Patent Application
20070297172
This application claims priority from Japanese Patent Application No. JP 2006-150415 filed in the Japanese Patent Office on May 30, 2006 and Japanese Patent Application No. JP 2007-108501 filed in the Japanese Patent Office on Apr. 17, 2007, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
This invention relates to a backlight apparatus and a color image display apparatus wherein a color display panel is illuminated from the back side.
2. Description of the Related Art
Very thin television receivers formed using a liquid crystal display (LCD) or a plasma display panel (PDP) in place of a cathode ray tube (CRT) which has been used for long years after television broadcasting was started have been proposed and placed into practical use. Particularly, a liquid crystal display apparatus which uses a liquid crystal display panel is advantageous in that it can be driven with low power consumption and can be formed as a large size display unit. Therefore, the liquid crystal display apparatus is estimated to be popularized progressively together with reduction of the price of a large size liquid crystal display panel, and further development in future of the liquid crystal display apparatus is anticipated.
Among color liquid crystal display apparatus, a color liquid crystal apparatus of the backlight type wherein a transmission type color liquid crystal display panel having color filters is illuminated from the back side by a backlight apparatus to display a color image has become the main current. For the light source of the backlight apparatus, a fluorescent lamp such as a cold cathode florescent lamp (CCFL) which uses a fluorescent tube to emit white light is used frequently.
Since the CCFL uses mercury enclosed in the fluorescent tube, it may possibly have a bad influence on the environment. Therefore, a light emitting diode (LED) is estimated hopeful as the light source for a backlight apparatus in place of the CCFL as disclosed, for example, in Japanese Patent Laid-Open No. 2001-142409 (hereinafter referred to as Patent Document 1).
As a result of development of a blue light emitting diode, light emitting diodes which emit red light, green light and blue light of the primary colors of light have become complete. By mixing red light, green light and blue light emitted from the light emitting diodes, white light having high purity of white can be obtained. Accordingly, where the light emitting diodes are used as a light source for a backlight apparatus, after the light from the light source passes through the liquid crystal display panel, resulting color light has high color purity. Therefore, the color reproduction range can be widened significantly when compared with that by the CCFL.
For the light emitting diodes to be used as a light source for a backlight apparatus, light emitting diodes which use a light emitting diode (LED) chip of a high output are used effectively. Where light emitting diodes of the type mentioned are used, the luminance of the backlight apparatus can be enhanced significantly.
Incidentally, in a color liquid crystal display apparatus of the backlight type, a color liquid crystal display panel upon which prescribed white light is illuminated from the back side by a backlight apparatus shades the white light to extract only light of an object color component for each pixel by means of color filters to display a color image.
In particular, from within the white light emitted from the backlight apparatus, only light of an object color component extracted through the color liquid crystal display panel is utilized. For example, in order to display the entire screen in red, the color liquid crystal display panel shades the white light at those pixels other than pixels for which the red filter is provided, that is, at those pixels for which the green filter and the blue filter are provided. Therefore, light of the pixels other than the pixels for which the red filter is provided is not utilized.
In this manner, in existing color liquid crystal display apparatus of the backlight type, since white light including color components which are not utilized is emitted from the backlight apparatus, power is consumed uselessly as much.
Therefore, the assignee of the present invention has proposed, in Patent Document 1 mentioned above, an apparatus and method wherein a backlight panel is driven in a unit of a divisional region from among a plurality of divisional regions and the luminance of the backlight is controlled in response to an image signal to reduce the power consumption.
Incidentally, where a backlight apparatus is driven in a unit of a divisional region from among a plurality of divisional regions and the luminance of the backlight is controlled in response to an image signal, since the driving condition is different among different divisional regions, if the light amount balance is displaced among the divisional regions, then the displacement among the divisional regions appears as irregularities in color of a display image.
Therefore, it may be demanded to provide a backlight apparatus wherein, where it is driven in a unit of a divisional region from among a plurality of divisional regions, appearance of irregularities in color of a display image caused by displacement in the light amount balance among the divisional regions is prevented.
