JP5255776B2 - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To fabricate a backlight device which is more reduced in color unevenness and less luminance unevenness and high in reliability, and to fabricate a high-performance display device which is provided with the backlight device, is high in reliability and can display a high quality image. <P>SOLUTION: A light emitting diode (LED) is used as a light source of the backlight device and thermoelectric elements are provided in a chassis for holding the light emitting diode so as to surround the light emitting diode (the thermoelectric elements are provided under the light emitting diode and on the four sides thereof). A temperature in the backlight device is adjusted by cooling and heating by the thermoelectric elements. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

The present invention relates to a backlight device and a structure of a display device including a liquid crystal element including the backlight device.

Currently, liquid crystal display devices are used in a wide variety of fields such as clocks and calculators, office automation equipment such as personal computers, liquid crystal televisions, PDAs, and mobile phones.

In this liquid crystal display device, liquid crystal is sealed between two light-transmitting substrates, and a voltage is applied to change the direction of liquid crystal molecules to change light transmittance, thereby optically displaying a predetermined image or the like. To do. In the liquid crystal display device, since the liquid crystal itself is not a light emitter, a backlight unit that functions as a light source is provided on the back surface of the liquid crystal display panel. The backlight unit includes a light source, a light guide plate, a reflection film, a prism film, a diffusion film, and the like, and uniformly supplies display light to the entire surface of the liquid crystal display panel.

As a light source of the backlight unit, a cold cathode fluorescent lamp in which mercury or xenon is enclosed in a fluorescent tube is generally used.

The light source of the backlight device as described above has a change in luminance with respect to the environmental temperature, and may cause a decrease in luminance due to a temperature increase due to its own heat generation. Therefore, heat dissipation measures such as air cooling with a heat sink, a heat pipe, and a cooling fan have been attempted so that the temperature of the light source becomes the optimum operating temperature. As one of the heat dissipation measures, there is a method in which a Peltier element is provided in a fluorescent tube and cooling is performed by the Peltier element (see, for example, Patent Document 1 and Patent Document 2).
JP-A-6-324304 JP-A-7-175035

However, in recent years, white light-emitting diodes and high-output red-green-blue light-emitting diodes have been used, and high-output red-green-blue light-emitting diodes have characteristics that drive voltage is high and luminance is low during high-temperature operation. In particular, red light-emitting diodes are highly temperature dependent. Furthermore, in a light emitting diode backlight unit, a large amount of heat is generated by using a plurality of high output red, green and blue light emitting diodes.

Due to this heat generation, the life of the light emitting diode itself is reduced, the brightness is reduced, the chromaticity is shifted, and the like, and the backlight unit is deformed or deteriorated in the diffusion film, the reflection film, the prism film, or the like.

In addition, since the liquid crystal display panel is placed in front of the backlight unit and is affected by the temperature of the backlight unit, the effect on the response speed, contrast, color unevenness and other characteristics of the liquid crystal display panel, polarizing film Further, deformation, deterioration, characteristic deterioration, etc. of the viewing angle widening film, retardation film, etc. occur.

In order to suppress this generated heat, the above heat dissipation measures are provided, but there are problems such as insufficient heat dissipation measures and an increase in the thickness of the backlight unit in any means.

In view of the above problems, the present invention is capable of displaying a highly reliable and high-quality image including a highly reliable backlight device with less color unevenness and luminance unevenness, and further including the backlight device. An object is to manufacture a high-performance display device that can be used.

In the present invention, a light emitting diode (hereinafter also referred to as LED: Light Emitting Diode) is used as a light source of a backlight device (also referred to as a backlight or a lighting device), and a housing for holding the light emitting diode is surrounded by the light emitting diode ( A thermoelectric element is provided under and around the light emitting diode (4), and the temperature in the backlight device is adjusted by cooling and heating the thermoelectric element. A thermoelectric element is a metal or semiconductor element that converts heat energy into electric energy using a phenomenon related to heat and electricity. Examples of thermoelectric elements that can be used in the present invention include Peltier elements. .

The light emission of the light emitting diode causes a temperature change in the backlight device. A temperature sensor for monitoring the temperature state is provided in the backlight device, and cooling or heating is performed by the thermoelectric element by a drive circuit that operates the thermoelectric element, and temperature control is performed by a temperature controller. Further, a color sensor for monitoring the output of the light emitting diode is provided, and the output of the light emitting diode is controlled by a light emitting diode control device that controls the output of the light emitting diode, and the light emitting diode is driven by the light emitting diode driving circuit.

The transmissive liquid crystal display panel module provided on the front surface of the backlight device also includes a thermoelectric element for heating and cooling the liquid crystal display panel, a drive circuit for operating the thermoelectric element, and a temperature state of the (color) liquid crystal display panel. A temperature sensor for monitoring and a temperature controller for controlling temperature may be included.

The thermoelectric element provided on the backlight device side and the thermoelectric element provided on the liquid crystal display panel module side may each have a temperature sensor and a temperature controller, and may be operated independently, or may be operated in common. Good.

The backlight device and the liquid crystal display panel module may be provided in contact with each other, or may be disposed with a space therebetween. When the liquid crystal display panel module and the backlight device are provided in contact with each other, and the thermoelectric element provided on the backlight device side is in contact with the liquid crystal display panel module, the temperature of the liquid crystal display panel module can also be controlled by cooling and heating the thermoelectric element. it can.

Further, a thermoelectric module is provided in the liquid crystal display device, and the temperature difference in the liquid crystal display device can be used to drive other light emitting diodes, thermoelectric elements, and the like. In the present invention, since a thermoelectric element that can be efficiently cooled and heated is provided in a housing, a desired temperature difference is easily obtained in a liquid crystal display device.

One embodiment of the backlight device of the present invention has a plurality of light emitting diodes arranged in a casing including thermoelectric elements, and the casing including the thermoelectric elements is provided so as to surround the plurality of light emitting diodes. Yes.

One embodiment of the backlight device of the present invention includes a first light emitting diode, a second light emitting diode, and a third light emitting diode arranged in a casing including a thermoelectric element, and the casing including the thermoelectric element includes: Provided to surround the plurality of light emitting diodes, the first light emitting diode has a red light emission color, the second light emitting diode has a green light emission color, and the third light emitting diode has a blue light emission color. is there.

One embodiment of the backlight device of the present invention includes a first light emitting diode, a second light emitting diode, and a third light emitting diode arranged in a casing including a thermoelectric element, and the casing including the thermoelectric element includes: Provided to surround a plurality of light emitting diodes, the emission color of the first light emitting diode has a wavelength peak of 625 nm ± 10 nm, and the emission color of the second light emitting diode has a wavelength peak of 530 nm ± 15 nm. The emission color of the third light emitting diode has a peak wavelength of 455 nm ± 10 nm.

One embodiment of a display device of the present invention includes a backlight device including a plurality of light emitting diodes arranged in a housing including a thermoelectric element, and a display module, and the housing including the thermoelectric element includes a plurality of light emitting diodes. It is provided so as to surround the periphery.

One embodiment of a display device of the present invention includes a backlight device including a plurality of light emitting diodes arranged in a casing including a Peltier element, and a display module. The casing including the Peltier elements includes a plurality of light emitting diodes. It is provided so as to surround the periphery.

One embodiment of a display device of the present invention includes a backlight device including a plurality of light emitting diodes arranged in a housing including a first thermoelectric element, and a display module including a second thermoelectric element, The housing including the thermoelectric element is provided so as to surround the plurality of light emitting diodes.

One form of a display device of the present invention includes a backlight device including a plurality of light emitting diodes arranged in a housing including a first Peltier element, and a display module including a second Peltier element, The housing including the Peltier element is provided so as to surround the plurality of light emitting diodes.

As the plurality of light emitting diodes used in the present invention, light emitting diodes exhibiting different light emission colors can be used, and for example, red light emitting diodes, green light emitting diodes, and blue light emitting diodes can be included. More specifically, the plurality of light emitting diodes includes a first light emitting diode having a peak of the emission color wavelength of 625 nm ± 10 nm, a second light emitting diode having a peak of the wavelength of emission color of 530 nm ± 15 nm, and 455 nm ± A third light emitting diode having a peak of the emission color wavelength of 10 nm can be included.

  By using the present invention, it is possible to suppress the heat generation of the light emitting diode used for the light source, and it is possible to suppress the life of the light emitting diode, the luminance, and the chromaticity shift. By suppressing the heat generation of the light source, deformation and alteration of the diffusion film, the reflection film, and the prism film can be suppressed.

  In addition, it is possible to suppress changes in characteristics such as response speed, contrast, and color unevenness of liquid crystal display panels, and deformation, alteration, and characteristics of polarizing films, viewing angle expansion films, retardation films, etc. used in liquid crystal display panels Decrease etc. can also be suppressed. Further, since a heat sink, a heat pipe, a cooling fan and the like are not required, the thickness of the backlight device can be reduced.

  Since the light emitting diodes of the three primary colors of light are used, the color temperature can be easily adjusted, and the color reproduction range can be widened as compared with the cold cathode fluorescent lamp. In addition, by using light emitting diodes, the operating temperature range is expanded and response is fast, making it easy to support moving images, enabling driving at low voltages, eliminating the need for inverters, improving contrast, and not using mercury. Because it is good for the environment.

Therefore, according to the present invention, a highly reliable backlight device with less color unevenness and luminance unevenness and the like, and a high-performance image display device having the backlight device with high reliability and high image quality. A display device can be manufactured.

