JPH10274593A - Liquid crystal panel light transmittance measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal light transmittance measuring device that can measure light transmittance accurately over a wide range of 0-100% to liquid crystal with simple structure without needing complicated operation and long time and can easily measure the fluctuating characteristic or the like of light transmittance of liquid crystal based on the change of an irradiation angle. SOLUTION: Two sets of optical sensors 5, 6 are installed on a table 1, rotatable by a requested angle around a shaft part, so that inspection light intersect, and the intersection point of inspection light is made a light transmittance measuring point 0 of a liquid crystal panel. The sensor 5 with a characteristic that can detect micro transmitted light quantity of light transmittance 0-2% of the liquid crystal panel is used as one of two sets of optical sensors, and a sensor with a characteristic that can detect the transmitted light quantity over the detection area of the sensor 5 is used as the other optical sensor 6. High accuracy measurement over the whole area of light transmittance can be performed with simple operation of fixing the installed attitude of the liquid crystal panel 9 and rotating the rotating table 1 by a specified angle to measure light transmittance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for measuring the light transmittance of a liquid crystal panel, and more particularly, to a device capable of performing highly accurate measurement over the entire range of the light transmittance with a simple operation, and at the same time, responding. The present invention relates to a light transmittance measurement device capable of analyzing various characteristics of a liquid crystal panel such as speed, temperature characteristics, angle dependence, and drive frequency dependence.

[0002]

2. Description of the Related Art In recent years, the development of liquid crystal technology has been remarkable, and the field of use has expanded from general calculator displays to personal computers, word processors, various controllers, digital cameras, various printers and marking devices, and finally large displays. It is getting.

When various types of liquid crystal panels are used in a wide range of fields, the effects of the surrounding environment cannot often be ignored due to their characteristics. Generally, it is known that the drive voltage and the temperature of the liquid crystal itself greatly affect the light transmittance and the response speed of the liquid crystal. Therefore, various measurements have conventionally been made to examine the effects of the light transmittance and the response speed based on various factors.

[0004] For example, regarding the light transmittance, a general measuring method is to irradiate a measuring point of a liquid crystal panel with inspection light having a required amount of light, receive an outgoing light passing through the measuring point with a light receiver, and receive the light. This is performed by measuring an output voltage based on the amount of light. The measurement environment at this time is usually measured by placing the measurement device in a thermostatic chamber in which light from outside is shut off, in order to guarantee a constant light irradiation amount and temperature while avoiding the influence of ambient light and temperature. Like that.

[0005]

However, the measuring range of the light transmittance of the conventional liquid crystal is determined by the resolution and gain setting of the photodetector, and the range from weak light to strong light can be measured. There is no receiver. Especially,
With a light receiver that measures the amount of normal light, the transmittance of the liquid crystal is 0
In order to perform high-precision measurement in the vicinity of%, that is, when the liquid crystal is closed and the light transmission amount is close to 0, it is necessary to adjust the gain of the photodetector again. in this case,
At the same time, the liquid crystal panel, which is the measurement sample, must be once removed from the measuring device, and the liquid crystal panel must be reattached when the adjustment is completed. This not only complicates the adjustment work, but also causes a problem that the re-attachment is likely to change the measurement points of the liquid crystal panel, and the reliability of reproducibility is lost.

In order to maintain the measurement environment as described above, a thermostat for accommodating the measurement device is required.
The size of the entire apparatus is increased, and the equipment cost is significantly increased, which makes the apparatus extremely expensive. Further, for example, when trying to measure the fluctuation of the light transmittance due to temperature change, it is necessary to change the entire temperature in the thermostat to a desired value, not only takes a long time to change the temperature, The energy required for that cannot be ignored. In particular, measurement at a high temperature of 120 ° C. or higher is almost impossible.

