JP2009169196A - Multidisplay device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve image quality by controlling the brightness of a light source, in a multidisplay system device arrayed with a plurality of displays. <P>SOLUTION: Each image display part constituting this multidisplay device has a backlight unit having the plurality of light sources for forming an image on the image display part, and a luminous energy regulating means for regulating the brightnesses of the light sources in the backlight unit. The lightness of each backlight is individually regulated by the luminous energy regulating means. Further, the light source included in each backlight is controlled in response to an arrangement position thereof. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a multi-display device that forms a multi-screen by arranging a plurality of liquid crystal video display devices, which are flat-type video display devices, in a two-dimensional manner (matrix shape).

  Conventionally, there has been known a multi-display device in which a plurality of video display devices are arranged vertically and horizontally (also referred to as a two-dimensional shape or a matrix shape), and an image divided by each video display device is displayed to constitute one large screen as a whole. It has been. For example, a rear projection display has been used as an image display device (hereinafter referred to as “display”) used in a multi-display device. However, in recent years, it is one of flat display devices in terms of lamp life and installation. A liquid crystal display is also used.

  The so-called direct-view type liquid crystal display diffuses illumination light emitted from a liquid crystal panel unit as a video display unit that forms an image, a backlight unit as a light source that illuminates the liquid crystal panel unit from the back side, and a backlight unit. And a diffusion plate that eliminates uneven brightness (brightness unevenness). Therefore, the luminance unevenness in the screen hardly occurs. However, a difference in luminance (brightness unevenness) between adjacent liquid crystal displays occurs in the same manner as in the case of a rear projection display. Therefore, it is necessary to adjust the luminance level of each display so that the luminance difference between the screens is eliminated.

  Further, in the liquid crystal display, a non-display area corresponding to a wiring portion for driving the panel exists at the peripheral portion of the liquid crystal panel unit, and a seam is generated between adjacent liquid crystal displays. For this reason, if there is a luminance difference in the vicinity of the seam, the seam is conspicuous, and the continuity or sense of unity of the image is applied.

  For example, Patent Documents 1 and 2 disclose a technique for reducing the luminance difference (brightness unevenness) between the screens described above and a technique for reducing the luminance difference at the joint portion of the screen boundary to make the joint inconspicuous. Yes.

  In order to eliminate a luminance difference between adjacent displays, Patent Document 1 includes a light detection unit that detects a luminance level in the vicinity of a boundary (seam), and measures the luminance of the screen near the joint with the light detection unit. Disclosed is a multi-display apparatus configured to correct a luminance difference between the two. This technique can reduce the luminance difference by detecting the luminance difference between adjacent display screens.

  Patent Document 2 discloses a multi-display device that overlaps a part of an image in the vicinity of a joint between adjacent displays and controls the luminance of the overlapped portion to reduce the luminance difference in the vicinity of the joint. With this technique, the luminance of the overlapped portion can be corrected so as to appear uniform in the same manner as the luminance of other portions, and the visual recognition of the joint can be relaxed.

Japanese Patent Laid-Open No. 4-117785 JP-A-6-95139

  In Patent Document 1, the luminance level of the video signal is varied in order to correct the luminance difference between the screens. If the luminance difference is adjusted, the contrast is lowered if the luminance level of the video signal is adjusted in a decreasing direction. It will be.

  By the way, the liquid crystal panel unit of the liquid crystal display forms an optical image (image) by modulating the light intensity irradiated from the back side substantially perpendicularly to the liquid crystal panel unit, and emits the image light to the viewer side. To do. For this reason, as is well known, the liquid crystal display has a characteristic that the brightness (luminance) is lowered when observing from an oblique direction of the screen as compared with the case of observing the screen directly. In other words, there is a problem that the luminance decreases when the angle (viewing angle) when the screen of the liquid crystal display is viewed from the observer increases. However, Patent Document 1 considers correction of a luminance difference between screens, and does not pay sufficient consideration to luminance reduction due to a viewing angle in a multi-display device.

  Further, since Patent Document 2 requires a means for superimposing a part of an image and a means for controlling the luminance of the superposed portion, the cost is increased. In addition, as in Patent Document 1, sufficient consideration is not given to luminance reduction due to viewing angle in a multi-display device.

  The present invention has been made in view of the above-described problems, and a first object of the invention is to provide a multi-display device that reduces luminance unevenness between screens without reducing contrast. A second object is to provide a multi-display device that reduces luminance deterioration due to viewing angle characteristics.

  The present invention is characterized by the structures described in the claims. That is, the present invention is characterized in that the brightness of the light source in the backlight unit installed on the back surface of each video display device constituting the multi-display can be controlled independently. Further, the present invention is characterized in that the brightness of a plurality of light sources provided in the backlight unit can be controlled for each light source.

