JP2009217056A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device which reduces an area of a non-display region with respect to a surface area of the liquid crystal display device. <P>SOLUTION: The liquid crystal display device includes a liquid crystal panel 2 which has a front substrate 11, a back substrate 12 and a liquid crystal layer 10, and displays an image by changing the light transmittance of each pixel 25 of the liquid crystal layer 10, and a back light 4 which has a light guiding means 5 and a light source 6 which irradiates the light from its side. The image display region 3 of the liquid crystal panel 2 has a reflection display region 3b constituted of the image 25a of the reflection type displaying the image by using only the reflected light of the external light made incident from the front substrate 11, and a transmission display region 3a constituted of the pixels (25b, 25c) of the transmission type displaying the image by using the irradiation light from the back light 4 made incident from the back substrate 12. A light source 6 of the back light 4 is disposed on the back of the reflection display region 3b of the liquid crystal panel 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device using a liquid crystal panel having two types of display areas, a reflective display area and a transmissive display area, and in particular, to reduce the area of a non-display area with respect to the surface area of the liquid crystal display apparatus. The present invention relates to a liquid crystal display device that can be used.

  In recent years, liquid crystal display devices having features such as low power consumption, thinness, and light weight have been widely used as image display devices. A liquid crystal panel used for a display unit of a liquid crystal display device usually applies a predetermined voltage between a pixel electrode provided on a rear substrate made of transparent glass and a counter electrode provided on a front substrate made of transparent glass. By applying the voltage, the transmittance of a liquid crystal layer formed between the front substrate and the rear substrate is controlled to display an image. In the liquid crystal panel, a fine region forming one unit (dot) of a display image is referred to as a pixel.

  Since the liquid crystal panel is a so-called non-light-emitting image display element that does not emit light itself, the liquid crystal display device requires a light source for displaying an image. In a liquid crystal display device, as a method of obtaining a light source for image display, a reflection method using reflection of so-called external light such as sunlight or illumination light incident from the front substrate side of the liquid crystal panel, and a liquid crystal panel There are two types of transmission systems that use light transmitted from a planar light source called a backlight that is incident on the back substrate side and is provided on the back surface of the liquid crystal panel.

  In the reflection method, the pixel electrode formed on the rear substrate is a reflective electrode formed of a metal having high light reflectance such as an aluminum film, and external light incident through the front substrate of the liquid crystal panel is reflected by this reflective electrode. The image is reflected and transmitted through the liquid crystal layer again. In the transmission method, the pixel electrode provided on the back substrate is a transparent electrode formed of a transparent conductive material such as an ITO film, and the backlight provided on the back surface of the liquid crystal panel that is transmitted through the back substrate and incident. The image is displayed by transmitting the irradiation light from through the liquid crystal layer. In this transmission method, a part of the pixel on the back substrate is provided with a part that reflects external light, and the like, so that the image is displayed by using both irradiation light from the backlight and external light. There are a pixel having a pixel called a mold and a pixel having a completely transmissive pixel that displays an image only by irradiation light from a backlight without providing a region that reflects external light in the pixel.

  The backlight of the liquid crystal display device is roughly classified into a direct type and a side light type (also referred to as an edge light type) depending on a method of forming planar light as a backlight.

  The direct type backlight has a large number of light sources arranged on the back side of the liquid crystal panel so as to irradiate the light toward the liquid crystal panel, and is preferably used in a large screen liquid crystal display device for a television receiver or the like. Yes. A sidelight-type backlight is a liquid crystal panel that is provided on the back of a liquid crystal panel, usually provided with a light source on the side of a plate-shaped light guide, and diffuses light from the light source by the light guide. It is a method of radiating to the side. Sidelight type backlights are suitably used in relatively small and thin liquid crystal display devices such as mobile devices such as mobile phones and display devices for notebook personal computers.

  Further, in recent years, as a light source of such direct type backlight and sidelight type backlight, color reproducibility is higher than a cold cathode fluorescent tube (CCFT) conventionally used, Focusing on the simplification and power saving of the drive circuit, light emitting diodes (LEDs) have been increasingly used.

