Photometric colorimeter

Abstract

Provided is a photometric colorimeter that can improve measurement accuracy by reducing noise. This photometric colorimeter comprises: an objective optical system; a light guide unit that guides incident light using the objective optical system; a photoelectric conversion unit that receives the light guided by the light guide unit and converts the light into an electric signal; and an analog substrate. The light guide unit is provided with a plurality of condensing lenses. The photoelectric conversion unit is provided with a plurality of filters that transmit light of different wavelength ranges, and a plurality of light-receiving sensors that receive the light transmitted through the plurality of filters. The plurality of light-receiving sensors and an amplification unit that amplifies the electric signal are mounted on the analog substrate.

Description

Photometric and colorimetric device

[0001] The present disclosure relates to a photometric and colorimetric device.

[0002] As a device for measuring the brightness and color of light in a measurement object, a photometric and colorimetric device is known (Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2003-247891

[0004] In a photometric and colorimetric device, the accuracy of measurement can be improved by improving the S / N ratio, which is the ratio of a signal to noise. To improve the S / N ratio, an increase in signal intensity (S) or a reduction in noise (N) can be considered. To increase the signal intensity, a method of increasing the amount of incident light in a light receiving sensor in the photometric and colorimetric device can be considered. However, the measurement diameter and the opening angle of the photometric and colorimetric device are set to predetermined values, and it is not preferable to greatly change the values.

[0005] Therefore, in order to improve the accuracy of measurement, further reduction of noise is required. The "noise" here refers to random noise such as thermal noise and shot noise generated in the amplification unit. The magnitude of the random noise increases according to the junction capacitance of the light receiving sensor and the parasitic capacitance of wiring from the light receiving sensor to the amplification unit and the like. Therefore, it is required to reduce both the junction capacitance and the parasitic capacitance of the light receiving sensor. Note that there is a relationship between the size of the light receiving sensor and the junction capacitance, and the junction capacitance increases as the size increases. Therefore, in order to reduce noise, it is desirable to make the light receiving sensor smaller.

[0006] The problem to be solved by the present disclosure is to provide a photometric and colorimetric device that improves the accuracy of measurement by reducing noise.

[0007] To solve the above problems, the photometric colorimeter of the present disclosure comprises an objective optical system, a light guide unit that guides light incident by the objective optical system, a photoelectric conversion unit that receives the light guided by the light guide unit and converts it into an electrical signal, and an analog substrate, wherein the light guide unit comprises a plurality of focusing lenses, the photoelectric conversion unit comprises a plurality of filters that transmit light in different wavelength ranges, and a plurality of light receiving sensors that receive the light that has passed through the plurality of filters, and the analog substrate mounts a plurality of light receiving sensors and an amplification unit that amplifies the electrical signal.

[0008] The invention described in claim 2 is the invention described in claim 1, wherein the analog substrate is connected to the light receiving sensor by wire bonding.

[0009] The invention described in claim 3 is the invention described in claim 1 or claim 2, wherein the analog substrate has the light receiving sensor mounted on its first surface and the amplification unit mounted on its second surface.

[0010] The invention described in claim 4 is the invention described in claim 1 or claim 2, wherein the analog board further mounts an A / D conversion unit that converts the analog signal amplified by the amplification unit into a digital signal.

[0011] The invention described in claim 5 is the invention described in claim 1 or claim 2, wherein the main surface of the analog substrate is perpendicular to the optical axis direction of the focusing lens.

[0012] The invention described in claim 6 is the invention described in claim 1 or claim 2, wherein the optical axis of the focusing lens is parallel to the optical axis direction of the objective optical system.

[0013] The invention described in claim 7 is the invention described in claim 1 or claim 2, wherein the analog board is equipped with a sensor board on which the light receiving sensor is mounted.

[0014] According to this disclosure, the accuracy of measurements in a photometric colorimeter can be improved.

[0015] This is a perspective view showing the external appearance of a photometric colorimeter. This is a block diagram showing the functional configuration of a photometric colorimeter. This is a diagram showing the specific configuration of the objective optical system, light guide unit, and photoelectric conversion unit. This is a diagram showing the illumination range of the light beam emitted from the optical fiber. This is a schematic cross-sectional view of the photometric colorimeter of this embodiment. This is a schematic cross-sectional view of a conventional photometric colorimeter. This is a schematic view of the main surface side in example 1 of the structure of an electronic component. This is a schematic view of the side side in example 1 of the structure of an electronic component. This is a schematic view of the side side in example 2 of the structure of an electronic component.