Also it may be demanded to provide a color image display apparatus wherein, where it includes a color display panel and a backlight apparatus for illuminating the color display panel from the back side and the backlight apparatus is driven in a unit of a divisional region from among a plurality of divisional regions, appearance of irregularities in color of a display image caused by displacement in the light amount balance among the divisional regions is prevented.
According to an embodiment of the present invention, there is provided a backlight apparatus for illuminating a color display panel from the back side, which may include a light source section having a composite light source configured to mix light fluxes of different colors from a plurality of monochromatic light sources and irradiate the mixed light upon the color display panel and having a plurality of optical regions grouped for each arbitrary number of the monochromatic light sources, a light detecting light introducing plate in the form of an optically transparent elongated plate disposed so as to traverse the optical regions of the light source section and having at least one light pickup portion provided thereon corresponding to each of the optical regions, a plurality of light amount sensors for the individual colors provided at least on one of the opposite end faces of the light detecting light introducing plate in the longitudinal direction, and control means for successively detecting the light in the individual optical regions using the color light sensors for the individual colors and controlling the light amount balance of the light of the colors emitted from the monochromatic light sources grouped for the individual optical regions based on detection outputs of the light amount sensors for the colors.
According to another embodiment of the present invention, there is provided a color image display apparatus having a color display panel, and a backlight apparatus configured to illuminate the color display panel from the back side, the backlight apparatus may include a light source section which may include a composite light source configured to mix light fluxes of different colors from a plurality of monochromatic light sources and irradiate the mixed light upon the color display panel and having a plurality of optical regions grouped for each arbitrary number of the monochromatic light sources, a light detecting light introducing plate in the form of an optically transparent elongated plate disposed so as to traverse the optical regions of the light source section and having at least one light pickup portion provided thereon corresponding to each of the optical regions, a plurality of light amount sensors for the individual colors provided at least on one of the opposite end faces of the light detecting light introducing plate in the longitudinal direction, and control means for successively detecting the light in the individual optical regions using the color light sensors for the individual colors and controlling the light amount balance of the light of the colors emitted from the monochromatic light sources grouped for the individual optical regions based on detection outputs of the light amount sensors for the colors.
With the backlight apparatus and the color image display apparatus, when the backlight apparatus is driven in a unit of each of a plurality of divisional regions, appearance of irregularities in color of a display image caused by displacement of the light amount balance among the divisional regions can be prevented.
The above and other features and advantages of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings in which like parts or elements denoted by like reference symbols.
Referring first to
The color image display apparatus 100 shown is a color liquid crystal display apparatus of the transmission type and includes a color liquid crystal display panel 110 of the transmission type and a backlight apparatus 140 provided on the back side of the color liquid crystal display panel 110. Further, though not shown, the color image display apparatus 100 may further include a receiver section such as an analog tuner or a digital tuner for receiving a ground wave or a satellite wave, an image signal processing section and a sound signal processing section for processing an image signal and a sound signal received by the receiver section, respectively, a sound signal outputting section such as a speaker for outputting the sound signal processed by the sound signal processing section, and so forth.
The transmission type color liquid crystal display panel 110 of the color image display apparatus 100 includes two transparent substrates including a TFT (Thin Film Transistor) substrate 111 and an opposing electrode substrate 112 made of glass or a like material and disposed in an opposing relationship to each other. The transmission type color liquid crystal display panel 110 further includes a liquid crystal layer 113 disposed in a gap formed between the TFT substrate 111 and the opposing electrode substrate 112 and having, for example, twisted nematic (TN) liquid crystal enclosed therein. The color liquid crystal display panel 110 further includes two polarizing plates 131 and 132 between which the TFT substrate 111 and the opposing electrode substrate 112 are sandwiched. Signal lines 114 and scanning lines 115 arrayed in a matrix, thin film transistors 116 arrayed at intersecting points of the signal lines 114 and the scanning lines 115 and serving as switching elements, and pixel electrodes 117 are formed on the TFT substrate 111. The thin film transistors 116 are successively selected by the scanning lines 115 and write image signals supplied from the signal lines 114 into the corresponding pixel electrodes 117. Meanwhile, opposing electrodes 118 and a color filter 119 are formed on the inner surface of the opposing electrode substrate 112.
