JP2008256821A - Display device, optical module and projection display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deterioration in image quality in a display device and degradation in the function of the display device by exactly measuring temperature of a layer to be driven in the display device. <P>SOLUTION: The display device 1 is equipped with a drive substrate (silicon drive substrate 20) equipped with a drive element corresponding to a pixel, the layer to be driven (liquid crystal 30) provided on the drive substrate (silicon drive substrate 20), and a temperature detection means (temperature sensor 50) provided in the area of the layer to be driven (liquid crystal 30) on the drive substrate (silicon drive substrate 20). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a display device using, for example, liquid crystal, an optical module in which the display device and an optical element are combined, and a projection display apparatus using the display device.

  In recent years, as projection systems have become higher in definition, smaller in size, and higher in brightness, reflective devices that can be miniaturized and high-definition as display devices and can be expected to have high light utilization efficiency have attracted attention and have been put into practical use. Yes. These are active reflection types in which a glass substrate on which a transparent electrode is formed on one side and a silicon substrate made of, for example, a C-MOS semiconductor circuit on the other side is used as a drive element substrate, and liquid crystal is injected between the pair of substrates. It is a liquid crystal display device.

  A pixel electrode for reflecting light and applying a voltage to the liquid crystal is arranged on the silicon drive substrate. This pixel electrode is a metal material mainly composed of aluminum used in an LSI process. Consists of.

  In these elements, a voltage is applied to the liquid crystal by applying a voltage to the transparent electrode and the pixel electrode provided on the counter electrode. At this time, the liquid crystal changes the refractive index anisotropy Δn of the liquid crystal according to the potential difference between the electrodes, changes the optical characteristics, and performs gradation display by modulating the incident light.

  Moreover, in these elements, in order to radiate the thermal energy absorbed by the irradiation light, a cooling mechanism is provided on the back side of the silicon driving substrate. The silicon reflective liquid crystal display device and the projection system using the display device are required to have high brightness, high definition, and high image quality year by year.

  Here, the change in the optical characteristics of the liquid crystal is caused by the difference in refractive index by changing the refractive index ne, no of the liquid crystal by the voltage applied to the liquid crystal as described above, but the refractive index ne, no of the liquid crystal depends on the temperature. There is also sex. In a projection system equipped with such a liquid crystal display element, there is a concern that the device temperature may change due to environmental changes, resulting in changes in brightness or chromaticity of the displayed image. The device cooling conditions are controlled by feedback, and the device temperature change is controlled.

JP 2005-156717 A

  However, since the temperature sensor is installed outside the device, the temperature of the liquid crystal that is the driven layer cannot be accurately measured. Even when the temperature sensor can be installed close to the device, there is always a difference between the device's original temperature and the sensor temperature because it is outside the device. Therefore, for example, when the amount of light irradiated to the device increases rapidly, the sensor measurement value does not follow the temperature rise of the device and cannot be cooled sufficiently, causing not only image quality deterioration such as chromaticity and luminance change but also deterioration of the device itself. Cause.

  In addition, when the above-described method of always excessively cooling the device in order to avoid the deterioration of the image quality and the device as described above, for example, there is a problem that the noise and power consumption of the entire set increase due to an increase in the cooling fan air volume. .

  Therefore, an object of the present invention is to accurately measure the temperature of a driven layer in a display device and to accurately avoid deterioration in image quality and device function.

  The present invention has been made to achieve the above object. That is, the present invention is a display device including a drive substrate including a drive element corresponding to a pixel, a driven layer provided on the drive substrate, and a temperature detection unit provided in a region of the driven layer on the drive substrate. is there.

  In the present invention, since the temperature detecting means is provided in the region of the driven layer in the driving substrate, the temperature of the driven layer can be directly measured.

  For example, as a display device for realizing the present invention, in a silicon reflective liquid crystal display device having a transparent electrode substrate on one side and a reflective electrode on the other side, a device for sensing temperature is driven by silicon in order to directly measure the device temperature. Include as part of the circuit in the board.