  FIG. 7 is an exploded perspective view showing a schematic configuration of a conventional liquid crystal display device including a sidelight type backlight using LEDs as light sources. As shown in FIG. 7, the conventional liquid crystal display device 51 is configured by a liquid crystal panel 52 and a backlight 54 provided on the back side thereof being housed in a bottomed box-shaped chassis 57.

  The liquid crystal panel 52 has an image display region 53 constituted by a large number of pixels, in which a liquid crystal layer (not shown) is divided into fine regions. The backlight 54 includes a light guide plate 55 that is a plate-shaped light guide means, and a white LED 56 that is a light source provided on one side surface of the light guide plate 55 with a light irradiation surface facing the light guide plate 55.

  7 has a problem that the area of the image display region 53 in the liquid crystal panel 52 is smaller than the surface area of the liquid crystal display device 51. In the sidelight-type backlight 54 in which the LEDs 56 are arranged on the side surface that is the side of the light guide plate 55, the light emitted from the LED 56 is not sufficiently spread in the light guide plate 55. It is difficult to eliminate the luminance unevenness in the vicinity of the portion where the LED 56 is provided. For this reason, the uniform irradiation region 55 a where uniform irradiation light is obtained from the light guide plate 55 is smaller than the area of the light guide plate 55. Further, since the LED 56 is disposed on the side of the light guide plate 55, the portion where the LED 56 as the light source is disposed does not function as a backlight. Therefore, the area of the non-display area 58 other than the image display area 53 in the liquid crystal panel 52 must be increased.

For example, in a conventional liquid crystal display device including a liquid crystal panel in which a transflective pixel having a transmissive region and a reflective region forms an image display region, and a sidelight type backlight, there is a technique for reducing a non-display region. Proposed. This is because the LED light source is arranged close to the light guide, and the non-uniform luminance distribution in the light guide, which is the light guide means generated at this time, is ineffective in blocking the transmitted light in the transmissive area portion in the pixel. A region is provided, and the area of the invalid region is set to be larger for pixels located near the light source (see Patent Document 1).
JP-A-2005-49664

  However, since the method described in Patent Document 1 eliminates uneven luminance of the display image by providing an ineffective region that blocks the light emitted from the backlight, the use efficiency of the backlight is increased. This may cause problems in obtaining a display image with high brightness and reducing the power consumption of the liquid crystal display device. Further, in the area where the light source on the side of the light guide is disposed, image display on the liquid crystal panel cannot be performed, and there is a limit to the reduction of the non-display area.

  The ratio of the area occupied by the image display area to the surface area of the liquid crystal display device due to the presence of the non-display area is particularly undesirable as a liquid crystal display device used in mobile devices that are required to be downsized.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a liquid crystal display device in which the area of the non-display region with respect to the surface area of the liquid crystal display device is reduced.

  In order to achieve the above object, a liquid crystal display device according to the present invention includes a front substrate, a rear substrate, and a liquid crystal layer sandwiched between the front substrate and the rear substrate, and pixels of the liquid crystal layer. A back panel provided on the back surface of the liquid crystal panel, having a liquid crystal panel for displaying an image by changing the light transmittance for each, a light guide means and a light source for irradiating light to the light guide means from the side thereof The liquid crystal panel includes a reflective display area configured by reflective pixels that display an image using only reflected light of external light incident from the front substrate, and the rear substrate. A transmissive display region configured by transmissive type pixels that display an image using irradiation light from the backlight incident from the backlight, and the light source of the backlight is the reflective type of the liquid crystal panel Set on the back of the display area It is characterized in that is.

  According to the present invention, in the liquid crystal display device, the area of the non-display region that does not contribute to image display can be reduced, and the ratio of the image display region to the surface area of the liquid crystal display device can be increased. Therefore, it is possible to realize a liquid crystal display device that is particularly suitable for use in mobile devices that require a reduction in the size of the entire device.

  The liquid crystal display device according to the present invention includes a front substrate, a rear substrate, and a liquid crystal layer sandwiched between the front substrate and the rear substrate, and changes the light transmittance for each pixel of the liquid crystal layer. A liquid crystal panel for displaying an image, and a backlight provided on the back surface of the liquid crystal panel, the light guide means and a light source for irradiating the light guide means with light from the side thereof, The image display area includes a reflective display area composed of reflective pixels that display an image using only reflected light of external light incident from the front substrate, and irradiation from the backlight incident from the rear substrate. A transmissive display area composed of transmissive type pixels that display an image using light, and the light source of the backlight is provided on the back surface of the reflective display area of the liquid crystal panel. .

