JP2007121597A - Liquid crystal display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display apparatus having a compact and inexpensive glass substrate without requiring a light source or the like to be mounted. <P>SOLUTION: An electric power/control signal supplied from an external driving circuit is supplied to an IC (integrated circuit) 22 mounted on an upper face of a lower glass substrate 26 through an upper side part 16 of an FPC (flexible printed circuit). A light source 12 is mounted not on the lower face of the lower glass substrate 26 but on the lower face of the lower side part 18 of the FPC branched from the upper side part 16 of the FPC, and the light source receives an electric power/control signal supplied from the external driving circuit through the part 18. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device.

  In general liquid crystal display devices, as described in Non-Patent Documents 1 to 3, a liquid crystal layer is sandwiched between a pair of glass substrates, and further sandwiched between a pair of polarizing plates. It has a structure in which a backlight is installed on the back. The backlight is mainly composed of a light source such as a light emitting diode (LED) or a fluorescent lamp (hot cathode tube or cold cathode tube), a light guide plate and a reflective sheet, and the light from the light source is used as a surface light source. Irradiate the polarizing plate on the side.

Conventionally, the light source is often installed on the lower surface of the lower glass substrate, and as described in Non-Patent Document 2, light from the light source is irradiated toward the light guide plate in the horizontal direction. Then, the light is irradiated to the lower polarizing plate as a surface light source by the reflection sheet exposed in the light reflecting dots provided on the light guide plate.
JP 2003-131222 A The Institute of Electronics, Information and Communication Engineers, “Encyclopedia Electronic Information Communication Handbook”, first edition, Ohm Co., Ltd., November 1998, p. 615 Hitachi, Ltd., “LCD-Backlight optical design technology for liquid crystal displays (display devices)-Comprehensive technology market i-engineering”, [online], 2002, [searched September 16, 2005], Internet <URL : Http://www.englink21.com/i-eng/guest/90pl0002.htm> Sharp Corporation, “Liquid Crystal Glossary”, [online], 2005, [searched on September 16, 2005], Internet <URL: http://www.sharp.co.jp/products/lcd/glossary/ file6.html # kana-ha-4>

  By the way, when the light source is mounted on the lower surface of the glass substrate on the lower side of the liquid crystal display device as described above, the conductive pattern for the light source for supplying power or a driving signal to the light source is routed from the lower surface of the glass substrate to the edge. Then, it must be extended to the upper surface and connected to an external drive circuit. In particular, when passing the edge of the glass substrate, a lead wire or the like is required, which causes troublesome handling.

  In general, a driver IC (Integrated Circuit) for driving a liquid crystal is mounted on the upper surface of the lower glass substrate. Therefore, the glass substrate needs to be mounted on both sides, an IC on the upper surface and a light source on the lower surface. However, such double-sided mounting leads to an increase in manufacturing man-hours and causes an increase in cost.

  Patent Document 1 discloses a backlight structure in which a light source itself is attached to the upper surface of a lower glass substrate. According to such a structure, the above problem is solved temporarily. That is, it is not necessary to handle the light source conductive pattern from the lower surface of the glass substrate to the upper surface through the edge using lead wires, etc., and there is no troublesome handling, and the man-hour is increased because it is not necessary to mount the glass substrate on both sides. do not do.

  However, in the case of Patent Document 1, since the light source is still installed on the glass substrate, it is necessary to provide a light source conductive pattern on the upper surface of the glass substrate. Therefore, the glass substrate must be a wide area that provides a certain area for the light source conductive pattern.

  In addition, the light from the light source in Patent Document 1 is transmitted through the lower glass substrate, unlike the light from the light source in other general prior art, which is directly irradiated toward the light guide plate in the horizontal direction. It is given to the light guide plate by the reflecting mirror. Therefore, it is inevitable that the intensity of light is reduced by the amount that passes through the glass substrate.

  SUMMARY OF THE INVENTION In view of such problems, the present invention has an object to provide a liquid crystal display device in which handling is not cumbersome and manufacturing man-hours are not increased, the glass substrate is compact, and the intensity of light from the light source does not decrease. .