[0016] Hereinafter, one or more embodiments of this disclosure will be described with reference to the drawings. However, the scope of this disclosure is not limited to the disclosed embodiments.

[0017] [Functional Configuration of Photometric Colorimeter] Figure 1 is a perspective view showing the external appearance of the photometric colorimeter 1. Figure 2 is a block diagram showing the functional configuration of the photometric colorimeter 1.

[0018] The photometric colorimeter 1 is used, for example, in the inspection process of a manufacturing line for liquid crystal displays or organic light-emitting diode (OLED) displays. The photometric colorimeter 1 measures, for example, the color, brightness, light waveform (change in light intensity), flicker, etc., of the display surface 12 of the display, which is the object to be measured. The photometric colorimeter 1 is positioned opposite the display surface 12 of the display at a predetermined distance (for example, 3 cm).

[0019] The configuration of the photometric colorimeter 1 will now be described. The photometric colorimeter 1 comprises an objective optical system 21, a light guide unit 24, a photoelectric conversion unit 25, an amplification unit 26, an A / D conversion unit 31, a storage unit 32, a control unit 36, a power supply unit 37, and a communication unit 38. Light from the display surface 12 of the display is photoelectrically converted into an electrical signal (analog signal), the converted analog signal is converted into a digital signal, and the converted digital signal is subjected to various processing. In addition, the photometric colorimeter 1 may also include an operation unit and a display unit (not shown).

[0020] The photometric colorimeter 1 may be connected to a personal computer (not shown) or the like. In this case, the operation unit and display unit (not shown) may be provided on the personal computer.

[0021] Details of each part will be explained.

[0022] Figure 3 shows the specific configuration of the objective optical system 21, the light guide unit 24, and the photoelectric conversion unit 25. In this embodiment, the measurement is performed using a direct reading type of tristimulus value.

[0023] The objective optical system 21 is provided as an incident section for receiving light from the display. The objective optical system 21 is, for example, a plano-convex lens and has a single positive power.

[0024] The light guide unit 24 guides the light incident by the objective optical system 21. The light guide unit 24 includes an optical fiber 55 that propagates the incident light and divides it into three light beams, and condensing lenses 56p, 56q, and 56r having positive power. Hereinafter, when it is not necessary to distinguish between the condensing lenses 56p, 56q, and 56r, they will be collectively referred to as the condensing lens 56.

[0025] The light guide unit 24 is located on the optical axis L1 of the light incident by the objective optical system 21. Hereinafter, "the optical axis L1 of the light incident by the objective optical system 21" will also be simply referred to as "the optical axis L1 of the objective optical system 21" or "the optical axis L1".

[0026] The optical fiber 55 is composed of multiple optical fibers bundled together. The bundled optical fibers are divided into three in the middle section, resulting in one light beam incident surface A and three light beam exit surfaces B1, B2, and B3. The optical fiber 55 is positioned such that the light beam incident surface A is located at a distance of the focal length f of the objective optical system 21 from the image-side principal point PP of the objective optical system 21. In other words, the objective optical system 21 and the optical fiber 55 constitute a telecentric optical system. For the sake of explanation, in this embodiment, the image-side principal point is shown to be approximately the same as the object-side principal point.

[0027] In this embodiment, an optical fiber 55 is used as the light beam splitting member of the light guide section 24, but the configuration is not limited to this. For example, other optical components that perform the same function as an optical fiber, such as an optical conduit, may be used as the light beam splitting member of the light guide section 24.

[0028] The photometric colorimeter 1 is positioned at a predetermined distance from the display surface 12 of the display. At this time, of the light beams emitted from each part of the area under measurement AR, only those light beams with an emission angle of less than or equal to the maximum value α with respect to the normal direction of the area under measurement AR are incident on the light beam incident surface A of the optical fiber 55. The normal direction of the area under measurement AR is the direction parallel to the optical axis L1. Hereinafter, the maximum value α of the emission angle will also be called the "maximum emission angle α". The maximum emission angle α is determined by the focal length f of the objective optical system 21 and the diameter R at the light beam incident surface A of the optical fiber 55. The incident light beam is divided into three light beams within the optical fiber 55 and emitted from the light beam emission surfaces B1, B2, and B3, respectively. Hereinafter, when it is not necessary to distinguish between the light beam emission surfaces B1, B2, and B3, they will be collectively referred to as the light beam emission surface B.

