JP2007155783A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a visual field-controlled liquid crystal display device capable of being obtained inexpensively. <P>SOLUTION: A surface light source 8 for selectively radiating first illumination light having such intensity distribution that the intensity of front light emitted in a direction of a normal of a liquid crystal display element 1 is higher than that of oblique light emitted at angles to the normal in one direction and its opposite direction, a second illumination light having such intensity distribution that the intensity of the oblique light is higher than that of the front light, is disposed on the side opposite to the observation side of the liquid crystal display element 1, and a display image data signal corresponding to a video signal and a selected data signal obtained by selecting one of the display image data signal and a fixed image data signal corresponding to a fixed image of a preliminarily registered pattern are alternately applied to each pixel of the liquid crystal display element 1 by a driving means 22, and the first illumination light is caused to be radiated from the surface light source 8 synchronously with application of the display image data signal, and the second illumination light is caused to be radiated from the surface light source 8 synchronously with application of the selected data signal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a visual field control type liquid crystal display device.

  A liquid crystal display device is a surface light source that irradiates illumination light toward the liquid crystal display element on the side opposite to the observation side of the liquid crystal display element having a screen region in which a plurality of pixels that control light transmission are arranged in a matrix (See Patent Document 1).

  By the way, in a liquid crystal display device mounted on an electronic device such as a mobile phone, the display field of view is a wide field of view and a narrow field of view so that the display cannot be seen by anyone other than the user of the liquid crystal display device. There is a demand for visual field controllability that can be switched.

  As a field-control liquid crystal display device, conventionally, a liquid crystal is sealed between a pair of substrates on one surface side of the liquid crystal display element, and a plurality of regions corresponding to the screen of the liquid crystal display element are arranged on the liquid crystal molecules. An alignment state having a visual field in a direction inclined in one direction with respect to the normal line of the liquid crystal display element and an alignment state having a visual field in a direction inclined in the opposite direction to each normal region of the liquid crystal display element And a field-limiting liquid crystal element in which electrodes of a predetermined shape are provided corresponding to each of the divided regions on each of the inner surfaces facing each other of the pair of substrates has been proposed ( Patent Document 2).

  The liquid crystal display device is configured to limit visibility of the display of the liquid crystal display element by reducing visibility from an oblique direction by applying a voltage between electrodes of the visual field limiting liquid crystal element. When a voltage is not applied between the electrodes of the liquid crystal element for display, that is, when the visual field limiting liquid crystal element is in a non-display state, the display image of the liquid crystal display element can be seen in a wide visual field.

On the other hand, when a voltage is applied between the electrodes of the visual field limiting liquid crystal element, the display image of the liquid crystal display element, when viewed from one direction and the opposite direction with respect to the front direction, By displaying each segmented region having a field of view in a direction inclined in one direction of the liquid crystal element for limiting the field of view and displaying corresponding to the electrode of the predetermined shape in each segmented region having a field of view in a direction inclined in the opposite direction. Since it is hidden, the display image of the liquid crystal display element cannot be recognized from the one direction and the direction inclined in the opposite direction, the field of view of the display image is apparently limited, and the field of view of the display is narrowed. .
JP 2003-149599 A JP 2000-133334 A

  However, the field-of-view-limiting liquid crystal element must be subjected to complicated alignment processing (rubbing processing of the alignment film) in which the direction is different for each of the divided regions on the inner surfaces of the pair of substrates. difficult.

  Therefore, the conventional visual field control type liquid crystal display device provided with the visual field limiting liquid crystal element has a problem of high cost.

  An object of the present invention is to provide a visual field control type liquid crystal display device that can be obtained at low cost.

The liquid crystal display device of the present invention is
A liquid crystal display element having a screen region in which a plurality of pixels for controlling light transmission are arranged in a matrix, an image data signal is applied to each of the plurality of pixels, and an image corresponding to the image data is displayed;
The liquid crystal display element is disposed on the side opposite to the observation side, and the intensity of the front light emitted in the normal direction of the liquid crystal display element toward the liquid crystal display element is in one direction with respect to the normal direction and A first illumination light having an intensity distribution higher than the intensity of the oblique light emitted in a direction inclined in the opposite direction; a second illumination light having an intensity distribution in which the intensity of the oblique light is higher than the intensity of the front light; A surface light source for selectively irradiating
One of a display image data signal corresponding to an image signal and a fixed image data signal corresponding to a fixed image having a pattern registered in advance is selected for each pixel of the liquid crystal display element. The selection data signal is applied alternately, the first illumination light is irradiated from the surface light source in synchronization with the application of the display image data signal to the pixel, and the selection data signal is applied to the pixel. Driving means for irradiating the second illumination light from the surface light source in synchronization with the light source.

  In the liquid crystal display device of the present invention, it is desirable that the intensity of the front light of the second illumination light is set to 20% or less of the intensity of the front light of the first illumination light.

  The surface light source has first and second incident end surfaces formed on one end surface and an end surface on the opposite side, and is incident on the surface facing the liquid crystal display element from the first and second incident end surfaces. An exit surface for emitting light is formed, and the first light incident from the first entrance end surface is inclined from the exit surface in a direction opposite to the first entrance end surface with respect to the normal line of the liquid crystal display element. The second light incident from the second incident end face is emitted from the outgoing face in a direction inclined in the direction opposite to the second incident end face with respect to the normal line of the liquid crystal display element. And a shape that is substantially parallel to the first and second incident end surfaces of the light guiding unit, and that the side surface on the first incident end surface side and the side surface on the second incident end surface side are different from each other. A plurality of elongate prisms formed on the light guide means and arranged opposite to the exit surface of the light guide means. Of the first and second lights emitted from the exit surface of the light guide means, one light incident on one of the side surfaces of the plurality of elongated prisms is made near the normal line of the liquid crystal display element. The other light that is emitted in the direction and enters the plurality of elongated prisms from the other side surface is one along the direction perpendicular to the length direction of the elongated prisms with respect to the normal line of the liquid crystal display element. And a prism sheet that emits light in a direction inclined to the opposite direction and the first incident end face and the second incident end face of the light guide means, respectively, and are selectively turned on. It is desirable that the second light emitting element is used.