  In order to solve the above-described problems, the present invention provides a liquid crystal display device in which light from a backlight having a light source and a light guide plate is irradiated to a liquid crystal layer through a glass substrate. It includes a member that arranges the light source at a position where light can be irradiated on the light receiving surface of the light plate, and a light source conductive means that is provided on this member and is connected to the light source. Supply.

  According to the present invention, since the light source is not installed on the glass substrate but on the FPC (Flexible Printed Circuit) which is the above member, the conductive pattern for the light source for supplying the control signal and power to the light source is only FPC. To the external drive circuit. Therefore, it is not necessary to provide the light source conductive pattern on the glass substrate, and it is not necessary to connect the upper and lower surfaces of the glass substrate, which has been conventionally performed, with lead wires. As a result, the glass substrate is made compact and there is no troublesome handling.

  In addition, the glass substrate is single-sided mounting where only the IC is mounted on the upper surface as required. Compared to the case of double-sided mounting with the IC on the upper surface of the glass substrate and the light source on the lower surface as in the prior art, it is manufactured. The number of man-hours is reduced and the cost can be reduced.

  The function of the IC is given to the drive circuit to which one end of the FPC is connected, or the IC is installed in the drive circuit, or the IC itself is installed outside the liquid crystal display device in the same way as the drive circuit, and the signal from the IC Can also be supplied via FPC. Thereby, it is not necessary to provide the IC on the glass substrate, and the glass substrate can be further downsized.

  Then, by installing the concave lens on the light receiving surface of the light guide plate, it is possible to improve the light diffusion efficiency and realize a liquid crystal display device with higher luminance.

  Also, by arranging the light source on the upper part of the light guide plate and diffusing the light of the light source by the two reflecting plates, the light diffusion efficiency can be increased, and the thickness of the light source can be made thinner than when the light source is installed on the side. In addition, the liquid crystal display device can be thinned. At this time, similarly to Patent Document 1, although light is irradiated vertically onto the light guide plate from above the light guide plate, unlike Patent Document 1, light does not pass through the glass plate, so the light intensity is weak. I wo n’t.

  Next, embodiments of the liquid crystal display device according to the present invention will be described in detail with reference to the accompanying drawings. In the drawings, elements not directly related to the present invention are not shown, and similar elements are designated by the same reference numerals.

  FIG. 1 is a block diagram showing a first embodiment of a liquid crystal display device according to the present invention. Characteristic constituent elements of this embodiment are FPCs (Flexible Printed Circuits) 16 and 18, which will be described later. This will be described later, and other constituent elements will be described first.

  As shown in FIG. 1, the liquid crystal display device 10 has a pair of glass substrates, that is, an upper glass substrate 24 and a lower glass substrate 26. There is a liquid crystal layer in this gap. A liquid crystal material (not shown) is sealed in the liquid crystal layer by a sealing material. The liquid crystal substance is in an intermediate state between crystal (solid) and liquid, and the molecules are arranged in a certain direction, but the three-dimensional order is not maintained with respect to the position of the center of gravity of the molecule. .

  As shown in FIG. 1, the liquid crystal display device 10 has a pair of polarizing plates, that is, an upper polarizing plate 50 and a lower polarizing plate 52, and the upper and lower glass substrates 24 and 26 are sandwiched between them. The upper and lower polarizing plates 50 and 52 are films having a property of transmitting only light having a wavelength in a specific direction. The upper and lower polarizing plates 50 and 52 are installed such that, for example, light transmitted through the lower polarizing plate 52 cannot be transmitted through the upper polarizing plate 50 unless it is twisted 90 degrees in a liquid crystal material (not shown).

  As shown in FIG. 1, the liquid crystal display device 10 includes a condensing sheet 36 below the lower polarizing plate 52, and the condensing sheet 36 transmits light entering a light guide plate 32 described later to the light guide plate 32. This is a sheet that is transmitted as light perpendicular to the incident light direction and improves the luminance of the liquid crystal display device 10.