  As an example of the element for sensing temperature, for example, a thermistor is incorporated. Since the resistance value of the thermistor changes depending on the device temperature, the device temperature can be measured by obtaining the data of the resistance value from the I / O line of the device.

  Further, a diode may be incorporated as an example of an element for sensing temperature. Since the diode has a temperature characteristic, the temperature can be detected from the current and voltage with respect to the diode by using this characteristic.

  As described above, in the present invention, since the temperature of the driven layer can be directly measured, the temperature of the driven layer in the display device is accurately measured, and the image quality deterioration in the display device and the function deterioration of the display device are performed. Can be accurately performed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Display device>
(First embodiment)
FIG. 1 is a schematic cross-sectional view of a silicon reflective liquid crystal display device which is an example of a display device 1 according to this embodiment. A glass substrate 10 on which a transparent electrode is formed and a silicon driving substrate 20 are bonded together at a predetermined interval, and a liquid crystal 30 serving as a driving layer is injected therebetween.

  Light enters the silicon reflective liquid crystal display device from the glass substrate 10 side, but about 10 to 25% of the energy is absorbed as heat in the liquid crystal display device, so that the device temperature rises. In order to prevent the temperature rise due to the absorption of heat energy, the reflective liquid crystal display device includes a fin-shaped cooling mechanism 40 on the back side of the silicon drive substrate 20.

  FIG. 2 is a schematic plan view of a silicon drive substrate applied in the display device of the present embodiment. That is, in the injection region of the liquid crystal 30 that is the driven layer (within the frame of the sealing material into which the liquid crystal 30 is injected), for example, a pixel to which a temperature measurement function (temperature sensor 50) is added at the center of the image display surface is formed. Enable device temperature detection. In the silicon drive substrate 20, a signal extraction wiring 500 that allows the detected signal to be read from the outside is formed, and this wiring is routed to the end of the silicon drive substrate 20 and connected to the reading terminal 60.

  The signal detected by the temperature sensor 50 can be taken out from the reading terminal 60. Based on this detection data, for example, the amount of cooling air sent to the cooling mechanism 40 is controlled to keep the temperature of the silicon reflective liquid crystal display device constant. Adjust as follows. In the present embodiment, since the temperature sensor 50 is provided on the image display surface, the temperature of the liquid crystal 30 directly related to the image display can be measured more accurately and can be fed back to accurate temperature control.

  FIG. 3 is a conceptual diagram of a circuit configuration of a pixel having a temperature measurement function of a silicon drive substrate applied in the present embodiment. In addition to the normal pixel display circuit, an NTC (negative temperature coefficient) type thermistor circuit 51 in which the resistance value decreases as the temperature rises as shown in Equation 1 is added.

  By providing the pixel to which the thermistor circuit 51 shown in FIG. 3 is added and the signal extraction wiring 500 shown in FIG. 2 in the silicon drive substrate 20, a temperature change of the liquid crystal 30 can be directly detected as a change in resistance value. The cooling mechanism 40 can be controlled based on the detected value. That is, it is possible to appropriately control the cooling mechanism 40 according to the detected temperature. This makes it possible to keep the device at a constant temperature, and it is possible to prevent image quality changes such as brightness and chromaticity due to temperature changes and device deterioration due to rapid temperature rise.

(Second Embodiment)
In the display device according to the second embodiment, the schematic cross-sectional view (FIG. 1) of the silicon reflective liquid crystal display device and the schematic plan view (FIG. 2) of the silicon drive substrate are the same as those of the first embodiment.

  FIG. 4 is a conceptual diagram of a circuit configuration of a pixel having a temperature measurement function of the silicon drive substrate according to the present embodiment. In addition to the normal pixel display circuit, a diode circuit 52 comprising two silicon semiconductor diodes D1 and D2 is added.

  The voltage of the two diodes D1 or D2 of the diode circuit 52 varies with temperature. Therefore, by providing the pixel to which the diode circuit 52 shown in FIG. 4 is added and the signal extraction wiring 500 shown in FIG. 2 in the silicon driving substrate, the temperature change of the liquid crystal 30 is directly changed as the voltage change of the diode D1 or D2. The cooling mechanism 40 can be controlled based on the detected value. That is, it is possible to appropriately control the cooling mechanism 40 according to the detected temperature. This makes it possible to keep the device at a constant temperature, and it is possible to prevent image quality changes such as brightness and chromaticity due to temperature changes and device deterioration due to rapid temperature rise.

