JP4333050B2 - Optical system for measurement and tristimulus photoelectric colorimeter equipped with this optical system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention mainly relates to a tristimulus type photoelectric colorimeter for measuring display characteristics (characteristics such as chromaticity, luminance, and color difference) of a color LCD, and more particularly to an optical system for the measurement.
[0002]
[Prior art]
FIG. 12 is a diagram showing an example of an optical system applied to a conventional tristimulus type photoelectric colorimeter.
[0003]
An optical system 100 shown in the figure is applied to a non-contact handy type colorimeter, and includes an optical system 101 for measuring tristimulus values (hereinafter referred to as measurement optical system 101) and an object 104 to be measured. It comprises a single-lens reflex optical system 102 (hereinafter referred to as a finder optical system 102) for allowing a measurer to confirm a measurement area AR of a liquid crystal panel (for example, a liquid crystal panel).
[0004]
The measurement optical system 101 condenses the light beam LF from the measurement area AR of the measurement object 104, for example, an objective lens L1 made of a plano-convex lens, and a field stop S that defines the measurement area AR of the measurement object 104. The light beam collected by the objective lens L1 is divided into three light beams, and each includes a fiber FB that leads to light receiving sensors (photoelectric conversion elements) D1, D2, and D3 of the light receiving unit 103. The light receiving unit 103 measures the light emission color of the object 104 to be measured with tristimulus values (X, Y, Z), and the light receiving sensitivities of the three light receiving sensors D1, D2, and D3 and the light receiving sensors D1 to D3. It consists of spectral sensitivity correction filters F1, F2, and F3 for correcting the spectral sensitivity of the standard observer specified by the CIE (Commission Internationale de I'Eclairage).
[0005]
The light beam LF emitted from the measurement area AR of the measurement object 104 is collected by the objective lens L1 and imaged at the position of the field stop S. An entrance surface of the fiber FB is disposed at the opening position of the field stop S, and the light beam LF transmitted through the field stop S enters the fiber FB, and is divided into three light beams by the fiber FB and emitted. The light beams emitted from the fiber FB are incident on the light receiving sensors D1, D2, and D3 through the spectral sensitivity correction filters F1, F2, and F3, and are converted into electric signals by the light receiving sensors D1, D2, and D3, respectively. The filter characteristic of the spectral sensitivity correction filter F1 is a color matching function (X bar lambda) having sensitivity in the red wavelength region, and the filter characteristic of the spectral sensitivity correction filter F2 is a color matching function having sensitivity in the green wavelength region (Y If the filter characteristic of the spectral sensitivity correction filter F3 is a color matching function (zet bar lambda) having sensitivity in the blue wavelength region, the tristimulus values (X , Y, Z) is output.
[0006]
On the other hand, the finder optical system 102 includes a half mirror M, a Porro prism PR, a scale glass G with a mark of a measurement area, and an eyepiece L2. A part of the light beam that has passed through the objective lens L1 is guided to the polo-type prism PR by the half mirror M, further passes through the scale glass G, and then is emitted to the ocular window (not shown) by the eyepiece lens L2. The optical image incident on the half mirror M (the optical image of the measurement area AR) is inverted by the half mirror M and guided to the polo prism PR, but is inverted again by the polo prism PR. An upright light image is incident on L2, and this light image (that is, the light image of the upright measurement area AR) is emitted to the eyepiece window. Since the scale glass G is disposed at a position equivalent to the light receiving sensors D1 to D3, the measurer can see the optical image of the measurement area AR with the measurement range mark by looking through the eyepiece window.
[0007]
[Problems to be solved by the invention]
In the optical system applied to the conventional tristimulus photoelectric colorimeter, as shown in FIG. 13, only a part of the light beam emitted from the emission surface SO of the fiber FB is incident on the light receiving sensor D. There is a problem that the amount of light received by the light receiving sensor D decreases.
[0008]
On the other hand, as is well known, liquid crystal panels have characteristics (light distribution characteristics) that vary in brightness and chromaticity depending on the viewing angle (angle from the normal to the center plane of the panel). For example, as shown in Japanese Patent Application Laid-Open No. 2000-221109, only a light beam having a predetermined angle (a predetermined angle based on the light distribution characteristic of the liquid crystal panel) with respect to the center plane normal is guided to the light receiving sensor. However, a measurement optical system is required so that the light beam emitted beyond that angle does not enter the light receiving sensor. However, when the measurement optical system shown in this publication is adopted for the colorimeter, as described below, Since only a part of the light flux having a predetermined angle with respect to the normal to the center plane of the liquid crystal panel is incident on the light receiving sensor, there is a problem that the amount of light received by the light receiving sensor is reduced.
[0009]
FIG. 14 is a diagram illustrating an example of a measurement optical system that guides only a light beam having a predetermined emission angle or less to a light receiving sensor among light beams emitted from a measurement region of an object to be measured described in the above publication.