  According to the present invention, since the brightness of the backlight unit is changed, it is possible to eliminate a luminance difference (brightness unevenness) between adjacent screens without causing a decrease in contrast. In addition, since the brightness can be changed for each of the plurality of light sources, it is possible to perform luminance control in accordance with the viewing angle, and to provide a multi-display device that suppresses a luminance decrease due to viewing angle characteristics of a liquid crystal display. Can do.

  Hereinafter, the best mode of the present invention will be described with reference to the drawings. In each figure, elements having common functions are denoted by the same reference numerals, and description of elements once described is omitted.

  Hereinafter, the multi-display apparatus according to the first embodiment will be described with reference to FIGS. 1, 2, 3, and 4. In this embodiment, in each liquid crystal display constituting the multi-display device, the amount of light emitted from the backlight unit paired with the video display unit composed of the liquid crystal panel unit (that is, the brightness of the backlight unit) is adjusted. This reduces the luminance difference between adjacent video display units (liquid crystal panel units) and improves the video quality of the multi-display device.

  FIG. 1 is a plan view showing an overview of a multi-display apparatus according to the present embodiment, where FIG. 1 (a) is a front view and FIG. 1 (b) is a side view. FIG. 2 is a schematic configuration diagram of a light amount adjustment unit that adjusts and drives the light amount of the backlight unit according to the present embodiment. FIG. 3 is a diagram illustrating an example of a backlight unit used in one liquid crystal display constituting the multi-display device according to the present embodiment. FIG. 4 is a diagram illustrating a state of the multi-display device after light amount adjustment in which a luminance difference between adjacent video display units is reduced.

  First, the configuration of the multi-display device according to the present embodiment will be described with reference to FIG. In FIG. 1, it is assumed that the multi-display apparatus of this embodiment is composed of liquid crystal displays having the same configuration # 1 to # 9, for example. Then, for example, when the liquid crystal displays # 1, # 2, # 6, and # 8 perform white display with a predetermined gradation on the entire screen, the other liquid crystal displays # 3, # 4, # 5, # 7, and # 9 are displayed. It is assumed that the brightness is darker than. Each liquid crystal display #i (i is a number from 1 to 9 indicating the arrangement position of the liquid crystal display) includes a video display unit 14i composed of a liquid crystal panel unit and a direct type backlight unit 15i that illuminates the video display unit 14i from behind. (I = 1 to 9) (the backlight unit behind the video display unit should be hidden in the front view of FIG. 1A, but is shown for convenience of explanation) ) For example, the liquid crystal display # 1 includes a video display unit 141 and a backlight unit 151. The liquid crystal display # 9 includes a video display unit 149 and a backlight unit 159. The same applies to the other liquid crystal displays #i. That is, in the present embodiment, the backlight unit has a pair configuration with the video display unit. In each backlight unit 15i (i = 1 to 9), the light amount (that is, the brightness) is varied by the corresponding light amount adjusting means 50i (i = 1 to 9) (described later in FIG. 2). Further, the direct type backlight unit refers to a form in which a plurality of lamps (for example, fluorescent tubes) are arranged in parallel behind the video display unit (described later in FIG. 3).

  Next, the light amount adjusting means of the backlight unit will be described with reference to FIG. It is assumed that each backlight unit paired with each video display unit has the same configuration, and each light amount adjusting means that drives by adjusting the light amount (brightness) of each backlight unit has the same configuration. Therefore, a description will be given using the light amount adjusting means 501 of the backlight unit 151 that typically constitutes the # 1 liquid crystal display.

  As shown in FIG. 2, the light amount adjusting means 501 that adjusts and drives the light amount (brightness) of the backlight unit 151 includes an inverter unit 501 a, a light control unit 501 b, a control unit 501 c, and a user interface unit (hereinafter, referred to as “light source adjustment unit”). , Abbreviated as “user IF section”) 501d.

  The control unit 501c includes a CPU (Central Processing Unit) or the like as a calculation control unit, and the light amount adjustment unit 501 is based on an instruction (for example, remote control or button operation) via a user IF unit 501d by a user (not shown). Control each element that composes. For example, a control signal (hereinafter referred to as “duty control signal”) for adjusting the light amount (brightness) of the backlight unit 151 is output to the dimming unit 501b. The control unit 501c may also be used as a control unit (not shown) that controls the entire liquid crystal display # 1.

  Based on the duty control signal from the control unit 501c, the dimming unit 501b performs on / off control (chopper control) of a power supply voltage (primary side voltage of the inverter transformer) (not shown) supplied to the inverter unit 501a to perform PWM (Pulse Width Modulation) signal is generated and supplied to the inverter unit 501a.

