JP2009053319A - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate luminance unevenness and color unevenness in a liquid crystal display wherein a liquid crystal panel is irradiated with light of a light source including a high luminance LED and a high color rendition LED. <P>SOLUTION: In the liquid crystal display 10, a liquid crystal panel 21, an optical sheet 22, a light guide plate 23, a monochrome liquid crystal panel 24 and a reflection sheet 25 are layered to form a display unit 20. When both of the two kinds of LEDs of a light source unit 30 are light-emitted, a first image pattern is displayed on the monochrome liquid crystal panel 24 and generation of luminance unevenness and color unevenness in the liquid crystal panel 21 is prevented. When only one of the two kinds of LEDs of the light source unit 30 is light-emitted, a second image pattern is displayed on the monochrome liquid crystal panel 24 and generation of luminance unevenness and color unevenness in the liquid crystal 21 is prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device in which luminance unevenness and color unevenness do not occur in a liquid crystal panel when a light emission state is switched using a light source unit including two types of LEDs having different light emission characteristics.

  Conventionally, small devices (display devices) such as mobile phones and digital cameras equipped with a liquid crystal panel often use a plurality of white LEDs (Light Emitting Diodes) as a light source for illuminating the liquid crystal panel. In general, a sidelight system is adopted. The sidelight system is a system in which a rectangular light guide plate is disposed on the back surface of a liquid crystal panel, and a light source such as a plurality of white LEDs is provided facing a side surface that is one side of the light guide plate. Since the light guide plate converts light from a point light source such as a white LED into a surface light source and guides the light to the back surface of the liquid crystal panel, the liquid crystal panel is irradiated with light from the light source by the function of such a light guide plate. The In a small display device, a chamfered slope may be formed at the corner of the light guide plate, and a light source may be disposed so as to irradiate the slope.

  A light source (white LED) that is currently mainstream used for illuminating a liquid crystal panel is a combination of a blue LED light-emitting chip and a phosphor. When a blue LED light emitting chip and a yellow phosphor (YAG) are combined, a white LED giving priority to luminance (referred to as a high luminance LED) is obtained. Further, when the blue LED light emitting chip and the red and green phosphors are combined, a white LED giving priority to color rendering (referred to as a high color rendering LED) is obtained. The color rendering property refers to the property of a light source that affects the appearance of the color of an object when a light source such as a lamp is illuminated. As a representative index of color rendering property, the average color rendering index Ra Is used. Ra indicates that the color rendering is better as the reference light source is 100, and the closer to 100.

  A small display device (liquid crystal display device) is usually portable and is used both outdoors and indoors, and display performance according to such changes in the usage environment is required. In other words, when used outdoors, it is exposed to sunlight, so that the sunlight reflects on the liquid crystal panel, making it difficult to see the display content, so that it is necessary to increase the luminance related to the display on the liquid crystal panel. On the other hand, in order to improve image quality under indoor light, it is necessary to improve color rendering for display. Therefore, two types of LEDs, a high-brightness LED and a high-color-rendering LED with different light emission characteristics, are used as the light source, and by illuminating the liquid crystal panel with both LEDs, the brightness is increased to make the display content easier to see, and high-color-rendering indoors. It is conceivable to perform switching control related to light emission of the LED such that display with enhanced color rendering is performed by irradiating only with the LED.

In the following Patent Document 1, a liquid crystal display device including a chromaticity correction LED in the vicinity of the LED is disclosed in order to reduce color unevenness of the liquid crystal panel of the liquid crystal display device. Patent Document 2 below discloses a liquid crystal display device that irradiates a liquid crystal panel using a plurality of light sources such as built-in LEDs and external light. Further, Patent Document 3 below discloses a liquid crystal display device that reduces luminance unevenness by changing the areas of a transmissive region and a reflective region provided in each pixel constituting a liquid crystal panel according to the distance from a light source. Yes. Furthermore, the following Patent Document 4 discloses a liquid crystal display device that eliminates color unevenness by using a dichroic mirror that reflects light according to the color (red, blue, green) of light emitted from the optical unit. .
JP 2001-209049 A JP 2005-130325 A JP 2005-49664 A JP 2005-107181 A

  FIG. 15 shows a conventional general liquid crystal display device 1, in which the liquid crystal panel 3, the diffusion sheet 4, the light guide plate 5, and the reflection sheet 6 (corresponding to a reflection member) are sequentially laminated. In addition, the light source unit 2 is arranged so as to face one side surface portion of the light guide plate 5. When the light source unit 2 of the liquid crystal display device 1 includes the high-intensity LED and the high color rendering LED described above and performs switching control of the LED to emit light, the light guide plate 2 has a light emission characteristic according to each LED. Since the light guide pattern has to be designed, there is a problem that luminance unevenness (and color unevenness associated therewith) occurs in the liquid crystal panel 3.

  The luminance unevenness will be described with reference to FIGS. 16 (a) and 16 (b) show the liquid crystal display device 1 provided with the light source unit 2 in which the high luminance LEDs 2a and the high color rendering LEDs 2b are alternately arranged on the base 2c, and the light guide plate 5 arranged on the back surface of the liquid crystal panel 3. Has a light guide pattern that makes the luminance of the liquid crystal panel 3 uniform in accordance with the irradiation of the high color rendering LED 2b. For this reason, as shown in FIG. 16A, when only the high color rendering LED 2b is used for indoor use, the region including the central portion of the liquid crystal panel 3 (shown by a wavy line in the drawing) is uniformly irradiated. Therefore, luminance unevenness and color unevenness do not occur. On the other hand, as shown in FIG. 16 (b), when both the high-brightness LED 2a and the high color rendering LED 2b are irradiated for outdoor use, the overall luminance increases, but the high-brightness LED 2a is irradiated. The light is not uniformly distributed by the light guide plate, and a bright area R1 (area shown by hatching in the drawing) is generated in the portion irradiated with the high-intensity LED 2a, thereby causing uneven brightness in the area R1. .