  As shown in FIG. 1, the liquid crystal display device 10 has a backlight composed of a light source 12, a light guide plate 32 and a reflection sheet 38 located further below the light collecting sheet 36. The light source 12 may be an LED (Light Emitting Diode) or a fluorescent lamp (a hot cathode tube or a cold cathode tube). The light source 12 is supplied with a power / control signal through a power supply line / control line having a lower part 18 of an FPC (Flexible Printed Circuit), which will be described later, as a route, and is emitted and controlled. The light source 12 is assumed to be an LED in this embodiment, but any light source can be used as long as it saves power and emits light sufficiently. The light source 12 irradiates light in a direction substantially parallel to the light guide plate 32, that is, in a direction substantially parallel to the wide surface 35 or 37 of the light guide plate 32 facing the light collecting sheet 36 or a reflection sheet 38 described later. Placed in position. In other words, light is irradiated in the horizontal direction in FIG.

  The light guide plate 32 may be a plastic plate such as a transparent acrylic resin, and is a plate that uniformly emits light incident from the end surface (light receiving surface) 34 by a special process applied to the surface. The light from the light source 12 enters from the light receiving surface 34 which is the end surface of the light guide plate 32 and passes through the light collecting sheet 36 installed on the upper surface of the light guide plate 32. A reflection sheet 38 that reflects light is installed on the lower surface of the light guide plate 32, and the reflection sheet 38 is exposed at light reflection dots (not shown) provided on the light guide plate 32. The reflection sheet 38 may be made of silver metal or aluminum metal having high reflectivity, but may be any sheet as long as it is thin and reflects light. The light from the light source 12 is diffused by the exposed reflection sheet 38, and is irradiated as a surface light source from the light guide plate 32 to the liquid crystal layer (not shown) through the light collecting sheet 36, the lower polarizing plate 52, and the lower glass substrate 26.

  As shown in FIG. 1, the liquid crystal display device 10 includes an IC 22. The IC 22 is mounted on the upper surface of the lower glass substrate 26, that is, the surface facing the liquid crystal layer. The IC 22 applies a voltage to a liquid crystal substance (not shown) encapsulated between the upper glass substrate 24 and the lower glass substrate 26 based on a control signal supplied from an FPC upper portion 16 described later, thereby displaying a liquid crystal display. It is an element that controls.

  The liquid crystal display is controlled as follows. That is, when no voltage is applied to the liquid crystal substance (not shown) between the glass substrates 24 and 26 by the IC 22, the polarized light from the lower polarizing plate 52 is twisted 90 degrees in the liquid crystal and transmitted through the upper polarizing plate 50. , Looks white. On the other hand, when a voltage is applied to the liquid crystal material (not shown) between the glass substrates 24 and 26 by the IC 22, the polarized light from the lower polarizing plate 52 travels straight through the upper polarizing plate 50 without being twisted in the liquid crystal. It cannot be seen and looks “black”. Needless to say, the liquid crystal display device 10 can also perform color display. In this case, although not shown, a color filter may be inserted between the liquid crystal layer and the upper glass substrate 24.

  As shown in FIG. 1, the liquid crystal display device 10 includes a case 56. The case 56 covers and protects the reflective sheet 38 of the liquid crystal display device 10 to the light source 12, the light guide plate 32, the light collecting sheet 36, and the lower polarizing plate 52.

  Here, the configuration of FPCs (Flexible Printed Circuits) 16 and 18 which are characteristic configurations of the present embodiment will be described. The FPCs 16 and 18 included in the liquid crystal display device 10 are circuit boards obtained by patterning Cu (copper) electrodes based on a polyimide film. FPCs 16 and 18 are elastic and have the property of returning to their original shape even if they are bent within a certain range.

  FIG. 2 is a block diagram showing the FPC shown in FIG. As shown in FIG. 2, the FPCs 16 and 18 are integrally formed, and have a shape in which a second part or a lower part 18 branches from a first part or an upper part 16. Similarly, as shown in FIG. 2, the upper portion 16 and the lower portion 18 have different heights. That is, the upper portion 16 is bent and extends to an upper position, while the branched lower portion 18 maintains a substantially unchanged height and has a substantially L-shaped flat plate shape below. It extends.

  FIG. 3 is a view of the positional relationship between the FPC and the lower glass substrate shown in FIG. 1 as viewed from above. As shown in FIG. 3, the lower glass substrate 26 is sandwiched from above and below by an upper portion 16 extending upward and a substantially L-shaped lower portion 18 extending downward.