[0010]
The measurement optical system shown in the figure has a single positive power and is located at the object side principal point PP of the objective lens L1 with the focal length f away from the measurement region AR by the focal length f toward the light receiving unit 103. And the light receiving surface at a position separated from the image side principal point PP of the objective lens L1 (FIG. 14 shows an example in which the image side principal point substantially coincides with the object side principal point) by the focal length f. The light receiving unit 103 is arranged so that the RS is located.
[0011]
This measuring optical system is a so-called telecentric optical system, and the light receiving unit 103 itself functions as a diaphragm for the telecentric optical system. Therefore, among the light beams emitted from each part of the measurement area AR, a light beam having an emission angle α or less enters each light receiving sensor D of the light receiving unit 103.
[0012]
However, in this measurement optical system, since the light receiving sensor D is disposed at a position separated from the image side principal point PP of the objective lens L1 by the focal length f, the light is emitted from each part of the measurement area AR of the liquid crystal panel 104. Of the light beams having the emission angles 0 to α, only the light beams having the emission angles β to α (light beams shown by oblique lines in FIG. 14) are incident on the light receiving sensor D. The amount of received light is reduced.
[0013]
In the optical system applied to the conventional tristimulus photoelectric colorimeter shown in FIG. 12, a finder optical system 102 is provided so that the measurer can confirm the measurement area AR of the measurement object 104, and the objective lens L1. Since a part of the light beam that has passed through the finder optical system 102 is guided to the finder optical system 102, there is a problem that the amount of light received by the light receiving sensor D is further reduced.
[0014]
Such a decrease in the amount of received light is the minimum measurable light amount (especially necessary for repeated measurement) when the light beam emitted from the measurement area AR of the object 104 to be measured is weak (in the case of low luminance). As a result, it becomes impossible to accurately measure the color of the light from the light source.
[0015]
The present invention has been made in view of the above problems, and a measurement optical system capable of reliably and accurately measuring the light emission characteristics of an object having high directivity even when the light intensity is weak, and the optical system The present invention provides a tristimulus photoelectric colorimeter equipped with a system.
[0016]
[Means for Solving the Problems]
The invention according to claim 1 is a condensing unit having a positive power for condensing only a light beam having a predetermined emission angle or less out of the light beam emitted from the measurement region of the object to be measured, and the image side of the light collecting unit. A light beam splitting unit that has an incident surface of a light beam collected by the light collecting unit at a position substantially away from the principal point by the focal length of the light collecting unit, and divides the incident light beam into a plurality of light beams and emits the light beam An illuminating means for illuminating the entire measurement area of the object to be measured at a position substantially separated from the image side principal point of the light collecting means by the focal length of the light collecting means, and an image side principal point of the light collecting means. At a position approximately away from the focal distance of the light collecting means, Condensed by the light collecting means Luminous flux On the incident surface of the light beam splitting means With a transparent part to transmit Incidence of the luminous flux to the incident surface A light path switching means capable of switching between the light shielding section and the light shielding section, and the illumination means is disposed in the light shielding section of the light path switching means. And illuminating the measurement area of the measurement object when the light beam is shielded by the light shielding portion. This is an optical system for measurement.
[0017]
According to this measuring optical system, the light beam emitted from the measurement area of the object to be measured is focused on the incident surface of the light beam splitting means by the light collecting means so that only the light beam having a predetermined emission angle or less is collected. The light is divided into a plurality of light beams by the means and emitted. Accordingly, among the light beams emitted from the measurement region of the object to be measured, a light beam having a predetermined emission angle or less can be guided to the light receiving sensor side without causing a decrease in the light amount.
[0018]
Also When the illuminating means emits light, the condensing means and the light beam splitting means constitute a telecentric optical system, so that the light beam emitted from the illuminating means passes through the condensing means and becomes a substantially parallel light beam to be measured. Irradiates the area to be measured of the object. Therefore, when applied to a non-contact type optical apparatus, the measurer can confirm the measurement area by illuminating the measurement area of the measurement object. Since the measurement area can be confirmed without using the finder optical system, the amount of light guided to the light receiving sensor by the finder optical system does not decrease.
[0019]
Also , Measurement in a light-shielded state (measurement of an offset correction value for performing zero adjustment of the measuring instrument) by blocking light incident on the light beam splitting means from the light collecting means by the light shielding portion of the optical path switching means ) Can be easily performed. Therefore, if the illumination means emits light with the light shielding portion of the optical path switching means set on the optical path of the light beam, the offset correction value can be measured, and the measurement area of the measurement object is illuminated at the time of this measurement. The person can confirm the measurement area of the measurement object when measuring the offset correction value.