  Also, the liquid crystal display device 1 ′ shown in FIGS. 17A and 17B has a high luminance LED 2a ′ and a high color rendering LED 2b ′ as a base 2c ′ in the same manner as the liquid crystal display device 1 shown in FIGS. The liquid crystal panel 3 'is irradiated by the arranged light source unit 2'. The light guide pattern of the light guide plate 5 'disposed on the back surface of the liquid crystal panel 3 is irradiated by both the high luminance LED 2a' and the high color rendering LED 2b '. In this case, the light from the LEDs 2a ′ and 2b ′ is uniformly distributed. For this reason, as shown in FIG. 17 (a), when the LEDs 2a 'and 2b' are irradiated for use outdoors, a region (indicated by a wavy line) including the center of the liquid crystal panel 3 'is formed. Irradiation is uniform and luminance unevenness and color unevenness do not occur. However, as shown in FIG. 17B, when irradiation is performed only with the high color rendering LED 2b 'for indoor use, the high color rendering LED 2b' is irradiated. On the other hand, an area R2 (area shown by hatching in the figure) that is dark and falls in the range corresponding to the high-intensity LED 2a 'occurs, and brightness unevenness occurs.

  Since the high luminance LED and the high color rendering LED emit white light having different color components, color unevenness occurs in the liquid crystal panel as luminance unevenness occurs. Specifically, the light emitted from the high-intensity LED is pseudo white light composed only of blue and yellow as color components. On the other hand, the light emitted from the high color rendering LED is composed of blue, red, and green color components, and is more natural white light. For this reason, the color tone of the display content is different between the region irradiated with the high luminance LED and the region irradiated with the high color rendering LED, and color unevenness occurs.

  Further, in FIGS. 16A and 16B described above, a light guide pattern in which light emitted from the high color rendering LED 2 b is uniformly distributed is provided on the light guide plate 5. In order to form unevenness on the surface, it is necessary to cut the working mold of the light guide plate 5 according to the light guide pattern, and in order to form the light guide pattern by printing, dot pattern printing is applied to the light guide plate 5. In any case, it is a factor that increases the manufacturing cost of the light guide plate 5. The same applies to the light guide plate 5 ′ shown in FIGS. 17 (a) and 17 (b).

  The present invention has been made in view of such problems, and a display element that is stacked on a liquid crystal panel is newly provided, and an image pattern corresponding to the contour shape of a region where luminance unevenness and color unevenness occur is provided on the display element. An object of the present invention is to provide a liquid crystal display device that eliminates luminance unevenness and color unevenness generated in a liquid crystal panel without forming a light guide pattern on the light guide plate.

  In order to solve the above problems, a liquid crystal display device according to the present invention includes a light source unit that irradiates the liquid crystal panel via a light guide plate disposed between the liquid crystal panel and a reflective member. The unit includes a first LED and a second LED having different light emission characteristics, wherein the first LED has a higher luminance than the second LED, and the second LED has a higher color rendering than the first LED, A switching means for switching between a first light emitting state in which both the first LED and the second LED emit light and a second light emitting state in which the second LED emits light; a monochrome liquid crystal panel disposed between the light guide plate and the reflecting member; Storage means for storing an image pattern to be displayed on the monochrome liquid crystal panel, and the monochrome liquid crystal panel for displaying an image on the liquid crystal panel. Characterized in that it comprises a display processing unit that performs processing for displaying the image pattern.

  In the present invention, the image pattern is displayed on the monochrome liquid crystal panel disposed between the light guide plate and the reflecting member in accordance with the display on the liquid crystal panel, so that the light emitted from the light source unit is transmitted through the light guide plate. When the light travels toward the reflecting member, the monochrome liquid crystal panel functions as a shutter function, and the light traveling toward the reflective member is blocked by the image pattern displayed on the monochrome liquid crystal panel. As a result, luminance scattering at a location corresponding to the image pattern is suppressed, and thereby brightness is also suppressed. Therefore, brightness in the liquid crystal panel can be adjusted as appropriate according to the shape of the image pattern displayed on the monochrome liquid crystal panel, and brightness adjustment is performed. This degree can also be set as appropriate depending on the coarse density of the black dots forming the image pattern. Therefore, if an image pattern is prepared according to the light emission state of the light source unit and appropriately displayed on the monochrome liquid crystal panel, the brightness adjustment according to each light emission state, that is, without forming the light guide pattern on the light guide plate, that is, Brightness adjustment can be performed, and accordingly color unevenness can be eliminated.

  In the liquid crystal display device according to the present invention, the liquid crystal panel has a rectangular shape around the panel, the light source unit is arranged to face one side of the liquid crystal panel, and the monochrome liquid crystal panel is The size of the liquid crystal panel is determined in accordance with a range that includes one side of the liquid crystal panel and does not include the other side that is opposite to the one side.

  In the present invention, since the monochrome liquid crystal panel has dimensions corresponding to a range including one side of the liquid crystal panel and not including the other side, the size of the monochrome liquid crystal panel is smaller than that of the liquid crystal panel. Can contribute to cost reduction. Even in this case, since the monochrome liquid crystal panel is located on the side close to the light source unit, a required image pattern is displayed on the monochrome liquid crystal panel in a range close to the light source unit where uneven brightness and color unevenness are likely to occur. Thus, the brightness can be adjusted so as to eliminate luminance unevenness and color unevenness. In the range where there is no monochrome liquid crystal panel, it is possible to form a light guide pattern on the light guide plate according to the degree of occurrence of luminance unevenness and color unevenness, but in this way the light guide pattern is partially formed In this case, the cost is much lower than when the light guide pattern is formed over the entire surface. Note that if a liquid crystal panel having so-called memory characteristics is used as the monochrome liquid crystal panel, display of an image pattern can be maintained without applying voltage, which is effective in reducing power consumption.

The liquid crystal display device according to the present invention includes a light source unit that irradiates the liquid crystal panel through a light guide plate disposed opposite to the liquid crystal panel, wherein the light source unit includes first LEDs having different light emission characteristics and Including a second LED, the first LED is higher in luminance than the second LED, and the second LED is higher in color rendering than the first LED;
Switching means for switching between a first light emitting state for emitting both the first LED and the second LED and a second light emitting state for emitting the second LED, and a surface opposite to the liquid crystal panel of the light guide plate A reflective display element disposed on the display, storage means for storing an image pattern to be displayed on the reflective display element, and a process for displaying the image pattern on the reflective display element when displaying an image on the liquid crystal panel Display processing means for performing the above.