The color filter 119 is divided into a plurality of segments corresponding to the pixels. For example, the color filter 119 is divided into three different kinds of segments of red filters CFR, green filters CFG and blue filters CFB for the three primary colors as seen in
In the color liquid crystal display panel 110, the thin film transistors arranged in a matrix are controlled to selectively apply a voltage to the liquid crystal layer 113 independently for the individual pixels so that incoming light is optically modulated to effect image display.
The color image display apparatus 100 can display a desired full color image by driving the color liquid crystal display panel 110 of the transmission type having such a configuration as described above in accordance with an active matrix system in a state in which white light is illuminated on the color image display apparatus 100 from the back side by the backlight apparatus 140.
The backlight apparatus 140 of the color image display apparatus 100 is formed as a backlight apparatus of the area light type which uses a large number of light emitting diodes. In particular, the backlight apparatus 140 includes, as seen in
An internal general configuration of the housing section 120 of the backlight apparatus 140 is shown in
The light detecting light introducing plates LGP1 to LGP4 are made of an optically transparent resin material such as an acrylic resin. At least one light pickup portion W11 to W44 is provided corresponding to each of the regions A11 to A44, and light amount sensor sections LS1 to LS4 each including light amount sensors for the individual lights are provided on at least one of the opposite ends in the longitudinal direction of the light detecting light introducing plates LGP1 to LGP4.
Each of the light pickup portions W (W11 to W44) has an upright face which is provided in an intersecting relationship with the longitudinal direction of a light detecting light introducing plate LGP (LGP1 to LGP4) and does not satisfy an angular condition for the total reflection. The light pickup portion W is formed, for example, in a concave shape as seen from the light pickup portions W11 to W14 of the light detecting light introducing plate LGP1 of
In the backlight apparatus 140, the light detecting light introducing plates LGP1 to LGP4 pick up light from the light emitting diode units LEDU11 to LEDU44 provided in the regions A11 to A44 through the light pickup portions W11 to W44 corresponding to the regions A11 to A44 and introduce the picked up light to the light amount sensor sections LS1 to LS4 provided at one end in the longitudinal direction. In the light amount sensor sections LS1 to LS4, the light emitting diode units LEDU11 to LEDU44 are individually turned on so that they can individually detect the light from the light emitting diode units LEDU11 to LEDU44, respectively, as seen in
Each of the light amount sensor sections LS1 to LS4 includes a red light sensor SR for detecting the amount of red light, a green light sensor SG for detecting the amount of green light, and a blue light sensor SB for detecting the amount of blue light.
The color image display apparatus 100 having such a configuration as described above is driven, for example, by such a drive circuit 200 as shown in
Referring to
In the drive circuit 200, an image signal inputted through the input terminal 220 is subject to signal processes such as a chroma process by the video decoder 230 and is then converted into of RGB data of m bits (m may be 8 to 12) suitable to drive the color liquid crystal display panel 110 from a composite signal. The RGB data is supplied to the control signal production section 240 together with a horizontal synchronizing signal H and a vertical synchronizing signal V.
The control signal production section 240 produces image signal data based on the RGB data supplied from the video decoder 230 and supplies the produced image signal data to the video encoder 260 together with the horizontal synchronizing signal H and the vertical synchronizing signal V. Further, the backlight driving control section 250 produces light amount control signals for controlling driving of the light emitting diode units LEDU11 to LEDU44 of the backlight apparatus 140 individually in response to the brightness of the image signal and supplies the produced light amount control signal to the backlight driving control section 250.
To the backlight driving control section 250, light amount detection signals produced by successively detecting the amounts of light from the light emitting diode units LEDU11 to LEDU44 by the light amount sensor sections LS1 to LS4 are supplied.
The backlight driving control section 250 controls the light emission amounts of the light emitting diode units LEDU11 to LEDU44 in accordance with light amount control signals corresponding to the brightness of the image signal supplied from the control signal production section 240 thereby to control the brightness of the regions A11 to A44. Further, the backlight driving control section 250 controls the magnitude of driving current to be supplied to the light emitting diodes 21R, 21G and 21B of the individual colors of the light emitting diode units LEDU11 to LEDU44 based on the light amount detection signals detected by the light amount sensor sections LS1 to LS4 thereby to control the light amount balance of the colors.