  According to this configuration, since the light source of the backlight is provided on the back surface of the reflective display area configured by the reflective pixels that display an image using only the reflected light of the external light incident from the front substrate, this The part does not become a non-display area. Therefore, a liquid crystal display device in which the ratio of the area of the non-display area to the surface area of the apparatus is narrow and the ratio of the area of the image display area is high can be realized.

  In addition, the transmissive type pixel displays an image using both reflected light of external light incident from the front substrate and irradiation light from the backlight incident from the rear substrate. It can be a pixel.

  By doing so, a liquid crystal display device capable of displaying an image in a transmissive display area in a state where the outside light is strong, such as outdoors in the daytime, or in the state where the outside light is weak such as at night or indoors. Obtainable.

  Further, the transmissive type pixel may be a completely transmissive type pixel that displays an image using only light emitted from the backlight incident from the rear substrate.

  By doing so, it is possible to obtain a liquid crystal display device that can reduce the influence of the external light condition and can display an image with high image quality such as brightness and hue in the transmissive display region.

  Furthermore, it is preferable that the light guide unit is plate-shaped, and the light source is disposed to face a side surface of the light guide unit. In this way, a thin backlight can be obtained, and the entire display device can be thinned. Therefore, a liquid crystal display device particularly suitable for use in mobile devices can be obtained.

  Furthermore, it is preferable that the light source is a light emitting diode.

  Moreover, it is preferable that a light shielding member that blocks light from the light source is provided between the light source and the liquid crystal panel. In this way, the leakage light from the light source can be surely prevented from entering the liquid crystal panel, so that the leakage light transmitted through the liquid crystal panel is not recognized by the supervisor and the quality of the display image is not deteriorated. .

  Hereinafter, preferred embodiments of the liquid crystal display device of the present invention will be described with reference to the drawings. In the following, a case where the liquid crystal display device according to the present invention is used as a display screen of a mobile phone will be described as an example. However, this description does not limit the application target of the present invention. The application of the liquid crystal display device according to the present invention is not limited to the display screen of a mobile phone, and can be used for display screens of a wide range of devices such as portable televisions and DVD players, mainly mobile applications.

  FIG. 1 is an exploded perspective view showing a schematic configuration of a liquid crystal display device according to an embodiment of the present invention. As shown in FIG. 1, the liquid crystal display device 1 according to the present embodiment is configured such that a liquid crystal panel 2 and a backlight 4 provided on the back side thereof are housed in a bottomed box-shaped chassis 7. Yes.

  The liquid crystal panel 2 has an image display area 3 constituted by a large number of pixels (not shown). The image display area 3 includes a transmissive display area 3a in which transmissive type pixels are formed using light emitted from a backlight 4 disposed on the back of the liquid crystal panel for image display, and a liquid crystal panel 2 from the front. A reflection type display area 3b on which reflection type pixels are formed, which uses only reflected light of incident external light for image display.

  The backlight 4 is provided with a white LED 6 that is a light source on one side surface of a light guide plate 5 that is a plate-like light guide. The light guide plate 5 is made of polycarbonate (PC) or acrylic resin (PMMA), and has a thickness of about 0.4 to 1 mm, for example. The light source of the backlight is provided on the side of the light guide means. Here, being provided on the side of the light guide means that the light source and the light guide are not completely overlapped when the liquid crystal display device is viewed from the image display surface side of the liquid crystal panel 2. Say. In the backlight 4 of this embodiment, the LED 6 that is a light source is disposed so that the light emission surface of the LED 6 faces the side surface of the light guide plate 5 that is a plate-shaped light guide. The light that has entered the light guide plate 5 from the LED 6 is repeatedly reflected and diffused inside the light guide plate 5, and is irradiated toward the back surface of the liquid crystal panel 2 from the uniform irradiation region 5 a as irradiation light with substantially uniform illuminance.