Embodiments of the present invention will be described below with reference to the drawings. However, the present invention can be implemented in many different modes, and those skilled in the art can easily understand that the modes and details can be variously changed without departing from the spirit and scope of the present invention. Is done. Therefore, the present invention is not construed as being limited to the description of this embodiment mode. Note that in all the drawings for describing the embodiments, the same portions or portions having similar functions are denoted by the same reference numerals, and repetitive description thereof is omitted.

(Embodiment 1)
In this embodiment, a concept of a backlight device (also referred to as a backlight or a lighting device) using the present invention and a display device including the backlight device will be described.

In the present invention, a light emitting diode (LED) is used as a light source of a backlight device, and a thermoelectric element is provided in a casing holding the light emitting diode so as to surround the light emitting diode (under and around the light emitting diode). The temperature inside the backlight device is adjusted by cooling and heating the thermoelectric elements. A thermoelectric element is a metal or semiconductor element that converts heat energy into electric energy using a phenomenon related to heat and electricity. Examples of thermoelectric elements that can be used in the present invention include Peltier elements. .

FIG. 1A is a top view of a display device using a light emitting diode (hereinafter also referred to as LED: Light Emitting Diode) as a light source and including a backlight unit including a thermoelectric element, and FIGS. 1B and 1C. Shows a cross-sectional view corresponding to line AB in FIG. FIG. 1B is a conceptual diagram that is simplified, and a more detailed example is shown in FIG. The display device of the present invention is a liquid crystal display device having a liquid crystal display element. Since the liquid crystal itself is not a light emitter, the backlight unit is disposed on the back surface of the liquid crystal display panel 150 as a light source.

In FIG. 1, light emitting diodes 101a to 101c are provided in a housing 100 including a thermoelectric element. The backlight unit is a light emitting diode 101a which is a red light emitting diode having a peak at 625 nm ± 10 nm, a light emitting diode 101b which is a green light emitting diode having a peak at 530 nm ± 15 nm, and a light emitting which is a blue light emitting diode having a peak at 455 nm ± 10 nm. The light emitted from the light emitting diodes 101a to 101c is transmitted through the liquid crystal display panel 150 in the direction of the arrows in FIGS. 1B and 1C and is emitted to the viewing side. The housing 100 including the thermoelectric element of the present invention is provided so as to surround at least three directions of the light emitting diodes 101a to 101c in a box shape. By disposing the liquid crystal display panel 150 on the housing 100 including the thermoelectric elements, the light emitting diodes 101 a to 101 c are provided in a box-shaped closed space formed by the housing 100 including the thermoelectric elements and the liquid crystal display panel 150.

As shown in FIG. 1C, a reflective sheet 102 is provided so as to cover a housing 100 including a thermoelectric element, and reflects light from the light emitting diodes 101a to 101c. A light guide plate 103 is disposed directly above the light emitting diodes 101a to 101c, and a diffusion plate 104 and a prism sheet 105 are disposed with a certain gap therebetween.

The light emitting diodes 101a to 101c are controlled so as to be always maintained at a constant temperature by the casing 100 including a thermoelectric element having heating and cooling functions. Since the casing 100 including the thermoelectric element of the present invention is provided so as to surround the four sides of the light emitting diodes 101a to 101c, not only the vicinity of the light emitting diodes 101a to 101c but also the entire backlight unit can be efficiently cooled or heated. Therefore, accurate temperature control without temperature unevenness can be performed.

The light emission of the light emitting diode causes a temperature change in the backlight device. A temperature sensor for monitoring the temperature state is provided in the backlight device, and cooling or heating is performed by the thermoelectric element by a drive circuit that operates the thermoelectric element, and temperature control is performed by a temperature controller. Further, a color sensor for monitoring the output of the light emitting diode is provided, and the output of the light emitting diode is controlled by a light emitting diode control device that controls the output of the light emitting diode, and the light emitting diode is driven by the light emitting diode driving circuit. As the color sensor and the temperature sensor, a color sensor and a temperature sensor configured from an IC chip can be used. At this time, the color sensor and the temperature sensor may be arranged so as to be hidden in the housing portion of the display device.

The transmissive liquid crystal display panel module provided on the front surface of the backlight device also includes a thermoelectric element for heating and cooling the liquid crystal display panel, a drive circuit for operating the thermoelectric element, and a temperature state of the (color) liquid crystal display panel. A temperature sensor for monitoring and a temperature controller for controlling temperature may be included.

The thermoelectric element provided on the backlight device side and the thermoelectric element provided on the liquid crystal display panel module side may each have a temperature sensor and a temperature controller, and may be operated independently, or may be operated in common. Good.

The backlight device and the liquid crystal display panel module may be provided in contact with each other, or may be disposed with a space therebetween. When the liquid crystal display panel module and the backlight device are provided in contact with each other, and the thermoelectric element provided on the backlight device side is in contact with the liquid crystal display panel module, the temperature of the liquid crystal display panel module can also be controlled by cooling and heating the thermoelectric element. it can.

Further, a thermoelectric module is provided in the liquid crystal display device, and the temperature difference in the liquid crystal display device can be used to drive other light emitting diodes, thermoelectric elements, and the like. In the present invention, since a thermoelectric element that can be efficiently cooled and heated is provided in a housing, a desired temperature difference is easily obtained in a liquid crystal display device.

The backlight unit can use light emitting diodes (LEDs) of various colors such as red, green, blue, and white as light sources. By using each color light emitting diode (LED), color reproducibility can be enhanced. Furthermore, when using light emitting diodes (LEDs) of RGB for each color as the light source, it is not necessary to have the same number and arrangement. For example, you may arrange | position more colors (for example, green) with low light emission intensity than the light emitting diode of another color.

In the case of having RGB light emitting diodes, when the field sequential mode is applied, color display can be performed by sequentially lighting the RGB light emitting diodes according to time.

When a light-emitting diode is used, it has high luminance and is suitable for a large display device. Further, since the color purity of each of the RGB colors is good, the color reproducibility is superior to that of the cold cathode tube, and the arrangement area can be reduced. Therefore, when the display is adapted to a small display device, the frame can be narrowed.

For example, when a backlight device having a light emitting diode is mounted on a large display device, the light emitting diode can be arranged on the back surface of the display device. At this time, the light emitting diodes can maintain predetermined intervals, and the light emitting diodes of the respective colors can be arranged in order. The color reproducibility can be improved by the arrangement of the light emitting diodes.

In particular, a backlight device including a light-emitting diode is suitable for a large display device, and a high-quality image can be provided even in a dark place by increasing the contrast ratio of the large display device.

An example in which the shape of the housing including the thermoelectric element is different is shown in FIG. As shown in FIG. 2, a part of the housing 120 including the thermoelectric element may be provided on the display panel side from which light is emitted from the backlight unit. If the casing 120 including the thermoelectric element is provided so as to wrap the backlight device as shown in FIG. 2, the entire backlight unit can be cooled or heated more efficiently, and accurate temperature control without temperature unevenness can be performed. it can.

In order to reduce the thickness of the display device, the backlight unit and the display panel may be provided in contact with each other. In the display device illustrated in FIG. 24, a housing including a thermoelectric element provided in the backlight unit is in part in contact with the display panel. In the case where the backlight device and the display panel are provided in contact with each other (even when part of the backlight device is in close contact with the display device), the display panel is easily affected by the temperature change of the backlight device. When the thermoelectric element included in the housing is provided in contact with the display panel, the display panel side is also cooled or heated by the thermoelectric element, and the temperature can be controlled.

Examples of different shapes of the housing including the thermoelectric element are shown in FIGS. 3 and 4 are examples in which housings 130 and 140 including thermoelectric elements are provided in contact with both the backlight unit and the display panel. FIG. 4 shows a structure in which a housing 140 including a thermoelectric element covers a part on the viewing side of the display panel as shown in FIG. 2, and is shaped to enclose the backlight unit and the display panel. As shown in FIGS. 3 and 4, the casing including the thermoelectric element may continuously cover the backlight unit and the display panel, or the casing including different thermoelectric elements in the backlight unit area and the display panel area. The body may be provided discontinuously.

Further, the light emitting diode used in the present invention may be covered with a resin or the like, and as shown in FIG. 5, a dome (hemisphere) resin cover for diffusing light may be provided around the light emitting diode. In addition, the cover of the light emitting diode may be reversely tapered, and the shape is not limited.

In addition, the liquid crystal display panel module includes a TN (Twisted Nematic) mode, an IPS (In-Plane-Switching) mode, an FFS (Fringe Field Switching) mode, an MVA (Multi-domain Vertical Alignment) mode, and a PVA (Vertinal Pattern). Mode, ASM (Axial Symmetrically Aligned Micro-cell) mode, OCB (Optically Compensated Birefringence) mode, FLC (Ferroelectric Liquid Crystal) mode, AFLC (Antirefractive Liquid) Or the like can be used over de.

By using the present invention, heat generation of the light-emitting diode used for the light source can be suppressed, so that the lifetime of the light-emitting diode, the luminance, and the chromaticity shift can be suppressed. By suppressing the heat generation of the light source, deformation and alteration of the diffusion film, the reflection film, and the prism film can be suppressed.