  In that case, the light guide means of the surface light source is made of a plate-shaped transparent member, and a first incident end surface is formed on one end surface thereof, and a first emission surface is formed on one of two opposing plate surfaces. The light incident from the first incident end surface is internally reflected on the other plate surface, and is opposite to the first incident end surface with respect to the normal line of the liquid crystal display element from the first emission surface. What is the first light guide plate formed with a first reflection surface that is emitted in an inclined direction, transmits light incident from the outer surface side, and is emitted from the first emission surface, and the first light guide plate? A second plate-shaped transparent member is formed, and a second incident end surface is formed on an end surface opposite to the first incident end surface of the first light guide plate, and a second is formed on one of the two opposed plate surfaces. The light exit surface is formed, the light incident from the second incident end surface is reflected on the other plate surface, and the liquid is transmitted from the second light exit surface. A second reflecting surface that emits light in a direction inclined in a direction opposite to the second incident end surface with respect to the normal line of the display element is formed, and the second light emitting surface is formed on the first light guide plate. And a second light guide plate disposed to face the reflecting surface of the first light guide plate, and a first light emitting element is disposed to face the first incident end surface of the first light guide plate. It is preferable to arrange the second light emitting element so as to face the second incident end face of the light plate.

  The liquid crystal display device of the present invention has a screen region in which a plurality of pixels for controlling the transmission of light are arranged in a matrix, and an image data signal is applied to each of the plurality of pixels, and an image corresponding to the image data is displayed. Either one of the display image data signal corresponding to the image signal and the fixed image data signal corresponding to the display image data signal and the fixed image of the pattern registered in advance is selected for each pixel of the liquid crystal display element to be displayed. The selected selection data signal is alternately applied, the first illumination light is irradiated from the surface light source in synchronization with the application of the display image data signal to the pixel, and the selection data signal is applied to the pixel. Since the second illumination light is irradiated from the surface light source in synchronization with the application, the display field of view of the liquid crystal display element is controlled to be a wide field and a narrow field. Can.

  That is, the liquid crystal display device alternately displays an image corresponding to the display image data, and an image corresponding to selection data in which one of the display image data and the fixed image data is selected. The display image data signal is applied to each pixel of the liquid crystal display element, and the first illumination light having an intensity distribution in which the intensity of the front light from the surface light source is higher than the intensity of the oblique light is synchronized with the display image data signal , The image corresponding to the display image data is displayed, the selection data signal is applied to each pixel of the liquid crystal display element, and the intensity of the oblique light from the surface light source is changed to the front light in synchronization with the selection data signal. An image corresponding to the selection data is displayed by irradiating the second illumination light having an intensity distribution higher than the intensity of the first illumination light.

  Therefore, the display corresponding to the display image data is a display whose field of view is limited to the front direction, that is, the direction near the normal line of the liquid crystal display element, and the display corresponding to the selection data is the field of view of the display image data. The display is limited to one direction with respect to the front direction and a direction inclined in the opposite direction.

  When a display image data signal is selected as the selection data signal, images corresponding to the display image data are alternately displayed, and in synchronization therewith, the first having a peak of luminance distribution in the front direction. Since the illumination light and the second illumination light having a luminance distribution peak in the left-right direction are alternately irradiated, both from the front direction and the direction inclined in one direction with respect to the front direction and the opposite direction. Wide-field display for observing a display image corresponding to the image signal can be performed.

  On the other hand, the fixed image data is data corresponding to a fixed image of a pre-registered pattern, and when the fixed image data signal is selected as the selection data signal, an image corresponding to the display image data Images corresponding to the fixed image data are alternately displayed, and the first and second illumination lights are irradiated in synchronization therewith, so that the first direction is inclined from the direction inclined with respect to the front direction. A display image corresponding to the display image data by illumination light cannot be visually recognized, and a fixed image of a pattern corresponding to the fixed image data by the second illumination light is displayed in the tilted direction, Since the display image is hidden by the fixed image, the display image cannot be recognized from an oblique direction. Therefore, it is possible to perform narrow-field display in which the range of the field of view in which the display image corresponding to the image signal can be visually recognized is limited to the front direction.

  In the liquid crystal display device, the intensity of the front light emitted in the normal direction of the liquid crystal display element toward the liquid crystal display element is opposite to the observation side of the liquid crystal display element with respect to the normal line. A first illumination light having an intensity distribution higher than the intensity of the oblique light emitted in one direction and a direction inclined in the opposite direction, and a first illumination light having an intensity distribution in which the intensity of the oblique light is higher than the intensity of the front light. A display image data signal corresponding to an image signal is provided to each pixel of the liquid crystal display element by a surface light source that selectively irradiates two illumination lights and driving means for driving the liquid crystal display element and the surface light source. And the display image data signal and a selection data signal in which one of the fixed image data signals corresponding to the fixed image of the pattern registered in advance is selected, and the display image data signal Synchronize with application The first illumination light is emitted from the surface light source, and the second illumination light is emitted from the surface light source in synchronization with the application of the selection data signal to control the display field of view to a wide field and a narrow field. Therefore, it can be obtained at a much lower cost than a conventional visual field control type liquid crystal display device provided with a liquid crystal element for visual field limitation that is difficult to manufacture.

  In the liquid crystal display device of the present invention, it is desirable that the intensity of the front light of the second illumination light is set to 20% or less of the intensity of the front light of the first illumination light. The contrast of the display image observed from the front direction during the narrow field display can be made sufficiently high.

  The surface light source has first and second incident end surfaces formed on one end surface and an end surface on the opposite side, and is incident on the surface facing the liquid crystal display element from the first and second incident end surfaces. An exit surface for emitting light is formed, and the first light incident from the first entrance end surface is inclined from the exit surface in a direction opposite to the first entrance end surface with respect to the normal line of the liquid crystal display element. The second light incident from the second incident end face is emitted from the outgoing face in a direction inclined in the direction opposite to the second incident end face with respect to the normal line of the liquid crystal display element. And a shape that is substantially parallel to the first and second incident end surfaces of the light guiding unit, and that the side surface on the first incident end surface side and the side surface on the second incident end surface side are different from each other. A plurality of elongate prisms formed on the light guide means and arranged opposite to the exit surface of the light guide means. Of the first and second lights emitted from the exit surface of the light guide means, one light incident on one of the side surfaces of the plurality of elongated prisms is made near the normal line of the liquid crystal display element. The other light that is emitted in the direction and enters the plurality of elongated prisms from the other side surface is one along the direction perpendicular to the length direction of the elongated prisms with respect to the normal line of the liquid crystal display element. And a prism sheet that emits light in a direction inclined to the opposite direction and the first incident end face and the second incident end face of the light guide means, respectively, and are selectively turned on. It is desirable that the second light emitting element is used, and by doing so, the intensity of the front light is higher than the intensity of the oblique light, and the intensity of the oblique light is higher. Stronger than the intensity of the front light Irradiates toward selectively the liquid crystal display device and a second illumination light distribution, to simplify the manufacturing of the surface light source, the liquid crystal display device can be further obtained in a low cost.