  In the present invention, a reflective display element is arranged on one surface of the light guide plate instead of a general reflective member (for example, a reflective sheet), and an image pattern is displayed on the reflective display element. The degree of light reflected by the reflective display element and directed to the light guide plate can be adjusted. That is, the reflective display element functions in the same manner as a normal reflective member when not displaying an image pattern, but when displaying the image pattern, the light directed to the location where the image pattern is displayed is suppressed in reflection, The amount of light traveling toward the light guide plate is reduced. Therefore, by adjusting the shape of the image pattern to the position and unevenness where the luminance unevenness and color unevenness of the liquid crystal panel are generated, the luminance unevenness and color unevenness can be eliminated. Note that the reflective display element corresponds to, for example, electronic paper. If this electronic paper is also of a type having memory characteristics, display of an image pattern can be maintained without applying voltage, and power consumption can be reduced. It becomes suitable for.

  The liquid crystal display device according to the present invention includes a light source unit that irradiates the liquid crystal panel through a light guide plate disposed opposite to the liquid crystal panel, wherein the light source unit includes first LEDs having different light emission characteristics and The second LED includes a second LED, the first LED has higher luminance than the second LED, the second LED has higher color rendering than the first LED, and emits both the first LED and the second LED. Switching means for switching between a first light emitting state and a second light emitting state for causing the second LED to emit light, a self-luminous display element disposed so as to face a surface of the light guide plate opposite to the liquid crystal panel, Storage means for storing an image pattern to be displayed on the light emitting display element, and the image pattern on the self light emitting display element when displaying an image on the liquid crystal panel. Characterized in that it comprises a display processing unit that performs a process of displaying the.

  In the present invention, a self-luminous display element is arranged on one surface of the light guide plate instead of a general reflective member (for example, a reflective sheet), and an image pattern is displayed on the self-luminous display element. Therefore, it is possible to adjust the degree of light reflected by the self-luminous display element and traveling toward the light guide plate. That is, the self-luminous display element reflects light in the same manner as the reflecting member when the image pattern is not displayed. However, when the image pattern is displayed, the reflection at the displayed position of the image pattern is the image. It becomes stronger than the part where the pattern is not displayed. Therefore, if an image pattern is displayed in a place that is dark due to luminance unevenness and color unevenness of the liquid crystal panel, the brightness of the dark portion of the display panel is increased and the luminance unevenness and color unevenness are eliminated. Become.

  In the liquid crystal display device according to the present invention, the storage means is irradiated with the first image pattern corresponding to the contour shape of the portion irradiated with the light emitted from the first LED and the light emitted from the second LED. And a second image pattern corresponding to the contour shape of the location to be stored, and the display processing means performs display processing of the first image pattern when the switching means switches to the first light emission state. In addition, when the switching unit switches to the second light emission state, the display processing of the second image pattern is performed.

  In this invention, while displaying the 1st image pattern according to the outline shape of the location irradiated with the light emitted from 1st LED in a 1st light emission state, it is irradiated with the light emitted from 2nd LED. Since the second image pattern corresponding to the contour shape of the portion is displayed in the second light emission state, luminance scattering is appropriately suppressed in each image pattern in any light emission state, so that luminance unevenness and color unevenness do not occur in the liquid crystal panel. The brightness is adjusted. Therefore, even if a light guide pattern is not provided on the light guide plate, appropriate light guide can be performed in any light emitting state, and the manufacturing cost of the light guide plate can be reduced.

In the liquid crystal display device according to the present invention, the light guide plate has a rectangular overall peripheral shape, and a chamfered oblique side portion is formed at at least one corner, and the light source unit includes: It arrange | positions so that the said oblique side part may be opposed.
In the present invention, since the light source unit is arranged facing the oblique side portion of the light guide plate, even in a structure applied to a small-sized liquid crystal display device, luminance unevenness and color unevenness are applied by applying the configuration according to the present invention. Can be eliminated.

In the present invention, an image pattern is displayed on the monochrome liquid crystal panel disposed between the light guide plate and the reflecting member in accordance with the display on the liquid crystal panel, so that the brightness of the liquid crystal panel is appropriately set based on the image pattern. Can be adjusted.
In the present invention, since the monochrome liquid crystal panel is sized according to the range including one side of the liquid crystal panel and not including the other side, the size of the monochrome liquid crystal panel is reduced. Thus, the cost associated with the liquid crystal display device can be reduced.

In the present invention, since the image pattern is displayed on the reflective display element arranged on one surface of the light guide plate, the brightness of the liquid crystal panel can be appropriately adjusted based on the image pattern.
In the present invention, since the image pattern is displayed on the self-luminous display element arranged on one surface of the light guide plate, the brightness of the liquid crystal panel is increased so as to increase the brightness of the portion of the liquid crystal panel corresponding to the image pattern. Adjustment related to brightness can be realized.

In the present invention, the first image pattern corresponding to the contour shape of the portion irradiated with the light emitted from the first LED is displayed in the first light emission state, while the light emitted from the second LED is emitted. Since the second image pattern corresponding to the contour shape of the location is displayed in the second light emission state, the brightness can be adjusted appropriately in the two light emission states without providing the light guide pattern on the light guide plate. The cost associated with the light plate can be reduced, and the luminance unevenness and color unevenness of the liquid crystal panel can be eliminated.
In the present invention, since the light source unit is arranged facing the oblique side portion of the light guide plate, even in a structure applied to a small-sized liquid crystal display device, the luminance unevenness and Color unevenness can be eliminated.