  The chassis 7 is a bottomed box-shaped object having four side walls and a bottom surface made of metal or a resin material, and the liquid crystal panel 2 and the backlight 4 are stacked in an inner space surrounded by the four side walls. It is designed to be housed in a state where Although not shown in FIG. 1, a circuit board for operating the liquid crystal panel 2 and a power supply circuit for lighting the LED 6 are also accommodated in the chassis 7.

  In the liquid crystal display device 1, the periphery of the image display area 3 of the liquid crystal panel 2 is covered so as to function as a restraining member for fixing the liquid crystal panel 2 to the chassis 7, and the non-display area around the display image is covered and looks good. In order to improve the quality, a frame-shaped masking member may be provided, but the illustration and detailed description are omitted in this embodiment.

  Further, between the light guide plate 5 and the liquid crystal panel 2, for the purpose of irradiating the liquid crystal panel 2 with the irradiation light irradiated from the light guide plate 5 in a more uniform state, and for the purpose of further improving the directivity of the irradiation light. An optical sheet such as a lens sheet or a diffusion sheet is appropriately disposed, but illustration and detailed description thereof are omitted in this embodiment.

  Next, with reference to FIGS. 2, 3, and 4, details of each component of the liquid crystal display device 1 according to the present embodiment and the mutual positional relationship will be described.

  FIG. 2 is a plan view of the liquid crystal display device 1 according to the present embodiment as viewed from the image display surface side, that is, from the supervisor side.

  As shown in FIG. 2, in the liquid crystal display device 1 according to the present embodiment, the liquid crystal panel 2 positioned inside the chassis 7 is an image display area 3 except for its peripheral portion. For example, in the case of a 3.2 type liquid crystal panel, the size of the image display region 3 is 75 mm in the long side direction and 44 mm in the short side direction.

  The left end portion in FIG. 2 of the image display area 3 is a reflective display area 3b composed of reflective pixels that display an image using only reflected light of external light. Further, the right side portion in FIG. 2 other than the reflective display area 3b of the image display area 3 uses a light radiated from the backlight 4 provided on the back side of the liquid crystal panel 2 for image display. It is. In the liquid crystal display device 1 of the present embodiment, the length of the transmissive display area 3a in the long side direction of the liquid crystal panel 2 is 60 mm.

  A drive circuit (COG) for driving the liquid crystal panel 2 is formed in the peripheral area of the image display area 3 of the liquid crystal panel 2 based on a known technique, and a drive circuit for driving the liquid crystal panel 2 and A terminal electrode to which a flexible substrate (FPC) is connected is formed, but the illustration and detailed description in FIG. 2 are omitted.

  On the back side of the reflective display area 3 b of the liquid crystal panel 2, the light source 6 of the backlight 4 is disposed so as to face the side surface of the light guide plate 5, as indicated by a broken line in FIG. 2.

  Hereinafter, the positional relationship between the backlight 4 in particular, the reflective display area 3b of the liquid crystal panel 2 will be described with reference to FIG.

  FIG. 3 is a diagram showing a cross-sectional structure of the portion indicated by the line A-A ′ in FIG. 2. 4 is a diagram showing the state of the electrodes on the surface of the back substrate 12, and is an enlarged view of a region indicated by a one-dot chain line B in FIG.

  In FIG. 3, the thickness of each member is highlighted to clearly show the positional relationship between the members. For this reason, in FIG. 3, the vertical and horizontal scales in the figure are not equal. Also in FIG. 3, a drive circuit for operating the liquid crystal panel 2, a power supply circuit for lighting the light source 6 of the backlight 4, and a display provided outside these circuits and the liquid crystal display device 1. Illustration of the connection substrate with the image signal control circuit is omitted.

  Further, when a drive circuit and terminal electrodes are mounted on the liquid crystal panel 2, the size of the pair of glass substrates constituting the liquid crystal panel 2 is not made the same, and the drive circuit and terminal electrode portions are placed on the other side. However, the illustration and detailed description in this embodiment including FIG. 3 are omitted.

The liquid crystal panel 2 has a glass front substrate 11 and a glass back substrate 12 formed with the liquid crystal layer 10 interposed therebetween. On the inner surface of the front substrate 11, that is, the surface on the liquid crystal layer 10 side, a counter electrode (not shown) is formed over the entire surface. The counter electrode is formed of a known transparent conductive film such as ITO or SnO ₂ .