  In that case, the light guide means of the surface light source is made of a plate-shaped transparent member, and a first incident end surface is formed on one end surface thereof, and a first emission surface is formed on one of two opposing plate surfaces. The light incident from the first incident end surface is internally reflected on the other plate surface, and is opposite to the first incident end surface with respect to the normal line of the liquid crystal display element from the first emission surface. What is the first light guide plate formed with a first reflection surface that is emitted in an inclined direction, transmits light incident from the outer surface side, and is emitted from the first emission surface, and the first light guide plate? A second plate-shaped transparent member is formed, and a second incident end surface is formed on an end surface opposite to the first incident end surface of the first light guide plate, and a second is formed on one of the two opposed plate surfaces. The light exit surface is formed, the light incident from the second incident end surface is reflected on the other plate surface, and the liquid is transmitted from the second light exit surface. A second reflecting surface that emits light in a direction inclined in a direction opposite to the second incident end surface with respect to the normal line of the display element is formed, and the second light emitting surface is formed on the first light guide plate. And a second light guide plate disposed to face the reflecting surface of the first light guide plate, and a first light emitting element is disposed to face the first incident end surface of the first light guide plate. It is preferable to arrange the second light emitting element so as to oppose the second incident end face of the optical plate. By doing so, the light from the first and second light emitting elements is transmitted to the first and second light emitting elements. The first illumination light having an intensity distribution sufficiently higher than the intensity of the oblique light from the first emission surface of the first light guide plate and efficiently guided by the light guide plate, and the oblique light. And the second illumination light having an intensity distribution sufficiently higher than the intensity of the front light. It can be irradiated towards.

  1 to 7 show an embodiment of the present invention, and FIG. 1 is an exploded perspective view of a liquid crystal display device.

  As shown in FIG. 1, this liquid crystal display device has a screen region 1a in which a plurality of pixels (not shown) for controlling the transmission of light are arranged in a matrix, and an image data signal is applied to each of the plurality of pixels. The liquid crystal display element 1 for displaying an image corresponding to the image data, and the liquid crystal display element 1 is disposed on the opposite side to the observation side (upper side in FIG. 1), and is directed toward the liquid crystal display element 1. The first illumination having an intensity distribution in which the intensity of the front light emitted in the normal direction of the liquid crystal display element 1 is higher than the intensity of the oblique light emitted in one direction with respect to the normal and in the opposite direction. A surface light source 8 that selectively irradiates light and second illumination light having an intensity distribution in which the intensity of the oblique light is higher than the intensity of the front light, and a drive that drives the liquid crystal display element 1 and the surface light source 8 And means 22.

  Although the internal structure of the liquid crystal display element 1 is not shown, a pair of transparent substrates 2 and 3 joined via a frame-shaped sealing material 4 surrounding the screen region 1a and the substrates 2 and 3 are opposed to each other. Liquid crystal sealed in a region surrounded by the sealing material 4 between the pair of substrates 2 and 3 and a transparent electrode which is provided on each inner surface and forms a plurality of pixels arranged in a matrix by regions facing each other. And a pair of polarizing plates 5 and 6 disposed on the outer surfaces of the pair of substrates 2 and 3, respectively.

  The liquid crystal display element 1 includes a plurality of pixel electrodes arranged in a matrix in the row direction and the column direction on the inner surface of one substrate 2, and the arrangement region of the plurality of pixel electrodes on the inner surface of the other substrate 3. An active matrix liquid crystal display element provided with a single film-like counter electrode facing each other, and an inner surface of the one substrate 2 is provided with an active element comprising TFTs respectively connected to the plurality of pixel electrodes, and each row A plurality of scanning lines for supplying gate signals to the TFTs and a plurality of data lines for supplying data signals to the TFTs in each column are provided.

  The one substrate 2 has a driver mounting portion 2a extending outward from the other substrate 3, and the plurality of gate lines and data lines are formed from an LSI mounted on the driver mounting portion 2a. Connected to the display driver 7.

  Further, an alignment film is provided on the inner surfaces of the pair of substrates 2 and 3 so as to cover the electrodes, and the liquid crystal molecules of the liquid crystal layer are defined by the alignment film between the pair of substrates 2 and 3. It is oriented in the orientation state.

  The liquid crystal display element 1 includes a TN or STN type in which liquid crystal molecules are twist-aligned, a vertical alignment type in which liquid crystal molecules are aligned substantially perpendicular to the surfaces of the substrates 2 and 3, and a substrate without twisting the liquid crystal molecules. The liquid crystal display element is either a horizontal alignment type that is aligned substantially parallel to two or three planes or a bend alignment type that bends liquid crystal molecules, or a ferroelectric or antiferroelectric liquid crystal display element. The pair of polarizing plates 5 and 6 are arranged with their transmission axes oriented so as to obtain good contrast characteristics.

  In the liquid crystal display element 1, a vertical electric field (electric field in the thickness direction of the liquid crystal layer) is generated between the electrodes provided on the inner surfaces of the pair of substrates 2 and 3 to change the alignment state of the liquid crystal molecules. For example, a comb-like first and second electrode for forming a plurality of pixels is provided on the inner surface of one of the pair of substrates 2 and 3, and a horizontal electric field ( A lateral electric field control type that changes the alignment state of the liquid crystal molecules by generating an electric field in a direction along the substrate surface may be used.

  Further, the liquid crystal display element 1 may be a normally white mode display element or a normally black mode display element.

  The surface light source 8 includes first and second incident end surfaces 11 and 15 formed on one end surface and the opposite end surface, and the first and second incident end surfaces on the surface facing the liquid crystal display element 1. An exit surface 12 for emitting light incident from the first incident end surface 11 is formed, and the first incident light from the first entrance end surface 11 is incident on the first incident surface with respect to the normal line of the liquid crystal display element 1 from the exit surface 12. The second light that is emitted in a direction inclined in the direction opposite to the end surface 11 and incident from the second incident end surface 15 is incident on the second incident surface from the emission surface 12 with respect to the normal line of the liquid crystal display element 1. The light guide 9 that emits light in a direction inclined in the direction opposite to the end face 15, and the first light emitted from the light emission surface 12 of the light guide 9 are disposed opposite to the light emission surface 12 of the light guide 9. And one of the second lights in the direction near the normal line of the liquid crystal display element 1 A prism sheet 19 that emits the other light in one direction with respect to the normal line of the liquid crystal display element 1 and a direction inclined in the opposite direction, and a first incident of the light guide means 9. The first and second light emitting elements 21a and 21b are arranged to face the end face 11 and the second incident end face 15 and are selectively lit.