[0007] The present invention solves the above-mentioned problems and, in the past, required complicated operability and long time for the measurement. For example, it is possible to easily measure the fluctuation characteristics of the light transmittance with respect to the change of the irradiation angle with respect to the liquid crystal panel. It is an object of the present invention to provide a liquid crystal light transmittance measuring apparatus which is simple in structure and operation and capable of performing high-precision measurement.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a main structure of the present invention, in which a table capable of rotating a desired angle around a shaft and a test light are fixed on the table so as to intersect. And two sets of optical sensors provided, the intersection of the inspection light is set on the axis of the shaft portion, and the light transmission measurement point of the liquid crystal panel is made to coincide with the intersection and the liquid crystal panel is One of the two sets of optical sensors is replaceable, and one of the two sets of optical sensors can detect a very small amount of transmitted light having a light transmittance of 0 to 2% of the liquid crystal panel, and the other optical sensor detects the amount of light transmitted by the one optical sensor. This is achieved by a light transmittance measuring device for a liquid crystal panel, characterized in that the amount of transmitted light outside the region can be detected.

To accurately measure a very small amount of transmitted light and another strong amount of transmitted light at the same measurement point on the liquid crystal panel, the driving voltage and the temperature of the liquid crystal are kept constant, and for example, First, the inspection light from the light projector of the optical sensor capable of detecting a small amount of transmitted light having a light transmittance of 0 to 2% is incident on the measurement point of the liquid crystal panel at right angles.
The table is rotated around the shaft and fixed in position, and the inspection light is emitted from the light emitter to the light receiver through the liquid crystal panel. As described above, this light receiver accurately receives the minute amount of transmitted light, converts it into a measurable voltage value, and outputs it. When this measurement is completed, the inspection light emitted from the other projector of the optical sensor capable of accurately detecting the transmitted light amount in a wide range of light transmittance of 0 to 2% or more is perpendicularly incident on the measurement point of the liquid crystal panel. As described above, the table is rotated around the shaft portion and positioned and fixed. Here, the inspection light is emitted from the projector through the liquid crystal panel toward the opposing light receiver. As described above, this light receiver accurately converts the transmitted light amount in a wide range having a light transmittance of 0 to 2% or more into a voltage value and outputs the voltage value. Thus, according to the measuring device of the present invention, the transmitted light amount of the liquid crystal in the entire range of 0 to 100% can be accurately measured by a simple operation of simply rotating the turntable by a predetermined angle. In addition, since the measurement point is always on the center line of the rotating shaft, the measurement point does not fluctuate and the reliability is secured.

In the measuring apparatus of the present invention, when a control means for controlling and driving at least the liquid crystal portion at the light transmittance measuring point of the liquid crystal panel is provided, for example, a change in transmittance due to a driving voltage or a temperature is measured. Can be measured at the same time. That is, if the measurement is performed sequentially according to the above procedure while changing the driving voltage of the liquid crystal portion, the correlation between the driving voltage of the liquid crystal portion and the light transmittance can be obtained, or the temperature of the liquid crystal portion can be controlled by the control means. If the setting is changed in multiple steps, a detailed correlation between the temperature and the light transmittance can be obtained. Further, when the drive voltage and the temperature are combined with each other and varied in multiple stages, for example, when the liquid crystal is completely closed, it is necessary to select an appropriate temperature and drive voltage in the range of the minute light amount. It becomes possible.

The drive voltage control means may be a normal drive control means, but it is preferable that the temperature is maintained not only at the measurement point of the liquid crystal panel but also at the periphery thereof at the same temperature. Thus, it is preferable that the temperature can be intentionally changed in various ways and that the liquid crystal temperature at the measurement point can be directly measured. Therefore, in the present invention, as the heating control means of the liquid crystal panel, the heating means of the light transmittance measurement point, the temperature detection means of the measurement point, and the heating amount by the heating means based on the detection signal by the detection means. It is desirable to have heating control means for controlling.