  The inverter unit 501a outputs a high-frequency voltage with a duty corresponding to the PWM signal from the dimming unit 501b to the backlight unit 151.

  For example, it is assumed that the user instructs the control unit 501c to increase the brightness via the user IF unit 501d in order to increase the brightness of the liquid crystal display # 1 to the light amount adjustment unit 501 having such a configuration. The control unit 501c sends a duty control signal corresponding to the instruction to the dimming unit 501b. The dimming unit 501b increases the length (period) of the on-voltage to turn on the backlight unit and shortens the length (period) of the off-voltage to turn off in correspondence with the received duty control signal. The PWM signal is generated and output to the inverter unit 501a. The inverter unit 501a drives the backlight unit 151 in accordance with the input PWM signal, for example, by extending the period for generating the high frequency voltage. That is, the light amount adjusting unit 501 emits light from the backlight unit 151 by changing the ratio (generally referred to as “duty ratio”) between the period during which the backlight unit 151 is turned off and the period during which the backlight unit 151 is driven to be lit. The amount of light (brightness) can be varied. For example, the backlight unit 151 can be brightened by lengthening the period during which the backlight unit 151 is turned on and shortening the period during which the backlight unit 151 is turned off. In the opposite case, it will be obvious that it will be dark. These light quantity adjustment methods are known, and are described in, for example, Japanese Patent Application Laid-Open No. 2002-117999. Here, the dimming unit 501b changes the duty ratio. However, for example, the brightness may be changed by changing the power supply voltage supplied to the inverter unit 501a. Alternatively, these methods may be combined.

  Next, an example of the backlight unit according to the present embodiment will be described with reference to FIG. Here also, description will be made using the backlight unit 151 as a representative.

  As shown in FIG. 3, the backlight unit 151 includes four fluorescent tubes 201, 202, 203, and 204 as an example (four in this example, but actually more than this). Here, each fluorescent tube is assumed to be an EEFL (External Electrode Fluorescent Lamp) in which an electrode that can be easily driven in parallel exists outside. The four fluorescent tubes are arranged such that their longitudinal directions are parallel to the long side of the video display unit 141 and the parallel directions to the short side of the video display unit 141 so that luminance unevenness does not occur. They are arranged in one row at intervals. The four fluorescent tubes 201, 202, 203, 204 are driven by adjusting the brightness (light quantity) by one light quantity adjusting means 501. Of course, the present embodiment is not limited to this, and each fluorescent tube may be adjusted and driven by separate light quantity adjusting means.

  In general, when using a liquid crystal display, comparing the brightness of the display unit, the brightness depends on the brightness of the light source (fluorescent tube) used in the backlight unit and the transmittance variation of various optical films and liquid crystal panels. Different. For this reason, the video display units 141, 142, 146, and 148 in the video display units constituting the multi-display device have substantially the same brightness, for example, in brightness, but the video display units 143, 144, 145, and 147 have the same brightness. 149 has a different brightness (here, for example, dark). Conventionally, a multi-screen with different brightness has been provided to the user in this state.

  Therefore, in this embodiment, as described above, for each backlight unit as a light source that illuminates the image display unit of each liquid crystal display, the amount of light emitted from the backlight unit is adjusted (that is, the brightness is adjusted). For example, a backlight unit of a liquid crystal display with a low brightness is provided so as to increase the amount of emitted light by the light amount adjusting unit attached to the backlight unit. More specifically, the light amount adjusting means 501, 502, the light amounts emitted from the backlight units 151, 152, 156, 158 are matched with the brightness of the video display units 143, 144, 145, 147, 149. It controls by 506,508. FIG. 4 shows the state of the multi-display device after the light amount adjustment. As apparent from FIG. 4, it can be seen that the brightness between the screens is uniform.

  Thus, according to the present embodiment, it is possible to reduce luminance unevenness between the liquid crystal displays. At this time, since the brightness of the light source is adjusted to adjust the brightness between the screens, the contrast does not decrease. Therefore, it is possible to provide a multi-screen with uniform brightness of the video display unit without reducing the contrast.

  In the above description, the dark image display unit is adjusted to be bright so that the luminance unevenness between the screens is eliminated. However, the present embodiment is not limited to this. Adjustment may be made so that the bright video display section becomes dark so that uneven brightness between the screens is eliminated. Alternatively, these methods may be combined.