  On the inner surface of one rear substrate 12, that is, the surface on the liquid crystal layer 10 side, as shown in FIGS. 4A and 4B, source electrode lines 21 are formed in the horizontal direction and data electrode lines 22 are formed in the vertical direction. Pixel electrodes 24 (24a, 24b, 24c) are formed in contact with the switching elements 23 provided at the intersections.

  The liquid crystal layer 10 changes its molecular alignment direction when a predetermined voltage is applied by the counter electrode on the inner surface of the front substrate 11 and the pixel electrode 24 on the inner surface of the rear substrate 12, so that the liquid crystal layer 10 is placed outside the front substrate 11 and the rear substrate 12. The transmittance varies depending on the combination with the formed polarizing plates 13 and 14, and an image is displayed. Such a fine region in which the transmittance of the liquid crystal layer 10 can be changed is called a pixel 25 (25a, 25b, 25c). The pixels 25 substantially correspond to the pixel electrodes 24 formed on the back substrate 12 and can be grasped as a large number of fine regions arranged in a matrix in the vertical and horizontal directions as shown in FIG. The pixel 25 is one unit for displaying an image in the liquid crystal display device 1, and in the case of color display, usually three color filters of red (R), green (G), and blue (B) are provided. A pixel 25 forms one picture element of the display image.

  The liquid crystal panel 2 used in the liquid crystal display device 1 of the present embodiment is provided with a switching element 23 at the intersection of the source electrode line 21 and the data electrode line 22 as a driving method for image display of the liquid crystal panel 2. Then, an active matrix method is applied in which a predetermined driving potential is applied to the pixel electrode 24 by operating the switching element 23. However, the liquid crystal panel used in the liquid crystal display device of the present invention is not limited to this, and a predetermined voltage is sequentially applied directly to the pixel electrode formed at the intersection of the vertical electrode line and the horizontal electrode line. A simple matrix system in which the liquid crystal layer is controlled by application can also be used.

  The liquid crystal panel 2 of the liquid crystal display device 1 according to the present embodiment includes a transmissive display area 3 a and a reflective display area 3 b as the image display area 3. As a transmissive type pixel forming the transmissive display area 3a, either a transflective pixel or a completely transmissive pixel can be employed.

  FIG. 4A shows an arrangement state of electrodes on the back substrate 12 when a transflective pixel is used as a transmissive type pixel as a first example.

As shown in FIG. 4A, the pixel electrode 24b formed in the region surrounded by the source electrode line 21 and the data electrode line 22 in the transmissive display region 3a is formed of a transparent conductive film 26 such as ITO or SnO _2. And a reflection region formed of a metal member that reflects external light such as the aluminum film 27. As described above, when the transflective pixel 25b is provided as the pixel 25 in the transmissive display area 3a, the external light incident through the front panel 11 and the rear panel 12 in the transmissive display area 3a are changed. An image can be displayed using both the light emitted from the backlight 4 incident thereon via the light source. For this reason, the liquid crystal panel 2 can be used in any case, even when it is used in a situation where the sunlight in the daylight is directly hitting the liquid crystal panel 2 or when it is used in a dark room with little external light. The displayed display image can be satisfactorily monitored, and is particularly suitable as an image display device such as a mobile phone used in various external light environments.

  On the other hand, in the reflective display region 3b, the pixel electrode 24a formed in the region surrounded by the source electrode line 21 and the data electrode line 22 is formed of a metal material that reflects external light such as an aluminum film 27. Pixels 25a are formed. In the reflection type pixel 25 a, an image is displayed using only external light incident on the liquid crystal layer 10 through the front substrate 11.

  As shown in FIG. 4A, a fine electrode is formed on the aluminum film 27 that forms the reflective region of the pixel electrode 24a of the reflective pixel 25a and the pixel electrode 24b of the transflective pixel 25b. A protrusion 28 is formed. By forming such protrusions 28 and making the surface of the aluminum film 27 uneven, the external light reflected by the aluminum film 27 is scattered, and the external light is strongly reflected depending on the monitoring direction of the observer. This prevents the display image from becoming difficult to see.

  FIG. 4B shows an arrangement state of electrodes on the back substrate 12 when a completely transmissive pixel is used as a transmissive type pixel as a second example.