  As shown in FIG. 3, the upper portion 16 is connected to the surface (upper surface) of the lower glass substrate 26 facing the liquid crystal layer (not shown). The upper portion 16 is provided with an element conductive pattern (not shown) connected to an element such as an IC mounted on the upper surface of the lower glass substrate 26. The element conductive pattern supplies the IC 22 with a control signal and power supplied from a drive circuit (not shown).

  FIG. 4 shows the FPC shown in FIG. 1 alone for the sake of simplicity, and is a configuration diagram seen from below. The lower part 18 branched from the upper part 16 has a substantially L-shaped flat plate shape, and one or more light sources 12 are mounted on the lower surface thereof.

  FIG. 5 is a view of the positional relationship between the FPC and the lower glass substrate shown in FIG. 1 as viewed from below. As shown also in FIG. 1, the light source 12 is arranged at a position where the light source 12 can irradiate the light receiving surface 34 of the light guide plate 32 by the lower portion 18.

  In the present embodiment, one or more light sources 12 are mounted on the lower surface of the substantially L-shaped flat plate-like lower portion 18, that is, the surface not facing the lower glass substrate 26. However, the light source 12 may be mounted on the upper surface of the lower portion 18 as long as the light source 12 is disposed at a position where the light receiving surface 34 of the light guide plate 32 can be irradiated with light.

  As shown in FIG. 5, a light source conductive pattern 20 connected to the light source 12 is provided on the lower surface of the substantially L-shaped flat plate-like lower portion 18, which is not shown, The power source of the light source 12 is reached from the portion 18 via the upper portion 16. It goes without saying that the light source conductive pattern 20 supplies not only electric power but also a drive signal to the light source 12. Therefore, the light source conductive pattern 20 may extend not only to the power source but also to a drive circuit (not shown).

  As described above, the element conductive pattern for IC 22 (not shown) provided on the upper surface of the upper portion 16 and the conductive pattern 20 for the light source 12 provided on the lower surface of the lower portion 18 are both common. It may extend to a power supply or drive circuit. In other words, the FPCs 16 and 18 may be integrated into a place where any pattern is provided and extended to a common power supply or drive circuit.

  The operation and effect of the first embodiment of the liquid crystal display device according to the present invention configured as described above will be described. Control signals and power are supplied to the FPCs 16 and 18 from a drive circuit (not shown), the upper part 16 of the FPC supplies control signals and power to the IC 22, and the lower part 18 of the FPC receives control signals and power. The light source 12 is supplied through the light source conductive pattern 20. At this time, the light source conductive pattern 20 reaches the light source 12 only through the lower portion 18 of the FPC, and supplies a control signal and power to the light source 12 without passing through the lower glass substrate 26. In addition, since the control signal and power to the IC 22 are separately supplied by an element conductive pattern (not shown) installed in the upper portion 16 of the FPC, it is not necessary to connect the upper and lower surfaces of the lower glass substrate 26 with lead wires.

  In FIG. 1, the IC 22 is installed on the upper surface of the lower glass substrate 26. However, the function of the IC 22 may be provided in a drive circuit (not shown) that arrives after the FPCs 16 and 18 are integrated. Alternatively, the IC 22 may be moved to the drive circuit. In this way, a control signal can be supplied from the outside of the liquid crystal display device 10 to the device 10 via the FPCs 16 and 18. Thereby, it is not necessary to provide the IC 22 on the glass substrate 28, and the glass substrate 28 can be further downsized.

  FIG. 6 is a block diagram showing a second embodiment of the liquid crystal display device according to the present invention. Hereinafter, only differences from the first embodiment will be described with reference to FIG. As shown in FIG. 6, the liquid crystal display device 100 in this embodiment is different from the first embodiment shown in FIG. 1 in that it includes a concave lens 30 that diffuses the light from the light source 12 into the light guide plate 32. The concave lens is installed on the light receiving surface 34 of the light guide plate 32. The concave lens 30 is a lens that increases the diffusion efficiency of radiation emitted from the light source 12. Thereby, the luminance of the liquid crystal display device 10 can be improved. In FIG. 6, a plano-concave lens is shown as the concave lens 30, but a bi-concave lens or a meniscus concave lens may be used.