The backlight driving control section 250 has, for example, such a configuration as shown in
The backlight driving control section 250 drives the light emitting diode units LEDU11 to LEDU44 for each light emitting diode unit, and the driving block 250A includes driving blocks 250A1 to 250A4 for driving the light emitting diode units LEDU11 to LEDU14, respectively.
The driving block 250A1 has, for example, such a configuration as shown in
Referring to
The PWM switch circuit 255 includes PWM switches 255R, 255G and 255B for PWM driving the light emitting diodes 21R, 21G and 21B of the colors connected in series, respectively, and composing the light emitting diode unit LEDU11 provided corresponding to the region A11.
The constant current driver 253R, the red light emitting diode 21R which composes the light emitting diode unit LEDU11, and the PWM switch 255R are connected in series. Meanwhile, the constant current driver 253G, the green light emitting diode 21G which composes the light emitting diode unit LEDU11, and the PWM switch 255G are connected in series. Further, the constant current driver 253B, the blue light emitting diode 21B which composes the light emitting diode unit LEDU11 and the PWM switch 255B are connected in series.
The light amount balance control section 251 produces a light amount balance control signal, for example, for making the light amount of green and the light amount of red and blue coincide with each other based on light amount detection signals from the red light sensor SR, green light sensor SG and blue light sensor SB of the light amount sensor section LS1. Then, the light amount balance control section 251 controls the constant current drivers 253R, 253G and 253B of the driving block 250A1 in accordance with the light amount balance signal to control driving current to be supplied to the light emitting diodes 21R, 21G and 21B of the colors which compose the light emitting diode unit LEDU11. The light amount balance of the light emitting diode unit LEDU11 is controlled thereby.
Meanwhile, the light amount control section 252 produces a light amount control signal indicative of the light emission amount of the entire light emitting diode unit LEDU11 based on the light amount detection signal of green from the green light sensor SG, and supplies the produced light amount control signal to the PWM driver 254 of the driving block 250A1. Then, the PWM driver 254 receives the light amount control signal produced by the control signal production section 240 and produces a PWM control signal of a duty ratio for assuring the brightness necessary for the region A11 in which the light emitting diode unit LEDU11 is provided corresponding to an image displayed by driving of the transmission type color liquid crystal display panel 110 based on the light amount control signal from the light amount control section 252 and the light amount control signal from the control signal production section 240. Then, the PWM driver 254 controls the PWM switches 255R, 255G and 255B of the PWM switch circuit 255 in accordance with the produced PWM control signal. The light amount of the light emitting diode unit LEDU11 is PWM controlled such that the brightness necessary for the region A11 may be assured corresponding to the image displayed by driving of the color liquid crystal display panel 110.
Meanwhile, the driving blocks 250A2 to 250A4 which drive the light emitting diode units LEDU12 to LEDU14 of the driving block 250A are controlled by the light amount balance control section 251 and the light amount control section 252 of the control block 250E based on light amount detection signals of the colors from the red light sensor SR, green light sensor SG and blue light sensor SB of the light amount sensor section LS1 similarly as in the driving block 250A1. Consequently, the light amount balance of the light emitting diode units LEDU12 to LEDU14 is controlled by the light amount balance control section 251, and the light amounts of the light emitting diode units LEDU12 to LEDU14 are PWM controlled by the light amount control section 252 based on the light amount detection signal of green from the green light sensor SG.
Here, when the control block 250E drives operation of the driving block 250A based on the light amount detection signals of the colors from the red light sensor SR, green light sensor SG and blue light sensor SB of the light amount sensor section LS1, the control block 250E supplies control pluses from the light amount control section 252 to the PWM drivers 254 of the driving blocks 250A1 to 250A4, which drive the light emitting diode units LEDU11 to LEDU14 of the driving block 250A, so that the light emitting diode units LEDU11 to LEDU14 are selectively and alternatively driven such that only one light emitting diode unit is placed into a light emitting state while the other light emitting diode units are placed into a no-light emitting state for a period of time within which no influence is had on the sense of sight, for example, for approximately 1/1000 second to perform detection of the light amount for each light emitting diode unit. It is to be noted that the order and the timing when one of the light emitting diode units LEDU11 to LEDU14 is placed into a light emitting state may be determined arbitrarily.