  In the first embodiment, the multi-display device that reduces the luminance unevenness between the liquid crystal displays (so-called luminance unevenness between the screens) has been described. However, in the first embodiment, since one video display unit is illuminated by one backlight unit, there may be a difference in brightness between the central part and the peripheral part of the video display unit. When this difference exists, a luminance difference is generated between the adjacent liquid crystal displays on both sides of the joint portion (non-display portion) of the boundary portion between the adjacent video display portions. For this reason, the frame-like non-display portion existing at the boundary between adjacent liquid crystal displays is noticeable, and there is a risk of continuity of images and a sense of unity.

  Next, a multi-display device according to a second embodiment that solves the above-described problem will be described. The present embodiment is characterized in that one backlight unit size is smaller than one video display unit size.

  The method for controlling the brightness of the backlight unit is not particularly limited. Also in the second embodiment, for example, the backlight unit light quantity adjustment control technique described in FIG. 2 of the first embodiment can be used.

  FIG. 5 is a conceptual diagram illustrating a multi-display apparatus according to the second embodiment. FIG. 6 is a diagram schematically showing the multi-display device after the luminance is controlled. 5 and 6, the backlight unit behind the video display unit should be hidden and cannot be seen, but is shown for convenience of explanation.

  As shown in FIG. 5, the display unit (display screen) of the multi-display device according to the present embodiment includes, for example, video display units 141 to 149 arranged in 3 rows and 3 columns. Each video display unit is configured to be illuminated by a plurality of backlight units having a size smaller than the size of the area (hereinafter simply referred to as “the size of the video display unit”). As a specific example, here, a display unit (display screen) composed of nine video display units arranged in three rows and three columns is a 16-screen back arranged in four rows and four columns. Illuminated by light units 161-176. For example, as a representative example, the video display unit 141 will be described. The video display unit 141 is illuminated by four backlight units 161, 162, 165, and 166. The boundary B14 between the video display units 141 and 144 is illuminated by two backlight units 165 and 166, and the boundary B12 between the video display units 141 and 142 is illuminated by two backlight units 162 and 166. Has been. That is, in this embodiment, two backlight units are arranged so as to straddle the boundary between adjacent video display units. Therefore, a difference in brightness (luminance difference) hardly occurs on both sides of the boundary portion between adjacent video display portions, and the frame-like non-display existing at the boundary of the adjacent liquid crystal display as described at the beginning of this embodiment. It is possible to greatly reduce the conspicuousness of the portion and to improve the continuity of the image and the sense of unity.

  Of course, as shown in FIG. 5, for example, when the brightness of the backlight units 161, 166, 173, and 176 is different from the others, for example, by the method described in FIG. It can be adjusted to the same brightness as the light unit.

  As described above, in this embodiment, a backlight unit smaller than the size of one video display unit is arranged in a matrix (with a larger number of screens than the number of video display units arranged in a matrix (two-dimensional). (2D). Therefore, a plurality of backlight units are arranged so as to straddle a boundary portion (non-display portion) between adjacent video display portions, which has been conventionally emphasized by a decrease in luminance around the video display portion. In addition, it is possible to reduce the luminance difference at the boundary (seam) between adjacent video display units. That is, it is possible to make the seam, which has been a problem in the conventional multi-display device, inconspicuous and to improve the sense of unity. Further, in this embodiment, it is not necessary to use a means for superimposing a part of an image used in the prior art (for example, Patent Document 2) or a means for controlling the luminance of the superposed part. It is possible to alleviate the luminance difference at the boundary (seam) between the video display units to be performed, and it is possible to suppress an increase in cost.

  Next, by using FIG. 7, 8, 9, 10, 11, 12, 13, 14, 15 to control the luminance (brightness) in the image display unit, the viewing angle characteristics of the observer and the image display unit are displayed. A multi-display device according to Embodiment 3 that can improve the luminance reduction caused by the above will be described.

  As described in the problem section, the liquid crystal panel unit (video display unit) of the liquid crystal display has a characteristic that the brightness (brightness) decreases when observing from the diagonal direction of the screen compared to when observing the screen directly. have. Therefore, in a multi-display device in which liquid crystal displays are arranged in a matrix, the luminance decreases when the angle (viewing angle) when the screen of the multi-display device is viewed by an observer increases. For example, when an observer views the screen of the multi-display device from the left-side end obliquely of the multi-display device, the brightness of the video display unit on the right-side end side is lower than that of the video display unit on the left-side end side. Therefore, in the present embodiment, adjustment is performed using the light amount adjusting means of each backlight unit so as to have a reverse characteristic of the viewing angle characteristic. In this way, viewing angle characteristics when viewing the screen of the multi-display device from the observer are offset, and viewing the video on the screen in a uniform state with uniform brightness as viewed from the observer Is possible.