In addition, it is possible to suppress changes in characteristics such as response speed, contrast, and color unevenness of liquid crystal display panels, and deformation, alteration, and characteristics of polarizing films, viewing angle expansion films, retardation films, etc. used in liquid crystal display panels Decrease etc. can also be suppressed. Further, since a heat sink, a heat pipe, a cooling fan and the like are not required, the thickness of the backlight device can be reduced.

Therefore, according to the present invention, a highly reliable backlight device with less color unevenness and luminance unevenness and the like, and a high-performance image display device having the backlight device with high reliability and high image quality. A display device can be manufactured.

(Embodiment 2)
In this embodiment mode, a backlight device using the present invention and a display device including the backlight device will be described in detail.

A display device illustrated in FIG. 6 includes a light-emitting diode 201 (light-emitting element 201a, cover 201b, terminal 201c), a thermally conductive layer 202 functioning as a thermally conductive adhesive, a metal core substrate 203, a housing 200 including a thermoelectric element, a reflection Sheet 204, light guide plate 205, diffusion plate 206, prism sheets 207a and 207b, backlight unit 230 including color sensor 220, substrate 211, layer 212 including display elements, substrate 213, polarizing plates 214 and 210, liquid crystal display panel A liquid crystal display panel 231 including a driver circuit 232 is included. Further, the backlight unit 230 includes a temperature sensor 221, a temperature controller 222, a thermoelectric element driving circuit 223, a light emitting diode control device 224, and a light emitting diode driving circuit 225 in the backlight unit region.

The metal core substrate is a substrate in which a metal core is disposed in an intermediate layer of the substrate, and is characterized by heat uniformity, mechanical strength improvement, shielding properties, and the like. Since the metal core substrate has good thermal conductivity, it is easy to adopt a structure in which the heat is collectively released by concentrating the heat on the metal core.

Although the light emitting diode of FIG. 6 has the dome-shaped cover 201b, the shape of the light emitting diode is not limited thereto, and may be an inversely tapered shape, or a plurality of light emitting diodes may be covered with resin. An example of a light-emitting diode that can be applied to the present invention is shown in FIG.

A light-emitting diode in FIG. 18A has a structure in which a light-emitting element 400 is covered with a cover 401 including a phosphor 402. The cover 401 has a reverse taper shape, and a partition wall may be provided around the cover 401. Various emission colors can be obtained by combining the phosphor and the emission color of the light emitting element. Moreover, you may use several types as fluorescent substance.

The light-emitting diode in FIG. 18B has a structure in which the light-emitting element 410 is covered with a cover 411 having an uneven surface. Since the cover 411 has irregularities on the surface, the light emitted from the light emitting element 410 diffuses. The direction and amount of light diffusion can be controlled by the shape of the unevenness.

A light emitting diode in FIG. 18C has a structure in which a light emitting element 420 is covered with a stack of a cover 422 and a cover 421. The cover 422 may be provided for light diffusion or may be provided as a protective film for the light emitting element. As described above, a plurality of covers of the light emitting elements may be stacked.

The light-emitting diode in FIG. 18D has a structure in which the light-emitting elements 430a, 430b, and 430c are covered with a cover 431. In this manner, a plurality of light emitting elements may be covered with the same cover. For example, a light emitting element 430a that is a red light emitting diode, a light emitting element 430b that is a green light emitting diode, and a light emitting element 430c that is a blue light emitting diode may be combined and covered with the same cover. The cover portion in the light emitting diode may be provided so as to surround the periphery without being in direct contact with the light emitting element, or the resin may be formed as a film in direct contact with the light emitting element. Further, as shown in FIG. 18A, the covers 411, 421, 422, and 431 may also contain phosphors and other diffusing substances.

An example of an operation mechanism of the display device of this embodiment will be described with reference to a block diagram of FIG. The liquid crystal display device 250 includes a liquid crystal display panel module 241 including a liquid crystal display panel 231 and a liquid crystal display panel drive circuit 232, a backlight unit 230, a temperature sensor 221 in the backlight unit region, a temperature controller 222, and a thermoelectric element drive circuit 223. A backlight module 242 including a color sensor 220, a light emitting diode control device 224, and a light emitting diode driving circuit 225, and a thermoelectric module 226.

The light emitting diode driving circuit 225 causes the light emitting diode in the backlight unit 230 to emit light, and the color sensor 220 provided in the backlight unit emits light in various unique colors (for example, red light emitting diode, green light emitting). Each of the diodes and the blue light emitting diodes) is monitored for a predetermined output, information is fed back to the light emitting diode control device 224 and output to the light emitting diode driving circuit 225.

In addition, the temperature of the backlight unit 230 is measured by the temperature sensor 221 provided in the backlight unit region, and the heat generation state of the light emitting diode is monitored. When the light emitting diode is outside a predetermined temperature (above or below), the thermoelectric element is driven by the thermoelectric element driving circuit 223 to cool or heat the light emitting diode, and the light emitting diode is outside the temperature range (high temperature or low temperature). The temperature controller 222 controls the temperature so that it is not driven at this time.

Further, the thermoelectric module 226 is provided in the liquid crystal display device, and the temperature difference in the liquid crystal display device can be used to drive other light emitting diodes and thermoelectric elements. In the present invention, since a thermoelectric element that can be efficiently cooled and heated is provided in a housing, a desired temperature difference is easily obtained in a liquid crystal display device. The thermoelectric module 226 may be provided anywhere in the liquid crystal display device. The thermoelectric module 226 may be provided in either the liquid crystal display panel module region or the backlight module region, and may be provided across both regions. Further, a structure provided separately from the liquid crystal display device may be employed. A plurality of thermoelectric modules, color sensors, and temperature sensors may be provided. If a plurality of color sensors and temperature sensors are provided, monitoring can be performed more accurately.

Further, as shown in FIG. 8, the liquid crystal display panel module 241 may also be provided with a thermoelectric element. In this case, a temperature sensor 233, a temperature controller 234, and a thermoelectric element driving circuit 235 in the liquid crystal display panel region are provided. Further, the temperature sensor 233 provided in the liquid crystal display panel region measures and monitors the temperature of the liquid crystal display panel 231. When the liquid crystal display panel 231 is outside a predetermined temperature (above or below), the thermoelectric element is driven by the thermoelectric element drive circuit 235 provided in the liquid crystal display panel 231 to cool or heat the liquid crystal display panel 231, Temperature control is performed by the temperature controller 234 so that the liquid crystal display panel 231 is within a predetermined temperature range.

FIG. 8 shows a structure in which thermoelectric element driving circuits 235 and 223 are independently provided in the backlight unit region and the liquid crystal display panel region. The thermoelectric element driving circuit can be operated in conjunction, the thermoelectric element driving circuit 235 is operated to heat the thermoelectric element, and the thermoelectric element driving circuit 223 is operated to cool the thermoelectric element at the same time. It can also be operated differently.

FIG. 9 shows an example in which the thermoelectric elements in the liquid crystal display panel module 241 and the backlight module 242 are driven by a common thermoelectric element driving circuit 243. When the thermoelectric element driving circuit is provided in common as shown in FIG. 9, there is an advantage that the liquid crystal display device can be thinned and the cost can be reduced.

By using the present invention, heat generation of the light-emitting diode used for the light source can be suppressed, so that the lifetime of the light-emitting diode, the luminance, and the chromaticity shift can be suppressed. By suppressing the heat generation of the light source, deformation and alteration of the diffusion film, the reflection film, and the prism film can be suppressed.

In addition, it is possible to suppress changes in characteristics such as response speed, contrast, and color unevenness of liquid crystal display panels, and deformation, alteration, and characteristics of polarizing films, viewing angle expansion films, retardation films, etc. used in liquid crystal display panels Decrease etc. can also be suppressed. Further, since a heat sink, a heat pipe, a cooling fan and the like are not required, the thickness of the backlight device can be reduced.

Therefore, according to the present invention, a highly reliable backlight device with less color unevenness and luminance unevenness and the like, and a high-performance image display device having the backlight device with high reliability and high image quality. A display device can be manufactured.

(Embodiment 3)
In this embodiment, a liquid crystal display device including a backlight device of the present invention and using a thin film transistor having a crystalline semiconductor film will be described.

FIG. 16A is a top view illustrating a structure of a display panel according to the present invention. A pixel portion 2701 in which pixels 2702 are arranged in a matrix over a substrate 2700 having an insulating surface, a scan line side input terminal 2703, a signal A line side input terminal 2704 is formed. The number of pixels may be provided in accordance with various standards. For full color display using XGA and RGB, 1024 × 768 × 3 (RGB), and for full color display using UXGA and RGB, 1600 × 1200. If it corresponds to x3 (RGB) and full spec high vision and is full color display using RGB, it may be 1920 x 1080 x 3 (RGB).

The pixels 2702 are arranged in a matrix by a scan line extending from the scan line side input terminal 2703 and a signal line extending from the signal line side input terminal 2704 intersecting. Each pixel of the pixel portion 2701 is provided with a switching element and a pixel electrode layer connected to the switching element. A typical example of a switching element is a TFT. By connecting the gate electrode layer side of the TFT to a scanning line and the source or drain side to a signal line, each pixel can be controlled independently by a signal input from the outside. It is said.

FIG. 16A illustrates a structure of a display panel in which signals input to the scan lines and the signal lines are controlled by an external driver circuit. As illustrated in FIG. 17A, COG (Chip on The driver IC 2751 may be mounted on the substrate 2700 by a glass method. As another mounting mode, a TAB (Tape Automated Bonding) method as shown in FIG. 17B may be used. The driver IC may be formed on a single crystal semiconductor substrate or may be a circuit in which a TFT is formed on a glass substrate. In FIG. 17, the driver IC 2751 is connected to an FPC (Flexible printed circuit) 2750.