(Third embodiment)
In the display device according to the third embodiment, the schematic cross-sectional view (FIG. 1) of the silicon reflective liquid crystal display device is the same as that of the first embodiment.

  FIG. 5 is a diagram showing the configuration of the terminals for inputting / outputting signals to / from the outside provided on the silicon drive substrate according to the present embodiment. That is, an input terminal for inputting a signal to the internal circuit of the panel is provided at the end of the silicon driving substrate 30, and two diodes D1 for preventing static electricity to the input signal are provided at this input terminal. , D2 are provided.

  Here, since there are input terminals that are not used for actual driving (one that is used only for operation check or a preliminary one), such an empty input terminal as the temperature sensor of the present embodiment. And its protective diode.

  The voltage of the two diodes D1 or D2 varies depending on the device temperature. Therefore, since the change in device temperature can be sent to the external cooling device by reading the voltage between the terminals, the cooling mechanism 40 can be appropriately controlled. Accordingly, it is possible to keep the device at a constant temperature by detecting the voltage, and it is possible to prevent a change in image quality such as luminance and chromaticity due to a temperature change, and deterioration of the device due to a rapid temperature rise.

  Note that a plurality of pixels to which the thermistor circuit shown in the first embodiment is attached may be provided in the liquid crystal region of the silicon drive substrate.

  Further, the pixel to which the thermistor circuit shown in the first embodiment is attached may be formed other than the center in the liquid crystal region in the silicon drive substrate.

  In addition, a plurality of pixels to which the temperature detection diode shown in the second embodiment is attached may be provided in the liquid crystal region of the silicon drive substrate.

  Further, the pixel to which the temperature detection diode shown in the first embodiment is attached may be formed in a region other than the center in the liquid crystal region in the silicon drive substrate.

  A plurality of terminals shown in the third embodiment may be formed at appropriate positions in the silicon driving substrate.

  Further, in the concept of the schematic cross-sectional view (FIG. 1) of the silicon reflective liquid crystal display device according to the first to third embodiments, the cooling mechanism 40 of the display device 1 is not limited to the fin, but a Peltier, liquid cooling mechanism. , Shows all cooling devices such as water cooling mechanism.

  In the first to third embodiments, the driving substrate for driving the driven layer may be a reflective film (a film that reflects light modulated by the driven layer) on the glass substrate even if it is a semiconductor other than silicon. ) Or a glass substrate capable of transmitting light.

  Next, a specific configuration example of the temperature sensor will be described. FIGS. 6A and 6B are schematic plan views for explaining an installation example of the temperature sensor. FIG. 6A is an example in which the temperature sensor is installed between the two effective pixels G1 and G2. FIG. The example installed between the pixels G1-G4 is shown.

  In the example shown in FIG. 6A, since the temperature sensor 50 is installed between the two effective pixels G1 and G2, the effective pixels G1 and G2 are offset in the horizontal direction in the drawing to secure the installation space for the temperature sensor 50. is doing.

  In the example shown in FIG. 6B, since the temperature sensor 50 is installed between the four effective pixels G1 to G4, each pixel electrode corresponding to the four effective pixels G1 to G4 and a circuit below the pixel electrode are provided. The installation space for the temperature sensor 50 is secured by offsetting. The wiring of the temperature sensor 50 is formed between the two data lines.

  FIG. 7 is a schematic cross-sectional view illustrating a portion where a temperature sensor is provided. A transistor 21 and a capacitor 22 are formed on the silicon drive substrate 20 corresponding to each pixel. In the example shown in FIG. 7, a diode circuit 52 is formed as a temperature sensor in the vicinity of the transistor 21 (between adjacent pixel regions not shown). Then, a wiring connected to the diode circuit 52 is formed beside the data line of the transistor 21 (between the data lines of adjacent pixels not shown).

