and 63 are added together by the calculation unit 7, and then a measurement value is calculated based on the added value.

[0029] In this embodiment, although not limited to this, the four signal processing circuits 61 to 64 are configured on a single semiconductor chip 8 that has undergone the same semiconductor process. The reason for this will be described later.

[0030] The fiber bundle 4 is composed of a number of thin optical fibers bundled together. The fiber bundle 4 functions as a light guide that guides the measurement light to each of the four color sensing units 51 to 54. The ends of the fiber bundle 4 on the objective lens 2 side are bundled together to form an incident surface for the measurement light. The fiber bundle 4 is split into four bundles midway downstream from the incident surface to form four branching units 41 to 44. The output ends 411 to 441 of the four branching units 41 to 44 extend to positions facing the color filters 511 to 541 of the color sensing units 51 to 54. With this configuration, the measurement light incident on the incident surface of the fiber bundle 4 is split into the four branching units 41 to 44 and guided to the output ends 411 to 441, and is emitted from the output ends 411 to 441 to enter each of the color sensing units 51 to 54.

[0031] Next, the operation of the color luminance meter 1 shown in FIG. 1 will be described.

[0032] The ray bundle 100 to be measured is converged by the objective lens 2. The objective optical system consisting of the objective lens 2 may be replaced by another type of objective optical system.

[0033] The peripheral ray bundles of the converged ray bundle 101 are restricted by the field stop 3 .

[0034] The limited ray bundle is incident on the incident surface of the fiber bundle 4. The incident ray bundle is branched by the branching units 41 to 44. The four ray bundles obtained by branching are emitted from the emission ends 411 to 441 of the branching units 41 to 44, respectively. Note that the branching mechanism of the fiber bundle 4 may be replaced with another type of branching mechanism.

[0035] The light beams emitted from the exit ends 411 to 441 of the four branching units 41 to 44 are input to the color sensing units 51 to 54, respectively, and pass through the color filters 511 to 541 of the color sensing units 51 to 54. The transmitted light beams are received by the light receiving sensors 512 to 542 of the color sensing units 51 to 54, respectively. The light receiving sensors 512 to 542 output electrical signals corresponding to the received light beams.

[0036] The relative spectral responsivity achieved by the color filter 511 and light-receiving sensor 512 of the first color sensing unit 51 is approximated to the X component of the color matching function. The relative spectral responsivity achieved by the color filters 521 and 531 and light-receiving sensors 522 and 532 of the two second color sensing units 52 and 53 is approximated to the Y component of the color matching function. The relative spectral responsivity achieved by the color filter 541 and light-receiving sensor 542 of the third color sensing unit 54 is approximated to the Z component of the color matching function.

[0037] The electrical signals from the light receiving sensors 512 to 542 are input to and integrated by the integrators 611 to 641 of the corresponding signal processing circuits 61 to 64. The integrated electrical signals are converted from analog to digital by the corresponding A / D converters 612 to 642.

[0038] Each digitally converted signal passes through a corresponding filter 613 to 643 to remove noise, and then is input to the calculation unit 7 .

[0039] The calculation unit 7 calculates a stimulus value X based on the signal value from the signal processing circuit 61. The calculation unit 7 adds two signal values ​​from the signal processing circuits 62 and 63, and calculates a luminance value Lv (stimulus value Y) based on the addition result. The calculation unit 7 calculates a stimulus value Z based on the signal value from the signal processing circuit 64.

[0040] In this way, the luminance value Lv (stimulus value Y) is determined by adding, in the calculation unit 7, the signals obtained after the outputs of the light-receiving sensors 522 and 532 of the two color sensing units 52 and 53 are processed by the signal processing circuits 62 and 63, respectively. Furthermore, the total area of ​​the light-receiving sensors 522 and 523 of the color sensing units 52 and 53 is approximately twice that of a single light-receiving sensor. It is also approximately twice the area of ​​the light-receiving sensors 512 and 542 of the other color sensing units 51 and 54. This increases the amount of light received by the two light-receiving sensors 522 and 532 in the low-luminance region, thereby increasing the signal value used to calculate the luminance value Lv (stimulus value Y). As a result, highly accurate color measurement is possible.