  FIG. 2 is an enlarged side view of a part of the surface light source 8, and the light guide means 9 is made of a plate-like transparent member such as an acrylic resin plate, and a first incident end face 11 is formed on one end face thereof. A first exit surface 12 is formed on one of the two opposing plate surfaces, and the light incident from the first incident end surface 11 is internally reflected on the other plate surface by total reflection at the interface with the outside air. Light emitted from the first emission surface 12 in a direction inclined in the direction opposite to the first incident end surface 11 with respect to the normal line of the liquid crystal display element 1 and incident from the outer surface side of the other plate surface A first light guide plate 10 having a first reflection surface 13 that is transmitted through the first output surface 12 and a plate such as an acrylic resin plate that is separate from the first light guide plate 10. On the end surface opposite to the first incident end surface 11 of the first light guide plate 10. Two incident end faces 15 are formed, a second exit face 16 is formed on one of the two opposing plate faces, and the light incident from the second incident end face 15 is reflected on the other plate face, thereby The second reflecting surface 17 is formed to emit light from the second emitting surface 16 in a direction inclined to the direction opposite to the second incident end surface 15 with respect to the normal line of the liquid crystal display element 1, and the second reflecting surface 17 is formed. The second light guide plate 14 is disposed so that the emission surface 16 faces the first reflection surface of the first light guide plate.

  In this embodiment, the reflection surface (second reflection surface) 17 of the second light guide plate 14 is formed by providing a reflection film 18 on the other plate surface. Further, it may be an internal reflection surface that totally reflects light incident from the incident end face (second incident end face) 15 of the second light guide plate 14 at the interface with the outside air.

  The first light guide plate 10 has an emission surface (first emission surface) 12 formed as a flat surface, and a reflection surface (first reflection surface) 13 from the first incident end surface 11 side to the light guide plate 10. The wedge-shaped plate is formed on an inclined surface that is inclined in a direction close to the emission surface 12 toward the other end of the liquid crystal display device, the emission surface 12 is opposed to the liquid crystal display element 1, and the emission surface 12 is While being substantially parallel to the liquid crystal display element 1, the first incident end face 11 is disposed toward the left side of the screen of the liquid crystal display element 1.

  Further, the second light guide plate 14 has a reflection surface (second reflection surface) 17 formed as a flat surface, and an emission surface (second emission surface) 16 guided from the second incident end surface 15 side. It consists of the wedge-shaped board formed in the inclined surface inclined at the same angle as the reflective surface 13 of the said 1st light-guide plate 10 in the direction close | similar to the said reflective surface 17 toward the other end side of the optical plate 14, The said output surface 16 is opposed to the reflective surface 13 of the first light guide plate with a gap A, and the output surface 16 is substantially parallel to the reflective surface 13 of the first light guide plate 10. The two incident end faces 15 are arranged in the right direction of the screen of the liquid crystal display element 1.

  1 and 2, the inclination angle of the reflection surface 13 of the first light guide plate 10 and the inclination angle of the emission surface 16 of the second light guide plate 14 are greatly exaggerated. Is set to about 2 to 10 degrees with respect to the emission surface 12 of the first light guide plate 10 and the reflection surface 17 of the second light guide plate 14.

  On the other hand, the prism sheet 19 is substantially parallel to the first and second incident end faces 11 and 15 of the light guiding means 9 on one surface of the transparent film, and the first sheet on the first incident end face 11 side. A plurality of elongated prisms 20 in which one side surface 20a and the second side surface 20b on the second incident end surface 15 side are formed in different shapes are equal to or more than the pixel pitch of the liquid crystal display element 1. The plurality of elongate prisms 20 are provided with a small pitch, and the first incident end face is formed, for example, such that the first side face 20a on the first incident end face 11 side is directed from the film surface toward the top of the prism. The second side surface 20b on the second incident end surface 15 side is formed on a straight surface with a steep angle inclined by 5 to 15 ° in the 11 direction, and the second incident end surface 15 is directed from the film surface toward the prism top. 30 in the direction Inclined at an average angle of 40 °, a radius is formed in a shape formed into a curved surface of the bulge outer 50～90Mm.

  The prism sheet 19 is disposed with its prism formation surface facing the light exit surface of the light guide means 9, that is, the light exit surface 12 of the first light guide plate 10.

  The first and second light emitting elements 21a and 21b are solid light emitting elements made of LEDs (light emitting diodes), and the first incident end face 11 of the first light guide plate 10 and the second light guiding element. A plurality of the incident end faces 11 and 15 are arranged at intervals in the length direction so as to face the second incident end face 15 of the optical plate 14.

  The surface light source 8 emits light from the first light emitting element 21a when the first and second light emitting elements 21a and 21b are selectively turned on and the first light emitting element 21a is turned on. The first light guided by the first light guide plate 10 and emitted from the emission surface 12 is emitted by the prism sheet 19 in a direction near the normal line of the liquid crystal display element 1.

  Further, the surface light source 8 emits from the second light emitting element 21b when the second light emitting element 21b is turned on, and is guided by the second light guide plate 14 and emitted from the emission surface 16. Further, the second light transmitted through the first light guide plate 10 and emitted from the emission surface 12 is further elongated by the prism sheet 19 with respect to the normal line of the liquid crystal display element 1. The light is emitted in one direction along the direction orthogonal to the vertical direction and a direction inclined in the opposite direction, that is, a direction inclined in the left-right direction of the screen of the liquid crystal display element 1.

  FIGS. 3A and 3B are diagrams of outgoing light rays of the first and second illumination light from the surface light source 8, wherein FIG. 3A shows the outgoing light beam of the first illumination light, and FIG. 3B shows the outgoing light beam of the first illumination light. Shows light rays.

  As shown in FIG. 3A, the first light emitted from the first light emitting element 21a and incident on the first light guide plate 10 from the first incident end face 11 is the first light guide plate. 10 is reflected by the interface between the reflecting surface 13 and the outside air (air in the gap A between the second light guide plate 14) and the interface between the emitting surface 12 and the outside air (air between the prism sheet 19). Then, the light is emitted from the emission surface 12 of the first light guide plate 10 in a direction inclined in the direction opposite to the first incident end surface 11 with respect to the normal line of the liquid crystal display element 1.

  The first light is incident on the plurality of elongated prisms 20 of the prism sheet 19 from the first side surface 20a made of the linear surface, and is refracted by the second side surface 20b made of the curved surface on the opposite side. Then, the light is emitted from the opposite surface of the prism sheet 19 in the direction near the normal line of the liquid crystal display element 1.

  Further, as shown in FIG. 3B, the second light emitted from the second light emitting element 21b and incident on the second light guide plate 14 from the second incident end face 15 is the second light. The light guide plate 14 is guided while being reflected by the interface between the reflection surface 17 and the emission surface 16 thereof and the outside air (air in the gap A with the first light guide plate 10), and is emitted from the second light guide plate 14. The light is emitted from the surface 16 in a direction tilted in the direction opposite to the second incident end face 15 with respect to the normal line of the liquid crystal display element 1, and further passes through the first light guide plate 10 to transmit the first light. The light is emitted from the first emission surface 12 of the light guide plate 10.