As shown in FIG. 4B, in this second example, the pixel electrode 24c formed in the region surrounded by the source electrode line 21 and the data electrode line 22 in the transmissive display region 3a is made of ITO, SnO ₂ or the like. The transparent conductive film 26 is formed only and does not have a reflective region as in the first example shown in FIG. In this way, by forming the transmissive display region 3a with the completely transmissive pixel 25c, it is possible to stably display a high-quality image that is not affected by the intensity or hue of external light. For this reason, when a completely transmissive pixel is used as the liquid crystal display device according to the present embodiment, it is particularly suitable as a display device for a device such as a portable television or a DVD player that requires a high image quality. .

  In the reflective display region 3b, as in the first example shown in FIG. 4A, the pixel electrode 24a formed in the region surrounded by the source electrode line 21 and the data electrode line 22 is replaced with the aluminum film 27. The reflective pixel 25a is formed of a metal material that reflects external light such as. Further, it is the same as the first example in that fine protrusions 28 are formed on the aluminum film 27 that forms the pixel electrode 24a of the reflective pixel 25a.

  As described above, the liquid crystal panel 2 used in the liquid crystal display device 1 according to the present embodiment has the reflective display area 3 b in the image display area 3. In the reflective display area 3b, since an image is displayed only with external light, it is not necessary to irradiate the light emitted from the backlight 4 from the back side of the liquid crystal panel 2. Therefore, as shown in FIG. 3, the LED 6 that is the light source of the backlight 4 for irradiating the transmissive display region 3a with the irradiation light can be disposed on the back surface of the reflective display region 3b.

  In the backlight 4, the LED 6 is disposed on the side of the light guide plate 5 that is a plate-shaped light guide unit so that the light irradiation surface thereof faces and contacts the side surface of the light guide plate 5. By doing in this way, the light from LED6 can be efficiently introduce | transduced in the light-guide plate 5. FIG.

  The light guide plate 5 is made of, for example, milky white polycarbonate, and the light of the LED 6 introduced into the inside from the side surface propagates through the light guide plate 5 while being scattered, and is irradiated toward the back surface of the liquid crystal panel 2. In order to efficiently irradiate light with uniform brightness from the light guide plate, a light scattering material is distributed in a predetermined distribution pattern in the light guide plate, or light is applied to the side of the light guide plate that does not face the liquid crystal panel. Various techniques are known, such as applying a reflective material, giving a predetermined distribution to the thickness of the light guide plate itself, and making the cross-sectional shape a wedge shape or a trumpet shape. These techniques can also be employed in the light guide plate 5 of the liquid crystal display device 1.

  Between the LED 6 on the side of the light guide plate 5 and the liquid crystal panel 2, a black or dark brown light shielding member 16 is disposed. As the light shielding member 16, for example, a resin sheet can be used, and the material and the thickness thereof are not particularly limited as long as the light leakage from the LED 6 that is a light source is reliably blocked. In addition, a spacer 15 is provided between the light guide plate 5 on the side where the LED 6 is not disposed and the liquid crystal panel 2 to define the distance therebetween.

  In the liquid crystal panel 2 of the liquid crystal display device 1 according to the present embodiment, a reflective pixel 25a is formed at a position overlapping the position where the LED 6 is arranged, but a pixel electrode formed by an aluminum film 27 or the like. Due to the relationship of ensuring insulation between the source electrode line 21 and the data electrode line 22 from 24a, there are cases where these electrodes cannot be arranged in an overlapping manner. For this reason, there is a possibility that the light of the LED 6 of the backlight 4 from the reflective pixel 25a is transmitted to the supervisor side and deteriorates the image quality of the display image. However, the leakage from the LED 6 by providing the light shielding member 16 Light can be reliably prevented.

  As shown in FIG. 3, the light shielding member 16 can cover not only the portion between the LED 6 and the liquid crystal panel 2 but also the entire back surface of the reflective display region 3 b of the liquid crystal panel 2. In this way, not only the leakage light from the LED 6 but also the leakage light leaking from the light guide plate 5 to the liquid crystal panel 2 side during propagation in the light guide plate 5 can be shielded. It is possible to more reliably block light leaking from the water. In particular, in the reflective display area 3b, a polarizing plate 14 provided on the back side of the back substrate 12 of the liquid crystal panel 2 is provided in order to perform image display using only external light incident on the liquid crystal panel 2 via the front substrate 11. There is no need. For this reason, the shielding member 16 can be provided in close contact with the back substrate 12 over the entire back surface side of the reflective display region 3 b of the back substrate 12.