  FIG. 1 is a block diagram showing a main internal configuration of the liquid crystal display device 10 according to the first embodiment of the present invention. The liquid crystal display device 10 is applicable to a device (display device that can be used both indoors and outdoors) having a display panel (liquid crystal panel) such as a mobile phone or a digital video camera. For example, the present invention can also be applied as a portable television apparatus compatible with one-segment broadcasting. The liquid crystal display device 10 includes a display 17 that stores a display data acquisition unit 11, a synchronization signal generation unit 12, a signal processing unit 13, a first interface unit 14, a second interface unit 15, an operation unit 16, and a pattern table 18 in advance. The control unit 19 and the display unit 20 are included. Hereinafter, the liquid crystal display device 10 of the present embodiment will be described in detail.

  The display data acquisition unit 11 performs a process of acquiring display screen data corresponding to the screen content displayed on the liquid crystal panel 21 included in the display unit 20, and acquires display screen data depending on the target to which the liquid crystal display device 10 is applied. The destination is different. For example, when the liquid crystal display device 10 corresponds to a portable television device compatible with one-segment broadcasting, the display data acquisition unit 11 acquires display screen data from the one-segment tuner. When the liquid crystal display device 10 is applied to a digital video camera, the display data acquisition unit 11 acquires display screen data from an image sensor (CCD, CMOS, etc.) that captures an image. The display data acquisition unit 11 sends the acquired display screen data to the signal processing unit 13 in RGB signal units.

  The synchronization signal generation unit 12 generates a horizontal synchronization signal and a vertical synchronization signal corresponding to the display on the liquid crystal panel 21 included in the display unit 20, and sends the generated synchronization signal to the signal processing unit 13 and the control unit 19. ing. In addition, the signal processing unit 13 performs a necessary process for displaying the display screen data sent from the display data obtaining unit 11 on the display unit 20 in synchronization with the synchronization signal sent from the synchronization signal generating unit 12. For example, gamma correction is performed as a required process. The signal processing unit 13 sends the processed display screen data to the first interface unit 14.

  The first interface unit 14 corresponds to a data supply means, and synchronizes the processed display screen data sent from the signal processing unit 13 to the liquid crystal panel 21 of the display unit 20 with the synchronization signal sent from the synchronization signal generating unit 12. Process to supply. The first interface unit 14 supplies the display screen data to the liquid crystal panel 21, so that a screen corresponding to the display screen data is displayed on the liquid crystal panel 21.

  In the display unit 20, an optical sheet 22, a light guide plate 23, a monochrome liquid crystal panel 24, and a reflection sheet 25 (corresponding to a reflection member) are sequentially laminated on the back side of the liquid crystal panel 21, and the periphery of the panel is rectangular in plan view. The light source unit 30 is arranged so as to face one side surface portion 23a of the light guide plate 23 on the same side as the one side portion 21a of the liquid crystal panel 21 having a shape. The optical sheet 22 is made of PET and has functions of a prism sheet and a diffusion sheet. The optical sheet 22 has a function of improving the front luminance by condensing, and improving the luminance with respect to the liquid crystal panel 21, diffusing light, reducing luminance unevenness, and the like. I do.

  The light guide plate 23 disposed between the liquid crystal panel 21 (a display panel having 320 pixels in the horizontal direction (X direction) and 240 pixels in the vertical direction (Y direction)) and the reflection sheet 25 is irradiated from the light source unit 30. This function has the function of directing the light to the liquid crystal panel 21 using the reflection of the reflection sheet 25. The light guide plate 23 of this embodiment is a light guide pattern like the light guide plate 5 included in the liquid crystal display device 1 shown in FIGS. 16A and 16B or the liquid crystal display device 1 shown in FIGS. Since the light guide pattern such as the light guide plate 5 'included in' is not formed, the manufacturing cost is reduced as compared with these light guide plates 5, 5 '.

  The monochrome liquid crystal panel 24 is a display panel composed of an active matrix type display element without a color filter, and has the same size and the same number of pixels as the liquid crystal panel 21. A second interface unit 15 is connected to the monochrome liquid crystal panel 24, and is stored in the memory 17 in accordance with the display of the image based on the display screen data on the liquid crystal panel 21 under the control of the control unit 19. The image pattern stored in the pattern table 18 is read out and displayed on the monochrome liquid crystal panel 24. The pattern table 18 stores two types of image patterns. The first is the first image pattern 35 shown in FIG. 2B, and the second is the first image pattern shown in FIG. This is a two-image pattern 36.

  The light source unit 30 irradiates the liquid crystal panel 21 through the light guide plate 23. As shown in FIG. 2A, the light source unit 30 corresponds to a total of four high-intensity LEDs (first LEDs. LED) 33 and a total of three high color rendering LEDs (corresponding to the second LED) 32 are alternately arranged at equal intervals on the base 31. The high luminance LED 33 has higher luminance than the high color rendering LED 32 in terms of light emission characteristics, and the high color rendering LED 32 has higher color rendering properties than the high luminance LEDs 33 in terms of light emission characteristics. These LEDs 32 and 33 are arranged so as to be symmetric from the center of one side portion 21a in the longitudinal direction of the liquid crystal panel 21 to the left and right sides in FIG.

In the present embodiment, the high-intensity LED 33 is a white LED composed of a blue LED light-emitting chip and a yellow phosphor (Ca-α sialon), and the high color rendering LED 32 is a blue LED. A white LED composed of a light emitting chip, a red phosphor (CaAlSiN ₃ ), and a green phosphor (β sialon) is used. Furthermore, in the present embodiment, a chip-shaped LED is applied to each of the LEDs 32 and 33, but it is of course possible to apply a bullet-type or flat-type LED.

  The display states of the LEDs 32 and 33 included in the light source unit 30 are controlled by the control unit 19, and the control unit 19 switches the display states of the LEDs 32 and 33 according to the operation state of the changeover switch included in the operation unit 16. Specifically, the operation unit 16 includes a changeover switch for switching between an outdoor display pattern and an indoor display pattern, and when this changeover switch is operated to the outdoor display pattern side by the user, The control unit 19 sets, as a switching unit, a state in which both the high luminance LED 33 and the high color rendering LED 32 included in the light source unit 30 emit light (first light emitting state). Further, when the switch of the operation unit 16 is operated to the indoor display pattern side by the user, the control unit 19 causes the high color rendering LED 32 included in the light source unit 30 to emit light (second light emission state) as a switching unit. Switch to.