  7, 8, and 9 are diagrams illustrating a state in which the light amount of each backlight unit is adjusted so as to have a reverse characteristic of the viewing angle characteristic at the observer position.

  As shown in FIG. 7, when the observer position 401 is on the left side of the multi-display device, the left-side video display unit (141) of the multi-display device has a uniform brightness when viewed from the multi-display device. , 142, 143) is bright, and the right image display unit (147, 148, 149) has a viewing angle characteristic (luminance characteristic) that becomes dark. Therefore, the amount of light of each backlight unit is adjusted so as to have the luminance characteristic of the reverse characteristic (specifically, the observer adjusts while viewing the screen so that the brightness of each video display unit is the same) ). That is, the light amount is adjusted by, for example, each light amount adjusting unit shown in FIG. 2 attached to each backlight unit so that the backlight unit on the left side becomes darker and the backlight unit becomes brighter toward the right side. If the light amount adjustment is performed in this way, the viewing angle characteristic seen by the observer and the luminance characteristic formed by each backlight unit adjusted for the light amount are offset, and when the screen of the multi-display device is viewed from the observer, It is possible to view the video on the screen with a uniform brightness.

  In FIG. 8, the observer position 402 is at a position where the multi-display device is looked up from below. Therefore, the light amount adjustment is performed by the light amount adjustment means corresponding to each backlight unit so that the lower image display portion becomes darker and becomes brighter toward the upper image display portion.

  In FIG. 9, the observer position 403 is at a position where the multi-display device is looked up obliquely from the lower left corner. Therefore, the light amount is adjusted by the light amount adjusting means corresponding to each backlight unit so that the video display unit 143 at the lower left corner is dark and the video display unit is brightened toward the upper right corner.

  As described above, in the present embodiment, the brightness of the light source (backlight unit) can be controlled to be arbitrarily changed using the corresponding light amount adjusting means. Therefore, as shown in FIGS. 7, 8, and 9, the light amount adjustment is performed by the corresponding light amount adjusting means so that the brightness of the backlight unit is increased as the distance from the position close to the observer positions 401, 402, and 403 increases. To do. Thereby, it is possible to provide a multi-display device that can be viewed with uniform brightness by correcting the viewing angle characteristics at the observer position.

  In the above description, the light amount adjustment is performed by the light amount adjustment unit corresponding to each backlight unit. However, the present embodiment is not limited to this. In advance, the viewing angle characteristics at a plurality of observer positions are experimentally obtained, luminance characteristics opposite to these viewing angle characteristics are calculated, and the control unit of the light amount adjusting means corresponding to each backlight unit is illustrated. Stored in a non-volatile memory. Then, when the observer designates any one of the plurality of observer positions via the user IF unit of each light amount adjusting unit, the control unit of each light amount adjusting unit is shown in FIGS. As described above, the light amount is adjusted according to the position of the backlight unit. With these control processes, it is possible to provide a multi-display device capable of correcting viewing angle characteristics at the viewer position and viewing with uniform brightness.

  In the embodiments so far, the example in which the brightness is controlled for each backlight unit has been shown, but it goes without saying that a smoother luminance distribution can be provided by controlling the individual light sources constituting the backlight unit.

  Therefore, first, the light amount adjusting means for controlling the individual light sources constituting the backlight unit will be described with reference to FIG.

  FIG. 19 is a schematic configuration diagram of a light amount adjusting unit capable of controlling individual light sources constituting the backlight unit. Here, the light amount adjusting means 511 for individually adjusting the amount of light and driving each fluorescent tube (211 to 214) constituting the backlight unit 191 will be described. In FIG. 19, the fluorescent tube is a cold cathode fluorescent lamp.

  As shown in FIG. 19, the light amount adjusting means 511 that adjusts and drives the light amount (brightness) of the backlight unit 191 has the same number (four in this case) of inverter units as the fluorescent tubes constituting the backlight unit 191. 5111a, 5112a, 51113a, 5114a (these are collectively referred to as the inverter unit 511a), dimming units 5111b, 51112b, 51113b, 51114b (these are collectively referred to as the dimming unit 511b), a control unit 511c, and a user IF unit 511d.

  The control unit 511c includes a CPU (Central Processing Unit) or the like as a calculation control unit, and the light amount adjustment unit 511 is based on an instruction (for example, a remote control or button operation) via a user IF unit 511d by a user (not shown). Control each element that composes. For example, a control signal (hereinafter referred to as “duty control signal”) for adjusting the light amount (brightness) of each fluorescent tube 211, 212, 213, 214 of the backlight unit 191 corresponds to each dimming unit 5111b, 51112b, 5113b. , 51114b.