[0029] Each optical fiber constituting the optical fiber 55 has a two-layer structure consisting of a core located in the center and a cladding surrounding the core. The core is designed to have a higher refractive index than the cladding, and light propagates confined within the core by total internal reflection.

[0030] The optical fiber 55 is bent into a predetermined shape while the light beam incident surface A and the light beam exit surface B are fixed. If there are no changes in state such as vibration, shock, or temperature changes, the position of the optical fiber 55 does not change, and the light incident on the light beam incident surface A exits from the light beam exit surface B at a predetermined angle. However, if there are changes in state such as vibration, shock, or temperature changes, the degree of bending of the optical fiber 55 changes, and the light incident on the light beam incident surface A exits from the light beam exit surface B at an angle that is shifted from the predetermined angle. In this case, since the angle of incidence of light to the filter 61, which will be described later, is shifted from the predetermined angle, it is preferable that the filter 61 does not depend on the angle of incidence in its spectral sensitivity characteristics.

[0031] Light emitted from the light beam emission surfaces B1, B2, and B3 of the optical fiber 55 enters the condensing lenses 56p, 56q, and 56r, respectively. The optical axis L21 of the condensing lens 56p coincides with the optical axis of the light emitted from the light beam emission surface B1 of the optical fiber 55. The optical axis L22 of the condensing lens 56q coincides with the optical axis of the light emitted from the light beam emission surface B2 of the optical fiber 55. The optical axis L23 of the condensing lens 56r coincides with the optical axis of the light emitted from the light beam emission surface B3 of the optical fiber 55. The condensing lens 56 focuses the incident light. Hereafter, when it is not necessary to distinguish between optical axes L21, L22, and L23, they will be collectively referred to as optical axis L2.

[0032] The optical axes L21 of the condensing lens 56p, L22 of the condensing lens 56q, and L23 of the condensing lens 56r are preferably parallel to the optical axis L1 of the objective optical system. This makes it possible to reduce the size of the photometric colorimeter 1 in the direction perpendicular to the optical axis L1, that is, to reduce the diameter of the photometric colorimeter 1 and make it more compact.

[0033] The photoelectric conversion unit 25 receives light guided by the light guide unit 24 and converts it into an electrical signal corresponding to its intensity. The photoelectric conversion unit 25 includes filters 61p, 61q, and 61r that transmit light in different wavelength ranges, and light receiving sensors 62p, 62q, and 62r that receive the transmitted light. Filters 61p, 61q, and 61r are filters for correcting to the spectral sensitivity of a standard observer as defined by the International Commission on Illumination (CIE), and light receiving sensors 62p, 62q, and 62r have the spectral sensitivity characteristics of a standard observer. Hereinafter, when it is not necessary to distinguish between filters 61p, 61q, and 61r, they will be collectively referred to as filter 61. When it is not necessary to distinguish between light receiving sensors 62p, 62q, and 62r, they will be collectively referred to as light receiving sensor 62.

[0034] Filter 61p is sensitive to the R (red) wavelength region. Due to this filter characteristic, the light receiving sensor 62p is corrected to have a light receiving sensitivity of a color matching function (X-bar-lambda) that has high sensitivity in the red wavelength region. Filter 61q is sensitive to the G (green) wavelength region. Due to this filter characteristic, the light receiving sensor 62q is corrected to have a light receiving sensitivity of a color matching function (Y-bar-lambda) that has high sensitivity in the green wavelength region. Filter 61r is sensitive to the B (blue) wavelength region. Due to this filter characteristic, the light receiving sensor 62r is corrected to have a light receiving sensitivity of a color matching function (Z-bar-lambda) that has high sensitivity in the blue wavelength region. The light receiving sensor 62 outputs a received signal corresponding to the tristimulus values ​​(X, Y, Z). Each filter 61 is positioned appropriately between the light receiving sensor 62 and the condensing lens 56.

[0035] The light-receiving sensor 62 is generally packaged in metal, ceramic, resin, etc., and has substantially the same light-receiving sensitivity. The light-receiving sensor 62 includes, for example, a silicon photocell (SPC). In this embodiment, as will be described later, the light-receiving sensor 62 is surface-mounted to the circuit board in a COB (Chip On Board) structure.

[0036] The light receiving sensor 62p is located on the optical axis L21 of the condensing lens 56p. The light receiving sensor 62q is located on the optical axis L22 of the condensing lens 56q. The light receiving sensor 62r is located on the optical axis L23 of the condensing lens 56r. The light receiving sensor 62 is positioned such that the illumination range of the light focused by the condensing lens 56 is included in the light receiving range of the light receiving sensor 62.