  Then, the second light is incident on the plurality of elongated prisms 20 of the prism sheet 19 from the second side surface 20b made of a curved surface and incident on the first side surface 20a made of the opposite linear surface. Depending on the angle, the liquid crystal display element 1 is reflected by the first side surface 20a, or refracted and transmitted through the first side surface 20a at the interface with the outside air. The light is emitted in the direction inclined to the left and right of the screen with respect to the normal line.

  As described above, the surface light source 8 has the intensity of the front light emitted in the normal direction of the liquid crystal display element 1 with respect to the normal line of the liquid crystal display element 1 by turning on the first light emitting element 21a. The first illumination light having an intensity distribution higher than the intensity of the oblique light emitted in the direction tilted to the left and right of the screen is irradiated toward the liquid crystal display element 1, and the second light emitting element 21b is turned on. Thus, the second illumination light having an intensity distribution in which the intensity of the oblique light is higher than the intensity of the front light is emitted toward the liquid crystal display element 1.

  4 and 5 are intensity distribution diagrams of the first and second illumination lights from the surface light source 8, FIG. 4 is an intensity distribution in the horizontal direction of the screen viewed from the liquid crystal display element 1, and FIG. The intensity distribution in the vertical direction of the screen viewed from the liquid crystal display element 1 side is shown. In FIG. 4, a negative angle is an angle in the left direction of the screen, a positive angle is an angle in the right direction of the screen. In FIG. 5, a positive angle is an upward angle in the screen, a negative angle. The angle is a downward angle of the screen.

  As shown in FIGS. 4 and 5, the first illumination light has the intensity of the front light emitted in the normal direction (0 ° direction) of the liquid crystal display element 1 in the horizontal and vertical intensity distributions. Is sufficiently higher than the intensity of the oblique light emitted in the horizontal and vertical directions with respect to the normal line of the liquid crystal display element 1, and in particular, the intensity distribution in the horizontal direction is about −10 ° to 10 °. The intensity of the front light in a narrow angle range of 0 ° is high, and the intensity of the outgoing light of the oblique light outside the angle range is 20% or less of the intensity of the front light.

  Further, the second illumination light has an intensity distribution in the horizontal direction and the vertical direction, and the intensity of the front light emitted in the normal direction of the liquid crystal display element 1 is the intensity of the front light of the first illumination light. When the intensity distribution in the left-right direction is 20% or less, the intensity of the oblique light in the angle ranges of about −40 ° to −70 ° and about 40 ° to 70 ° is the front light (front light of the second illumination light). The intensity distribution in the vertical direction is light having a distribution with a very small intensity difference depending on the angle.

  Next, the driving means 22 for driving the liquid crystal display element 1 and the surface light source 8 will be described. The driving means 22 sends a display image data signal corresponding to an image signal to each pixel of the liquid crystal display element 1, and A display image data signal and a selection data signal selected from one of fixed image data signals corresponding to a fixed image having a pre-registered pattern are alternately applied and synchronized with the application of the display image data signal. Then, the first illumination light is emitted from the surface light source 8 and the second illumination light is emitted from the surface light source 8 in synchronization with the application of the selection data signal.

  FIG. 6 is a block circuit diagram of the driving means 22. The driving means 22 includes a fixed image data generator 23 for generating fixed image data corresponding to a fixed image registered in advance, and first and second images. Data memory 24 and 25, and display image data corresponding to an image signal supplied from the outside are written into first memory 24 of first and second image data memories 24 and 25, and the display image data and A memory write control unit 26 that selectively writes fixed image data to the second memory 25 in accordance with a visual field selection signal, and alternately reads the image data written to the first memory 24 and the second memory 25. The memory read controller 27 supplied to the data line controller 7a of the display driver 7 mounted on the liquid crystal display element 1 and the first and second light emitting elements 21a and 21b of the surface light source 8 are selectively used. A light source driving unit 28 for lit, and is from the drive control unit 29 for controlling the scan line control unit 7b of the memory write controller 26 and the memory read controller 27 and the light source driver 28 and the display driver 7.

  The driving means 22 is supplied to the drive control unit 29 from a circuit unit (not shown) of the electronic device by operating a visual field selection key provided in the electronic device such as a mobile phone equipped with a liquid crystal display device. The same display image corresponding to the display image data is alternately displayed on the liquid crystal display element 1 according to a field selection signal, or a display image corresponding to the display image data and a fixed image data corresponding to the fixed image data are displayed. Display images alternately.

  That is, the driving means 22 writes display image data corresponding to the image signal to the first memory 24 and the second memory 25 when a visual field selection signal for selecting wide-field display is input. The display image data is read from the first memory 24 and supplied to the data line driver in one of two divided periods obtained by dividing one frame for displaying the image of the image into two, and a display corresponding to the display image data is displayed. An image data signal is applied to each pixel of the liquid crystal display element 1, and the first illumination light is irradiated from the surface light source 8 by turning on the first light emitting element 21 a in synchronization therewith, and in the other divided period. The display image data read from the second memory 25 is supplied to the data line driving unit, and a display image data signal corresponding to the display image data is applied to each pixel of the liquid crystal display element 1. It irradiates the second illumination light from the surface light source 8 is synchronized with lighting of the second light emitting element 21b in.

  The driving means 22 writes the display image data into the first memory 24 and reads out the fixed image data from the fixed image data generator 23 when a visual field selection signal for selecting narrow-field display is input. The fixed image data is written into the second memory 25, and the display image data is read from the first memory 24 and supplied to the data line driving unit in one of two divided periods obtained by dividing the one frame into two, A display image data signal corresponding to the display image data is applied to each pixel of the liquid crystal display element 1, and the first illumination light is emitted from the surface light source 8 by turning on the first light emitting element 21a in synchronization therewith. In the other divided period, the fixed image data is read from the second memory 25 and the fixed image data is supplied to the data line driving unit. Applying a fixed image data signal corresponding to data to each pixel of the liquid crystal display device 1, it is irradiated with the second illuminating light from the surface light source 8 is synchronized with lighting of the second light emitting element 21b in.

  In the liquid crystal display device, the liquid crystal display element 1 is a display element that does not include a color filter, and the first and second light emitting elements 21a and 21b of the surface light source 8 are respectively a red LED, a green LED, and a blue LED. In the field sequential liquid crystal display device, the first illumination light and the second illumination light of the three colors red, green, and blue are sequentially emitted from the surface light source 8. The liquid crystal display element 1 is provided with color filters of three colors of red, green, and blue respectively facing the plurality of pixels, and white first illumination light and second illumination light are emitted from the surface light source 8. A liquid crystal display device which is selectively irradiated may be used.