  The dimmer 511b (5111b, 51112b, 51113b, 51114b) generates a PWM signal to be supplied to the corresponding inverter 511a (5111a, 51112a, 51113a, 51114a) based on the duty control signal from the controller 511c. To the inverter unit 511a.

  Each inverter unit 511a (5111a, 51112a, 51113a, 51114a) constitutes a backlight unit 191 with a high frequency voltage having a duty corresponding to the PWM signal from each corresponding dimming unit 511b (5111b, 51112b, 51113b, 51114b). To each fluorescent tube (211, 212, 213, 214) to be driven.

  Since the light amount adjusting means is configured as described above, the control unit 511c, based on an instruction via the user IF unit 511d, each fluorescent tube (211, 212, 213, 214) constituting the backlight unit 191. Can be driven while adjusting the amount of light by the corresponding dimmer 511b and inverter 511a.

  When individually controlling the light sources (for example, fluorescent tubes) constituting the backlight unit with the above-described light amount adjusting means so that the entire screen of the multi-display device has a uniform brightness according to the observer position, If the size of the light source controlled by the adjusting means is large, there is a risk that a luminance gradient will occur between adjacent light sources. Next, an example of the arrangement of the light sources constituting the backlight unit in which the luminance gradient is unlikely to occur and a smooth luminance distribution can be easily obtained will be described with reference to FIGS.

  FIG. 10 shows an example of a backlight unit in which the fluorescent tubes according to this embodiment are arranged in parallel. In FIG. 10, the backlight unit 192 has cold cathode fluorescent tubes 241 and 251 whose length in the longitudinal direction is shorter than half of the long side of the video display unit, parallel to the long side and parallel to the short side of the video display unit. And a plurality of fluorescent tubes arranged in two rows at a predetermined interval. Here, six cold cathode fluorescent tubes 241 are arranged in one row and six cold cathode fluorescent tubes 251 are arranged in one row. Note that 241a and 241c are electrodes, and 241b is a light emitting area. Similarly, 251a and 251c are electrodes, and 251b is a light emitting area. In FIG. 10, fluorescent tubes are arranged in two rows, and finer light amount control is possible than in the case of one row. By adjusting the amount of light for each of these total twelve by individually corresponding light amount adjusting means, it becomes possible to cancel the viewing angle characteristics at the observer position and view an image with uniform brightness. Of course, if the number of light sources (for example, fluorescent tubes) constituting each backlight unit is increased, the same number of light quantity adjusting means for adjusting each fluorescent tube is required, which increases the cost. Therefore, for example, if six fluorescent tubes in one row are divided into three groups G2411, G2412, G2511, and G2512 for a total of four groups, and each group is controlled by one light amount adjusting means, the cost increases. A smooth luminance distribution can be realized while suppressing.

  FIG. 11 shows an example in which the ends, which are the electrodes of the fluorescent tubes arranged in the backlight unit, are wrapped. In FIG. 11, 242 and 252 are cold cathode fluorescent tubes. Reference numerals 242a and 242c denote electrodes, and 242b denotes a light emitting area. Similarly, 252a and 252c are electrodes, and 252b is a light emitting area. As shown in FIG. 11, by arranging the electrode parts of the cold cathode fluorescent tubes arranged in the backlight unit 192B so as to wrap, the light emitting areas are arranged continuously, avoiding the electrode part at the end which is a non-lighting part. Therefore, the non-lighting portion DA that occurs in the case of FIG. 10 can be eliminated.

  FIG. 12 shows an example of a backlight unit in which cold cathode fluorescent tubes are arranged in three rows. In FIG. 12, the backlight unit 193 is alternately long by wrapping cold cathode fluorescent tubes 261, 271 and 281 whose length in the longitudinal direction is shorter than 1/3 of the long side of the image display unit at the electrode ends. It consists of a plurality of fluorescent tubes arranged in parallel to the side and arranged in three rows at a predetermined interval parallel to the short side of the video display unit. In FIG. 12, fluorescent tubes are arranged in three rows, and finer light amount control is possible than in the case of two rows in FIG.

  FIG. 13 shows an example of a backlight unit in which cold cathode fluorescent tubes are arranged in five rows. In FIG. 13, the backlight unit 194 includes cold cathode fluorescent tubes 291, 292, 293, 294 and 295 which are alternately arranged in parallel with the long side by wrapping the electrode end portions, and the short side of the video display unit. And a plurality of fluorescent tubes arranged in five rows at predetermined intervals in parallel. By arranging in this way, more accurate luminance control is possible, and a smooth luminance distribution can be realized.