[0041] Furthermore, the outputs of the two second color sensing units 52 and 53 having spectral sensitivities corresponding to the Y component are processed by the signal processing circuits 62 and 63, respectively, and then added up by the calculation unit 7, so that the following effects can be obtained.

[0042] That is, compared to when the outputs of the two second color sensing units 52, 53 are added before being input to the signal processing circuits 62, 63, there is no need to switch the input signals from each second color sensing unit 52, 53. This allows the second color sensing units 52, 53 to be connected to the signal processing circuits 62, 63 via the shortest possible connections. This allows the wiring between the second color sensing units 52, 53 and the signal processing circuits 62, 63 to be shortened, thereby suppressing noise components. Furthermore, circuit-induced noise caused by switching the input signals from the second color sensing units 52, 53 is also not generated. As a result, noise is suppressed, enabling highly accurate color measurement in low-brightness areas.

[0043] Furthermore, in this embodiment, the four signal processing circuits 61 to 64 are configured on a single semiconductor chip 8, which has the following advantages.

[0044] That is, when the four signal processing circuits 61 to 64 are formed on separate semiconductor chips (discrete), each of the signal processing circuits 61 to 64 is fabricated in a separate process, resulting in large individual variations such as variations between lots.

[0045] In contrast, in this embodiment, the integrators 611 to 641, the A / D converters 612 to 642, and the filters 613 to 643 of the signal processing circuits 61 to 64 are fabricated using the same semiconductor process. Therefore, when the signals from the signal processing circuits 62 and 63 are equivalent, the difference in their signal values ​​is small. Furthermore, compared to when the signal processing circuits 62 and 63 are formed on separate semiconductor chips, there is less individual variation in the output after the two signal values ​​are added together and less individual variation in the amount of fluctuation due to temperature characteristics. This enables more accurate color measurement in low-brightness areas.

[0046] In this embodiment, the branched portions 41 to 44 of the bundle fiber 4 are configured as follows.

[0047] That is, as shown in Fig. 3, the incident surface A of the bundle fiber 4 is partitioned into eight sector-shaped incident areas A11, A12, A21, A22, A31, A32, A41, and A42, each having a central angle of 45 degrees and equal areas. As is clear from Fig. 3, the incident areas A11 and A12, the incident areas A21 and A22, and the incident areas A31 and A32 are each located at positions that are point-symmetric with respect to the optical axis 40 (the center of the incident surface A). The light beams that have entered these two incident areas located at point-symmetric positions are guided to one color sensing unit via one branching unit and are emitted from the exit end of the branching unit.

[0048] That is, the light beams incident on the entrance regions A11 and A12 are guided by the branching unit 41 to the first color sensing unit 51 and emitted from the exit end 411 of the branching unit 41 to the color filter 511 of the first color sensing unit 51. The light beams incident on the entrance regions A21 and A22 are guided by the branching unit 42 to the second color sensing unit 52 and emitted from the exit end 421 of the branching unit 42 to the color filter 521 of the second color sensing unit 52. The light beams incident on the entrance regions A31 and A32 are guided by the branching unit 43 to the second color sensing unit 53 and emitted from the exit end 431 of the branching unit 43 to the color filter 531 of the second color sensing unit 53. The light beams incident on the entrance areas A41 and A42 are guided by the branching unit 44 to the third color sensing unit 54, and are emitted from the exit end 441 of the branching unit 44 to the color filter 541 of the third color sensing unit 54. In Fig. 3, the symbols X, Y, and Z indicate which of the stimulus values ​​X, Y, and Z the light beams input from each entrance area are used to measure.

[0049] Therefore, even if the light beam incident on the incident surface A of the bundle fiber 4 has unevenness within the incident surface A, the unevenness is averaged by adding the light beams incident on the two incident regions located at point-symmetric positions around the optical axis 40, and light beams with reduced unevenness are emitted from each of the branching sections 41 to 44.