  Further, by using a resin sheet having a predetermined thickness as the shielding member 16, it is possible to fulfill a function as a spacer that defines the interval between the liquid crystal panel 2 and the light guide plate 5. In this case, by providing appropriate elasticity as the material of the shielding member 16, it is possible to play a role as a cushioning material for the liquid crystal panel 2 and the light guide plate 5 against shock and vibration applied to the liquid crystal display device 1.

  Next, the effect of reducing the number of LEDs 6 that are light sources in the backlight 4 of the liquid crystal display device 1 according to the present embodiment will be described with reference to FIG.

  FIG. 5 is an image diagram showing a relationship between the image display area 3 of the liquid crystal panel 2 and the uniform irradiation area 5 a in the light guide plate 5 of the backlight 4.

  5 shows the positional relationship between the liquid crystal panel 2 and the backlight 4 of the liquid crystal display device 1 according to the present embodiment. As shown in the middle part of FIG. 5, in the backlight 4 of the liquid crystal display device 1 according to the present embodiment, the positional relationship between the transmissive display area 3 a of the liquid crystal panel 2 and the uniform irradiation area 5 a of the light guide plate 5 can be made to correspond. Therefore, the distance C from the side surface portion where the LED 6 of the light guide plate 5 is provided to the uniform irradiation amount region 5a can be made relatively large. For this reason, even if the low-intensity part 31 which the light which entered into the light-guide plate 5 from LED6 which is a light source does not fully spread within the light-guide plate 5 is considered, for example with two LED6, it is from the uniform irradiation area | region 5a. Uniform irradiation light can be realized.

  On the other hand, if the entire image display area 3 of the liquid crystal panel 2 is to be the uniform irradiation area 35a of the light guide plate 35 as in the case of the backlight 34 in the comparative example shown in the lower part of FIG. Even if the LED 36 is arranged outside the liquid crystal panel 2 and the three LEDs 36 are provided, the low-luminance portion 32 where the light from the LED 36 is not sufficiently propagated reaches the uniform irradiation region 35a.

  Thus, in the liquid crystal display device 1 according to the present embodiment, the uniform irradiation region 5a in the light guide plate 5 of the backlight 4 can be reliably formed with a small number of LEDs 6.

  Next, an image display example of the liquid crystal display device 1 according to the present embodiment will be described with reference to FIG.

  FIG. 6 shows an image display example when the liquid crystal display device 1 according to the present embodiment is used as a display unit of a mobile phone. As shown in FIG. 6, the reflective display area 3b in the image display area 3 is used to display the time and radio wave status, and the transmissive display area 3a is used to display the image of the other party when using the videophone. Display 1Seg TV images, text images such as mail. The liquid crystal display device 1 according to the present embodiment has a reflective display area 3b that displays an image using only external light as part of the image display area 3. In the reflective display area 3b, the brightness of the display image is easily affected by the situation of the external light, and the monitor image may not be recognized when there is no external light in the most extreme case. . Therefore, if the supplementary information as described above is displayed in the reflective display area 3b, the problem when the display image cannot be monitored can be reduced. For the same reason, when the liquid crystal display device 1 according to the present embodiment is used as a display device for a portable DVD player or a one-segment television, supplementary information such as disk information and channel information in the reflective display area 3b. May be displayed.

  6 is only a display example of image display of the liquid crystal display device according to the present embodiment, and the entire image display area 3 is used by using the transmissive display area 3a and the reflective display area 3b without distinction. Needless to say, one display image can be displayed.

  As described above, the liquid crystal display device of the present invention has been described with reference to specific embodiments. According to the liquid crystal display device of the present invention, the ratio of the area of the non-display region that does not contribute to the image display to the surface area of the liquid crystal display device by having the transmissive display region and the reflective display region as the image display region of the liquid crystal panel. Can be effectively reduced.