  7A and 7B are driving sequence diagrams of the liquid crystal display element 1 and the surface light source 8 in the field sequential liquid crystal display device. FIG. 7A shows a driving sequence for wide-field display, and FIG. 7B shows a driving sequence for narrow-field display. The drive sequence is shown.

In the case of this field sequential liquid crystal display device, one frame is divided into six fields t _{1 to} t _6, and in the case of wide-field display, the one frame is divided into two as shown in FIG. On the other hand, for example, for each of the first to third fields t ₁ , t ₂ , and t ₃ that are the first divided period, a red unit color display image data signal and a green color are displayed on each pixel of the liquid crystal display element 1. A unit color display image data signal and a blue unit color display image data signal are sequentially applied, and in synchronization with the application of each unit color display image data signal, red light is transmitted from the surface light source 8. One illumination light, green first illumination light, and blue first illumination light are sequentially emitted.

Further, a red unit color is displayed on each pixel of the liquid crystal display element 1 for each of the _{fourth to} sixth fields t ₄ , t ₅ , and t ₆ , which is the latter half of the one frame divided into two. The image data signal, the display image data signal of the green unit color, and the display image data signal of the blue unit color are sequentially applied, and the surface is synchronized with the application of the display image data signal of each unit color. The light source 8 sequentially emits red second illumination light, green second illumination light, and blue second illumination light.

In the narrow-field display, as shown in FIG. 7B, for example, the liquid crystal display element is used for each of the first to third fields t ₁ , t ₂ , and t ₃ that are the first divided period. A display image data signal of a red unit color, a display image data signal of a green unit color, and a display image data signal of a blue unit color are sequentially applied to each pixel 1 to display these unit colors. In synchronization with the application of the image data signal, the surface light source 8 sequentially emits the red first illumination light, the green first illumination light, and the blue first illumination light, which is the latter half of the divided period. For each of the _{fourth to} sixth fields t ₄ , t ₅ , t ₆ , a red unit color fixed image data signal and a green unit color fixed image data signal are applied to each pixel of the liquid crystal display element 1. And a fixed image data signal of blue unit color are sequentially applied, and a fixed image data signal of each unit color is applied. In synchronization with the application of the signal, the surface light source 8 sequentially emits red second illumination light, green second illumination light, and blue second illumination light.

  FIG. 7 shows a driving sequence in which the sequential application of the display image data signals in the unit colors of red, green, and blue and the sequential application of the fixed image data signals in the unit colors of red, green, and blue are alternately performed. However, the present invention is not limited to this, for example, application of a display image data signal of one unit color of red, green, and blue, and application of a fixed image data signal of one unit color of red, green, and blue The first illumination light of the unit color is emitted in synchronization with the application of the display image data signal, and the second illumination light of the unit color is synchronized with the application of the fixed image data signal. May be emitted.

  FIG. 8 is a drive sequence diagram of the liquid crystal display element 1 and the surface light source 8 in the liquid crystal display device in which the liquid crystal display element 1 is provided with color filters of three colors of red, green, and blue that face the plurality of pixels. A, (a) shows a driving sequence for wide-field display, and (b) shows a driving sequence for narrow-field display.

For this liquid crystal display device, the one frame is divided into two periods, when the wide-field display, as shown in FIG. 8 (a), the example in the first divided period t _11, the liquid crystal display device 1 A display image data signal of each color of red, green, and blue is applied to each pixel corresponding to each of the red, green, and blue color filters, and in synchronization with the application of the display image data signal, white light is emitted from the surface light source 8. the first is emitted illumination light, similarly to the second divided period t _12, the each pixel of the liquid crystal display device 1, the red, green, and applying a respective color display image data signals of blue, the displayed image The white second illumination light is emitted from the surface light source 8 in synchronization with the application of the data signal.

Also, when the narrow-angle view, as in FIG. 8 (b), for example, the the first divided period t _11, the liquid crystal display device 1, red, green, and each pixel corresponding to the blue color filter , Red, green, and blue display image data signals are applied, and in synchronization with the application of the display image data signals, white second illumination light is emitted from the surface light source 8, and the second divided period t ₁₂ , a fixed image data signal of each color of red, green, and blue is applied to each pixel of the liquid crystal display element 1, and in synchronization with the application of the fixed image data signal, a white second light is emitted from the surface light source 8. Illumination light is emitted.

  This liquid crystal display device has a screen region 1a in which a plurality of pixels for controlling the transmission of light are arranged in a matrix, and an image data signal is applied to each of the plurality of pixels to display an image corresponding to the image data. The intensity of the front light emitted in the normal direction of the liquid crystal display element 1 toward the liquid crystal display element 1 on the side opposite to the observation side of the liquid crystal display element 1 is The first illumination light having an intensity distribution higher than the intensity of the oblique light emitted in the opposite direction, that is, the direction inclined in the left direction and the right direction, and the intensity distribution in which the intensity of the oblique light is higher than the intensity of the front light. The surface light source 8 that selectively irradiates the second illumination light is disposed, and an image is applied to each pixel of the liquid crystal display element 1 by the driving means 22 that drives the liquid crystal display element 1 and the surface light source 8. Display image data signal corresponding to the signal The display image data and a selection data signal selected from any one of the fixed image data signals corresponding to a fixed image having a pre-registered pattern are alternately applied and synchronized with the application of the display image data signal. Then, the first illumination light is emitted from the surface light source 8, and the second illumination light is emitted from the surface light source 8 in synchronization with application of the selection data signal (display image data signal or fixed image data signal). Since irradiation is performed, the display field of view of the liquid crystal display element 1 can be controlled to a wide field and a narrow field.

  That is, the liquid crystal display device alternately displays an image corresponding to the display image data and an image corresponding to selection data in which one of the display image data and the fixed image data is selected. The display image data signal is applied to each pixel of the liquid crystal display element 1, and the first illumination light having an intensity distribution in which the intensity of the front light from the surface light source 8 is higher than the intensity of the oblique light is synchronized with the display image data signal. , The image corresponding to the display image data is displayed, the selection data signal is applied to each pixel of the liquid crystal display element 1, and the intensity of the oblique light from the surface light source 8 is synchronized with the selected data signal. An image corresponding to the selection data is displayed by irradiating the second illumination light having an intensity distribution higher than the intensity of the front light.

  Therefore, the display corresponding to the display image data is a display having a luminance distribution peak in the front direction (direction near the normal line of the liquid crystal display element 1), that is, a display in which the field of view is limited to the front direction. The display corresponding to the selection data is a display having a peak of luminance distribution in a direction inclined in one direction (left direction) and the opposite direction (right direction) with respect to the front direction, that is, the field of view is the front side. The display is limited to the direction tilted leftward and rightward with respect to the direction.