[0050] This point will be explained in more detail. When the incident surface A of the bundle fiber 22 is simply divided into four incident areas A1 to A4 as shown in Figure 4, unevenness in the amount of light will occur among the four incident areas A1 to A4 depending on the light distribution characteristics of the object Q. Therefore, when the rotational angle positional relationship of the incident surface A with respect to the object Q changes, the amount of light received by each of the light-receiving sensors 512 to 542 of each of the color sensing units 51 to 54 will fluctuate, and as a result, there is a risk that the tristimulus values ​​obtained as measurement values ​​will change.

[0051] That is, for example, as shown in Fig. 5, consider a light beam KSa with a circular cross section that emerges from a certain point in the measurement area AR and is incident on the incident surface A. Of this light beam KSa, the upper half of the light beam (the portion indicated by diagonal lines in Fig. 5) is incident on the upper half of the incident surface A, and the lower half of the light beam (the portion without diagonal lines in Fig. 5) is incident on the lower half of the incident surface A. This does not pose a problem if the light distribution characteristic of the object Q under measurement is symmetrical with respect to the normal, but it does pose a problem if the light distribution characteristic is asymmetrical.

[0052] 6, if the upward emitting beam of light KS from the object Q is greater than the downward emitting beam, the upper half of the incident surface A will be brighter and the lower half will be darker. As a result, the amount of light incident on the four incident areas A1 to A4 will be uneven. Therefore, if the rotational angle positional relationship of the incident surface A with respect to the object Q changes, the amount of light received by the same light-receiving sensor will fluctuate.

[0053] For example, in the case of the rotation angle position shown in Figure 4, the amount of light received by the upper incident area A1 is the greatest, but when the bundle fiber 4 rotates and the rotation angle position changes 180 degrees so that the incident area A1 is at the bottom, the amount of light received there becomes the smallest. In this way, the tristimulus values ​​obtained as measured values ​​change depending on the relative positions of the object Q and the bundle fiber 4, and this may appear as a measurement error. The phenomenon of light distribution characteristics becoming asymmetrical in the vertical direction is often seen in liquid crystal panels, and can therefore be a problem when measuring the optical characteristics of liquid crystal displays.

[0054] Therefore, as shown in FIG. 3 , two incident regions (e.g., incident regions A21 and A22) located on opposite sides of the optical axis 40 of the incident surface A are paired to form a plurality of pairs. Each pair is then associated with the output ends 411 to 441 of the branching units 41 to 44. As a result, even if the light distribution characteristic of the object Q is asymmetrical in the vertical direction, as shown in FIG. 6 , the amounts of light received by the two incident regions are added together, thereby canceling out the asymmetry of the light distribution characteristic. Therefore, regardless of the rotational angle position of the fiber bundle 4, approximately the same amount of light is emitted from the output ends 411 to 441 of the branching units 41 to 44. Therefore, the electrical signals output by the light-receiving sensors 512 to 542 of the color sensing units 51 to 54 are not affected by the asymmetry of the light distribution characteristic of the object Q, thereby improving the accuracy of the measurement values.

[0055] Next, the effect of providing two second color sensing units 52 and 53 having spectral sensitivity corresponding to the Y component will be described.

[0056] Consider the case where light beams emitted from the exit ends 411 to 441 of the branching units 41 to 44 are received by the light-receiving sensors 512 to 542 via the color filters 511 to 541 without a condenser lens. In this case, as shown by an example of the color sensing unit 52 in FIG. 7, the color filter 521 and the light-receiving sensor 522 are larger than the exit end 421 of the branching unit 42. This poses problems in terms of installation space and cost. Since the color filter 521 and the light-receiving sensor 522 become more expensive as their size increases, there is a demand for them to be as small as possible. Note that in FIG. 7, reference numeral 522a denotes the cell surface of the light-receiving sensor 522.