[0020]
Claim 2 The described invention includes a first condensing means having a positive power for condensing only a light beam having a predetermined emission angle or less out of the light beam emitted from the measurement region of the object to be measured, and the first light collecting device. An aperture stop disposed at a position substantially away from the image-side principal point of the means by the focal length of the first condensing means, and a beam splitting unit that splits a light beam that has passed through the aperture stop into a plurality of light beams and emits the light beam Between the aperture stop and the beam splitting means, the aperture stop and the incident surface of the beam splitting means are arranged in a conjugate relationship, and the beam splitting means transmits the beam that has passed through the aperture stop. Second condensing means for condensing light, illumination means for illuminating the entire measurement area of the object to be measured at a position near the entrance surface of the aperture stop or the light beam splitting means, and the aperture stop or the light flux In the vicinity of the entrance surface of the dividing means, Condensed by the light collecting means Luminous flux On the incident surface of the light beam splitting means With a transparent part to transmit Incidence of the luminous flux to the incident surface A light path switching means capable of switching between the light shielding section and the light shielding section, and the illumination means is disposed in the light shielding section of the light path switching means. And illuminating the measurement area of the measurement object when the light beam is shielded by the light shielding portion. This is an optical system for measurement.
[0021]
According to this measuring optical system, only the light beam emitted from the measurement region of the object to be measured is equal to or smaller than the predetermined light emission angle by the first light collecting means and the aperture stop. Then, the light beam is guided to the incident surface of the light beam dividing unit by the second light collecting unit, and is divided into a plurality of light beams by the light beam dividing unit and emitted. Therefore, even in this measurement optical system, it is possible to guide a light beam having a predetermined emission angle or less out of the light beam emitted from the measurement region of the object to be measured to the light receiving sensor side without causing a decrease in the light amount.
[0022]
Also When the illumination unit is provided in the vicinity of the aperture stop, when the illumination unit emits light, the condensing unit and the aperture stop form a telecentric optical system. After passing through one condensing means, it becomes a substantially parallel light beam and irradiates the measurement area of the measurement object. When the illuminating means is provided in the vicinity of the incident surface of the light beam dividing means, when the illuminating means emits light, the position of the aperture stop and the position of the incident surface of the light beam dividing means are in a conjugate relationship, and Since the first focusing means and the aperture stop constitute a telecentric optical system, the light beam emitted from the illumination means is once condensed at the position of the aperture stop by the second focusing means, and then the first The light is incident on the light collecting means, and is irradiated on the measurement area of the object to be measured by the first light collecting means. Therefore, when applied to a non-contact type optical apparatus, the measurer can confirm the measurement area by illuminating the measurement area of the measurement object. Since the measurement area can be confirmed without using the finder optical system, the amount of light guided to the light receiving sensor by the finder optical system does not decrease.
[0023]
Also When the illumination means emits light with the light shielding portion of the optical path switching means set on the optical path of the light beam, the offset correction value can be measured, and the measurement area of the measurement object is illuminated at the time of the measurement. Can confirm the measurement area of the measurement object when measuring the offset correction value.
[0024]
Claim 3 The invention described in claim 1 Or 2 In the measurement optical system described in (1), the light beam splitting means has a positive power. In addition, the said division | segmentation means is good to comprise with the light guide member which divides | segments a light beam into plurality, and the condensing member which has several positive power provided corresponding to the several output surface of the said light guide member ( Claim 4 ).
[0025]
According to this measuring optical system, since the light beam emitted from the light beam splitting means is collected, the light beam splitting means, the light receiving sensor, The light guide loss between the two is reduced.
[0026]
Claim 5 The invention described in claims 1 to 4 And a plurality of light receiving portions respectively disposed opposite to the plurality of light exit surfaces of the light beam splitting means in the measurement optical system, and emitted from the light exit surface. A light receiving means for separating the luminous flux into three primary color components, photoelectrically converting them into electrical signals and outputting them, and a computing means for calculating tristimulus values based on the light receiving signals of the three primary color components output from the light receiving means. Tristimulus type photoelectric colorimeter.
[0027]
In this tristimulus type photoelectric colorimeter, among the light beams emitted from the measurement region of the object to be measured by the measurement optical system, the light beams having a predetermined emission angle or less are divided into three parts and are incident on the light receiving means. Each light receiving means photoelectrically converts the incident light beam into electrical signals of the three primary color components and outputs them, and the computing means uses these electrical signals to calculate tristimulus values. Among the light beams emitted from the measurement area of the object to be measured, all the light beams having a predetermined emission angle or less are guided to the light receiving means by the measurement optical system, so there is little loss of the light guide light amount in the measurement optical system, Tristimulus values can be reliably measured even when the light emission of the object to be measured is small.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a perspective view showing an external appearance of a tristimulus value type photoelectric colorimeter according to the present invention.
[0029]
The tristimulus value type photoelectric colorimeter 1 (hereinafter abbreviated as “color meter 1”) includes a measurement probe 2 and a measuring instrument body 3. The measurement probe 2 and the measuring instrument main body 3 are connected by a dedicated cable 4.