In the case where the TFT provided for the pixel is formed using a crystalline semiconductor, the scan line driver circuit 3702 can be formed over the substrate 3700 as shown in FIG. In FIG. 16B, the pixel portion 3701 is controlled by an external driver circuit as in FIG. 16A connected to the signal line side input terminal 3704. In the case where a TFT provided for a pixel is formed using a polycrystalline (microcrystalline) semiconductor, a single crystal semiconductor, or the like with high mobility, as illustrated in FIG. 16C, a pixel portion 4701, a scan line driver circuit 4702, and a signal The line driver circuit 4704 can be formed over the substrate 4700 integrally.

FIG. 23 is a top view of a liquid crystal display device including the backlight unit of the present invention, and FIG. 14 is a cross-sectional view taken along line CD in FIG.

As shown in FIGS. 23 and 14, a pixel region 606, a driving circuit region 608a which is a scanning line driving circuit, and a driving circuit region 608b which is a scanning line driving region are formed between a substrate 600 and a counter substrate 695 by a sealant 692. A driving circuit region 607 which is a signal line driving circuit which is sealed in between and formed on the substrate 600 by an IC driver is provided. A transistor 622 and a capacitor 623 are provided in the pixel region 606, and a driver circuit including a transistor 620 and a transistor 621 is provided in the driver circuit region 608b.

The substrate 600 and the counter substrate 695 are light-transmitting insulating substrates (hereinafter also referred to as light-transmitting substrates). In particular, it has translucency in the wavelength region of visible light. For example, a glass substrate such as barium borosilicate glass or alumino borosilicate glass, a quartz substrate, or the like can be used. In addition, a substrate made of plastics typified by polyethylene-terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polycarbonate (PC), or flexible synthetic resin such as acrylic is applied. can do. In addition, a film (made of polypropylene, polyester, vinyl, polyvinyl fluoride, vinyl chloride, or the like), a base film (polyester, polyamide, inorganic vapor deposition film, or the like) can also be used. In general, substrates made of synthetic resin have a concern that the heat-resistant temperature is lower than other substrates, but they can also be adopted by transposing after a manufacturing process using a substrate with high heat resistance. Is possible.

In the pixel region 606, a transistor 622 serving as a switching element is provided over the substrate 600 with the base film 604a and the base film 604b interposed therebetween. In this embodiment, a multi-gate thin film transistor (TFT) is used for the transistor 622, a semiconductor layer having an impurity region functioning as a source region and a drain region, a gate insulating layer, a gate electrode layer having a two-layer structure, a source An electrode layer and a drain electrode layer are included, and the source electrode layer or the drain electrode layer is in contact with and electrically connected to the impurity region of the semiconductor layer and the pixel electrode layer 630. Thin film transistors can be manufactured by a number of methods. For example, a crystalline semiconductor film is applied as the active layer. A gate electrode is provided over the crystalline semiconductor film with a gate insulating film interposed therebetween. An impurity element can be added to the active layer using the gate electrode. Thus, it is not necessary to form a mask for adding the impurity element by adding the impurity element using the gate electrode. The gate electrode can have a single-layer structure or a stacked structure. The impurity region can be a high concentration impurity region and a low concentration impurity region by controlling the concentration thereof. A thin film transistor having such a low concentration impurity region is referred to as an LDD (Light Doped Drain) structure. The low-concentration impurity region can be formed so as to overlap with the gate electrode. Such a thin film transistor is referred to as a GOLD (Gate Overlapped LDD) structure. The polarity of the thin film transistor is n-type by using phosphorus (P) or the like in the impurity region. When p-type is used, boron (B) or the like may be added. After that, an insulating film 611 and an insulating film 612 that cover the gate electrode and the like are formed. A dangling bond in the crystalline semiconductor film can be terminated by a hydrogen element mixed in the insulating film 611 (and the insulating film 612).

In order to further improve flatness, an insulating film 615 and an insulating film 616 may be formed as interlayer insulating films. For the insulating films 615 and 616, an organic material, an inorganic material, or a stacked structure thereof can be used. For example, silicon oxide, silicon nitride, silicon oxynitride, silicon nitride oxide, aluminum nitride, aluminum oxynitride, aluminum nitride oxide or aluminum oxide whose nitrogen content is higher than oxygen content, diamond like carbon (DLC), polysilazane, nitrogen content It can be formed of a material selected from carbon (CN), PSG (phosphorus glass), BPSG (phosphorus boron glass), alumina, and other inorganic insulating materials. An organic insulating material may be used, and the organic material may be either photosensitive or non-photosensitive, and polyimide, acrylic, polyamide, polyimide amide, resist, benzocyclobutene, siloxane resin, or the like can be used. . Note that a siloxane resin corresponds to a resin including a Si—O—Si bond. Siloxane has a skeleton structure formed of a bond of silicon (Si) and oxygen (O). As a substituent, an organic group containing at least hydrogen (for example, an alkyl group or an aromatic hydrocarbon) is used. A fluoro group may be used as a substituent. Alternatively, an organic group containing at least hydrogen and a fluoro group may be used as a substituent.
The

In addition, by using a crystalline semiconductor film, the pixel region and the driver circuit region can be formed over the same substrate. In that case, the transistor in the pixel portion and the transistor in the driver circuit region 608b are formed at the same time. Transistors used for the driver circuit region 608b constitute a CMOS circuit. Although the thin film transistor included in the CMOS circuit has a GOLD structure, an LDD structure such as the transistor 622 can also be used.

Without being limited to this embodiment mode, the thin film transistor in the pixel region may have a single gate structure in which one channel formation region is formed, a double gate structure in which two channel formation regions are formed, or a triple gate structure in which three channel formation regions are formed. . The thin film transistor in the peripheral driver circuit region may have a single gate structure, a double gate structure, or a triple gate structure.

Note that not only the method for manufacturing the thin film transistor described in this embodiment mode, but a top gate type (for example, a forward staggered type), a bottom gate type (for example, an inverted staggered type), or a gate insulating film above and below a channel region is used. The present invention can also be applied to a dual gate type or other structure having two gate electrode layers arranged.

Next, an insulating layer 631 called an alignment film is formed by a printing method or a droplet discharge method so as to cover the pixel electrode layer 630 and the insulating film 616. Note that the insulating layer 631 can be selectively formed by a screen printing method or an offset printing method. Thereafter, a rubbing process is performed. This rubbing process may not be performed in the liquid crystal mode, for example, the VA mode. The insulating layer 633 functioning as an alignment film is similar to the insulating layer 631. Subsequently, a sealant 692 is formed in a peripheral region where pixels are formed by a droplet discharge method.

After that, a counter substrate 695 provided with an insulating layer 633 functioning as an alignment film, a conductive layer 634 functioning as a counter electrode, a colored layer 635 functioning as a color filter, and a substrate 600 which is a TFT substrate are interposed through a spacer 637. The liquid crystal layer 632 is provided in the gap by bonding. After that, a polarizing plate 641 is provided outside the counter substrate 695, and a polarizing plate 643 is also provided on the side opposite to the surface having the elements of the substrate 600. The polarizing plate can be provided on the substrate with an adhesive layer. Further, a retardation plate may be provided between the polarizing plate and the substrate. A filler may be mixed in the sealing material, and a shielding film (black matrix) or the like may be formed on the counter substrate 695. Note that the color filter or the like may be formed from a material exhibiting red (R), green (G), and blue (B) when the liquid crystal display device is set to full color display. It may be formed of a material that eliminates or exhibits at least one color.

Note that a color filter may not be provided when an RGB light-emitting diode (LED) or the like is disposed in the backlight device and a continuous additive color mixing method (field sequential method) that displays colors by time division is employed. The black matrix is preferably provided so as to overlap with the transistor or the CMOS circuit in order to reduce reflection of external light due to the wiring of the transistor or the CMOS circuit. Note that the black matrix may be formed so as to overlap with the capacitor. This is because reflection by the metal film constituting the capacitor element can be prevented.

As a method for forming the liquid crystal layer, a dispenser method (a dropping method) or an injection method in which liquid crystal is injected using a capillary phenomenon after the substrate 600 having an element and the counter substrate 695 are bonded to each other can be used. The dropping method is preferably applied when handling a large substrate to which the injection method is difficult to apply.

The spacer may be provided by spraying particles of several μm, but in this embodiment, a method of forming a resin film on the entire surface of the substrate and then etching it is employed. After applying such a spacer material with a spinner, it is formed into a predetermined pattern by exposure and development processing. Further, it is cured by heating at 150 to 200 ° C. in a clean oven or the like. The spacers produced in this way can have different shapes depending on the conditions of exposure and development processing, but preferably, the spacers are columnar and the top is flat, so that the opposite substrate is When combined, the mechanical strength of the liquid crystal display device can be ensured. The shape can be a conical shape, a pyramid shape, or the like, and there is no particular limitation.

Subsequently, an FPC 694 that is a wiring board for connection is provided on the terminal electrode layer 678 electrically connected to the pixel region with an anisotropic conductive layer 696 interposed therebetween. The FPC 694 plays a role of transmitting an external signal or potential. Through the above steps, a liquid crystal display device having a display function can be manufactured.