[0037] Figure 4 shows the illumination range of the light beam emitted from the optical fiber. The focusing lens 56p focuses the light beam emitted from the light beam emission surface B1 of the optical fiber 55 onto the light receiving sensor 62p, and makes the illumination range LA of the light beam approximately coincide with the light receiving range SA of the light receiving sensor 62p. As shown in Figure 4, it is preferable that the entire illumination range LA of the light beam is included within the light receiving range SA.

[0038] Similarly, the focusing lens 56q focuses the light beam emitted from the light beam emission surface B2 of the optical fiber 55 onto the light receiving sensor 62q, and adjusts the illumination range of the light beam to approximately match the light receiving range of the light receiving sensor 62q. The focusing lens 56r focuses the light beam emitted from the light beam emission surface B3 of the optical fiber 55 onto the light receiving sensor 62r, and adjusts the illumination range of the light beam to approximately match the light receiving range of the light receiving sensor 62r.

[0039] In this way, the focusing lens 56 can focus the light beam emitted from the optical fiber 55 into the light-receiving range of the light-receiving sensor 62. This allows the light-receiving sensor 62 to be miniaturized and its junction capacitance to be reduced, thereby reducing random noise generated in the amplification unit 26.

[0040] On the other hand, by including a condensing lens 56, the photometric colorimeter 1 requires a length in the optical axis L2 direction of the condensing lens 56 equal to the thickness of the condensing lens 56 and the optical path length associated with condensation. In other words, the photometric colorimeter 1 tends to be long in the optical axis L2 direction. However, in this embodiment, the light receiving sensor 62 does not have a package and is mounted on the analog substrate 43, so even though the photometric colorimeter 1 includes a condensing lens 56, the length in the optical axis L2 direction can be shortened and the profile can be reduced.

[0041] The light beam incident on the optical fiber 55 is incident on the light receiving sensor 62 in three equal parts. The light beam here refers to all the light beams emitted from each part of the measurement area AR of the display, with an emission angle α or less relative to the normal direction in the measurement area AR. In other words, even if the light receiving sensor 62 is miniaturized by using the focusing lens 56, the amount of light received by the light receiving sensor 62 does not decrease.

[0042] The amplification unit 26 amplifies the electrical signal output from the light receiving sensor 62, for example, by integrating it. By having the amplification unit 26 simultaneously integrate the electrical signal output from the light receiving sensor 62, the tristimulus values ​​(X, Y, Z) can be converted into a synchronized time-series signal. In other words, simultaneity can be ensured.

[0043] Even if the amplification unit 26 does not guarantee simultaneity, if the delay time of each signal is known in advance, it is possible to correct the time shift in each signal of the finally output stimulation value and guarantee the simultaneity in each signal. That is, when the time shift in each signal of the finally output stimulation value can be corrected, each signal can be regarded as a time-series signal that can be synchronized.

[0044] The amplification unit 26 may be amplified by an integrating circuit or may be amplified by other transimpedance circuits. Also, the light guide unit 24 and the photoelectric conversion unit 25 may be four channels, three of which are amplified by an integrating circuit to obtain the above-mentioned three stimulation values, and the remaining one channel may be amplified by a transimpedance circuit to obtain a signal for flicker measurement. Note that flicker refers to the flickering of a display, and generally, a signal corrected by an equal-energy function (CIE 1931 color-matching function) is used as the light reception sensitivity.

[0045] The A / D conversion unit 31 converts the electrical signal (analog signal) input from the amplification unit 26 into a digital signal.

[0046] The storage unit 32 stores the digital signal output from the A / D conversion unit 31.

[0047] The control unit 36 controls the measurement operation by centrally controlling the operations of each part in the photometric and colorimetric apparatus 1. The control unit 36 performs predetermined arithmetic processing such as correction of dark output using the measurement data stored in the storage unit 32. Also, the control unit 36 calculates the three stimulation values (X, Y, Z), xyY (chromaticity coordinates, luminance) defined by the CIE, TΔuvY (correlated color temperature, color difference from the blackbody locus, luminance), etc. Furthermore, the control unit 36 may also derive an index for flicker.

[0048] The control unit 36 controls the photoelectric conversion unit 25, the amplification unit 26, the A / D conversion unit 31, the storage unit 32, the power supply unit 37, and the communication unit 38. Also, the control unit 36 may be connected to the measurement object. By connecting to the measurement object, the light emission conditions of the object during measurement can be set.