In particular, in order to satisfy the above-mentioned requirements, the heating means is a transparent film heater, and the temperature detecting means at the measurement point is a non-contact infrared detector, and the liquid crystal panels are transparent. A liquid crystal is disposed between first and second transparent substrates having electrodes, and the transparent film heater is disposed on a back surface of the first transparent substrate.
A third transparent substrate is provided between the first transparent substrate and the transparent film heater. At this time, assuming that the thickness of the third transparent substrate is equal to the thickness of the first transparent substrate, the measurement point of the infrared detector is located on an extension of the transmittance measurement point of the liquid crystal panel. When the infrared detector is set at one point on the plate surface and the infrared detector of the infrared detector is opposed to the inspection light transmission point of the third transparent substrate, the first and second light sources are heated by the transparent film heater. 2
Since the temperature distribution in the thickness direction of the transparent substrate is symmetrical with respect to the transparent film heater, the temperature at the measurement point of the liquid crystal panel and the temperature at the measurement point on the third transparent substrate coincide with each other. This is equivalent to directly detecting the temperature at the above measurement point.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a perspective view showing the overall schematic structure of a light transmittance measuring device for a liquid crystal panel which is a typical embodiment of the present invention, FIG. 2 is a plan view showing details of the measuring device, and FIG. It is. FIG.
FIG. 4 is an explanatory diagram of a measurement principle and a function of a light transmittance according to the present invention.

In these figures, reference numeral 1 denotes a rotary table, which is provided on a top surface of a fixed base 2 having a substantially square shape as shown in FIGS. The angle is supported rotatably. At this time, the rotation angle of the rotation table 1 can be fixed at a desired rotation angle by, for example, a positioning pin 4 as shown in FIG. According to the illustrated example, this rotation angle is 30 degrees.
Although it is set to °, the present invention is not limited to this. For example, in order to measure the change in light transmittance due to the incident angle of the inspection light applied to the liquid crystal, the light is rotated in multiple stages at a desired rotation angle. It is preferable to be able to move and fix.

The rotary table 1 has a rectangular shape in which two opposing sides are substantially equal to the length of one side of the fixed base 2 and the other two opposing sides are shorter than the length of one side of the fixed base 2. And two sets of optical sensors 5 and 6 at both ends in the longitudinal direction.
And two sets of mounting columns 7 and 8 for mounting and fixing the
Is erected. The two sets of optical sensors 5 and 6 form a part of the main constituent members of the present invention, and the two projectors 5
a, 6a and two light receivers 5b, 6b that respectively receive the inspection light emitted from the light projectors 5a, 6a. One of the optical sensors 5 detects that the transmitted light of the liquid crystal is zero.
%, And the other optical sensor 5 has a characteristic that the transmitted light of the liquid crystal can accurately detect a light amount equal to or more than the minute light amount.

Generally, this type of optical sensor has a non-linear region (A) as shown by a solid line in FIG. 5, and unless measurement is performed while adjusting the gain of the non-linear region (A), It is impossible to accurately detect everything from a small amount of light to a large amount of light with a single sensor.
In particular, according to a normal optical sensor, as shown by a solid line in the figure, when the light transmittance when the liquid crystal is in a closed state is near 0, it is extremely difficult to accurately detect the transmitted light,
Near impossible. Conversely, as shown by the broken line in FIG. 5, a detection light sensor exists accurately from a region where the amount of transmitted light is small to a region where the amount of transmitted light is large to some extent.

On the other hand, when the drive voltage of the liquid crystal is increased or the temperature of the liquid crystal is increased, the light transmittance increases. As described above, the light transmittance is near 0, but the drive voltage is the same, for example. However, when the liquid crystal temperature is increased, the closed state is broken, and a very small amount of light that should not have been transmitted is transmitted, and the closed state cannot be maintained. In such a case, normally, the liquid crystal temperature is controlled or the drive voltage is controlled so as to be lowered so that the liquid crystal is kept closed.