Note that a wiring included in the transistor, a gate electrode layer, a pixel electrode layer 630, and a conductive layer 634 which is a counter electrode layer include indium tin oxide (ITO), indium oxide and zinc oxide (ZnO) mixed in IZO (indium zinc oxide). Indium oxide mixed with silicon oxide (SiO ₂ ), indium oxide, organic tin, indium oxide containing tungsten oxide, indium zinc oxide containing tungsten oxide, indium oxide containing titanium oxide, titanium oxide For example, indium tin oxide can be used. Also, tungsten (W), molybdenum (Mo), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), cobalt (Co), nickel (Ni ), Titanium (Ti), platinum (Pt), aluminum (Al), copper (Cu), silver (Ag), or the like, or an alloy thereof, or a metal nitride thereof.

The backlight unit included in the display device illustrated in FIG. 14 includes a light emitting diode 651, a housing 650 including a thermoelectric element, a reflection sheet 652, a light guide plate 653, a diffusion plate 654, a prism sheet 655, and a color sensor 656.

In the present embodiment, a light emitting diode is used as a light source of a backlight device, and a thermoelectric element is provided in a casing that holds the light emitting diode so as to surround the light emitting diode (under and around the light emitting diode). The temperature in the backlight device is adjusted by cooling and heating the thermoelectric element. A thermoelectric element is a metal or semiconductor element that converts heat energy into electric energy using a phenomenon related to heat and electricity. Examples of thermoelectric elements that can be used in the present invention include Peltier elements. .

The light emission of the light emitting diode causes a temperature change in the backlight device. A temperature sensor for monitoring the temperature state is provided in the backlight device, and cooling or heating is performed by the thermoelectric element by a drive circuit that operates the thermoelectric element, and temperature control is performed by a temperature controller. Further, a color sensor for monitoring the output of the light emitting diode is provided, and the output of the light emitting diode is controlled by a light emitting diode control device that controls the output of the light emitting diode, and the light emitting diode is driven by the light emitting diode driving circuit.

A transmissive liquid crystal display panel module provided in front of the backlight device also has a thermoelectric element for heating and cooling the liquid crystal display panel, a drive circuit for operating the thermoelectric element, and a temperature state of the (color) liquid crystal display panel. A temperature sensor that performs temperature control and a temperature controller that performs temperature control may be included.

The thermoelectric element provided on the backlight device side and the thermoelectric element provided on the liquid crystal display panel module side may each have a temperature sensor and a temperature controller, and may be operated independently, or may be operated in common. Good.

The backlight device and the liquid crystal display panel module may be provided in contact with each other, or may be disposed with a space therebetween. When the liquid crystal display panel module and the backlight device are provided in contact with each other, and the thermoelectric element provided on the backlight device side is in contact with the liquid crystal display panel module, the temperature of the liquid crystal display panel module can also be controlled by cooling and heating the thermoelectric element. it can.

Further, a thermoelectric module is provided in the liquid crystal display device, and the temperature difference in the liquid crystal display device can be used to drive other light emitting diodes, thermoelectric elements, and the like. In the present invention, since a thermoelectric element that can be efficiently cooled and heated is provided in a housing, a desired temperature difference is easily obtained in a liquid crystal display device.

By using the present invention, heat generation of the light-emitting diode used for the light source can be suppressed, so that the lifetime of the light-emitting diode, the luminance, and the chromaticity shift can be suppressed. By suppressing the heat generation of the light source, deformation and alteration of the diffusion film, the reflection film, and the prism film can be suppressed.

In addition, it is possible to suppress changes in characteristics such as response speed, contrast, and color unevenness of liquid crystal display panels, and deformation, alteration, and characteristics of polarizing films, viewing angle expansion films, retardation films, etc. used in liquid crystal display panels Decrease etc. can also be suppressed. Further, since a heat sink, a heat pipe, a cooling fan and the like are not required, the thickness of the backlight device can be reduced.

Therefore, according to the present invention, a highly reliable backlight device with less color unevenness and luminance unevenness and the like, and a high-performance image display device having the backlight device with high reliability and high image quality. A display device can be manufactured.

This embodiment mode can be freely combined with the above embodiment modes.

(Embodiment 4)
In this embodiment mode, a liquid crystal display device including a backlight device of the present invention and using a thin film transistor having an amorphous semiconductor film will be described.

In the display device illustrated in FIG. 15, a transistor 320 which is an inverted staggered thin film transistor, a pixel electrode layer 301, an insulating layer 302, an insulating layer 303, a liquid crystal layer 304, a spacer 381, an insulating layer 305, An electrode layer 306, a color filter 308, a black matrix 307, a counter substrate 310, a polarizing plate 331, a polarizing plate 333, a sealing material 382, a terminal electrode layer 387, an anisotropic conductive layer 385, and an FPC 386 are provided in a sealing region. .

A gate electrode layer, a source electrode layer, and a drain electrode layer of the transistor 320 which is an inverted staggered thin film transistor manufactured in this embodiment are formed by a droplet discharge method. The droplet discharge method is a method in which a composition having a liquid conductive material is discharged and solidified by drying or baking to form a conductive layer or an electrode layer. An insulating layer can also be formed by discharging a composition containing an insulating material and solidifying it by drying or baking. Since a structure of the display device such as a conductive layer or an insulating layer can be formed selectively, the process can be simplified and material loss can be prevented, so that the display device can be manufactured with low cost and high productivity.

In this embodiment mode, an amorphous semiconductor is used as a semiconductor layer, and a semiconductor layer having one conductivity type may be formed as needed. In this embodiment mode, an amorphous n-type semiconductor layer is stacked as a semiconductor layer and a semiconductor layer having one conductivity type. In addition, an n-type semiconductor layer is formed, an NMOS structure of an n-channel thin film transistor, a PMOS structure of a p-channel thin film transistor in which a p-type semiconductor layer is formed, and a CMOS structure of an n-channel thin film transistor and a p-channel thin film transistor. it can.

In order to impart conductivity, an element imparting conductivity is added by doping, and an impurity region is formed in the semiconductor layer, whereby an n-channel thin film transistor or a P-channel thin film transistor can be formed. Instead of forming the n-type semiconductor layer, conductivity may be imparted to the semiconductor layer by performing plasma treatment with PH ₃ gas.

In this embodiment, the transistor 320 is an n-channel inverted staggered thin film transistor. Alternatively, a channel-protective inverted staggered thin film transistor in which a protective layer is provided over the channel region of the semiconductor layer can be used.

Alternatively, an organic semiconductor material can be used as a semiconductor, and a semiconductor layer can be formed by an evaporation method, a printing method, a spray method, a spin coating method, a droplet discharge method, a dispenser method, or the like. In this case, since the etching process is not necessarily required, the number of processes can be reduced. As the organic semiconductor, a low molecular material such as pentacene, a polymer material, or the like is used, and materials such as an organic dye or a conductive polymer material can also be used. The organic semiconductor material used in the present invention is preferably a π-electron conjugated polymer material whose skeleton is composed of conjugated double bonds. Typically, a polymer material that is soluble in a liquid such as polythiophene, polyfluorene, poly (3-alkylthiophene), or a polythiophene derivative can be used.

The backlight unit included in the display device illustrated in FIG. 15 includes a light emitting diode 351, a casing 350 including a thermoelectric element, a reflection sheet 352, a light guide plate 353, a diffusion plate 354, a prism sheet 355, and a color sensor 356.

In the present embodiment, a light emitting diode is used as a light source of a backlight device, and a thermoelectric element is provided in a casing that holds the light emitting diode so as to surround the light emitting diode (under and around the light emitting diode). The temperature in the backlight device is adjusted by cooling and heating the thermoelectric element. A thermoelectric element is a metal or semiconductor element that converts heat energy into electric energy using a phenomenon related to heat and electricity. Examples of thermoelectric elements that can be used in the present invention include Peltier elements. .

The light emission of the light emitting diode causes a temperature change in the backlight device. A temperature sensor for monitoring the temperature state is provided in the backlight device, and cooling or heating is performed by the thermoelectric element by a drive circuit that operates the thermoelectric element, and temperature control is performed by a temperature controller. Further, a color sensor for monitoring the output of the light emitting diode is provided, and the output of the light emitting diode is controlled by a light emitting diode control device that controls the output of the light emitting diode, and the light emitting diode is driven by the light emitting diode driving circuit.

The transmissive liquid crystal display panel module provided on the front surface of the backlight device also includes a thermoelectric element for heating and cooling the liquid crystal display panel, a drive circuit for operating the thermoelectric element, and a temperature state of the (color) liquid crystal display panel. A temperature sensor for monitoring and a temperature controller for controlling temperature may be included.

The thermoelectric element provided on the backlight device side and the thermoelectric element provided on the liquid crystal display panel module side each have a temperature sensor and a temperature controller, and may be operated independently, or may be operated in common and simultaneously. .

The backlight device and the liquid crystal display panel module may be provided in contact with each other, or may be disposed with a space therebetween. When the liquid crystal display panel module and the backlight device are provided in contact with each other, and the thermoelectric element provided on the backlight device side is in contact with the liquid crystal display panel module, the temperature of the liquid crystal display panel module can also be controlled by cooling and heating the thermoelectric element. it can.