  FIG. 2A shows the display state of the display panel 21 in a state where the processing according to the present invention is not performed when the changeover switch of the operation unit 16 is set to the outdoor display pattern (first light emission state). It is the schematic which showed. In this case, a region R10 corresponding to a location facing each LED 32, 33 (a location irradiated to each LED 32, 33) is in another location in the range on the side 21a side of the liquid crystal panel 21 close to the light source unit 30. Since it becomes brighter than that, luminance unevenness and color unevenness occur. Moreover, the outline shape of area | region R10 is just the waveform curve L10 which the location which opposes the center part of each LED32 and 33 protruded sharply. In the region R10, the brightened level is not uniform, and the brightest is the portion corresponding to the center line of each of the LEDs 32 and 33, and the brighter level decreases as the distance from the center line increases to the left and right. ing.

  FIG. 2B shows a first image pattern 35 displayed on the monochrome liquid crystal panel 24 under the control of the control unit 19 when an image is displayed on the liquid crystal panel 21. The first image pattern 35 has a pattern shape 35a equivalent to the waveform curve L10 corresponding to the contour of the region R10 generated in the first light emission state of FIG. A portion surrounded by the light source unit 30 side of the pattern shape 35a is simply represented by a black solid in FIG. 2A, but this black solid portion is formed by a set of black dots. Corresponding to the brightness level of the region R10 in FIG. 2 (a), the black dots are dense in the portion where the brightness level is high, and the black dots become sparse as the brightness level decreases. The coarse density of black dots is changed according to the location of the brightness level.

  By displaying the first image pattern 35 described above on the monochrome liquid crystal panel 24, luminance scattering in the region R10 in FIG. 2A is suppressed, and brightness of the luminance distribution is controlled so as not to be noticeable. Unevenness and color unevenness are eliminated. Specifically, as shown in FIG. 1, the first image pattern displayed on the monochrome liquid crystal panel 24 once the light emitted from the light source unit 30 passes through the light guide plate 23 toward the monochrome liquid crystal panel 24. Depending on the traveling position of the light with respect to 35, light whose progress is suppressed is generated.

  FIG. 3A shows the degree of light travel along the line AA in FIG. 2B, and the light K1 hits the pattern shape 35a of the first image pattern 35 displayed on the monochrome liquid crystal panel 24. FIG. The black dots that are displayed are almost absorbed, and the amount of light K1 decreases. On the other hand, the light K2 directed toward the monochrome liquid crystal panel 24 at a location away from the arrangement side of the light source unit 30 does not hit the pattern shape 35a, and therefore passes through the monochrome liquid crystal panel 24 and is reflected by the reflection sheet 25. The liquid crystal panel 21 passes through the monochrome liquid crystal panel 24.

  FIG. 3B shows the degree of light traveling along the line BB in FIG. 2B, and the light K3 is the pattern shape 35a of the first image pattern 35 displayed on the monochrome liquid crystal panel 24. Therefore, similar to the light K1 in FIG. 3A, the black dots are almost absorbed and the light quantity of the light K3 decreases. On the other hand, the light K4 directed to the monochrome liquid crystal panel 24 at a location away from the arrangement side of the light source unit 30 travels in the same manner as the light K2 in FIG. Since the pattern shape 35a of the first image pattern 35 has a difference in the density of black dots depending on the location, even if the pattern shape 35a hits the pattern shape 35a, there is a difference in the degree of light amount reduction depending on the hit location. Since this difference corresponds to the difference in brightness level of the region R10 described above, the amount of light decreases as the brightness level increases, and the degree of decrease in light amount decreases as the brightness level decreases.

  FIG. 4 shows a display state of the liquid crystal panel 21 whose brightness is adjusted by the display of the first image pattern 35 on the monochrome liquid crystal panel 24 described above, and the first image is displayed even when the light source unit 30 is in the first light emission state. As a result of the luminance scattering being suppressed by the pattern 35, luminance unevenness and color unevenness in the liquid crystal panel 21 are eliminated.

  FIG. 5A shows the pattern of the second image pattern 36 displayed on the monochrome liquid crystal screen 24 when the changeover switch of the operation unit 16 is set to the indoor display pattern (second light emission state). The shape 36a is shown. This pattern shape 36a also corresponds to the contour of the region where the luminance unevenness and the color unevenness are displayed on the liquid crystal panel 21 when the processing according to the present invention is not performed (corresponding to the portion irradiated to the high color rendering LED 32). In FIG. 5A, the black solid portion in FIG. 5A is a set of black dots, and the brightness levels of the areas where the luminance unevenness and color unevenness of the liquid crystal panel 21 are generated are different. The sparse density of the black dots differs according to the same as the first image pattern 35.

  Therefore, the liquid crystal display device 10 of the first embodiment displays the second image pattern 36 as shown in FIG. 5A on the monochrome liquid crystal screen 24 in the second light emission state in which only the high color rendering LED 32 emits light. As shown in FIG. 5B, the liquid crystal panel 21 does not cause luminance unevenness and color unevenness.

  Note that the liquid crystal display device 10 according to the present invention is not limited to the above description, and there are various modifications. For example, switching between the first light emission state and the second light emission state is performed based on an operation instruction with a change-over switch provided in the operation unit 16, but switching is performed using an illuminance sensor that detects illuminance. Also good. In this case, the illuminance sensor is connected to the control unit 19, and a threshold value related to illuminance is stored in the memory 17. When the value detected by the illuminance sensor exceeds the threshold value, it is determined that the user is outdoors and the first light emission state When the detected value falls below the threshold value, the control unit 19 performs control to determine that the detected value is indoors and switch to the second light emission state. Further, the number of the high luminance LEDs 33 and the high color rendering LEDs 32 of the light source unit 30 can be appropriately increased or decreased according to the size or specification of the liquid crystal panel 21, and the order in which the high luminance LEDs 33 and the high color rendering LEDs 32 are arranged is shown in FIG. It is also possible to reverse the case shown in FIG.