  Therefore, when display image data is selected as the selection data, images corresponding to the same display image data are alternately displayed and tilted from the front direction to the left and right directions with respect to the front direction. It is possible to perform wide-field display that allows a display image corresponding to an image signal to be observed from a different direction.

  FIG. 9 shows an example of the display viewed from the front direction and the display viewed from the direction tilted leftward and rightward in the wide-field display.

  On the other hand, when the fixed image data is selected as selection data, an image corresponding to the display image data and an image corresponding to the fixed image data are alternately displayed, and the fixed image data is Since the data corresponds to the fixed image of the pattern registered in advance, the display image corresponding to the display image data cannot be viewed from the direction inclined with respect to the front direction, and the display image However, since a fixed image having a pattern corresponding to the fixed image data is displayed, the display image cannot be viewed at all, and a narrow field display in which the field of view of the display image corresponding to the image signal is limited to the front direction can be performed. .

  FIG. 10 shows an example of the display viewed from the front direction and the display viewed from the direction tilted leftward and rightward in the narrow-field display. Here, a display image corresponding to the display image data is shown. And a checkered fixed image are alternately displayed.

  The checkered fixed image may be an image of a pattern in which a plurality of rectangular patterns of red, green, blue, or a mixed color of yellow, magenta, cyan, and black are alternately arranged in a row direction and a column direction. Alternatively, an image of a pattern in which white and black rectangular patterns of mixed colors of red, green, and blue are alternately arranged in a row direction and a column direction may be used.

  Furthermore, the fixed image is not limited to a checkered pattern, and may be a stripe pattern, a mark, a character, or the like.

  In this liquid crystal display device, the intensity of the front light emitted in the normal direction of the liquid crystal display element 1 toward the liquid crystal display element 1 is opposite to the observation side of the liquid crystal display element 1. First illumination light having an intensity distribution higher than the intensity of the oblique light emitted in one direction with respect to the line and the direction inclined in the opposite direction, and the intensity of the oblique light is higher than the intensity of the front light A surface light source 8 that selectively irradiates the second illumination light of the distribution is disposed, and an image is applied to each pixel of the liquid crystal display element 1 by the liquid crystal display element 1 and a driving unit 22 that drives the surface light source 8. The display image data signal corresponding to the signal, and the display image data signal and the selection data signal selected from any one of the fixed image data signals corresponding to the fixed image of the pattern registered in advance are alternately applied to the display For image data signal application The first illumination light is emitted from the surface light source 8 and the second illumination light is emitted from the surface light source 8 in synchronism with the application of the selection data signal. Since it is controlled to have a narrow field of view, it can be obtained at a much lower cost as compared with a conventional field-of-view control type liquid crystal display device having a field-limiting liquid crystal element that is difficult to manufacture.

  In this liquid crystal display device, the intensity of the front light of the second illumination light is desirably set to 20% or less of the intensity of the front light of the first illumination light, as described above. Thereby, the contrast of the display image observed from the front direction in the narrow-field display can be sufficiently increased.

  In the liquid crystal display device, the surface light source 8 includes first and second incident end surfaces 11 and 15 formed on one end surface and the opposite end surface, and the surface facing the liquid crystal display element 1 An emission surface 12 for emitting light incident from the first and second incident end surfaces 11 and 15 is formed, and the first light incident from the first incident end surface 11 is transmitted from the emission surface 12 to the liquid crystal display element 1. The liquid crystal display element 1 emits second light incident from the second incident end face 15 through the second incident end face 15 in a direction inclined in the direction opposite to the first incident end face 11 with respect to the normal line. Light guide means 9 that emits light in a direction inclined in the direction opposite to the second incident end face 15 with respect to the normal line, and substantially the same as the first and second incident end faces 11 and 15 of the light guide means 9. Parallel to the first incident end face 11 side and the second incident end face 15 side. The first prism that has a plurality of elongated prisms 20 formed in different shapes from the side surfaces, is disposed to face the light exit surface 12 of the light guide means 9, and exits from the light exit surface 12 of the light guide means 9. Of the second light, one light incident on the plurality of elongated prisms 20 from one side surface (first side surface) 20a is emitted in a direction near the normal line of the liquid crystal display element 1. The other light incident on the plurality of elongated prisms 20 from the other side surface (second side surface) 20 b is perpendicular to the length direction of the elongated prisms 20 with respect to the normal line of the liquid crystal display element 1. The prism sheet 19 that emits light in one direction along the direction and the direction inclined in the opposite direction, and the first incident end surface 11 and the second incident end surface 15 of the light guide means 9 are arranged to face each other, and are selected. First and second illuminated Light emitting elements 21a and 21b, the first illumination light having an intensity distribution in which the intensity of the front light is higher than the intensity of the oblique light, and the intensity of the oblique light is greater than the intensity of the front light. In addition, the liquid crystal display element 1 can be selectively irradiated with the second illumination light having a high intensity distribution, and the surface light source 8 can be easily manufactured, so that the liquid crystal display device can be obtained at a lower cost.

  Further, in this liquid crystal display device, the light guide means 9 of the surface light source 8 is made of a plate-shaped transparent member, and a first incident end surface 11 is formed on one end surface thereof, and one of two opposing plate surfaces is formed. A first exit surface 12 is formed, and the light incident from the first incident end surface 11 is internally reflected on the other plate surface, so that the first exit surface 12 and the normal line of the liquid crystal display element 1 are reflected. Thus, a first reflecting surface 13 is formed that is emitted in a direction inclined in a direction opposite to the first incident end surface 11 and transmits light incident from the outer surface side and is emitted from the first emission surface 12. The first light guide plate 10 and the first light guide plate 10 are made of a plate-like transparent member that is a separate body, and the first light guide plate 10 has a first end face on the opposite side to the first incident end face 11. 2 incident end faces 15 are formed, a second exit face 16 is formed on one of the two opposing plate faces, and the other The light incident on the plate surface from the second incident end face 15 is reflected and tilted in the direction opposite to the second incident end face 15 with respect to the normal line of the liquid crystal display element 1 from the second emission face 16. A second reflection surface 17 that emits light in a predetermined direction is formed, and the second light guide plate 14 is disposed so that the second emission surface 16 faces the first reflection surface 13 of the first light guide plate 10. The first light-emitting element 21a is disposed so as to face the first incident end face 11 of the first light guide plate 10, and is made to face the second incident end face 15 of the second light guide plate 14. It is preferable to arrange the second light emitting element 21b, and by doing so, the light from the first and second light emitting elements 21a, 21b is transmitted by the first and second light guide plates 10, 14. Efficiently guiding, from the first exit surface 12 of the first light guide plate 10, the A first illumination light having an intensity distribution in which the intensity of the surface light is sufficiently higher than the intensity of the oblique light; and a second illumination light having an intensity distribution in which the intensity of the oblique light is sufficiently higher than the intensity of the front light; Can be selectively irradiated toward the liquid crystal display element 1.