Further, a thermoelectric module is provided in the liquid crystal display device, and the temperature difference in the liquid crystal display device can be used to drive other light emitting diodes, thermoelectric elements, and the like. In the present invention, since a thermoelectric element that can be efficiently cooled and heated is provided in a housing, a desired temperature difference is easily obtained in a liquid crystal display device.

By using the present invention, heat generation of the light-emitting diode used for the light source can be suppressed, so that the lifetime of the light-emitting diode, the luminance, and the chromaticity shift can be suppressed. By suppressing the heat generation of the light source, deformation and alteration of the diffusion film, the reflection film, and the prism film can be suppressed.

In addition, it is possible to suppress changes in characteristics such as response speed, contrast, and color unevenness of liquid crystal display panels, and deformation, alteration, and characteristics of polarizing films, viewing angle expansion films, retardation films, etc. used in liquid crystal display panels Decrease etc. can also be suppressed. Further, since a heat sink, a heat pipe, a cooling fan and the like are not required, the thickness of the backlight device can be reduced.

Therefore, according to the present invention, a highly reliable backlight device with less color unevenness and luminance unevenness and the like, and a high-performance image display device having the backlight device with high reliability and high image quality. A display device can be manufactured.

This embodiment mode can be freely combined with the above embodiment modes.

(Embodiment 5)
In this embodiment mode, another structure example of a backlight device using the present invention and a display device including the backlight device will be described.

The backlight device of the present invention can be a side light system (also referred to as an edge light system) as shown in FIGS.

The display device in FIG. 25A includes a liquid crystal display panel module 459, a housing 450 including a thermoelectric element, light emitting diodes 451a and 451b, reflection sheets 452a, 452b and 452c, a diffusion plate 454, and a prism sheet 455. The light emitting diodes 451a and 451b are provided on the side portion of the housing 450 including the thermoelectric element. The reflection sheets 452a, 452b, and 452c reflect the light emitted from the light emitting diodes 451a and 451b and emit the light toward the liquid crystal display panel module. The reflection sheet 452a has a convex portion at the center so as to reflect light so that light can be efficiently propagated into the backlight device.

The display device in FIG. 25B includes a liquid crystal display panel module 479, a housing 470 including a thermoelectric element, light emitting diodes 471a and 471b, a light guide plate 473, a diffusion plate 474, and a prism sheet 475. The light emitting diodes 471a and 471b are provided on a side portion of the housing 470 including a thermoelectric element. The light guide plate 473 propagates the light emitted from the light emitting diodes 471a and 471b into the backlight device and radiates it to the liquid crystal display panel module side.

25C includes a liquid crystal display panel module 469, a housing 460 including a thermoelectric element, a light emitting diode 461, reflection sheets 462a, 462b, 462c, and 462d, light guide plates 463a and 463b, a diffusion plate 464, and a prism sheet. 465. The light emitting diode 461 is provided at the bottom of the housing 460 including the thermoelectric element. The reflection sheets 462a and 462b reflect the light emitted from the light emitting diode 461 and propagate to the light guide plate 463a. Light propagating through the light guide plate 463a is reflected by the reflection sheet 462c, propagates to the light guide plate 463b, and is radiated to the liquid crystal display panel module side by the reflection sheet 462d.

As the plurality of light emitting diodes used in the present invention, light emitting diodes that emit light having different light emission colors can be used, and for example, red light emitting diodes, green light emitting diodes, and blue light emitting diodes can be included. More specifically, the plurality of light emitting diodes includes a first light emitting diode having a peak of the emission color wavelength of 625 nm ± 10 nm, a second light emitting diode having a peak of the wavelength of emission color of 530 nm ± 15 nm, and 455 nm ± A third light emitting diode having a peak of the emission color wavelength of 10 nm can be included.

In this embodiment, a light-emitting diode is used as a light source of a backlight device, and a thermoelectric element is provided around a light-emitting diode in a casing that holds the light-emitting diode. Adjust the temperature inside the unit. A thermoelectric element is a metal or semiconductor element that converts heat energy into electric energy using a phenomenon related to heat and electricity. Examples of thermoelectric elements that can be used in the present invention include Peltier elements. .

The light emission of the light emitting diode causes a temperature change in the backlight device. A temperature sensor for monitoring the temperature state is provided in the backlight device, and cooling or heating is performed by the thermoelectric element by a drive circuit that operates the thermoelectric element, and temperature control is performed by a temperature controller. Further, a color sensor for monitoring the output of the light emitting diode is provided, and the output of the light emitting diode is controlled by a light emitting diode control device that controls the output of the light emitting diode, and the light emitting diode is driven by the light emitting diode driving circuit.

The transmissive liquid crystal display panel module provided on the front surface of the backlight device also includes a thermoelectric element for heating and cooling the liquid crystal display panel, a drive circuit for operating the thermoelectric element, and a temperature state of the (color) liquid crystal display panel. A temperature sensor for monitoring and a temperature controller for controlling temperature may be included.

The thermoelectric element provided on the backlight device side and the thermoelectric element provided on the liquid crystal display panel module side may each have a temperature sensor and a temperature controller, and may be operated independently, or may be operated in common. Good.

The backlight device and the liquid crystal display panel module may be provided in contact with each other, or may be disposed with a space therebetween. When the liquid crystal display panel module and the backlight device are provided in contact with each other, and the thermoelectric element provided on the backlight device side is in contact with the liquid crystal display panel module, the temperature of the liquid crystal display panel module can also be controlled by cooling and heating the thermoelectric element. it can.

Further, a thermoelectric module is provided in the liquid crystal display device, and the temperature difference in the liquid crystal display device can be used to drive other light emitting diodes, thermoelectric elements, and the like. In the present invention, since a thermoelectric element that can be efficiently cooled and heated is provided in a housing, a desired temperature difference is easily obtained in a liquid crystal display device.

By using the present invention, heat generation of the light-emitting diode used for the light source can be suppressed, so that the lifetime of the light-emitting diode, the luminance, and the chromaticity shift can be suppressed. By suppressing the heat generation of the light source, deformation and alteration of the diffusion film, the reflection film, and the prism film can be suppressed.

In addition, it is possible to suppress changes in characteristics such as response speed, contrast, and color unevenness of liquid crystal display panels, and deformation, alteration, and characteristics of polarizing films, viewing angle expansion films, retardation films, etc. used in liquid crystal display panels Decrease etc. can also be suppressed. Further, since a heat sink, a heat pipe, a cooling fan and the like are not required, the thickness of the backlight device can be reduced.

Therefore, according to the present invention, a highly reliable backlight device with less color unevenness and luminance unevenness and the like, and a high-performance image display device having the backlight device with high reliability and high image quality. A display device can be manufactured.

This embodiment mode can be freely combined with the above embodiment modes.

(Embodiment 6)
In this embodiment mode, operations of circuits and the like included in the display device are described.

FIG. 19 is a system block diagram of the pixel portion 505 and the driver circuit portion 508 of the display device.

The pixel portion 505 includes a plurality of pixels, and a switching element is provided in an intersection region between the signal line 512 serving as each pixel and the scanning line 510. Application of a voltage for controlling the tilt of liquid crystal molecules can be controlled by the switching element. A structure in which switching elements are provided in each intersection region in this way is called an active type. The pixel portion of the present invention is not limited to such an active type, and may have a passive configuration. Since the passive type has no switching element in each pixel, the process is simple.

The driver circuit portion 508 includes a control circuit 502, a signal line driver circuit 503, and a scanning line driver circuit 504. The control circuit 502 to which the video signal 501 is input has a function of performing gradation control according to the display content of the pixel portion 505. Therefore, the control circuit 502 inputs the generated signal to the signal line driver circuit 503 and the scan line driver circuit 504. When a switching element is selected via the scanning line 510 based on the scanning line driving circuit 504, a voltage is applied to the pixel electrode in the selected intersection region. The value of this voltage is determined based on a signal input from the signal line driver circuit 503 via the signal line.

Further, the control circuit 502 generates a signal for controlling the power supplied to the lighting unit 506, and the signal is input to the power source 507 of the lighting unit 506. The backlight unit described in the above embodiment can be used as the illumination unit. In addition to the backlight device, the illumination means includes a front light. The front light is a plate-like light unit that is mounted on the front side of the pixel portion and is composed of a light emitter and a light guide that illuminate the whole. Such illumination means can illuminate the pixel portion evenly with low power consumption.

As illustrated in FIG. 19B, the scan line driver circuit 504 includes circuits that function as a shift register 541, a level shifter 542, and a buffer 543. Signals such as a gate start pulse (GSP) and a gate clock signal (GCK) are input to the shift register 541. Note that the scan line driver circuit of the present invention is not limited to the structure shown in FIG.

As shown in FIG. 19C, the signal line driver circuit 503 includes circuits that function as a shift register 531, a first latch 532, a second latch 533, a level shifter 534, and a buffer 535. The circuit functioning as the buffer 535 is a circuit having a function of amplifying a weak signal and includes an operational amplifier or the like. A signal such as a start pulse (SSP) is input to the level shifter 534, and data (DATA) such as a video signal is input to the first latch 532. A latch (LAT) signal can be temporarily held in the second latch 533 and is input to the pixel portion 505 all at once. This is called line sequential driving. Therefore, the second latch can be omitted if the pixel performs dot sequential driving instead of line sequential driving. As described above, the signal line driver circuit of the present invention is not limited to the structure shown in FIG.