Further, the driving blocks 250A2 to 250A4 which drive the light emitting diode units LEDU21 to LEDU44 of the driving block 250A are controlled by the light amount balance control section 251 and the light amount control section 252 of the control block 250E based on the light amount detection signals of the colors from the red light sensor SR, green light sensor SG blue light sensor SB of the light amount sensor sections LS2 to LS4 similarly as in the driving block 250A1. Consequently, the light amount balance of the light emitting diode units LEDU21 to LEDU44 is controlled by the light amount balance control section 251 of the control block 250E, and the light amounts of the light emitting diode units LEDU21 to LEDU44 are PWM controlled by the light amount control section 252.
Here, when the control block 250E drives operation of the driving block 250A based on the light amount detection signals of the colors from the red light sensor SR, green light sensor SG and blue light sensor SB of the light amount sensor section LS1, the control block 250E supplies control pluses from the light amount control section 252 to the PWM drivers 254 of the driving blocks 250A1 to 250A4, which drive the light emitting diode units LEDU11 to LEDU14 of the driving block 250A, so that the light emitting diode units LEDU11 to LEDU14 are selectively and alternatively driven such that only one light emitting diode unit is placed into a light emitting state while the other light emitting diode units are placed into a no-light emitting state for a period of time within which no influence is had on the sense of sight to perform detection of the light amount for each light emitting diode unit. Then, the light amount balance of the light emitting diode units LEDU11 to LEDU14 is controlled by the light amount balance control section 251.
Similarly, when the control block 250E drives operation of the driving block 250B based on the light amount detection signals of the colors from the red light sensor SR, green light sensor SG and blue light sensor SB of the light amount sensor section LS2, the control block 250E supplies control pluses from the light amount control section 252 to the PWM drivers of the driving blocks, which drive the light emitting diode units LEDU21 to LEDU24 of the driving block 250B, so that the light emitting diode units LEDU21 to LEDU24 are selectively and alternatively driven such that only one light emitting diode unit is placed into a light emitting state while the other light emitting diode units are placed into a no-light emitting state for a period of time within which no influence is had on the sense of sight to perform detection of the light amount for each light emitting diode unit. Then, the light amount balance of the light emitting diode units LEDU21 to LEDU24 is controlled by the light amount balance control section 251.
Further, the control block 250E performs similar detection operation also by the red light sensor SR, green light sensor SG and blue light sensor SB of the light amount sensor section LS3 to control the light amount balance of the light emitting diode units LEDU31 to LEDU44 by means of the light amount balance control section 251.
In other words, the color image display apparatus 100 according to the present embodiment is a color liquid crystal display apparatus of the transmission type which includes a color liquid crystal display panel 110 and a backlight apparatus 140 which illuminates the color liquid crystal display panel 110 from the back side and wherein the backlight apparatus 140 includes, as a light source section, a plurality of light emitting diode units LEDU11 to LEDU44 provided corresponding to optical regions A11 to A44 which mix light fluxes of different colors from light emitting diodes 21R, 21G and 21B of the colors. Then, the amounts of light of the colors from the light emitting diode units LEDU11 to LEDU44 are successively and individually detected by light detecting light introducing plates each in the form of an optically transparent elongated plate which are disposed so as to traverse the regions A11 to A44 and have light pickup portions W11 to W44 provided corresponding to the regions A11 to A44, respectively. The backlight driving control section 250 controls the magnitude of driving current to be supplied to the light emitting diodes 21R, 21G and 21B of the colors of the light emitting diode units LEDU11 to LEDU44 based on the light amount detection signals from the light amount sensor sections LS1 to LS4, respectively.
Accordingly, in the present color image display apparatus 100, when the backlight apparatus 140 is to be driven in a unit of one of the regions A11 to A44, appearance of irregularities in color of a display image caused by displacement of the light amount balance among the regions A11 to A44 can be prevented. It is to be noted that, in the backlight apparatus 140, since light introduced from the regions A11 to A44 through the light detecting light introducing plates LGP1 to LGP4 disposed so as to traverse the regions A11 to A44 is detected by the light amount sensor sections LS1 to LS4 to individually control the light amount balance of the light of the colors in the regions A11 to A44, the overall area of the rear side of the backlight apparatus 140 can be used for cooling.