  Furthermore, in addition to the monochrome liquid crystal panel 24 that can display an image only when a voltage is applied, a so-called memory liquid crystal panel composed of pixels having memory characteristics can be applied to the monochrome liquid crystal panel 24. is there. In this case, once the first image pattern 35 or the second image pattern 36 is displayed on the monochrome liquid crystal panel 24, the first image pattern 35 or the second image pattern 35 can be used without applying a voltage to the monochrome liquid crystal panel 24 thereafter. Since the display of the image pattern 36 can be maintained, it is preferable in terms of suppressing power consumption. Furthermore, it is also possible to use a so-called white liquid crystal panel for the monochrome liquid crystal panel 24 in which the portion where the image is displayed becomes white and the portion where the image is not displayed becomes black. In this case, as shown in FIG. In the first image pattern 35, a white portion is displayed in the figure, and a white portion is also displayed in the second image pattern 36 of FIG.

  FIG. 6A shows a display unit 40 according to a modification of the first embodiment. In this display unit 40, an oblique side portion 41c is formed at a corner portion where the long side portion 41a and the short side portion 41b of the rectangular liquid crystal panel 41 intersect, and the light source unit 50 is disposed so as to face the oblique side portion 41c. It is a feature. In the light source unit 50, a high luminance LED 53 and a high color rendering LED 52 are arranged on the base 51. Further, the optical sheet 42, the light guide plate 43, the monochrome liquid crystal panel 44, and the reflection sheet 45 disposed on the back side of the liquid crystal panel 41 have the same peripheral shape as the liquid crystal panel 41.

  Since the light guide pattern is not formed on the light guide plate 43, in the first light emitting state shown in FIG. 6A, luminance unevenness and color unevenness occur in the region R20 including the portion irradiated to each LED 52, 53, The contour of the region R20 is a waveform curve L20 in which the facing portions of the LEDs 52 and 53 protrude most sharply. FIG. 6B shows a first image pattern 55 of a modified example displayed on the monochrome liquid crystal panel 44, and this first image pattern 55 has the shape of the waveform curve L10 in the region R20 of FIG. It has a pattern shape 55a according to the above. Therefore, even in the display unit 40 having such a configuration, the luminance unevenness and color unevenness shown in FIG. 6A are eliminated by displaying the first image pattern 55 of the monochrome liquid crystal panel 44. In this modification as well, in the second light emitting state, the second image pattern corresponding to the contour shape of the irradiated portion of the high color rendering LED 52 is read from the pattern table 18 of the memory 17 and displayed on the monochrome liquid crystal panel 44 in the same manner. Thus, luminance unevenness and color unevenness in the second light emission state can be eliminated.

  FIG. 7A shows a display unit 60 according to another modification. The display unit 60 has a monochrome liquid crystal panel 64 on the side where the light source unit 66 is located as compared with the monochrome liquid crystal panel 24 of FIG. The feature is that it is the size of the lower half. In the display unit 60, the light source unit 66 is arranged on the one side 61a side of the liquid crystal panel 61. Therefore, the other side 61b opposite to the one side 61a is away from the light source unit 66, thereby causing uneven brightness. Hateful.

  For this reason, as shown in FIG. 7B, the monochrome liquid crystal panel 64 includes the one side portion 61a on the light source unit 66 side, and does not include the opposite side portion 61b side on the one side portion 61a (Y = 119 to The size of the monochrome liquid crystal panel 64 can be reduced by making the dimensions according to the range corresponding to the pixel of Y = 239), and accordingly, the first shape including the pattern shape 68a equivalent to the pattern shape 35a of FIG. The size of one image pattern 68 can be halved, and the occupation ratio of the memory 17 can be reduced. In this case, the light guide pattern may be formed in the range 63b of the light guide plate 63 where the monochrome liquid crystal panel 64 does not exist. However, the formation range is small compared to the case where the light guide pattern is formed over the entire surface. A light guide pattern can be formed at low cost.

  FIG. 8 shows a liquid crystal display device 70 according to the second embodiment of the present invention. The liquid crystal display device 70 has substantially the same specifications as those of the first embodiment except for the configuration of the display unit 80, and includes a display data acquisition unit 71, a synchronization signal generation unit 72, a signal processing unit 73, a first interface unit 74, A second interface unit 75, an operation unit 76, a memory 77 (corresponding to storage means) that stores a pattern table 78 in advance, a control unit 79, and a display unit 80 are included. On the other hand, in the display unit 80, the optical sheet 82, the light guide plate 83, and the electronic paper 84 are sequentially stacked on the back side of the liquid crystal panel 81, and one side portion of the liquid crystal panel 81 having a rectangular periphery in plan view. The light source unit 90 is arranged on the side facing 81a.

  The electronic paper 84 corresponds to a reflective display element, and can display a first image pattern, a second image pattern, and the like equivalent to those of the first embodiment stored in a pattern table 78 stored in the memory 77. When the pattern is not displayed, a reflection function equivalent to that of the reflection sheet is secured.

  FIG. 9A corresponds to the state of FIG. 2A of the first embodiment. When the processing according to the second embodiment is not performed, the base 91 of the light source unit 90 is displayed on the display panel 81. Luminance unevenness and color unevenness are generated in a region R30 corresponding to a portion irradiated to the arranged high luminance LED 93 and high color rendering LED 92. FIG. 9B shows a first moving image pattern 95 displayed on the electronic paper 95. This first moving image pattern 95 is equivalent to the first moving image pattern 35 of the first embodiment. 9 (a) has a pattern shape 95a corresponding to the waveform curve L30 in the region R30.

  FIG. 10A illustrates the degree of light reflection on the surface 84a of the electronic paper 84 taken along the line CC in FIG. 9B, and the light K10 is the first displayed on the surface 84a of the electronic paper 84. Since the light hits the pattern shape 95a of the image pattern 95, almost all of the light is absorbed by the displayed black dots, and the light K10 is hardly reflected by the surface 84a of the electronic paper 84. On the other hand, the light K11 directed toward the surface 84a of the electronic paper 84 at a location away from the arrangement side of the light source unit 90 does not hit the pattern shape 95a, and therefore is reflected by the surface 84a and passes through the light guide plate 83 and the like. Head to 81.