[0030]
The measurement probe 2 is disposed opposite to the display surface 51 of the liquid crystal panel 5 that is the object to be measured by a predetermined distance d (for example, about 3 cm), receives light from the display surface 51 of the liquid crystal panel 5, and A signal (analog signal) is photoelectrically converted and input to the measuring device main body 3. The measurement probe 2 is configured to receive light from the liquid crystal panel 5 in a non-contact manner. For this reason, the measurement probe 2 is attached to a tripod 6 as shown in the figure, the height is adjusted by the tripod 6, and the position facing the liquid crystal panel 5 is adjusted to face the desired measurement area AR. Be placed.
[0031]
The measuring device main body 3 converts the received light signal input from the measuring probe 2 into a digital signal, and then performs a predetermined calculation process, for example, tristimulus values (X, Y, Z), Yxy established by CIE, for example. (Luminance, chromaticity coordinates), TΔuvY (correlated color temperature, color difference from black body locus, luminance), and the like are calculated, and the calculation result is displayed on the display panel 301.
[0032]
FIG. 2 is a block diagram showing the internal configuration of the measurement probe 2 and the measurement device main body 3. The measurement probe 2 includes, for example, a single positive power objective lens 21 (condensing means) made of a plano-convex lens, an optical path switching member 22 (optical path switching means), a driving member 23 for driving the optical path switching member 22, and an objective. A measurement optical system including a light beam splitting member 24 (light beam splitting means) that splits a light beam transmitted through the lens 21 into three light beams, and three light receiving sensors having spectral sensitivity characteristics of a standard observer; The photoelectric conversion unit 25 that photoelectrically converts the three light beams emitted from the light 24 into electric signals corresponding to the incident intensity by the light receiving sensors and outputs the electric signals (voltages) output from the light receiving sensors to a predetermined level. And a light receiving system including an amplifying unit 26 for amplifying.
[0033]
FIG. 3 is a diagram illustrating a specific configuration of the measurement optical system and the photoelectric conversion unit of the measurement probe 2. As shown in the figure, the light beam splitting member 24 includes a fiber 241 in which a plurality of optical fibers are bundled and three lenses 242a, 242b, and 242c having positive power.
[0034]
In the fiber 241, a plurality of bundled optical fibers are divided into three at an intermediate portion, and one light incident surface A and three light exit surfaces B1, B2, and B3 are provided. In the fiber 241, the incident surface A has the image side principal point PP of the objective lens 21 (for convenience of explanation, in this embodiment and other embodiments described later, the image side principal point substantially coincides with the object side principal point. The objective lens 21 is disposed so as to be separated from the objective lens 21 by the focal length f. That is, the objective lens 21 and the fiber 241 constitute a telecentric optical system. In the present embodiment, an optical fiber is used as the light beam splitting member 24. However, other optical components that perform the same function as the optical fiber, such as an optical conduit, may be used.
[0035]
With this configuration, when the measurement probe 2 is set away from the display surface 51 of the liquid crystal panel 5 by a predetermined distance d (for example, about 3 cm), among the light beams emitted from each part of the measurement area AR of the liquid crystal panel 5, Only the luminous flux below the maximum value α (hereinafter referred to as the maximum emission angle α) of the emission angle with respect to the normal direction of the measurement area AR (the direction parallel to the optical axis L in FIG. 3) is incident on the incident surface A of the fiber 241. Incident. The maximum emission angle α is determined by the focal length f of the objective lens 21 and the diameter R of the incident surface A of the fiber 241. The incident light beam is divided into three in the fiber 241 and emitted from the emission surfaces B1, B2, and B3, respectively.
[0036]
As shown in FIG. 4, the lens 242a condenses the light beam emitted from the emission surface B1 of the fiber 241 on the light receiving sensor 252a, and substantially matches the irradiation range LA of the light beam with the light receiving range SA of the light receiving sensor 252a. It is. Similarly, the lenses 242b and 242c condense the light beams emitted from the emission surfaces B2 and B3 of the fiber 241 to the light receiving sensors 252b and 252c, respectively, and set the irradiation range of each light beam to the light receiving ranges of the corresponding light receiving sensors 252b and 252c. It is a thing to make it substantially coincide.
[0037]
In this way, the light beam emitted from the fiber 241 is condensed in the light receiving range SA of the light receiving sensor 252, so that the light beam incident on the fiber 241 (the measured object emitted from each part of the measured region AR of the liquid crystal panel 5). All the luminous fluxes having a maximum emission angle α or less with respect to the normal direction of the area AR are respectively incident on the respective light receiving sensors 252a, 252b, and 252c by 1/3, and are received by the light receiving sensors as in the conventional measurement optical system shown in FIG. The amount of received light does not decrease.
[0038]
The optical path switching member 22 switches between the incidence of light flux collected by the objective lens 21 on the fiber 241 and the light shielding, and illuminates the display surface 51 of the liquid crystal panel 5 at the time of the light shielding so that the measurer can measure the area AR to be measured. Is made visible.