  After forming the transistor 21, the capacitor 22, and the diode circuit 52, a gate line and a ground line are formed as the first metal layer (1), and then a data line and a ground line are formed as the second metal layer (2). Next, a light shielding layer is formed as a third metal layer (3), and finally a pixel electrode is formed as a fourth metal layer (4).

  FIG. 8 is a schematic plan view for explaining the wiring structure. The left diagram in FIG. 8 shows a normal wiring structure (first metal layer, second metal layer, uppermost layer) in which no temperature sensor is provided. On the other hand, the right diagram in FIG. 8 shows a wiring structure when a diode circuit 52 as a temperature sensor is provided. In the first configuration, the upper and lower pixels in the figure are offset to form the diode circuit 52, and the wiring 520 of the diode circuit 52 is provided between the two data lines of the second metal layer.

  In the second structure, the left and right pixels in the drawing are offset to form the diode circuit 52, and the wiring of the diode circuit 52 is provided between the two gate lines of the first metal layer. In any example, the diode circuit 52 is disposed between the transistors 21 of adjacent pixels, and the wiring 520 of the diode circuit 52 is provided between two gate lines or data lines.

  FIG. 9 is a circuit configuration diagram illustrating an example of another diode circuit constituting the temperature sensor. 9A shows a configuration in which a voltage detection terminal is provided on one end side of the diode, and FIG. 9B shows a voltage detection from one end side of the diode, which is converted into a digital signal by the analog / digital conversion circuit 52a. In this configuration, it is taken out from the output terminal.

  Here, the theoretical formula regarding the temperature characteristics of the diode is shown in Equation 2.

  By utilizing such temperature characteristics of the diode, the temperature of the liquid crystal can be directly detected and accurate temperature control can be performed. In particular, when a silicon drive substrate is used as one substrate of the display device, it is possible to easily form resistors and diodes constituting the temperature sensor 50 together with normal TFT formation. In addition, in the case of a reflective liquid crystal display device, even if the temperature sensor 50 is provided in the image display area, the influence of reflection in the display image is very small.

  FIG. 10 is a schematic diagram for explaining the cooling control means. The cooling control means includes a D / A (digital-to-analog converter) or decoder 25 that converts a signal output from the temperature sensor 50 of the display device 1, and a controller 26 that controls the temperature regulator 41 based on the temperature sensor output value. Composed. The cooling control means may be outside the display device 1 or may be built in the silicon driving substrate 20.

  The signal detected by the temperature sensor 50 is converted into an analog signal by the D / A of the cooling control means or the decoder 25, and the controller 26 generates a control signal based on the analog signal. The temperature regulator 41 is controlled by this control signal, and the cooling or heating of the display device 1 is controlled to accurately control the temperature.

  The temperature regulator 41 is a fan that sends cooling air to the fin when the cooling mechanism 40 is a fin, or a control mechanism for these when the cooling mechanism 40 is a Peltier, liquid cooling mechanism, or water cooling mechanism. Or

With the above configuration, the display device of this embodiment has the following effects.
(1) Since the original temperature of the device can be directly detected, an external temperature measuring device is not required. Thereby, the cost of the set can be reduced.
(2) Since the original temperature of the device can be measured, the cooling device can be linked accurately, and the device can always be controlled to an appropriate temperature.
(3) Since the device temperature can be kept constant, for example, the device temperature can be kept appropriate even when a sudden illuminance change occurs on the device, and the image quality can always be kept at a constant level. Can be avoided.
(4) The device life can be extended and the reliability of device characteristics can be maintained longer.
(5) Since the device temperature can be appropriately maintained without being affected by the temperature of the installation environment of the display device, the image quality can always be maintained at a constant level, and the image quality deterioration and the device deterioration can be avoided.
(6) Even if there is a sudden rise in temperature, quick cooling to the cooling mechanism eliminates the need for overcooling, making it possible to reduce noise and also reducing power consumption due to overcooling. It becomes.