  FIG. 10B shows the degree of light travel along the line DD in FIG. 9B, and the light K12 is a pattern of the first image pattern 95 displayed on the surface 84a of the electronic paper 84. Since it hits the shape, like the light K10 in FIG. 9A, it is almost absorbed by the black dots, and the light quantity of the light K12 decreases. On the other hand, the light K13 directed toward the surface 84a of the electronic paper 84 at a location away from the arrangement side of the light source unit 90 travels in the same manner as the light K11 in FIG. Note that the pattern shape 95a of the first image pattern 95 also has a difference in the density of black dots depending on the location, as in the first embodiment.

  In the second embodiment, as described above, an image pattern is displayed on the electronic paper 84 used in place of the reflection sheet, so that the amount of reflection of light emitted from the light source unit 90 is changed to a position where luminance unevenness and color unevenness occur. Since the adjustment is made accordingly, it is possible to control the luminance distribution so that the luminance is not conspicuous by suppressing the luminance scattering, and the luminance unevenness and the color unevenness are eliminated. In the liquid crystal display device 70 according to the second embodiment, when the second light emitting state is switched, a pattern shape equivalent to the second image pattern 36 according to the first embodiment shown in FIG. Thus, luminance unevenness and color unevenness are prevented from occurring even in the second light emission state. In the second embodiment, the various modifications described in the first embodiment can be applied. In particular, once the electronic paper 84 displays an image pattern, the display is maintained even if the voltage application is canceled. This is preferable in terms of power saving.

  The display unit 100 according to the modification of the second embodiment shown in FIGS. 11 (a) and 11 (b) corresponds to the modification shown in FIGS. 7 (a) and 7 (b) of the first embodiment. The paper 104 is formed in a size corresponding to the lower half (the range of Y = 119 to Y = 239 of the liquid crystal panel 101) on the side where the light source unit 106 is disposed. In the second embodiment, the upper half is formed. The reflective sheet 105 is joined to the upper side portion 104b of the electronic paper 104 at the location. In this way, the pattern shape 108a of the first image pattern 108 shown in FIG. 11B can be displayed on the surface 104a of the electronic paper 104, and the brightness of the liquid crystal panel 101 can be adjusted. In the upper half away from 106, the light is reflected by the normal reflection sheet 105, passes through the light guide plate 103 and the optical sheet 102, travels to the liquid crystal panel 101, and the liquid crystal panel 101 can be appropriately irradiated.

  FIG. 12 shows a liquid crystal display device 110 according to the third embodiment of the present invention. The liquid crystal display device 110 has substantially the same specifications as those of the first and second embodiments except for the configuration of the display unit 120. The display data acquisition unit 111, the synchronization signal generation unit 112, the signal processing unit 113, A first interface unit 114, a second interface unit 115, an operation unit 116, a memory 117 (corresponding to storage means) that stores a pattern table 118 in advance, a control unit 119, and a display unit 120 are included. On the other hand, in the display unit 120, the optical sheet 122, the light guide plate 123, and the EL element panel 124 are sequentially stacked on the back side of the liquid crystal panel 121, and one side of the liquid crystal panel 121 having a rectangular periphery in plan view. The light source unit 130 having the same configuration as that of the first embodiment is disposed on the side facing the portion 121a.

  An EL (Electro-Luminescence) element panel 124 corresponds to a self-luminous display element (for example, a white light-emitting active matrix EL element), and the first embodiment stored in the pattern table 118 stored in the memory 117. A first image pattern, a second image pattern, and the like having the same pattern shape can be displayed, and when the image pattern is not displayed, a reflection function equivalent to that of the reflection sheet is secured. Note that the EL element panel 124 has a characteristic that when the image pattern is displayed, the whiteness of the displayed image pattern increases, so that the luminance of the portion corresponding to the image pattern increases. Therefore, the first image pattern and the second image pattern of the third embodiment are the same as the first embodiment in the pattern shape itself, but the first image pattern 35 of FIG. 2A and the pattern of FIG. The pattern shape of the white portion in the second image pattern 36 is displayed on the EL element panel 124.

  FIG. 13 shows a state in which the first image pattern 135 corresponding to the first light emission state is displayed on the surface 124a of the EL element panel 124, and a region R40 indicated by hatching in FIG. It is assumed that a region R41 (a portion represented in white in FIG. 13) outside the waveform curve L40 representing the contour of the region R40 is displayed on the EL liquid crystal panel 124.

  FIG. 14A shows the degree of light reflection on the surface 124a of the EL element panel 124 taken along the line E-E in FIG. 13B, and the light K20 is not displayed on the EL element panel 124. Since the light is reflected from the region R40, there is no increase in the amount of light. On the other hand, the light K21 reflected by the region R41 where the display is performed has an increased luminance after reflection. FIG. 14B shows the degree of light travel along the line FF in FIG. 13B, and the light K22 strikes the region R40 displayed on the surface 124a of the EL element panel 124. Is reflected without increasing, and the light K23 is reflected by the region R41 where the display is performed, so that the luminance after reflection is increased. In addition, although light K21-K23 will all irradiate the liquid crystal panel 121 after reflection, since the brightness | luminance of the light K21 and K23 reflected by area | region R41 has increased, after all the irradiation location of each LED of the light source unit 130 As a result, the luminance difference is eliminated in the liquid crystal panel 121 as a whole, and accordingly, the occurrence of luminance unevenness and color unevenness is prevented.

  In the above description, the case where the first image pattern 135 is displayed on the EL element panel 124 in the first light emission state has been described. However, the same processing as described above is performed when the second image pattern is displayed in the second light emission state. In particular, the configuration of the second image pattern is the same as the first image pattern 135 shown in FIG. 13, but the display location is the reverse of the first embodiment and the second embodiment. Also in the third embodiment, various modifications described in the first embodiment can be applied.