[0039]
The light beam incident on the fiber 241 can be blocked because the stray light of the measurement optical system including the objective lens 21 and the light beam splitting member 24 is received by the light receiving unit 25 even when the liquid crystal panel 5 is not provided (that is, when no light is incident). This is to make it possible to accurately perform calibration (offset correction) for canceling the noise signal. That is, the measured value is zero-adjusted in a state where the optical path switching member 22 completely shields the fiber 241 or the measured value in the light-shielded state can be stored in the memory as an offset correction value.
[0040]
As shown in FIG. 5, the optical path switching member 22 is a disk-shaped member that can rotate around a central axis 222. A circular opening 223 having a predetermined size is formed at a position eccentric from the center by a predetermined distance. A light emitting element 224 is provided at a point-symmetrical position with respect to the central axis 222 of the circular opening 223 on the surface facing the objective lens 21 (surface opposite to the fiber 241).
[0041]
Note that the size of the circular opening 223 is such that when the circular opening 223 is disposed opposite to the incident surface A of the fiber 241, the light beam collected by the objective lens 21 is completely vignetted without being vignetted by the optical path switching member 22. It is set to a size that can be incident on A. The light-emitting element 224 can be any light-emitting element such as an LED, a semiconductor laser, or a lamp.
[0042]
The optical path switching member 22 is rotationally driven by a driving member 23 such as a motor. At the time of measurement, the circular opening 223 is set at a position (light guiding position) facing the fiber 241 as shown in FIG. As shown in FIG. 4, the light emitting element 224 is set to a position on the optical axis L of the objective lens 21 (position overlapping the incident surface A of the fiber 241; light shielding position). When the optical path switching member 22 is set at the light blocking position, the light emitting element 22 is positioned at a position substantially equal to the incident surface A of the fiber 241 because the measurer sets the measured area AR of the liquid crystal panel 5 during calibration. This is so that it can be confirmed.
[0043]
That is, when the optical path switching member 22 is set at the light shielding position, the light emitting element 224 emits light. Since the objective lens 21 and the fiber 241 constitute a telecentric optical system as described above, the light emitted from the light emitting element 224 disposed at a position substantially equal to the incident surface A of the fiber 241 is shown in FIG. After passing through the objective lens 21 as described above, the light becomes substantially parallel light and is irradiated onto an area substantially equal to the measurement area AR of the display surface 51 of the liquid crystal panel 5. Therefore, the measurer can confirm the measurement area AR (illumination area) by the illumination area of the display surface 51 of the liquid crystal panel 5.
[0044]
In the present embodiment, the switching of the optical path switching member 22 is performed using a drive source such as a motor, but may be performed manually. In this way, it is not necessary to incorporate a drive source in the measurement probe 2, so that the measurement probe 2 can be reduced in size and weight.
[0045]
In the present embodiment, the optical path switching member 22 has a disk shape, but may have a rectangular plate shape as shown in FIG. Further, in this embodiment, the light path switching member 22 is switched between the light blocking position and the light guiding position by a rotation operation. However, as shown in FIG. 7, it may be performed by sliding movement (sliding direction is arbitrary). .
[0046]
Furthermore, although the optical path switching member 22 is built in the measurement probe 2 in this embodiment, the optical path switching member 22 may be omitted. In this case, the measurer puts a light-shielding member such as a cap on the tip of the measurement probe 2 to make the light-shielded state, and calibration may be performed in this state. On the other hand, in the light emitting element 224 for confirming the measurement region AR, for example, as shown in FIG. 8, a flange 241A is provided at the tip of the incident surface A side of the fiber 241, and the objective lens 21 of the flange 241A faces. What is necessary is just to arrange | position so that a light beam may not be interrupted | blocked by the fiber 241 on the surface. In this case, the light emitting element 224 may be one or plural. In the example of FIG. 8, two light emitting elements 224 and 224 ′ are provided. The light emitted from each of the light emitting elements 224 and 224 ′ passes through the optical path shown in FIG. Irradiation is made in a range substantially the same as the measurement area AR of the display surface 51 of the panel 5.
[0047]
FIG. 9 is a diagram showing another embodiment of the measurement optical system.
[0048]
The measurement optical system shown in the figure is the same as the measurement optical system shown in FIG. 3 except that the relay lens 211 (second condensing means) is placed at a predetermined position between the objective lens 21 (first condensing means) and the fiber 241. ), An aperture stop S1 and a field stop S2. The aperture stop S1 is provided at a position C away from the image-side principal point PP of the objective lens 21 by the focal length f, and the field stop S2 is provided at the imaging position of the objective lens 21. The relay lens 211 guides the optical image formed on the field stop S2 to the fiber 241, and the aperture stop so that the aperture stop S1 and the position C ′ of the incident surface A of the fiber 241 have a conjugate positional relationship. It is arranged between S1 and the fiber 241.
[0049]
The aperture stop S1 and the objective lens 21 constitute a telecentric optical system, and among the light beams emitted from the measurement area AR of the liquid crystal panel 5, a light beam having a maximum emission angle α or less enters the field stop S1. Since the maximum emission angle α is determined by the focal length f of the objective lens 21 and the aperture diameter of the aperture stop S1, the aperture diameter of the aperture stop S1 is set to a desired maximum emission angle α and the focal length f of the objective lens 21. Has been adjusted based on.