<Projection type display device>
FIG. 11 is a schematic diagram illustrating an example of a liquid crystal projector (projection display device) using the liquid crystal display device which is the display device of the present embodiment. That is, the liquid crystal projector 1000 includes a lamp light source 101, a lens unit 102, a dichroic color separation filter 103, beam splitters 104r, 104g, and 104b, liquid crystal display devices 1r, 1g, and 1b, drive circuits 105r, 105g, and 105b, and a prism (dichroic mirror). ) 106 and the projection lens 107.

  As the liquid crystal display devices 1r, 1g, and 1b, the reflective liquid crystal display device with a temperature sensor described above is used.

  In this system, the light emitted from the lamp light source 101 is sent from the lens unit 102 to the dichroic color separation filter 103, where it is separated in two directions. The light separated in two directions corresponds to three colors of R (RED), G (GREEN), and B (BLUE) by total reflection mirrors 108 and 109, beam splitters 104r, 104g, and 104b, dichroic mirror 110, and prism 106. Each of them is sent to a display unit composed of a reflective liquid crystal display device 1r, 1g, 1b.

  For example, the light from the lamp light source 101 is incident on the liquid crystal display device 1r corresponding to R (RED) from the dichroic color separation filter 103 via the total reflection mirror 108 and the beam splitter 104r, and corresponds to G (GREEN). Light from the lamp light source 101 enters the liquid crystal display device 1g through the total reflection mirror 108, the dichroic mirror 110, and the beam splitter 104g from the dichroic color separation filter 103, and enters the liquid crystal display device 1b corresponding to B (BLUE). The light from the lamp light source 101 enters from the dichroic color separation filter 103 via the total reflection mirror 109 and the beam splitter 104b.

  Each of the liquid crystal display devices 1r, 1g, and 1b is provided via beam splitters 104r, 104g, and 104b in a state corresponding to the plurality of surfaces of the prism 106 that is a dichroic mirror. Each of the liquid crystal display devices 1r, 1g, and 1b is driven by the corresponding drive circuits 105r, 105g, and 105b, reflects the incident light as an image on the liquid crystal layer, synthesizes it by the prism 106, and sends it to the projection lens 107. . As a result, an image corresponding to three colors R (RED), G (GREEN), and B (BLUE) is projected onto a screen (not shown) and reproduced as a color image.

  Further, since each liquid crystal display device 1r, 1g, 1b is provided with the temperature sensor 50 (see FIG. 2) as described above, even if the temperature rises due to the light emitted from the lamp light source 101, The liquid crystal display devices 1r, 1g, and 1b can be kept at a constant temperature by accurately detecting the temperature and prompt feedback.

  As a result, even if the temperature of the liquid crystal display devices 1r, 1g, and 1b changes due to environmental changes and changes over time, it is possible to always maintain stable modulation performance by accurate temperature control to the liquid crystal display devices 1r, 1g, and 1b. Therefore, the liquid crystal projector 1000 can stably provide an image.

<Optical module>
The display device according to the present embodiment can be applied as an optical module by combining with an optical component. That is, the optical module is a combination of the display device and the optical component according to the present embodiment. For example, among the configurations of the liquid crystal projector 1000 illustrated in FIG. 11, each display device (liquid crystal display device 1r) according to the present embodiment. 1g, 1b) and the respective optical splitters 104r, 104g, 104b which are optical components corresponding thereto, the liquid crystal display devices 1r, 1g, 1b, the respective beam splitters 104r, 104g, 104b and these Can be attached to the prism 106. It should be noted that other combinations are possible as an optical module.

<Organic EL device>
The display device according to the present embodiment can be applied to an organic EL element. FIG. 12 is a schematic cross-sectional view illustrating an example of an organic EL element to which the display device of this embodiment is applied. That is, this organic EL element forms a thin film transistor Tr in which a gate electrode 1003, a gate insulating film 1005, and a semiconductor layer 1007 are sequentially stacked on a glass substrate 1001. In the present embodiment, the temperature sensor 50 is formed in an adjacent space together with the formation of the thin film transistor Tr.

  The thin film transistor Tr and the temperature sensor 50 are covered with an interlayer insulating film 1009, and a wiring 1011 connected to the thin film transistor Tr through a connection hole formed in the interlayer insulating film 1009 is provided to form a pixel circuit. As described above, a so-called TFT substrate 1020 which is a driving substrate is formed.