Therefore, in such control, it is necessary to know the exact correlation between the light transmittance of the liquid crystal and the liquid crystal temperature or drive voltage. The most important measurement object to know it is the light transmittance of the liquid crystal, especially to know the fluctuation of light transmittance due to temperature change and change of driving voltage which are other factors affecting the light transmittance. It is. The liquid crystal light transmittance measuring device according to the present invention uses the first optical sensor 5 and the second optical sensor 6 having different non-linear regions (A) as described above, and specifically as follows. Based on another configuration of the device to be described, the two sets of optical sensors 5 and 6 can be switched by a simple operation, and the light transmittance at the same measurement point of the liquid crystal panel can be changed over the entire range of 0 to 100%. Makes accurate measurements possible. Further, in the present embodiment, it is possible to accurately and easily obtain each of the above-mentioned correlations.

The shaft portion 3 projects vertically downward from the center of the rotary table 1, and the coaxial portion 3 is rotatably fitted to the fixed base 2 via a bearing (not shown). The rotation table 1 is rotatable in a horizontal plane about the shaft 3.

Reference numeral 9 denotes a liquid crystal panel serving as a light transmittance measurement sample according to the present invention. The basic configuration of the liquid crystal panel 9 according to the present embodiment is not substantially different from that of the conventional liquid crystal panel. For example, in the example shown in FIG. 6, a liquid crystal 9c is provided between the first glass substrate 9a and the second glass substrate 9b, which are disposed with a transparent electrode facing each other via a spacer (not shown), and the spacer. In the present embodiment, a transparent film heater 10 is adhered to the plate surface of the first glass substrate 9a on the side where the detection light is incident, and the transparent film heater 10 is sandwiched therebetween. A holding glass plate 11, which is a transparent substrate of No. 3, is provided. The material and thickness of the holding glass 11 are the first
The material and thickness of the glass substrate 9a are matched.

In the liquid crystal panel 9 according to the present embodiment having such a configuration, as shown in FIGS. 2 and 3, the measurement point O of the light transmittance is positioned on the extension line above the shaft portion 3 of the rotary table 1. At the same time, their liquid crystal surfaces are parallel to each other on two opposite sides of the fixed base 2 corresponding to the light emitting and receiving devices 5a, 6a: 5b, 6b of the first and second optical sensors 5, 6. As described above, it is supported and fixed to the fixed base 2 via the support member 12. In the illustrated example, the support member 12 includes a frame 12a and left and right frame members 12 at upper and lower intermediate portions of the frame 12a.
a 'and a pair of brackets 12b fixed to
The liquid crystal panel 9 is provided at opposite ends of the left and right brackets 12b.
Are exchangeably supported and fixed.

The fixed base 2 has a temperature detecting end 13a.
A non-contact type temperature sensor 13 is provided so as to face the light transmission measurement point O ′ of the holding glass 11. As the temperature sensor 13, an infrared detector is used. The temperature sensor 13 is a gate-type temperature sensor fixed with screws or the like to the end of the fixed base 2 on the side where the light projectors 5a and 6a of the first and second optical sensors 5 and 6 are disposed. Mounting table 14
Is fixedly supported above the bracket through a bracket 14a. The temperature sensor mounting table 14 is made of a metal plate, and it is necessary to expose the light projectors 5a and 6a of the first and second optical sensors 5 and 6 upward from the temperature sensor mounting table 14. Therefore, each of the projectors 5a, 6
A part of the mounting surface of the temperature sensor mounting table 14 that interferes with the rotation range of a is cut out.

The temperature sensor 13 is connected to the transparent film heater 10 via a temperature controller 15 and a heater amplifier 16 as shown in FIG.
The temperature detected by 3 is compared with a set temperature in the temperature control unit 15, and when the temperature deviates from the set temperature, the voltage applied to the transparent film heater 10 is controlled based on a control signal from the control unit 15. The temperature at the measurement point of the liquid crystal panel 9 is kept constant. The set temperature can be changed as appropriate.