[0049] The power supply unit 37 transforms the voltage of the power supplied from an external AC adapter (not shown) and supplies power to each component via the control unit 36.

[0050] The communication unit 38 outputs the calculation results from the control unit 36 ​​to the outside. The output calculation results are displayed in the form of a data list, graph, etc., on a personal computer (not shown). In addition, various information related to the measurement is input from the personal computer via the communication unit 38. Examples of such information include measurement instructions, display mode settings, and measurement range.

[0051] [Internal Structure of Photometric Colorimeter] The internal structure of the photometric colorimeter 1 is described below. The terms "parallel" and "perpendicular" as used below refer to "approximately parallel" and "approximately perpendicular" within the range of manufacturing tolerances, and specifically include a range of ±5° error.

[0052] Figure 5 is a schematic cross-sectional view of the photometric colorimeter 1 of this embodiment. In the drawings described below, the direction of the optical axis L1 of the objective optical system 21 is defined as the X-axis, the first direction perpendicular to the optical axis L1 is defined as the Y-axis, and the second direction perpendicular to both the optical axis L1 and the first direction is defined as the Z-axis. Figure 5 illustrates the internal configuration of the photometric colorimeter 1 when viewed from the second direction (Z-axis direction), where the Z-axis is perpendicular to the plane of the paper. Note that Figure 5 is a schematic representation of the internal configuration, and in particular, the arrangement of the components of the light guide unit 24 and the photoelectric conversion unit 25 differs from the arrangement in an actual photometric colorimeter.

[0053] In the photometric colorimeter 1, the above-mentioned parts and the circuit boards described later are housed within a housing 49. The housing 49 forms the exterior of the photometric colorimeter 1. When the photometric colorimeter 1 is installed inside a complex measuring device, the housing 49 contacts and is fixed to other components of the complex measuring device. In the example shown in Figure 5, the housing 49 is a rectangular box, but its shape is not particularly limited.

[0054] The housing 49 includes a reference plate 45 and a support plate 30. The reference plate 45 is interposed between the lens barrel of the objective optical system 21 and the light guide unit 24 in the direction of the optical axis L1 of the objective optical system 21, and directly or indirectly holds the objective optical system 21 and the light guide unit 24. The support plate 30 extends in the direction of the optical axis L1 on the optical path progression side of the objective optical system 21 and directly or indirectly holds the CPU board 41 and power supply board 42 described later. The light beam incident surface A side of the optical fiber 55 is indirectly held by the reference plate 45 via the first holding member 46. The light beam exit surface B side of the optical fiber 55, the condensing lens 56 and the filter 61 are indirectly held by the reference plate 45 via the second holding member 47, the protective member 57 and the first holding member 46.

[0055] The material of the housing 49 is not particularly limited. However, the support plate 30 is preferably made of a conductive material, from the viewpoint of directly or indirectly connecting to the analog board 43. This makes it possible to equalize the ground level on various boards.

[0056] The photometric colorimeter 1 includes an analog circuit board 43. In this embodiment, "analog circuit board" refers to a circuit board that processes analog signals. In this embodiment, the analog circuit board 43 does not include the light receiving sensor 62 and the amplification unit 26.

[0057] The photometric colorimeter 1 may also include a CPU board 41, a power supply board 42, and the like. These boards are adjacent to the analog board 43 in the direction of the optical axis L1 of the objective optical system 21. These boards are also held on the support plate 30 in a two-tiered structure via a third holding member 48. For example, the CPU board 41 mounts the memory unit 32 and the control unit 36, and the power supply board 42 mounts the power supply unit 37 and the communication unit 38. The configuration and position of the CPU board 41 and the power supply board 42 are not limited thereto. The CPU board 41 and the power supply board 42 may be combined onto a single board, or they may be subdivided into three or more boards.

[0058] In this embodiment, the light receiving sensor 62 and the amplification unit 26 are mounted on the analog substrate 43. In this embodiment, "mounted" means that each part is attached to the substrate, and the attached parts and the substrate form an integrated electronic component 50. Preferably, each attached part is plate-shaped (chip-shaped), and preferably attached so that the main surface of the substrate and the main surface of each part are in contact. Here, "main surface" refers to the surface with the largest area among multiple surfaces. In a plate-shaped substrate and each part, there are two main surfaces, and these two surfaces face each other.