The signal line driver circuit 503, the scan line driver circuit 504, and the pixel portion 505 can be formed using semiconductor elements provided over the same substrate. The semiconductor element can be formed using a thin film transistor provided over a glass substrate. In this case, a crystalline semiconductor film is preferably used for the semiconductor element (see Embodiment Mode 5). Since the crystalline semiconductor film has high electrical characteristics, particularly mobility, a circuit included in the driver circuit portion can be formed. In addition, the signal line driver circuit 503 and the scan line driver circuit 504 can be mounted on a substrate using an IC (Integrated Circuit) chip. In this case, an amorphous semiconductor film can be applied to the semiconductor element in the pixel portion (see Embodiment Mode 5).

In such a display device, a light emitting diode is used as a light source of the backlight device, and a thermoelectric element is provided in a casing that holds the light emitting diode so as to surround the light emitting diode (under and around the light emitting diode). The temperature inside the backlight device is adjusted by cooling and heating the thermoelectric elements. By using the present invention, heat generation of the light-emitting diode used for the light source can be suppressed, so that the lifetime of the light-emitting diode, the luminance, and the chromaticity shift can be suppressed. By suppressing the heat generation of the light source, deformation and alteration of the diffusion film, the reflection film, and the prism film can be suppressed.

In addition, it is possible to suppress changes in characteristics such as response speed, contrast, and color unevenness of liquid crystal display panels, and deformation, alteration, and characteristics of polarizing films, viewing angle expansion films, retardation films, etc. used in liquid crystal display panels Decrease etc. can also be suppressed. Further, since a heat sink, a heat pipe, a cooling fan and the like are not required, the thickness of the backlight device can be reduced.

Therefore, according to the present invention, a highly reliable backlight device with less color unevenness and luminance unevenness and the like, and a high-performance image display device having the backlight device with high reliability and high image quality. A display device can be manufactured.

(Embodiment 7)
With the display device formed according to the present invention, a television device (also simply referred to as a television or a television receiver) can be completed. FIG. 20 is a block diagram illustrating a main configuration of the television device. In the display panel, only the pixel portion 701 is formed in the display panel as shown in FIG. 16A, and the scan line driver circuit 703 and the signal line driver circuit 702 are replaced with a TAB as shown in FIG. A TFT is formed as shown in FIG. 16B, and a pixel portion 701 and a scan line driver circuit 703 are mounted on a substrate when mounted by a method, when mounted by a COG method as shown in FIG. When the signal line driver circuit 702 formed over is separately mounted as a driver IC, the pixel portion 701, the signal line driver circuit 702, and the scan line driver circuit 703 are integrally formed over the substrate as shown in FIG. There are cases, but any form is acceptable.

As other external circuit configurations, on the input side of the video signal, among the signals received by the tuner 704, the video signal amplification circuit 705 that amplifies the video signal, and the signals output from the video signal amplification circuit 705 are red, green, and blue colors. And a control circuit 707 for converting the video signal into the input specifications of the driver IC. The control circuit 707 outputs signals to the scanning line side and the signal line side, respectively. In the case of digital driving, a signal dividing circuit 708 may be provided on the signal line side and an input digital signal may be divided into m pieces and supplied.

Of the signals received by the tuner 704, the audio signal is sent to the audio signal amplification circuit 709, and the output is supplied to the speaker 713 through the audio signal processing circuit 710. The control circuit 711 receives the receiving station (reception frequency) and volume control information from the input unit 712, and sends a signal to the tuner 704 and the audio signal processing circuit 710.

As shown in FIGS. 21A, 21B, and 21C, these liquid crystal display panel modules can be incorporated into a housing to complete a television device. In FIG. 21A, a main screen 2003 is formed using a display module, and a speaker portion 2009, operation switches, and the like are provided as accessory equipment. Thus, a television device can be completed according to the present invention.

A display panel 2002 is incorporated in a housing 2001, and general television broadcasting is received by a receiver 2005, and connected to a wired or wireless communication network via a modem 2004 (one direction (from a sender to a receiver)). ) Or bi-directional (between the sender and the receiver, or between the receivers). The television device can be operated by a switch incorporated in the housing or a separate remote control device 2006, and the remote control device 2006 also includes a display unit 2007 for displaying information to be output. good.

In addition, the television device may have a configuration in which a sub screen 2008 is formed using the second display panel in addition to the main screen 2003 to display channels, volume, and the like. In this structure, the main screen 2003 and the sub screen 2008 can be formed using the liquid crystal display panel of the present invention, the main screen 2003 is formed using an EL display panel with an excellent viewing angle, and the sub screen can be manufactured with low power consumption. You may form with the liquid crystal display panel which can be displayed. In order to prioritize the reduction in power consumption, the main screen 2003 may be formed using a liquid crystal display panel, the sub screen may be formed using an EL display panel, and the sub screen may blink. When the present invention is used, a highly reliable display device can be obtained even when such a large substrate is used and a large number of TFTs and electronic components are used.

FIG. 21B illustrates a television device having a large display portion of 20 to 80 inches, for example, which includes a housing 2010, a keyboard portion 2012 that is an operation portion, a display portion 2011, a speaker portion 2013, and the like. The present invention is applied to manufacture of the display portion 2011. The display portion in FIG. 21B is a television device having a curved display portion because a bendable substance is used. Since the shape of the display portion can be freely designed as described above, a television device having a desired shape can be manufactured.

FIG. 21C illustrates a television device having a large display portion of 20 to 80 inches, for example, which includes a housing 2030, a display portion 2031, a remote control device 2032 that is an operation portion, a speaker portion 2033, and the like. The present invention is applied to manufacturing the display portion 2031. The television device in FIG. 21C is a wall-hanging type and does not require a large installation space.

Of course, the present invention is not limited to a television device, but can be applied to various uses such as a monitor for a personal computer, an information display board in a railway station or airport, an advertisement display board in a street, etc. can do.

(Embodiment 8)
As electronic devices according to the present invention, portable information such as a television device (also simply referred to as a television or a television receiver), a digital camera, a digital video camera, a cellular phone device (also simply referred to as a cellular phone or a cellular phone), a PDA, etc. Examples include a terminal, a portable game machine, a computer monitor, a computer, an audio playback device such as a car audio, and an image playback device including a recording medium such as a home game machine. A specific example will be described with reference to FIG.

A portable information terminal device illustrated in FIG. 22A includes a main body 9201, a display portion 9202, and the like. The display device of the present invention can be applied to the display portion 9202. As a result, a high-performance portable information terminal device that can display a high-quality image with high reliability can be provided.

A digital video camera shown in FIG. 22B includes a display portion 9701, a display portion 9702, and the like. The display device of the present invention can be applied to the display portion 9701. As a result, it is possible to provide a high-performance digital video camera that has high reliability and can display high-quality images.

A cellular phone shown in FIG. 22C includes a main body 9101, a display portion 9102, and the like. The display device of the present invention can be applied to the display portion 9102. As a result, a high-performance mobile phone that is highly reliable and can display high-quality images can be provided.

A portable television device shown in FIG. 22D includes a main body 9301, a display portion 9302, and the like. The display device of the present invention can be applied to the display portion 9302. As a result, a high-performance portable television device that can display a high-quality image with high reliability can be provided. In addition, the present invention can be applied to a wide variety of television devices, from a small one mounted on a portable terminal such as a cellular phone to a medium-sized one that can be carried and a large one (for example, 40 inches or more). The display device can be applied.

A portable computer shown in FIG. 22E includes a main body 9401, a display portion 9402, and the like. The display device of the present invention can be applied to the display portion 9402. As a result, a high-performance portable computer that can display a high-quality image with high reliability can be provided.

As described above, the display device of the present invention can provide a high-performance electronic device that can display a high-quality image with high reliability.

In this example, the characteristics of the light emitting diode used in the present invention were measured and evaluated. An experimental result is demonstrated using FIG.10, FIG12 and FIG.13.

The emission spectra of the RGB light emitting diodes were measured with a spectrophotometer capable of measuring the spectrum from ultraviolet to near infrared. The measurement results of the emission spectrum are shown in FIG. In FIG. 10, FIG. 10 (B) shows the result of emission spectrum using a light emitting diode emitting blue light, and FIG. 10 (A) shows bitumen instead of the blue light emitting diode used in FIG. 10 (B). It is an emission spectrum using a blue light emitting diode that emits light. 10A and 10B, the wavelength spectrum of the blue light emitting diode and the blue light emitting diode is indicated by a dotted line, the wavelength spectrum of the green light emitting diode is indicated by a solid line, and the wavelength spectrum of the red light emitting diode is indicated by a one-dot chain line.

When blue light emitting diodes are used, the peak position is shifted from 470 nm to 455 nm on the short wavelength side compared to when blue light emitting diodes are used, so that the area mixed with the spectrum of green light emitting diodes is reduced. Since the full width at half maximum was narrowed, it was confirmed that the color purity was higher and the color reproduction range was expanded.

As a light source, a cold cathode tube (also referred to as CCFL: Cold Cathode Fluorescent Lamp), an RGB light emitting diode using a blue light emitting diode, and an RGB light emitting diode backlight unit using a blue light emitting diode are driven. Adjust to the standard of NTSC chromaticity coordinates and measure the chromaticity of each RGB color with a color luminance meter when two types of film thickness filters (film thickness 1.7 μm, film thickness 2.5 μm) are mounted. Went. The measurement result of chromaticity coordinates is shown in FIG. In FIG. 12, the chromaticity coordinates of NTSC are indicated by solid lines, the RGB light emitting diodes including blue light emitting diodes are indicated by a one-dot chain line, the RGB light emitting diodes including blue light emitting diodes are indicated by fine dotted lines, and the chromaticity coordinates of CCFL are indicated by long dotted lines. Yes. 12A shows chromaticity coordinates when the film thickness of the color filter is 1.7 μm, and FIG. 12B shows chromaticity coordinates when the film thickness of the color filter is 2.5 μm. is there.