[0057] Next, consider the case where a condenser lens 92 is interposed between the exit end 421 of the branching unit 42 and the color filter 521 as shown in Figure 8 in order to reduce the size of the light-receiving sensor 522. In this case, the area of ​​the cell surface 522a of the light-receiving sensor 522 is defined as S. Because the light beam emitted from the exit end 421 of the branching unit 42 is condensed by the condenser lens 92, the area S of the cell surface 522a can be made smaller than in the case of Figure 7 in which the condenser lens 92 is not present.

[0058] However, if the area S of the cell surface 522a is doubled to increase the spectral sensitivity of the Y component, as shown in Figure 9, the size of the output end 421 of the branching portion 42 of the bundle fiber 4 must also be doubled. Furthermore, the effective diameter of the condenser lens 92 and the size of the color filter 521 must also be doubled. This still results in an increase in cost.

[0059] Therefore, by providing two second color sensing units 52 and 53, it is possible to use, as the Y component light receiving sensors 522 and 532, sensors of the same size as the X component light receiving sensor 512 and the Z component light receiving sensor 542. In other words, because it is sufficient to use general-purpose light receiving sensors as the Y component light receiving sensors 522 and 532, there is no need for large, specialized light receiving sensors or color filters, etc., and it is possible to increase the spectral sensitivity of the Y component while avoiding an increase in costs.

[0060] Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, although two second color sensing units 52 and 53 are provided for the Y stimulus value, three or more units may be provided.

[0061] This application claims priority from Japanese Patent Application No. 2023-219747, filed on December 26, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0062] This invention can be used as a stimulus value direct reading colorimeter.

[0063] 1 Color luminance meter (stimulus value direct reading color meter) 2 Objective lens 3 Field stop 4 Fiber bundle 7 Calculation unit 8 Single semiconductor chip 41 to 44 Branching unit 51 First color sensing unit 52 Second color sensing unit 53 Second color sensing unit 54 Third color sensing unit 61 to 64 Signal processing circuit 92 Condenser lens 100 Measured light beam bundle 101 Converged light beam bundle 411 to 441 Output end of branching unit 511 to 541 Color filters 512 to 542 Light receiving sensor 522a Cell surface 611 to 641 Integrator 612 to 642 A / D converter 613 to 643 Filter A Incident surface of fiber bundle A11 to A42, A1 to A4 Incident area

Claims

1. A stimulus value direct-reading colorimeter comprising: a plurality of color sensing units each having a plurality of color filters and a plurality of light receiving sensors for receiving light transmitted through each color filter; a plurality of signal processing circuits corresponding to each of the plurality of color sensing units and having an integrating function for receiving signals from each color sensing unit; and an arithmetic unit for calculating outputs from the plurality of signal processing circuits, wherein the plurality of color sensing units include a first color sensing unit having spectral sensitivity corresponding to the X component of the equal-color function, a second color sensing unit having spectral sensitivity corresponding to the Y component, and a third color sensing unit having spectral sensitivity corresponding to the Z component, the second color sensing unit includes a plurality of units, and signals from the plurality of second color sensing units are each processed by a corresponding signal processing circuit and then added by the arithmetic unit.

2. The stimulus value direct-reading colorimeter according to claim 1, wherein a total area of a plurality of light receiving sensors constituting the plurality of second color sensing units is larger than an area of each light receiving sensor constituting the first color sensing unit and the third color sensing unit.

3. The stimulus value direct-reading colorimeter according to claim 1 or 2, wherein one signal processing circuit includes an integrator, an A / D converter, and a filter, and the plurality of signal processing circuits are constituted by a single semiconductor chip.

4. The stimulus value direct-reading colorimeter according to claim 1 or 2, further comprising a light guiding unit for guiding light to be measured to each of the plurality of color sensing units.

5. The stimulus value direct-reading colorimeter according to claim 4, wherein the light guiding unit is formed by an optical fiber.

6. The stimulus value direct-reading colorimeter according to claim 5, wherein light incident on an incident region at a point-symmetric position centered on the optical axis on the incident surface of the optical fiber through which light from the object to be measured enters each color sensing unit is guided.

7. The stimulus value direct-reading colorimeter according to claim 5, wherein the light receiving sensor is constituted by a Si photodiode.

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