[0059] In this embodiment, the light receiving sensor 62 and the amplification unit 26 are mounted on the analog board 43 and are integrated. In this embodiment, this integrated component is referred to as the electronic component 50. Since the electronic component 50 is an integrated component, when the electronic component 50 is held by the second holding member 47, the light receiving sensor 62 and the amplification unit 26 are also held within the photometric colorimeter 1. The light receiving sensor 62 does not need to be held separately.

[0060] This embodiment will be described in comparison with a conventional example. Figure 6 is a schematic cross-sectional view of a conventional photometric colorimeter 100. In the example shown in Figure 6, the light-receiving sensor 62 is not fixed to the analog board 43, but is fixed independently within the photometric colorimeter 1. In this case, the light-receiving sensor 62 is enclosed in a package and has a relatively long terminal in the direction of the optical axis L1 (X-axis direction) of the objective optical system 21. From the viewpoint of workability, the terminal of the light-receiving sensor 62 and the analog board 43 are connected via wiring 44, and from the viewpoint of securing workspace for soldering, the analog board 43 extends in the direction of the optical axis L1. Therefore, the photometric colorimeter 1 tends to be relatively long in the direction of the optical axis L1. Also, in this case, because the wiring 44 is relatively long and has a large parasitic capacitance, random noise tends to increase, and the accuracy of measurement tends to decrease.

[0061] On the other hand, in this embodiment shown in Figure 5, the light receiving sensor 62 and the amplification unit 26 are connected by wiring 44 in the analog board 43. In this case, since the wiring 44 is relatively short and has small parasitic capacitance, random noise can be reduced and the accuracy of measurement can be improved. In particular, sufficient accuracy can be obtained even when measuring low brightness.

[0062] Furthermore, in this case, it is preferable that the main surface of the analog substrate 43 is perpendicular to the optical axis L2 direction of the condensing lens 56. This makes the photometric colorimeter 1 relatively short in the direction of the optical axis L1 and easy to reduce in height.

[0063] [Structure of Electronic Components] Next, the structure of the electronic component 50 will be described. In the electronic component 50, the analog board 43 mounts the light receiving sensor 62 and the amplification unit 26.

[0064] (Structural Example 1) Figures 7 and 8 are schematic diagrams of structural example 1 of the electronic component 50. Figure 7 is a schematic diagram of the electronic component 50 as seen from the main surface side on which the light receiving sensor 62 is mounted, and Figure 8 is a schematic diagram of the electronic component 50 as seen from the side side. Note that in Figure 8, the light receiving sensor 62q is not shown because it overlaps with the light receiving sensor 62r behind it.

[0065] In structural example 1, the analog board 43 mounts a sensor board 53 on which a light receiving sensor 62 is mounted. In other words, the electronic component 50 includes a sensor board 53 between the light receiving sensor 62 and the analog board 43. In this case, it is preferable to first fabricate the sensor board 53 to which the light receiving sensor 62 is connected, and then connect the sensor board 53 to the analog board 43.

[0066] The light-receiving sensor 62 is preferably surface-mounted to the sensor substrate 53 using a COB (Chip On Board) structure. The light-receiving sensor mounting portion on the main surface of the sensor substrate 53 and the main surface of the light-receiving sensor 62 (the surface opposite to the light-receiving side) are electrically connected by any die-bonding material, and the light-receiving sensor 62 is fixed to the sensor substrate 53. In addition, the sensor substrate 53 is electrically connected to the main surface (light-receiving side) of the light-receiving sensor 62 by wire bonding.

[0067] The light receiving sensors 62p, 62q, and 62r are connected to pads (not shown) in the sensor board 53 by wires 51p, 51q, and 51r, respectively. Hereafter, when it is not necessary to distinguish between wires 51p, 51q, and 51r, they will be collectively referred to as wire 51.

[0068] The shape and position of the wire 51 are not particularly limited and are appropriately selected depending on the size and mounting position of the light receiving sensor 62. Examples of the main components of the wire 51 include conductive materials such as gold, silver, copper, and aluminum.

[0069] The analog circuit board 43 is plate-shaped and has two main surfaces. Of the two main surfaces, the surface on which the light-receiving sensor 62 is mounted is called the first surface, and the surface opposite the first surface is called the second surface. Through-hole vias are formed on the analog circuit board 43 so as to penetrate from the first surface to the second surface, and lands for mounting the sensor circuit board 53 are provided on the first surface. The sensor circuit board 53 is connected to and integrated with the analog circuit board 43 by soldering. With this connection method, compared to the case in which a light-receiving sensor using a general package is used, there is no need to solder the light-receiving sensor 62 to the wiring (lead wires) and the wiring to the analog circuit board 43, and no space is required for that. Therefore, the photometric colorimeter 1 is short in the direction of the optical axis L2 of the condensing lens 56 and can be made low-profile. Note that the method of connecting the sensor circuit board 53 and the analog circuit board 43 is not limited to this.