Here, the temperature measurement point O 'by the temperature sensor 13 is set to one point on the plate surface of the holding glass 11 which is on the extension of the transmittance measurement point O of the liquid crystal 9c. When the material and thickness of the holding glass 11 in the panel 11 are made to match the material and thickness of the first glass substrate 9a, the first glass substrate 9a generated by heating the transparent film heater 10 as shown in FIG. The temperature distribution in the thickness direction between the pressure glass 9 and the holding glass 9 is symmetrical with respect to the transparent film heater 10. Therefore, if the temperature detecting end 13a of the temperature sensor 13 is opposed to the temperature measuring point O 'of the holding glass 11, the temperature between the temperature measuring point of the liquid crystal 9c and the temperature measuring point O' of the holding glass 11 can be obtained. And the holding glass 11
The measurement temperature at the upper measurement point O 'can be made substantially equal to the measurement temperature of the liquid crystal 9c.

With the apparatus of this embodiment having the above configuration,
At the same light transmittance measurement point O of the liquid crystal panel 9, when it is desired to accurately detect a small amount of transmitted light and a large amount of transmitted light, the drive voltage of the liquid crystal 9c is kept constant, In this way, when the liquid crystal temperature at the light transmittance measurement point O of the liquid crystal itself is controlled to be constant, for example, when a small amount of transmitted light having a light transmittance of 0 to 2% is to be detected,
The rotating table 1 is rotated around the shaft 3 until the inspection light from the projector 5a of the first optical sensor 5 is incident on the measurement point of the liquid crystal panel at right angles until the position shown by the solid line in FIG. The projector 5a is moved and fixed in position, and the inspection light is emitted from the light emitter 5a through the liquid crystal panel 9 toward the opposing light receiver 5b. As described above, the light receiver 5b accurately receives a very small amount of transmitted light, converts it into a measurable voltage value, and outputs it.

When this measurement is completed, the light transmittance 2
The rotary table 1 is pivoted so that the inspection light emitted from the projector 6a of the other optical sensor 6 that can accurately detect the transmitted light amount in a wide range of about 100% enters the measurement point of the liquid crystal panel at right angles. 2 is rotated by 30 ° from the solid line position to the virtual line position shown in FIG. Next, the inspection light is irradiated from the light projector 6a to the opposing light receiver 6b through the liquid crystal panel 9. As described above, the light receiver 6b accurately converts the transmitted light amount in a wide range of the light transmittance of 2 to 100% into a voltage value and outputs the voltage value.

As described above, according to the measuring apparatus of the present invention, the amount of transmitted light of the liquid crystal in the entire range of 0 to 100% can be accurately measured by a simple operation of rotating the rotary table by a predetermined angle. Moreover, since the measurement point O does not need to be detached from the liquid crystal panel 9 as in the prior art, the measurement point O is always on the center line of the rotating shaft 3 and the measurement point O does not fluctuate, and high reliability is secured. Furthermore, the liquid crystal panel 9
Can be fixed at a fixed position by the left and right brackets 12a, 12b of the support member 12 fixed to the fixing base 2, so that if the fixing specification of the liquid crystal panel 9 is matched, the measurement accuracy can be changed even if it is replaced with another liquid crystal panel. Has no effect.

Although the above-described measurement is performed while maintaining the drive voltage and the liquid crystal temperature constant, in this embodiment, although not shown, a control for controlling a normal drive voltage for the liquid crystal is omitted. With the provision of the temperature sensor 13 described above, it is possible to simultaneously measure a change in transmittance due to a change in the drive voltage of the liquid crystal 9c and / or a set temperature. That is, by sequentially performing the measurement according to the above-described procedure while changing the set driving voltage of the liquid crystal 9c, the correlation between the driving voltage of the liquid crystal 9c and the light transmittance can be obtained accurately, or the temperature can be obtained. Sensor 1
By changing the set temperature of the liquid crystal 9c in step 3, a detailed correlation between the temperature and the light transmittance can be obtained. When the set drive voltage and the set temperature are changed in combination with each other, for example, it is possible to select an appropriate temperature and drive voltage in the range of the minute light amount when the liquid crystal is completely closed. Becomes

In the apparatus of the above embodiment, for example, the positioning pin 4 shown in FIG. 2 is elastically protruded and retractable so that the rotation angle of the rotation table 1 can be changed in multiple stages. 2 and a rotating table 1
If a pin hole engaging with the positioning pin 4 is provided at a predetermined pitch in a portion corresponding to the positioning pin 4 at the time of turning, the incident angle of light on the liquid crystal surface can be changed in multiple stages. , Liquid crystal 9 based on change of incident angle
It is also possible to accurately measure the change in the light transmittance of c.