[0050]
In this measurement optical system, among the light beams emitted from the measurement region AR of the liquid crystal panel 5, only the light beam having a maximum emission angle α or less passes through the aperture stop S1, and the optical image of the measurement region AR is from the field stop S2. The image is formed at the position. This optical image is guided to the incident surface A of the fiber 241 by the relay lens 211. Since the aperture stop S1 and the incident surface A of the fiber 241 are arranged in a conjugate relationship, the light beam passing through the aperture stop S1 is incident on the incident surface A of the fiber 241 by the relay lens 211, and is measured by this measurement optical system. In the same way as the measurement optical system shown in FIG. 3, all of the light beams emitted from the measurement area AR of the liquid crystal panel 5 with the maximum emission angle α or less are guided to the light receiving unit 25 without losing the light amount. .
[0051]
Further, in this measuring optical system, when the light path switching member 22 is set to the light shielding position and the light emitting element 224 emits light, the light from the light emitting element 224 is reflected in the optical path shown in FIG. 10 (the incident light from the liquid crystal panel 5 to the fiber 241 An area substantially coincident with the area to be measured AR of the display surface 51 of the liquid crystal panel 5 is irradiated through an optical path substantially opposite to the optical path). Therefore, even in this measurement optical system, the measurer can confirm the measurement area AR of the liquid crystal panel 5 by the illumination light of the light emitting element 224.
[0052]
In this measurement optical system, since the aperture stop S1 and the incident surface A of the fiber 241 are in a conjugate positional relationship, the light emitting element 224 is positioned at the position of the aperture stop S1 as indicated by a dotted line in FIGS. Can be arranged. For example, when the aperture stop S1 is configured by a ring-shaped disk member, an appropriate number is arranged at an appropriate position on the surface of the disk member facing the objective lens 21 as a structure similar to the optical path switching member 22 shown in FIG. Good.
[0053]
As described above, since the aperture stop S1 and the objective lens 21 constitute a telecentric optical system, the light emitted from the light emitting element 224 disposed at substantially the same position as the aperture stop S1 enters the objective lens 21. After that, since it becomes substantially parallel light and is emitted to the display surface 51 of the liquid crystal panel 5 (see the optical path shown in FIG. 6), the measurement area AR of the liquid crystal panel 5 can be illuminated.
[0054]
Returning to FIG. 3, the photoelectric conversion unit 25 has three light receiving sensors 252a, 252b, and 252c having substantially the same light receiving sensitivity, such as SPC, and the CIE standard observation for each of the light receiving sensors 252a, 252b, and 252c. And three spectral sensitivity correction filters 251a, 251b, and 251c for giving the user's spectral sensitivity.
[0055]
The light receiving sensors 252a, 252b, and 252c are on the optical axes of the lenses 242a, 242b, and 242c, respectively, and the irradiation ranges of the light collected by the lenses 242a, 242b, and 242c are received by the light receiving sensors 252a, 252b, and 252c, respectively. It is arranged at a position that is a range. The spectral sensitivity correction filters 251a, 251b, and 251c are disposed at appropriate positions between the light receiving sensors 252a, 252b, and 252c and the lenses 242a, 242b, and 242c, respectively.
[0056]
The spectral sensitivity correction filter 251a has, for example, a filter characteristic having sensitivity in the R (red) wavelength region. Due to this filter property, the light reception sensitivity of the light receiving sensor 252a is a color matching function (X) having a large sensitivity in the red wavelength region. (Bar / lambda) On the other hand, the spectral sensitivity correction filters 251b and 251c have filter characteristics having sensitivity in the wavelength regions of G (green) and B (blue), respectively, and the light receiving sensitivity of the light receiving sensor 252b and the light receiving sensor 252c is based on these filter characteristics. Corrected to light sensitivity of color matching function (Yi bar lambda) having high sensitivity in the green wavelength range and light receiving sensitivity of color matching function (Zet bar lambda) having high sensitivity in the blue wavelength range. Has been. Therefore, the light receiving signals corresponding to the tristimulus values (X, Y, Z) are output from the light receiving sensors 252a, 252b, 252c, respectively.
[0057]
Returning to FIG. 2, the measuring instrument body 3 outputs from the A / D converter 31 and the A / D converter 31 that convert the received light signal input from the measurement probe 2 into a digital signal (hereinafter referred to as measurement data). Data memory 32 for storing measured data, tristimulus values (X, Y, Z), Yxy (luminance, chromaticity coordinates) established by CIE, TΔuvY using measurement data stored in the data memory (Data processing unit 33 for calculating (correlated color temperature, color difference from black body locus, luminance), etc., display unit 34 for displaying the calculation result, various information relating to measurement (measurement instruction, display mode setting, measurement range, etc.) The control unit 36 controls the measurement operation by intensively controlling the operation of the operation unit 35 and the operation of the measurement probe 2 and the operation of each unit in the measuring instrument main body 3.