When the area of the NTSC chromaticity coordinates is 100%, 67 to 92% when a cold cathode tube is used, 72 to 101% when a blue light emitting diode is used, and 87 to 110 when a dark blue light emitting diode is used. %. Therefore, it was confirmed that the area of chromaticity coordinates can be widened by using a dark blue light emitting diode.

As described above, a backlight device using a light emitting diode as a light source can expand a color reproduction range. Therefore, by providing such a backlight device, a high-performance display device that can display higher-quality images can be manufactured.

In this example, the characteristics of the light emitting diode used in the present invention were measured and evaluated. An experimental result is demonstrated using FIG.

The back when the light emitting diode is turned on when the light emitting diode is not provided with a heat dissipation measure and when the light emitting diode is provided in the housing having the thermoelectric element using the present invention and the thermoelectric element is cooled. The temperature change in the light device was measured. Specifically, the temperature of the vicinity of the resin covering the back surface of the substrate (metal core substrate), the surface of the substrate (metal core substrate), and the light emitting diode was measured with a thermocouple. FIG. 11A shows the temperature change on the substrate surface with respect to time, FIG. 11B shows the temperature change on the back surface of the substrate, and FIG. 11C shows the temperature change near the resin covering the light emitting diode. In FIG. 11A to FIG. 11C, thin lines are those that have not been subjected to heat radiation countermeasures by thermoelectric elements, and thick lines are those that have been subjected to heat radiation countermeasures by thermoelectric elements. In this embodiment, a Peltier element is used as the thermoelectric element.

When heat dissipation measures are not taken, the substrate is 50 ° C (both on the back and front surfaces) and the vicinity of the light emitting diode (near the light emitting diode resin) is 60 ° C, whereas when using a Peltier device, the metal core substrate It was confirmed that the temperature at the time of use of the light emitting diode was low, that is, 20 ° C. on the back surface, 40 ° C. on the surface of the metal core substrate, and 45 ° C. near the light emitting diode (near the light emitting diode resin).

As described above, by using the present invention, heat generation of the light emitting diode used for the light source can be suppressed, so that the lifetime of the light emitting diode, the luminance, and the chromaticity shift can be suppressed. By suppressing the heat generation of the light source, deformation and alteration of the diffusion film, the reflection film, and the prism film can be suppressed.

In addition, it is possible to suppress changes in characteristics such as response speed, contrast, and color unevenness of liquid crystal display panels, and deformation, alteration, and characteristics of polarizing films, viewing angle expansion films, retardation films, etc. used in liquid crystal display panels Decrease etc. can also be suppressed. Further, since a heat sink, a heat pipe, a cooling fan and the like are not required, the thickness of the backlight device can be reduced.

Therefore, according to the present invention, a highly reliable backlight device with less color unevenness and luminance unevenness and the like, and a high-performance image display device having the backlight device with high reliability and high image quality. A display device can be manufactured.

In this example, the characteristics of a light emitting diode to which the present invention was applied were measured and evaluated. The experimental results will be described with reference to FIGS.

A light-emitting diode was provided in a housing having a thermoelectric element, and a temperature change in the backlight device was measured when the light-emitting diode was turned on when cooling by the thermoelectric element was performed. Specifically, the temperature near the resin covering the light emitting diode was measured with a thermocouple.

The samples are Sample A (A1 to A3) and Sample B (B1 to B3) having different arrangements of thermoelectric elements with respect to the light emitting diode. 27 and 28 show the configurations of Sample A and Sample B. FIG. 27 and 28, FIGS. 27A and 28A are top views, FIG. 27B is a cross-sectional view taken along line X1-Y1 in FIG. 27A, and FIG. FIG. 29 is a cross-sectional view taken along line X2-Y2 in FIG. The sample A has a structure in which the thermoelectric element 802 is provided only below the light emitting diode 801 in the housing 800, and the light emitting diode 801 is installed at the center of the housing 800 (see FIGS. 27A and 27B). .) The sample B has a structure in which thermoelectric elements 822b to 822e are provided in the housing 820 so as to surround the four sides of the light emitting diode 821 below the light emitting diode 821, and the light emitting diode 821 is connected to the thermoelectric element 822a. It is arranged near the thermoelectric elements 822b and 822e, not in the center of (see FIGS. 28A and 28B).

Sample A1 and Sample B1 are red light emitting diodes, Sample A2 and Sample B2 are green light emitting diodes, and Sample A3 and Sample B3 are blue (Royal Blue) light emitting diodes.

FIG. 26A shows the temperature change in the vicinity of the resin covering the light emitting diodes of the samples A1 and B1 showing red light emission with respect to time, and FIG. 26A shows the temperature change in the vicinity of the resin covering the light emitting diodes of the samples A2 and B2 showing blue light emission with respect to time. FIG. 26 (B) shows the temperature change in the vicinity of the resin covering the light emitting diodes of Samples A3 and B3 that exhibit green light emission with respect to time. In FIGS. 26A to 26C, sample A (A1, A2, A3) is indicated by a thin line, and sample B (B1, B2, B3) is indicated by a thick line. In Sample A and Sample B, Peltier elements were used as thermoelectric elements. In all the samples, 0.3 ampere (A) was passed through the light emitting diodes, and 2 ampere (A) was passed through the thermoelectric elements.

As shown in FIGS. 26 (A) to (C), B1 in which thermoelectric elements are provided on five sides so as to surround the light emitting diodes using the present invention, rather than A1 to A3 in which thermoelectric elements are provided only on the lower side of the light emitting diodes. Through B3, the temperature rise is suppressed. Therefore, it can be confirmed that the structure in which the thermoelectric element is provided so as to surround the light emitting diode as in the present invention has a high heat radiation effect with respect to the light emitting diode.

As described above, by using the present invention, heat generation of the light emitting diode used for the light source can be suppressed, so that the lifetime of the light emitting diode, the luminance, and the chromaticity shift can be suppressed. By suppressing the heat generation of the light source, deformation and alteration of the diffusion film, the reflection film, and the prism film can be suppressed.

In addition, it is possible to suppress changes in characteristics such as response speed, contrast, and color unevenness of liquid crystal display panels, and deformation, alteration, and characteristics of polarizing films, viewing angle expansion films, retardation films, etc. used in liquid crystal display panels Decrease etc. can also be suppressed. Further, since a heat sink, a heat pipe, a cooling fan and the like are not required, the thickness of the backlight device can be reduced.

Therefore, according to the present invention, a highly reliable backlight device with less color unevenness and luminance unevenness and the like, and a high-performance image display device having the backlight device with high reliability and high image quality. A display device can be manufactured.

It is the top view and sectional drawing which showed the display apparatus of this invention. It is the top view and sectional drawing which showed the display apparatus of this invention. It is the top view and sectional drawing which showed the display apparatus of this invention. It is the top view and sectional drawing which showed the display apparatus of this invention. It is the top view and sectional drawing which showed the display apparatus of this invention. It is the figure which showed the display apparatus of this invention. It is the block diagram which showed the display apparatus of this invention. It is the block diagram which showed the display apparatus of this invention. It is the block diagram which showed the display apparatus of this invention. 4 is a diagram showing experimental data of Example 1. FIG. 6 is a diagram showing experimental data of Example 2. FIG. 4 is a diagram showing experimental data of Example 1. FIG. 4 is a diagram showing experimental data of Example 1. FIG. It is sectional drawing which showed the display apparatus of this invention. It is sectional drawing which showed the display apparatus of this invention. It is the top view which showed the display apparatus of this invention. It is the top view which showed the display apparatus of this invention. It is sectional drawing which showed the light emitting diode which can be applied to this invention. It is the block diagram which showed the display apparatus of this invention. It is a block diagram which shows the main structures of the electronic device with which this invention is applied. It is the figure which showed the electronic device of this invention. It is the figure which showed the electronic device of this invention. It is the top view which showed the display apparatus of this invention. It is the top view and sectional drawing which showed the display apparatus of this invention. It is sectional drawing which showed the display apparatus of this invention. 6 is a diagram showing experimental data of Example 3. FIG. 6 is a diagram showing experimental conditions of Example 3. FIG. 6 is a diagram showing experimental conditions of Example 3. FIG.

Claims (2)

A housing having a thermoelectric element;
A plurality of light emitting diodes;
A display panel,
The housing has a shape having a bottom and a side,
The plurality of light emitting diodes are disposed above the bottom,
The plurality of light emitting diodes are disposed so as to be surrounded by the side portions,
The display panel is disposed above the plurality of light emitting diodes ,
Before Kikatamitai a display device characterized by having a portion in contact under the display panel. A housing having a thermoelectric element;
A plurality of light emitting diodes;
A display panel,
The housing has a shape having a bottom and a side,
The plurality of light emitting diodes are disposed above the bottom,
The plurality of light emitting diodes are disposed so as to be surrounded by the side portions,
The display panel is disposed above the plurality of light emitting diodes ,
Before Kikatamitai a display device characterized by having a portion in contact with on the display panel.

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