  FIG. 14 is an example of a backlight unit using LEDs as a light source. 451R indicates a red LED, 451G indicates a green LED, and 451B indicates a blue LED. In this embodiment, red, green, and blue LEDs are used one by one to form one light source 451. The color and the number of each LED are not limited, and the configuration is not limited as long as a desired color and brightness can be realized.

  FIG. 15 is a graph showing the relationship between the viewing angle and the luminance, and is a luminance distribution measured according to the viewing angle of the observer. In FIG. 15, the horizontal axis of the graph is the viewing angle, and A indicates the maximum viewing angle position. For example, when the observer position is in a positional relationship as shown in FIG. 9 with respect to the multi-display device, A corresponds to the upper right corner portion. The vertical axis indicates the luminance ratio, and in this figure, the state viewed from the front, that is, when the viewing angle is 0 ° is maximized. Reference numeral 901 denotes a luminance distribution curve of a conventional multi-display device, and reference numeral 902 denotes a luminance distribution curve according to this embodiment. As shown in a luminance distribution curve 901, the conventional luminance distribution usually decreases in brightness as the direction deviates from the front, that is, as the viewing angle increases. On the other hand, in this embodiment, since the luminance can be adjusted by the light amount adjusting means so as to cancel the decrease in the viewing angle, the luminance distribution curve 902 is obtained, and the luminance decrease due to the viewing angle characteristics can be improved. , It is possible to adjust only to the position of the observer.

  Next, the relationship between the signal control wiring of the liquid crystal display and the backlight unit in the multi-display device will be described with reference to FIGS.

  FIG. 16 is a schematic diagram illustrating wiring of a liquid crystal display according to the fourth embodiment. In FIG. 16, the multi-display apparatus according to the present embodiment includes four screens 121, 122, 123, and 124 arranged in two rows and two columns. Each video display unit is provided with signal and signal control wires 131 and 132 on two outer peripheral side surfaces that do not face the adjacent video display unit. With such a configuration, each liquid crystal display constituting the multi-display device can change (select) the position where the wiring is drawn out either in the left-right direction or in the up-down direction. That is, the wiring can be arbitrarily drawn to the outer periphery of each video display unit. Therefore, the space on the back side of each video display unit can be used arbitrarily, and the arrangement of the backlight unit can be arbitrarily set.

  FIG. 17 is a schematic diagram illustrating a relationship between the wiring of the liquid crystal display according to the fourth embodiment and the backlight unit. As shown in FIG. 17, the display unit (display screen) of the multi-display device is composed of four screen image display units 121 to 124 arranged in two rows and two columns. Each video display unit is configured to be illuminated by a plurality of backlight units having a size smaller than the size of the video display unit. Here, illumination is performed by nine backlight units 181 to 189 arranged in three rows and three columns.

  In this embodiment, the positional relationship between the signal control wiring of the liquid crystal display and the backlight unit is shown, but the method of arranging the backlight unit on the back of the liquid crystal display is not particularly limited.

  Next, a multi-display device according to a fifth embodiment in which a liquid crystal display having a light amount adjusting unit and a liquid crystal display having no light amount adjusting unit are mixed will be described with reference to FIG.

  When the number of screens of a multi-display device increases, the angle (viewing angle) at which the image display portion around the device is viewed increases even if the observer is at the center of the device, and the brightness of the image display portion located in the periphery portion increases. (Luminance) decreases. On the other hand, the video display unit in the vicinity of the center of the apparatus has a small prospective angle (viewing angle), and a decrease in brightness is not a problem. Therefore, in this embodiment, in a multi-display apparatus in which an observer is located near the center of the apparatus, a liquid crystal display provided with a light amount adjusting means is disposed in the periphery of the apparatus. An example of such a multi-display device for use is a monitoring multi-display device.

  FIG. 18 is a schematic diagram illustrating a multi-display apparatus according to the fifth embodiment. As is clear from FIG. 18, the multi-display device of this embodiment arranges a plurality of liquid crystal displays 20 having no light amount adjusting means in a region 601 surrounded by a dotted line at the center of the device so as to surround the region 601. A plurality of liquid crystal displays 40 provided with light amount adjusting means are arranged. The change of the angle (viewing angle) θ3 at which the observer located at the center of the apparatus looks at the liquid crystal display in the region 601 is small, and the decrease in brightness is at a level with no problem. However, the angle (viewing angle) θ4 at which the liquid crystal display located in the peripheral portion of the apparatus is viewed becomes large, and a decrease in luminance becomes a problem. Therefore, in this embodiment, the liquid crystal display 40 provided with the light amount adjusting means is disposed in the peripheral portion of the apparatus, and the luminance reduction is corrected by the light amount adjusting means.