  In this embodiment, the light guide means 9 of the surface light source 8 is constituted by the first and second light guide plates 10 and 14, but the light guide means 9 is made of a plate-like transparent member. The first incident end surface and the second incident end surface are formed on one end surface and the other end surface facing each other, the exit surface is formed on one of the two opposing plate surfaces, and the first plate is formed on the other plate surface. The light incident from the first incident end face is internally reflected and emitted from the emission face in a direction inclined to the direction opposite to the first incident end face with respect to the normal line of the liquid crystal display element 1. A light guide plate configured to reflect the light incident from the incident end face on the inner surface and emit the light from the emission face in a direction inclined to the direction opposite to the second incident end face with respect to the normal line of the liquid crystal display element 1. The first incident end face and the second incident end face of the light guide plate are respectively opposed to the first incident end face. Of the light emitting element 21a and may be the second light emitting element 21b is arranged.

1 is an exploded perspective view of a liquid crystal display device showing an embodiment of the present invention. The expansion side of a part of surface light source of the said liquid crystal display device. FIG. 3 is an outgoing ray diagram of first and second illumination light from the surface light source. The intensity distribution figure in the left-right direction of the screen of the 1st and 2nd illumination light from the said surface light source. The intensity distribution figure in the up-down direction of the screen of the 1st and 2nd illumination light from the said surface light source. FIG. 3 is a block circuit diagram of driving means of the liquid crystal display device. FIG. 4 is a drive sequence diagram of a liquid crystal display element and a surface light source when performing wide field display and narrow field display in a field sequential liquid crystal display device. FIG. 5 is a drive sequence diagram of a liquid crystal display element and a surface light source in a wide-field display and a narrow-field display in a liquid crystal display device provided with three color filters of red, green, and blue in the liquid crystal display element. The figure which shows an example of the display seen from the front direction at the time of the wide-field display of the said liquid crystal display device, and the display seen from the direction inclined in the left direction and the right direction. The figure which shows an example of the display seen from the front direction at the time of the narrow-field display of the said liquid crystal display device, and the display seen from the direction leaning to the left direction and the right direction.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display element, 1a ... Screen area | region, 8 ... Surface light source, 9 ... Light guide means, 10 ... 1st light guide plate, 11 ... 1st incident end surface, 12 ... 1st light emission surface (of light guide means) Emission surface), 13... First reflection surface, 14... Second light guide plate, 15... Second incident end surface, 16. ... elongated prisms, 21a, 21b ... light emitting elements, 22 ... driving means.

Claims (4)

A liquid crystal display element having a screen region in which a plurality of pixels for controlling light transmission are arranged in a matrix, an image data signal is applied to each of the plurality of pixels, and an image corresponding to the image data is displayed;
The liquid crystal display element is disposed on the side opposite to the observation side, and the intensity of the front light emitted in the normal direction of the liquid crystal display element toward the liquid crystal display element is in one direction with respect to the normal direction and A first illumination light having an intensity distribution higher than the intensity of the oblique light emitted in a direction inclined in the opposite direction; a second illumination light having an intensity distribution in which the intensity of the oblique light is higher than the intensity of the front light; A surface light source for selectively irradiating
One of a display image data signal corresponding to an image signal and a fixed image data signal corresponding to a fixed image having a pattern registered in advance is selected for each pixel of the liquid crystal display element. The selection data signal is applied alternately, the first illumination light is irradiated from the surface light source in synchronization with the application of the display image data signal to the pixel, and the selection data signal is applied to the pixel. And a driving means for irradiating the second illumination light from the surface light source in synchronization with the liquid crystal display device.   The liquid crystal display device according to claim 1, wherein the intensity of the front light of the second illumination light is set to 20% or less of the intensity of the front light of the first illumination light.   The surface light source has first and second incident end surfaces formed on one end surface and the opposite end surface, and emits light incident from the first and second incident end surfaces to a surface facing the liquid crystal display element. An exit surface is formed, and the first light incident from the first entrance end surface is inclined in a direction opposite to the first entrance end surface with respect to the normal direction of the liquid crystal display element from the exit surface. The second light incident from the second incident end face is guided from the outgoing face in a direction inclined in the direction opposite to the second incident end face with respect to the normal direction of the liquid crystal display element. The light means and the first incident end face side surface are substantially parallel to the first and second incident end faces of the light guide means, and the second incident end face side face and the second incident end face side are formed in different shapes. A plurality of elongated prisms arranged opposite to the light exit surface of the light guide means. Of the first and second lights emitted from the exit surface of the light guide means, one light incident on the plurality of elongated prisms from one side surface thereof is directed in the direction near the normal line of the liquid crystal display element. One direction along the direction perpendicular to the length direction of the elongated prism with respect to the normal line of the liquid crystal display element, the other light emitted from the other side surface to the plurality of elongated prisms. And a prism sheet that emits light in a direction inclined in the opposite direction, and the first and second light sources that are arranged to face the first incident end surface and the second incident end surface of the light guiding unit, and are selectively lit. The liquid crystal display device according to claim 1, wherein the liquid crystal display device comprises:   The light guide means of the surface light source is made of a plate-like transparent member, a first incident end surface is formed on one end surface thereof, a first emission surface is formed on one of two opposing plate surfaces, and the other plate The light incident on the surface from the first incident end face is internally reflected and emitted from the first emission face in a direction inclined in the direction opposite to the first incident end face with respect to the normal line of the liquid crystal display element. A first light guide plate formed with a first reflection surface that transmits light incident from the outer surface side and is emitted from the first output surface; and a plate shape separate from the first light guide plate A second incident end surface is formed on the end surface opposite to the first incident end surface of the first light guide plate, and a second exit surface is formed on one of the two opposing plate surfaces. The light incident on the other plate surface from the second incident end surface is reflected, and is reflected from the second emission surface to the normal line of the liquid crystal display element. Then, a second reflecting surface that emits light in a direction inclined in a direction opposite to the second incident end surface is formed, and the second emitting surface is made to face the first reflecting surface of the first light guide plate. The second light guide plate is disposed in the first light emitting element so as to face the first incident end face of the first light guide plate, and the second light guide plate receives the second incident light. The liquid crystal display device according to claim 3, wherein a second light emitting element is disposed to face the end face.

Images