As can be understood from the above description, the present invention is not limited to the above-described embodiment, and various changes can be made within the scope of the claims.

[Brief description of the drawings]

FIG. 1 is an overall perspective view schematically showing a typical embodiment device of the present invention.

FIG. 2 is a top view showing a detailed configuration of the apparatus of the embodiment.

FIG. 3 is a side view of the same.

FIG. 4 is a schematic explanatory diagram showing operations and functions of the present invention.

FIG. 5 is a diagram showing general measurement characteristics of an optical sensor.

FIG. 6 is an explanatory diagram schematically showing a configuration of a liquid crystal panel according to an embodiment of the present invention and a temperature distribution by a transparent film heater thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotating table 2 Fixed base 3 Shaft part 4 Positioning pin 5 1st optical sensor 6 2nd optical sensor 5a, 6a Projector 5b, 6b Light receiver 7, 8 1st and 2nd sensor mounting pillar 9 Liquid crystal panel 9a 1st Transparent substrate (glass substrate) 9b Second transparent substrate (glass substrate) 9c Liquid crystal 10 Transparent film heater 11 Holding glass 12 Support member 12a Frame 12a 'Frame 12b Bracket 13 Temperature sensor 14 Temperature sensor mounting table 14a Bracket 15 Temperature controller 16 Heater amplifier

Claims (9)

[Claims] 1. A light transmittance measuring device for a liquid crystal panel, comprising: a table capable of rotating a desired angle around a shaft portion; and a table fixed to the table so that inspection light intersects the table.
A set of optical sensors, wherein the intersection of the inspection light is set on the axis of the shaft portion, and the light transmittance measurement point of the liquid crystal panel is made coincident with the intersection, so that the liquid crystal panel is replaceably arranged. One of the two sets of optical sensors is capable of detecting a very small amount of transmitted light having a light transmittance of 0 to 2% of the liquid crystal panel, and the other optical sensor is configured to transmit light in areas other than the detection area of the one optical sensor. An apparatus for measuring the light transmittance of a liquid crystal panel, wherein the light amount can be detected. 2. The light transmittance measuring apparatus according to claim 1, further comprising control means for controlling and driving at least a liquid crystal portion of said liquid crystal panel at said light transmittance measuring point. 3. The light transmittance measuring apparatus according to claim 2, wherein said control means is a voltage control circuit for controlling a voltage applied to said liquid crystal portion. 4. The light transmittance measuring device according to claim 2, wherein said control means is a temperature control means for controlling a temperature of said liquid crystal portion. 5. The apparatus according to claim 1, wherein the temperature control means includes a heating means for the light transmittance measurement point, a temperature detection means for the measurement point, and a heating control means for controlling a heating amount by the heating means based on a detection signal from the detection means. The light transmittance measurement device according to claim 4, wherein 6. The light transmittance measuring apparatus according to claim 5, wherein the heating means is a transparent film heater, and the temperature detecting means at the measurement point is an infrared detector. 7. The liquid crystal panel includes a liquid crystal disposed between first and second transparent substrates each having a transparent electrode, and an infrared incident portion of the infrared detector detects an inspection light of the liquid crystal panel. 7. The device according to claim 6, which is opposed to the transmission point.
The light transmittance measuring device as described in the above. 8. The transparent film heater is disposed on the back surface of the first transparent substrate, and a third transparent substrate is disposed with the transparent film heater interposed therebetween, wherein the infrared detector of the infrared detector is The light transmittance measurement device according to claim 7, wherein the light transmittance measurement device is provided to face the inspection light transmission point of the third transparent substrate. 9. The material and thickness of the third transparent substrate are equal to the material and thickness of the first transparent substrate.
The light transmittance measuring device as described in the above.