  In addition, as an embodiment of the liquid crystal display device according to the present invention, a light guide member of a backlight is used as a plate-shaped light guide plate, and an LED as a light source is disposed close to the side surface. It is not limited to this. For example, in order to use a large number of LEDs, the light guide member may be one or a plurality of blocks having a predetermined thickness. In addition, as a positional relationship between the light guide member and the light source, the light guide member may be a backlight having a shape in which the light source is disposed on the side of the light guide member when the liquid crystal display device is viewed from the display image side. The present invention can be applied not only to the case where the light source is disposed close to the side surface.

  The liquid crystal panel used in the liquid crystal display device according to the present invention is of a vertical electric field type in which a counter electrode is provided on the front substrate, a pixel electrode is provided on the rear substrate, and an electric field is applied in a direction perpendicular to the liquid crystal layer. However, the method of the liquid crystal panel that can be used in the liquid crystal display device of the present invention is not limited to this, and various electric field application methods, alignment methods, and driving methods including a driving method using a lateral electric field such as an IPS method. Can be used.

  Further, in the liquid crystal display device according to the present embodiment described above, a transflective pixel that forms a transmissive display region is described as having a configuration in which a part of the pixel electrode is a reflective electrode and the remaining part is a transparent electrode. However, for example, a half-mirror-like pixel electrode that transmits the irradiation light from the back backlight and reflects external light can be used as the pixel electrode.

  The present invention is a liquid crystal display device in which the area of a non-display area that does not contribute to image display is reduced with respect to the surface area of the display device, and in particular, an image of a wide range of devices centering on applications as a display unit for mobile devices. It can be used industrially as a display device.

It is a disassembled perspective view which shows schematic structure of the liquid crystal display device concerning embodiment of this invention. It is the top view seen from the image display surface side of the liquid crystal display device concerning embodiment of this invention. It is the schematic which shows the cross-sectional structure of the liquid crystal display device concerning embodiment of this invention. It is a figure which shows the state of the various electrode arrangement | positioning on the back substrate of the liquid crystal display device concerning embodiment of this invention. (A) shows a case where a transflective pixel is provided in the transmissive display area, and (b) shows a case where a completely transmissive pixel is provided in the transmissive display area. It is a figure which shows the positional relationship of the image display area of a liquid crystal panel, and the uniform irradiation area | region of a backlight. It is a figure which shows the example of the display image in the liquid crystal display device concerning embodiment of this invention. It is a disassembled perspective view which shows schematic structure of the conventional liquid crystal display device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 2 Liquid crystal panel 3 Image display area 3a Transmission type display area 3b Reflection type display area 4 Backlight 5 Light guide plate (light guide means)
6 LED (light source)
DESCRIPTION OF SYMBOLS 10 Liquid crystal layer 11 Front substrate 12 Rear substrate 25 Pixel 25a Reflective pixel 25b Transflective pixel 25c Completely transmissive pixel

Claims (6)

A liquid crystal panel having a front substrate, a rear substrate, a liquid crystal layer sandwiched between the front substrate and the rear substrate, and displaying an image by changing its light transmittance for each pixel of the liquid crystal layer;
Comprising a light guide means and a backlight provided on the back surface of the liquid crystal panel, comprising a light source for irradiating the light guide means with light from the side thereof;
The image display area of the liquid crystal panel includes a reflective display area composed of reflective pixels that display an image using only reflected light of external light incident from the front substrate, and the back incident from the rear substrate. A transmissive display area composed of transmissive type pixels that display an image using light emitted from the light,
The liquid crystal display device, wherein the light source of the backlight is provided on a back surface of the reflective display area of the liquid crystal panel.   The transmissive type pixel is a transflective pixel that displays an image using both reflected light of external light incident from the front substrate and irradiation light from the backlight incident from the rear substrate. The liquid crystal display device according to claim 1.   2. The liquid crystal display device according to claim 1, wherein the transmissive type pixel is a completely transmissive type pixel that displays an image using only light emitted from the backlight incident from the back substrate.   4. The liquid crystal display device according to claim 1, wherein the light guide unit has a plate shape, and the light source is disposed to face a side surface of the light guide unit. 5.   The liquid crystal display device according to claim 1, wherein the light source is a light emitting diode.   The liquid crystal display device according to claim 1, wherein a light shielding member that blocks light from the light source is provided between the light source and the liquid crystal panel.

Images