[0070] The mounting positions of the light receiving sensors 62p, 62q, and 62r are preferably set according to design conditions such as the size of the maximum emission angle α and the characteristics of the various materials used. For example, when the light receiving sensor 62 and the analog board 43 are directly connected as in structural example 2 described later, the analog board 43 is designed so that the light receiving sensor 62 can be mounted in a predetermined position. Therefore, if the mounting position of the light receiving sensor 62 is changed, the same analog board 43 cannot be used, and the design of the analog board 43 must be changed.

[0071] On the other hand, when a sensor board 53 is provided as in structural example 1, the sensor board 53 has a fixed shape, and only the mounting position of the light receiving sensor 62 on the sensor board 53 is changed. In this case, since the sensor board 53 has a fixed shape, the mounting position of the sensor board 53 relative to the analog board 43 is not changed. The mounting position of the light receiving sensor 62 can be changed without changing the design of the analog board 43. The sensor board 53 is designed according to the mounting position of the light receiving sensor 62. In other words, by providing a sensor board 53, the mounting position of the light receiving sensor 62 can be changed by only changing the design of the sensor board 53, which has a simpler structure than the analog board 43.

[0072] The analog board 43 may have the amplification unit 26 mounted on either of its two main surfaces, but it is preferable to mount it on the second surface opposite to the light receiving sensor 62. Generally, the dark current of the light receiving sensor 62 tends to increase due to the effects of heat. However, by mounting the amplification unit 26 on the second surface, heat transfer due to radiation emitted from the amplification unit 26 and heat transfer through the air can be suppressed, thereby suppressing the increase in dark current in the light receiving sensor 62. As a result, a decrease in the measurement accuracy of the photometric colorimeter 1 can be suppressed.

[0073] The light-receiving sensor 62 has its position constrained by the optical system, such as the condensing lens 56, and therefore occupies a certain area overall. The amplification unit 26 also has peripheral circuits for noise reduction and therefore occupies a certain area. By mounting the amplification unit 26 on the second surface, various components and wiring can be mounted in suitable positions on the analog board 43, while the main surface area of ​​the analog board 43 can be reduced, and the diameter of the photometric colorimeter 1 can be reduced.

[0074] The analog board 43 may have an analog front-end (AFE) 52 mounted on its second surface. The analog front-end 52 is a signal processing circuit that has both the function of an amplification unit 26 and the function of an A / D conversion unit 31. In other words, it is preferable to mount the A / D conversion unit 31 in addition to the amplification unit 26 on the second surface of the analog board 43. As a result, the analog signal amplified by the amplification unit 26 is converted into a digital signal by the A / D conversion unit 31 with a shorter wiring path, thereby reducing random noise. In addition, the design man-hours for the circuit can be reduced by mounting a single component as the analog front-end 52.

[0075] (Structural Example 2) Figure 9 is a schematic diagram of structural example 2 of the electronic component 50. Figure 9 is a schematic diagram of the electronic component 50 as viewed from the side. Note that in Figure 9, the light receiving sensor 62q is not shown because it overlaps with the light receiving sensor 62r.

[0076] In structural example 2, the light receiving sensor 62 and the analog board 43 are directly connected. In other words, there is no sensor board between the light receiving sensor 62 and the analog board 43. In this case, the length of the wiring connecting the light receiving sensor 62 and the amplification unit 26 (analog front end 52) can be shortened by the thickness of the sensor board. As a result, random noise can be reduced and the accuracy of the measurement can be improved.

[0077] (Structural example 3) The light receiving sensor 62 may be a surface-mount type package. In this case, the terminals of the light receiving sensor 62 are fixed to the analog board 43 or sensor board 53 by soldering.