[0058]
Next, the measurement process of the colorimeter 1 will be briefly described with reference to the flowchart of FIG. In this measurement process, a case where the chromaticity of the liquid crystal panel (LCD) 5 to be measured is measured will be described.
[0059]
First, as shown in FIG. 1, the measurement probe 2 is opposed to a region to be measured on the liquid crystal panel 5 and set at a position separated from the display surface 51 of the liquid crystal panel 5 by a predetermined distance d (about several centimeters) ( Step # 1). Subsequently, a video signal is given to the liquid crystal panel 5 from a pattern generator (not shown) to display a predetermined measurement image on the display surface 51 of the liquid crystal panel 5 (step # 3).
[0060]
When the measurement image is displayed in this way, the respective light receiving sensors 252a, 252b, and 252c output three light receiving signals (analog signals) SX, SY, and SZ related to the tristimulus values X, Y, and Z, respectively. The signals SX, SY, and SZ are amplified to a predetermined level by the amplifying unit 26 and then input to the measuring device main body 3. In the measuring instrument body 3, the received light signals SX, SY, SZ are converted into digital signals DX, DY, DZ by the A / D converter 31 and stored in the data memory 32 (step # 5).
[0061]
Next, the measurement data DX, DY, DZ and the calibration data KX, KY, KZ stored in advance in the data memory 32 are read from the data memory 32 to the data processing unit 33, and the tristimulus values of the measurement image are read. X, Y, Z are calculated (step # 7). The tristimulus values X, Y, and Z are calculated by X = KX · DX, Y = KY · DY, and Z = KZ · DZ. When the true tristimulus values X, Y, and Z are calculated in this way, the calculation results are displayed on the display unit 34 (that is, the display panel 301) (# 9).
[0062]
In the above-described embodiment, the light receiving sensors 252a to 252a through the red filter 251a, the green filter 251b, and the blue filter 251c corresponding to the three spectral sensitivities defined as the standard observer's spectral sensitivities by the International Commission on Illumination (CIE). The spectral sensitivity of 252c is corrected, but the type of filter is not limited to this.
[0063]
【The invention's effect】
As described above, according to the present invention, the condensing unit having a positive power and the light beam having the incident surface at a position that is substantially separated from the image-side principal point of the condensing unit by the focal length of the condensing unit. Since the measuring optical system is configured with the splitting means, all the light beams having a predetermined emission angle or less out of the light fluxes emitted from the measurement region of the object to be measured can be guided to the light receiving sensor side through the light flux splitting means without loss. In addition, even when the light emission intensity of the object to be measured is small, the optical characteristics of the object to be measured can be accurately measured (claim 1).
[0064]
Further, according to the present invention, the first condensing unit having a positive power and a position separated from the image-side principal point of the first condensing unit by a focal distance of the first condensing unit. The aperture stop disposed, the light beam splitting means for splitting the light beam transmitted through the aperture stop into a plurality of light beams, and the entrance surface of the aperture stop and the light beam splitting means are arranged in a conjugate relationship. Since the measurement optical system is constituted by the second light collecting means for condensing the light beam transmitted through the aperture stop on the light beam splitting means, the light beam emitted from the measurement region of the object to be measured is equal to or less than a predetermined emission angle. The light beam can be guided to the light receiving sensor side through the light beam splitting means without loss, and the same effect as described above can be obtained. 2 ).
[0065]
Further, according to the present invention, the illumination means is provided in the vicinity of the entrance surface of the light beam splitting means or the aperture stop, and the whole measurement area of the object to be measured is illuminated by this illumination means. This eliminates the need to reduce the amount of light guided to the light receiving sensor due to the provision of the finder optical system. 1, 2 ).
[0066]
Further, since the light beam splitting means has a positive power, the light beam splitting means emits light between the light beam splitting means and the light receiving sensor by substantially matching the irradiation range of the light flux emitted from the light beam splitting means with the light receiving range of the light receiving sensor. The light guide loss can be reduced. As a result, it is possible to further prevent a decrease in the amount of light received by the light receiving sensor. 3, 4 ).
[0067]
Further, since the tristimulus photoelectric colorimeter is configured by using the measurement optical system according to the present invention, the measurement optical system emits a light beam having a predetermined emission angle or less out of the light beams emitted from the measurement region of the measurement object. Therefore, the tristimulus value can be measured reliably and accurately even when the light flux from the measurement area of the object to be measured is small. 5 ).
[Brief description of the drawings]
FIG. 1 is a perspective view showing an external appearance of a tristimulus type photoelectric colorimeter according to the present invention.
FIG. 2 is a block diagram showing an internal configuration of a measurement probe and a measuring instrument main body.
FIG. 3 is a diagram showing a specific configuration of a measurement optical system of a measurement probe.