  FIG. 7 is a block diagram showing a third embodiment of the liquid crystal display device according to the present invention. Hereinafter, only differences from the first embodiment will be described with reference to FIG. As shown in FIG. 7, in the liquid crystal display device 200, unlike the first embodiment, the light source 12 is installed above the light guide plate 32. That is, the light source 12 is disposed at a position where light is irradiated in a direction substantially perpendicular to the light guide plate 32, that is, a direction substantially perpendicular to the surface 35 or 37 of the light guide plate 32. In response to this, the light receiving surface 58 of the light guide plate 32 also faces upward and receives light from the light source 12 coming from above. In this case, since the light source 12 has a horizontally long posture, the entire liquid crystal display device 200 is made thinner than the case where the light source 12 is installed on the side of the light guide plate 32 to have a vertically long posture as in the first embodiment. be able to.

  The liquid crystal display device 200 further includes two reflectors 42 and 44, which may be a highly reflective mirror or metal. As shown in FIG. 7, the reflecting plate 42 has a curved shape from the surface 35 to the surface 37 of the light guide plate 32. In the present embodiment, the shape of the reflection sheet 38 is also curved corresponding to the shape. Alternatively, the reflector 42 may be simply inclined with a straight shape, but in any case, the light source 12 is arranged to reflect light coming from above and reflect it toward the other reflector 44. Has been.

  The reflection plate 44 is a mirror or metal having a high reflectance that is installed on the upper portion of the light guide plate 32 and reflects incident light to the inside of the light guide plate 32. Due to the reflectors 42 and 44, the diffusion efficiency of light coming from the light source 12 is increased.

1 is a configuration diagram of a first embodiment of a liquid crystal display device according to the present invention; It is the block diagram which looked at FPC shown in FIG. 1 independently from the top. It is the figure which looked at the positional relationship of FPC shown in FIG. 1 and a lower glass substrate from the top. It is the block diagram which looked at FPC shown in FIG. 1 independently from the bottom. It is the figure which looked at the positional relationship of FPC shown in FIG. 1 and a lower glass substrate from the bottom. It is a block diagram of the 2nd Example of the liquid crystal display device by this invention. It is a block diagram of the 3rd Example of the liquid crystal display device by this invention.

Claims (9)

In a liquid crystal display device in which light from a backlight having a light source and a light guide plate is irradiated to a liquid crystal layer through a glass substrate, the device includes:
A member that mounts the light source, and the light source is disposed at a position where the light receiving surface of the light guide plate can irradiate light; and
A light source conductive means provided on the member and connected to the light source,
Thereby, power is supplied to the light source without passing through the glass substrate.   2. The liquid crystal display device according to claim 1, wherein the member is an FPC (Flexible Printed Circuit). The liquid crystal display device according to claim 1, wherein the member is
A first portion connected to a surface of the glass substrate facing the liquid crystal layer;
A second portion that is branched from a first portion, includes the light source, and the light source is disposed at a position where the light source can irradiate light to the light receiving surface of the light guide plate;
The liquid crystal display device, wherein the light source conductive means reaches the power source of the light source from the second portion via the first portion.   4. The liquid crystal display device according to claim 3, wherein the first portion of the member is provided with element conductive means connected to an element mounted on a surface of the glass substrate facing the liquid crystal layer. A liquid crystal display device.   5. The liquid crystal display device according to claim 3, wherein the second portion of the member has a flat portion, and the light source is mounted on a surface of the portion that does not face the glass substrate. A liquid crystal display device characterized by the above.   6. The liquid crystal display device according to claim 1, wherein the light source is an LED (Light Emitting Diode). 7. The liquid crystal display device according to claim 1, wherein the light source is disposed at a position where light is emitted in a direction substantially parallel to the light guide plate.   8. The liquid crystal display device according to claim 7, further comprising a concave lens that diffuses the light into the light guide plate.   7. The liquid crystal display device according to claim 1, wherein the light source is disposed at a position where light is emitted in a direction substantially perpendicular to the light guide plate, and the device further emits the light. A liquid crystal display device comprising a reflection plate that diffuses into a light guide plate.