It is a block diagram which shows the principal part of the liquid crystal display device which concerns on 1st Embodiment of this invention. (A) is the schematic which shows the display state when not performing the process which concerns on this invention in a 1st light emission state, (b) is the schematic which shows the state which displayed the 1st image pattern on the monochrome liquid crystal panel. FIG. 2A is a schematic cross-sectional view showing the light traveling state along the line AA in FIG. 2B, and FIG. 2B is a schematic cross-sectional view illustrating the light traveling state along the line BB in FIG. It is. It is the schematic which shows the state by which the brightness nonuniformity in the liquid crystal panel and the color nonuniformity were eliminated by the display of the 1st image pattern in a monochrome liquid crystal panel. (A) is a schematic diagram illustrating a state in which a second image pattern is displayed on a monochrome liquid crystal panel, and (b) is a schematic diagram illustrating a state in which luminance unevenness and color unevenness are eliminated by displaying the second image pattern on the monochrome liquid crystal panel. FIG. It is a display unit of a modification, (a) is a schematic diagram showing a display state when the processing according to the present invention is not performed in the first light emission state, (b) is a state in which the first image pattern is displayed on the monochrome liquid crystal panel FIG. (A) is the schematic from the side of the display unit which concerns on another modification, (b) It is the schematic which shows the state which displayed the 1st image pattern on the monochrome liquid crystal panel of a modification. It is a block diagram which shows the principal part of the liquid crystal display device which concerns on 2nd Embodiment of this invention. (A) is the schematic which shows the display state when not performing the process which concerns on this invention in a 1st light emission state, (b) is the schematic which shows the state which displayed the 1st image pattern on the electronic paper. 9A is a schematic cross-sectional view showing a light reflection state at the CC line in FIG. 9B, and FIG. 9B is a schematic cross-sectional view showing a light reflection state at the DD line in FIG. 9B. It is. (A) is the schematic from the side of the display unit which concerns on another modification of 2nd Embodiment, (b) It is the schematic which shows the state which displayed the 1st image pattern on the electronic paper of a modification. It is a block diagram which shows the principal part of the liquid crystal display device which concerns on 3rd Embodiment of this invention. It is the schematic which shows the state which displayed the 1st image pattern on the EL element panel. (A) is schematic sectional drawing which shows the reflective state of the light in the EE line of FIG.13 (b), (b) is schematic sectional drawing which shows the reflective state of the light in the FF line of FIG.13 (b). It is. It is the schematic from the side which shows the structure of a general liquid crystal display device. (A) is the schematic which shows a 2nd light emission state, (b) is the schematic which shows the condition where the brightness nonuniformity produced in the 1st light emission state. (A) is the schematic which shows the 1st light emission state, (b) is the schematic which shows the condition where the brightness nonuniformity produced in the 2nd light emission state.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Liquid crystal display device 11 Display data acquisition part 14 1st interface part 15 2nd interface part 16 Operation part 17 Memory 18 Pattern table 19 Control part 20 Display unit 21 Liquid crystal panel 23 Light guide plate 24 Monochrome liquid crystal panel 30 Light source unit 32 High color rendering LED (Second LED)
33 High-brightness LED (first LED)
35 First image pattern 36 Second image pattern 84 Electronic paper 124 EL element panel

Claims (6)

In a liquid crystal display device comprising a light source unit that irradiates the liquid crystal panel through a light guide plate disposed between the liquid crystal panel and the reflecting member,
The light source unit includes a first LED and a second LED having different light emission characteristics,
The first LED has a higher brightness than the second LED,
The second LED has higher color rendering than the first LED,
Switching means for switching between a first light emitting state for emitting both the first LED and the second LED and a second light emitting state for emitting the second LED;
A monochrome liquid crystal panel disposed between the light guide plate and the reflecting member;
Storage means for storing an image pattern to be displayed on the monochrome liquid crystal panel;
And a display processing unit configured to display the image pattern on the monochrome liquid crystal panel when displaying an image on the liquid crystal panel. The liquid crystal panel has a rectangular shape around the panel,
The light source unit is arranged to face one side of the liquid crystal panel,
2. The liquid crystal display device according to claim 1, wherein the monochrome liquid crystal panel is sized according to a range including one side of the liquid crystal panel and not including the other side opposite to the one side. . In a liquid crystal display device including a light source unit that irradiates the liquid crystal panel through a light guide plate disposed to face the liquid crystal panel,
The light source unit includes a first LED and a second LED having different light emission characteristics,
The first LED has a higher brightness than the second LED,
The second LED has higher color rendering than the first LED,
Switching means for switching between a first light emitting state for emitting both the first LED and the second LED and a second light emitting state for emitting the second LED;
A reflective display element arranged to face the surface of the light guide plate opposite to the liquid crystal panel;
Storage means for storing an image pattern to be displayed on the reflective display element;
And a display processing unit configured to display the image pattern on the reflective display element when displaying an image on the liquid crystal panel. In a liquid crystal display device including a light source unit that irradiates the liquid crystal panel through a light guide plate disposed to face the liquid crystal panel,
The light source unit includes a first LED and a second LED having different light emission characteristics,
The first LED has a higher brightness than the second LED,
The second LED has higher color rendering than the first LED,
Switching means for switching between a first light emitting state for emitting both the first LED and the second LED and a second light emitting state for emitting the second LED;
A self-luminous display element disposed so as to face the surface of the light guide plate opposite to the liquid crystal panel;
Storage means for storing an image pattern to be displayed on the self-luminous display element;
And a display processing means for performing a process of displaying the image pattern on the self-luminous display element when displaying an image on the liquid crystal panel. The storage means has a first image pattern corresponding to a contour shape of a portion irradiated with light emitted from the first LED and a contour shape of a portion irradiated with light emitted from the second LED. The second image pattern is stored,
The display processing means performs display processing of the first image pattern when the switching means is switched to the first light emission state, and also displays the second image pattern when the switching means is switched to the second light emission state. The liquid crystal display device according to claim 1, wherein the display processing is performed. The light guide plate has a rectangular overall shape around it, and a chamfered oblique side is formed at at least one corner,
The liquid crystal display device according to claim 1, wherein the light source unit is disposed so as to face the oblique side portion.

Images