FIG. 4 is a diagram showing a relationship between an illumination range by a light beam emitted from a fiber and a light receiving range of a light receiving unit.
FIG. 5 is a view showing a structure of an optical path switching member.
FIG. 6 is a diagram illustrating a state in which a measurement region is illuminated by a light emitting element of an optical path switching member.
FIG. 7 is a view showing another structure of the optical path switching member.
FIG. 8 is a view showing another mounting structure of the light emitting element.
FIG. 9 is a diagram showing another embodiment of a measurement optical system.
FIG. 10 is a diagram showing an illumination range of a light emitting element in another embodiment of the measurement optical system.
FIG. 11 is a flowchart showing a procedure of measurement processing.
FIG. 12 is a diagram showing an example of an optical system applied to a conventional tristimulus type photoelectric colorimeter.
FIG. 13 is a diagram showing a relationship between an illumination range by a light beam emitted from a fiber and a light receiving range of a light receiving unit in a conventional measuring optical system.
FIG. 14 is a diagram illustrating an example of a conventional measurement optical system that guides, to a light receiving sensor, only a light beam having a predetermined emission angle or less among light beams emitted from a measurement region of a measurement object.
[Explanation of symbols]
1 Tristimulus type photoelectric colorimeter
2 Measuring probe
21 Objective lens (condensing means, first condensing means)
211 relay lens (second condensing means)
22 Optical path switching member (optical path switching means)
224 Light emitting element (illumination means)
23 Drive member
24 beam splitting member (beam splitting means)
241 fiber
242a, 242b, 242c Positive lens
25 Photoelectric converter
251a, 251b, 251c Spectral sensitivity correction filter
252a, 252b, 252c Light receiving sensor (light receiving means)
26 Amplifier
3 Measuring instrument body
31 A / D converter
32 data memory
33 Data processing unit (calculation means)
34 Display section
35 Operation unit
36 Control unit
4 Cable
5 LCD panel (measurement object)
6 Tripod
AR Measurement area
S1 Aperture stop
S2 Field stop

Claims (5)

A condensing means having a positive power for condensing only a light beam having a predetermined emission angle or less out of the light flux emitted from the measurement area of the object to be measured, and the light condensing from the image side principal point of the light collecting means. A light beam splitting unit having an incident surface of a light beam collected by the light collecting unit at a position separated by a focal length of the unit, dividing the incident light beam into a plurality of light beams, and an image of the light collecting unit An illuminating means for illuminating the entire measurement area of the object to be measured at a position approximately away from the side principal point by the focal length of the light collecting means; and A transmission part that transmits the light beam condensed by the light collecting unit to the incident surface of the light beam dividing unit and a light shielding unit that blocks the incidence of the light beam on the incident surface can be switched at a position separated by a focal length. Optical path switching means, and the illuminating means is arranged in a light shielding portion of the optical path switching means. Are, the when shielding the light beam by the light shielding portion, the measurement optical system, characterized in that illuminating the measurement area of the object to be measured. A first condensing means having a positive power for condensing only a light beam having a predetermined emission angle or less out of light beams emitted from the measurement region of the object to be measured; and an image side main of the first light condensing means. An aperture stop disposed at a position approximately away from the point by the focal length of the first light collecting means, a light beam splitting means for splitting a light beam transmitted through the aperture stop into a plurality of light beams, and the aperture A first light beam is disposed between the stop and the light beam splitting unit, and is disposed at a position where the aperture stop and the incident surface of the light beam splitting unit have a conjugate relationship, and the light beam that has passed through the aperture stop is condensed on the light beam splitting unit. Two condensing means, an illuminating means for illuminating the entire measurement area of the measured object at a position near the entrance surface of the aperture stop or the light beam splitting means, and an entrance surface of the aperture stop or the light beam splitting means in the vicinity of the light collecting in the focusing means And a light shielding portion and is switchable optical path switching means for interrupting the incidence of the luminous flux of the light flux to the incident surface and the transmission portion for transmitting the incident surface of the beam splitting means has, the illumination means, the light path switching An optical system for measurement , which is disposed in a light shielding portion of the means, and illuminates a measured region of the object to be measured when the light beam is shielded by the light shielding portion . Is the beam splitting means, a positive measurement optical system according to claim 1 or 2, characterized in that it has a power. The light beam splitting means includes a light guide member that splits a light beam into a plurality of light beams, and a plurality of light collecting members having positive power provided corresponding to a plurality of light exit surfaces of the light guide member. The measuring optical system according to claim 3 . Includes a measuring optical system according to any one of claims 1-4, a plurality of light receiving portions arranged respectively to face a plurality of the exit surface of the beam splitting means in the measuring optical system, the exit A tristimulus value is calculated based on a light receiving unit that divides a light beam emitted from the surface into three primary color components, photoelectrically converts them into electrical signals, and outputs light signals of the three primary color components output from the light receiving unit. A tristimulus value type photoelectric colorimeter comprising a calculation means.

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