[0078] In this embodiment, the photometric colorimeter 1 comprises an objective optical system 21, a light guide unit 24 that guides light incident by the objective optical system 21, a photoelectric conversion unit 25 that receives the light guided by the light guide unit 24 and converts it into an electrical signal, and an analog substrate 43. The light guide unit 24 comprises a plurality of focusing lenses 56. The photoelectric conversion unit 25 comprises a plurality of filters 61 that transmit light in different wavelength ranges, and a plurality of light receiving sensors 62 that receive the light transmitted through the plurality of filters 61. The analog substrate 43 mounts a plurality of light receiving sensors 62 and an amplification unit 26 that amplifies the electrical signal. This allows the wiring from the light receiving sensors 62 to the amplification unit 26 to be shortened and parasitic capacitance to be reduced. As a result, random noise can be reduced and the accuracy of measurement can be improved.

[0079] In this embodiment, it is preferable to connect the analog board 43 to the light receiving sensor 62 by wire bonding. This allows for even shorter wiring from the light receiving sensor 62 to the amplification unit 26, further reducing parasitic capacitance. As a result, random noise can be further reduced, and the accuracy of the measurement can be further improved.

[0080] In this embodiment, it is preferable that the analog substrate 43 has a light-receiving sensor 62 mounted on its first surface and an amplification unit 26 mounted on its second surface. This suppresses the increase in dark current in the light-receiving sensor 62 and prevents a decrease in measurement accuracy. In addition, the main surface of the analog substrate 43 can be made smaller, and the diameter of the photometric colorimeter 1 can be made smaller.

[0081] In this embodiment, it is preferable to further mount an A / D conversion unit 31 on the analog board 43 that converts the analog signal amplified by the amplification unit 26 into a digital signal. This further reduces random noise and improves the accuracy of the measurement.

[0082] In this embodiment, it is preferable that the main surface of the analog substrate 43 is perpendicular to the optical axis L2 direction of the condensing lens 56. This allows the photometric colorimeter 1 to be made lower in profile.

[0083] In this embodiment, it is preferable that the optical axis L2 of the condensing lens 56 is parallel to the direction of the optical axis L1 of the objective optical system 21. This allows for miniaturization of the photometric colorimeter 1.

[0084] In this embodiment, it is preferable that the analog board 43 is equipped with a sensor board 53 on which a light receiving sensor 62 is mounted. This allows the mounting position of the light receiving sensor 62 to be changed simply by modifying the design of the sensor board 53.

[0085] Furthermore, the detailed configuration of each device constituting the photometric colorimeter can also be modified as appropriate, without departing from the spirit of this disclosure.

[0086] This disclosure makes it possible to improve the accuracy of measurements in a photometric colorimeter.

[0087] 1 Photometric colorimeter 12 Display surface 21 Objective optical system 24 Light guide unit 25 Photoelectric conversion unit 26 Amplifier unit 30 Support plate 31 A / D conversion unit 32 Memory unit 37 Power supply unit 38 Communication unit 41 CPU board 42 Power supply board 43 Analog board 44 Wiring 45 Reference plate 46 First retaining member 47 Second retaining member 48 Third retaining member 49 Housing 50 Electronic components 51 Wire 52 Analog front end 53 Sensor board 55 Optical fiber 56p, 56q, 56r Focusing lens 61p, 61q, 61r Filter 62p, 62q, 62r Light receiving sensor

Claims

1. A photometric colorimeter comprising: an objective optical system; a light guide unit for guiding light incident by the objective optical system; a photoelectric conversion unit for receiving the light guided by the light guide unit and converting it into an electrical signal; and an analog substrate, wherein the light guide unit comprises a plurality of focusing lenses; the photoelectric conversion unit comprises a plurality of filters that transmit light in different wavelength ranges, and a plurality of light receiving sensors that receive the light transmitted through the plurality of filters; and the analog substrate mounts a plurality of light receiving sensors and an amplification unit that amplifies the electrical signal.

2. The photometric colorimeter according to claim 1, wherein the analog board is connected to the light receiving sensor by wire bonding.

3. The photometric colorimeter according to claim 1 or 2, wherein the analog circuit board has the light receiving sensor mounted on its first surface and the amplification unit mounted on its second surface.

4. The photometric and colorimetric apparatus according to claim 1 or 2, wherein the analog board further mounts an A / D conversion unit that converts the analog signal amplified by the amplification unit into a digital signal.

5. The photometric and colorimetric apparatus according to claim 1 or 2, wherein the main surface of the analog substrate is perpendicular to the optical axis direction of the focusing lens.

6. The photometric and colorimetric apparatus according to claim 1 or 2, wherein the optical axis of the focusing lens is parallel to the optical axis direction of the objective optical system.

7. The photometric and colorimetric apparatus according to claim 1 or 2, wherein the analog board is mounted on a sensor board on which the light receiving sensor is mounted.

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