  The TFT substrate 1020 is covered with a planarization insulating film 1021, and a connection hole reaching the wiring 1011 is formed in the planarization insulating film 1021. A pixel electrode (first electrode) 1023 connected to the wiring 1011 through a connection hole is formed over the planarization insulating film 1021 as an anode, for example, and an insulating film pattern 1025 having a shape covering the periphery of the pixel electrode 1023 is formed.

  An organic EL material layer 1027 is stacked to cover the exposed surface of the pixel electrode 1023. A counter electrode (second electrode) 1029 is formed by the insulating pattern 1025 and the organic EL material layer 1027 while maintaining the insulating property with respect to the pixel electrode 1023. The counter electrode 1029 is formed as a cathode made of a transparent conductive material, for example, and is formed in a solid film shape common to all pixels.

  Thereafter, a transparent substrate 1033 is attached to the counter electrode 1029 via a light-transmitting adhesive layer 1031 to complete the organic EL element 1040. Even in such an organic EL element 1040, the temperature change of the organic EL material layer 1027 that is the driven layer can be directly detected by forming the temperature sensor 50 as in the present embodiment. The temperature of the organic EL element 1040 can be kept constant by quick feedback.

1 is a schematic cross-sectional view of a silicon reflective liquid crystal display device which is an example of a display device 1 according to the present embodiment. It is a schematic plan view of the silicon drive substrate applied with the display device of this embodiment. It is a conceptual diagram of the circuit structure of the pixel provided with the temperature measurement function of the silicon drive substrate applied in this embodiment. It is a conceptual diagram of the circuit structure of the pixel provided with the temperature measurement function of the silicon drive substrate concerning this embodiment. It is the figure which showed the structure of the terminal provided in the silicon | silicone drive board | substrate in connection with this embodiment and the signal input / output. It is a model top view explaining the example of installation of a temperature sensor. It is a schematic cross section explaining the part which provides a temperature sensor. It is a schematic plan view explaining a wiring structure. It is a circuit block diagram explaining the example of another diode circuit which comprises a temperature sensor. It is a schematic diagram explaining a cooling control means. It is a schematic diagram which shows the example of the liquid crystal projector (projection type display apparatus) using the liquid crystal display device which is a display device of this embodiment. It is a schematic cross section explaining an example of an organic EL element to which the display device of this embodiment is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Display device, 10 ... Glass substrate, 20 ... Silicon drive substrate, 30 ... Liquid crystal, 40 ... Cooling mechanism, 50 ... Temperature sensor

Claims (10)

A drive substrate including a drive element corresponding to the pixel;
A driven layer provided on the driving substrate;
And a temperature detecting means provided in a region of the driven layer on the driving substrate. The display device according to claim 1, wherein the drive substrate is made of a semiconductor substrate. The display device according to claim 1, wherein the temperature detection unit includes a diode. The display device according to claim 1, wherein the temperature detection unit includes a resistor. The display device according to claim 1, wherein the driven layer is a liquid crystal layer. The display device according to claim 1, wherein the driving substrate is a silicon substrate, and the driven layer is a liquid crystal layer. The display device according to claim 1, wherein a reflection film that reflects light modulated by the driven layer is formed on the driving substrate. In an optical module in which a display device is attached to an optical component,
The display device is
A drive substrate including a drive element corresponding to the pixel;
A driven layer provided on the driving substrate;
An optical module comprising temperature detecting means provided in a region of the driven layer on the driving substrate. A light source;
At least one display device;
A condensing optical system for guiding the light emitted from the light source to the display device;
A projection optical system for projecting the light modulated by the display device in an enlarged manner;
The display device is
A drive substrate including a drive element corresponding to the pixel;
A driven layer provided on the driving substrate;
And a temperature detecting means provided in a region of the driven layer on the driving substrate. The projection display device according to claim 9, further comprising cooling control means for controlling cooling of the display device in accordance with the temperature detected by the temperature detection means.

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