  As described above, according to the present embodiment, it is possible to correct a decrease in luminance due to viewing angle characteristics while reducing the amount of light amount adjusting means to be used. Therefore, the multi display device can be configured at low cost.

  In Examples 1 to 4 described above, an example in which a cold cathode fluorescent tube, an external electrode fluorescent tube, or the like is used as a light source has been shown, but the present invention is not limited to this. It goes without saying that the light source used may be, for example, a hot cathode fluorescent tube or an LED.

FIG. 2 is a plan view illustrating an overview of the multi-display device according to the first embodiment. FIG. 3 is a schematic configuration diagram of a light amount adjusting unit according to the first embodiment. FIG. 3 is a diagram illustrating an example of a backlight unit according to the first embodiment. The figure which shows the state of the multi-display apparatus after light quantity adjustment. FIG. 6 is a conceptual diagram illustrating a multi-display device according to a second embodiment. The figure which shows the state after luminance control. The figure explaining the state which adjusted the light quantity of each backlight which correct | amends the viewing angle characteristic in an observer position. The figure explaining the state which adjusted the light quantity of each backlight which correct | amends the viewing angle characteristic in an observer position. The figure explaining the state which adjusted the light quantity of each backlight which correct | amends the viewing angle characteristic in an observer position. The 1st example of the light source which comprises a 3rd Example. The 2nd example of the light source which comprises a 3rd Example. A third example of a light source constituting the third embodiment. The 4th example of the light source which comprises a 3rd Example. The 5th example of the light source which comprises a 3rd Example. The graph which shows the luminance distribution of a 3rd Example. FIG. 6 is a schematic diagram showing wiring of a liquid crystal display according to Example 4. FIG. 6 is a schematic diagram showing a relationship between wiring of a liquid crystal display according to Example 4 and a backlight unit. The schematic diagram which shows the multi-display apparatus by an Example. The schematic block diagram of the light quantity adjustment means which can control each light source which comprises a backlight unit.

Explanation of symbols

# ₁ to # 9: liquid crystal display, B12, B14: boundary, G241 ₁ , G241 ₂ , G251 ₁ , G251 ₂ ... group, 20 ... liquid crystal display, 40 ... liquid crystal display, 121-124 ... Video display unit, 131, 132 ... Wiring, backlight unit, 141-149 ... Video display unit, 151-159 ... Backlight unit, 161-176 ... Backlight Units, 181 to 189 ... Backlight unit, 191, 192, 193, 194 ... Backlight unit, 201-204 ... Fluorescent tube, 211-214 ... Fluorescent tube, 241, 242, 251, 252 ... Cold cathode fluorescent tube, 261, 271, 281 ... Cold cathode fluorescent tube, 291-295 ... Cold cathode fluorescent tube, 401- 03 ... Observer position, 451 ... LED light source, 501 to 509 ... Light quantity adjusting means, 501a ... Inverter part, 501b ... Dimming part, 501c ... Control part, 501d ... User IF unit, 511... Light amount adjusting means, 511a (5111a to 5114a)... Inverter unit, 511b (5111b to 5114b). IF section, 601... Region, 901, 902... Luminance distribution curve

Claims (6)

In a multi-display device that forms a multi-screen by arranging a plurality of video display units at least in the vertical direction or the horizontal direction,
The video display unit constituting the multi-display device includes a backlight unit having a plurality of light sources for forming an image on the video display unit, and an amount of light for adjusting the brightness of the light source in the backlight unit. Adjusting means,
A multi-display device characterized in that the brightness of the light source in the backlight is controlled by the light amount adjusting means. In a multi-display device that forms a multi-screen by arranging a plurality of video display units at least in the vertical direction or the horizontal direction,
The video display unit constituting the multi-display device includes a backlight unit having a plurality of light sources for forming an image on the video display unit, and an amount of light for adjusting the brightness of the light source in the backlight unit. Adjusting means,
The multi-display apparatus characterized in that the light amount adjusting means can individually control brightness of the plurality of light sources. The multi-display device according to claim 1 or 2,
The backlight unit is configured to be smaller than the video display unit, and is arranged so as to straddle a boundary portion between the adjacent video display devices.   The multi-display apparatus according to claim 1, further comprising a backlight unit in which brightness of a light source is not controlled by the light amount adjusting hand. 5. The multi-display device according to claim 1, wherein the image display unit includes:
Wiring for transmitting a signal or control signal to the video display unit is provided on at least two sides of the outer periphery of the video display unit, and two sides of the video display unit on which the wiring is provided can be changed. A multi-display device, characterized in that   6. The multi-display device according to claim 1, wherein the light source is an LED.

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