It is to be noted here that, while the light pickup portions W11 to W44 of the light detecting light introducing plates LGP1 to LGP4 in the color image display apparatus 100 described above are formed in a shape of a concave portion, it is only necessary for the light pickup portion W to have an upright face which is provided uprightly so as to intersect with the longitudinal direction of the light detecting light introducing plate LGP and does not satisfy an angular condition for the total reflection. Further, the upright face which does not satisfy the angular condition for the total reflection may be provided in an inclined relationship by 45 degrees with respect to and an intersecting relationship with the longitudinal direction of the light detecting light introducing plates LGP1 to LGP4 as seen in
Further, while the light pickup portions W11 to W44 of the light detecting light introducing plates LGP1 to LGP4 in the color image display apparatus 100 are provided in a one-by-one corresponding relationship to the regions A11 to A44, it is otherwise possible to provide a plurality of light pickup portions W for each of the regions to enhance the light pickup efficiency.
Further, while the light pickup portions W11 to W44 of the light detecting light introducing plates LGP1 to LGP4 in the color image display apparatus 100 are provided in a one-by-one corresponding relationship to the regions A11 to A44 so that the light amount balance is controlled for each of the regions, it is otherwise possible to provide one light pickup portion W for each predetermined number of regions so that the light amount balance is controlled for each predetermined number of regions.
Further, while the light emitting diode units LEDU11 to LEDU44 in the color image display apparatus 100 are provided individually in the regions A11 to A44 formed by partitioning the inside of the housing section 120 of the backlight apparatus 140 by means of the partition walls 121, it is otherwise possible to dispose the light emitting diode units LEDU11 to LEDU44 without the partition walls 121 as seen in
Furthermore, while the light amounts of the colors of the light emitting diode units LEDU11 to LEDU44 in the color image display apparatus 100 are detected by the light amount sensor sections LS1 to LS4 provided on the end faces on one end in the longitudinal direction of the light detecting light introducing plates LGP1 to LGP4, respectively, it is otherwise possible to provide light amount sensor sections LS1a and LS1b to LS4a and LS4b on the opposite ends in the longitudinal direction of the light detecting light introducing plates LGP1 to LGP4 as seen in
Since the light fluxes of the colors picked up through the light pickup portions W11 to W44 of the light detecting light introducing plates LGP1 to LGP4 are mixed while they are introduced through the light detecting light introducing plates LGP1 to LGP4, the backlight driving control section 250 controls the light amount sensors of the light amount sensor sections LS1a to LS4a and LS1b to LS4b so that each of the light amount sensors detects a plurality of light fluxes of different colors emitted from those of the light emitting diode units LEDU11 to LEDU44 which correspond to those of divisional portions obtained by dividing the associated light detecting light introducing plate LGP1 to LGP4 equally into two portions in the longitudinal direction which are positioned on the remote side from the light amount sensor, and then controls the light amount balances of the light fluxes to be emitted from the light emitting diode units LEDU11 to LEDU44 based on detection outputs of the light amount sensor sections LS1a to LS4a and LS1b to LS4b.
In particular, the light amount balance of the light emitting diode units LEDU11 and LEDU12 is controlled based on the detection output of the light amount sensor section LS1a provided on the right end face of the light detecting light introducing plate LGP1. Meanwhile, the light amount balance of the light emitting diode units LEDU13 and LEDU14 is controlled based on the detection output of the light amount sensor section LS1b provided on the left end face of the light detecting light introducing plate LGP1.
Meanwhile, the light amount balance of the light emitting diode units LEDU21 and LEDU22 is controlled based on the detection output of the light amount sensor section LS2a provided on the right end face of the light detecting light introducing plate LGP2. Meanwhile, the light amount balance of the light emitting diode units LEDU23 and LEDU24 is controlled based on the detection output of the light amount sensor section LS2b provided on the left end face of the light detecting light introducing plate LGP2.
Further, the light amount balance of the light emitting diode units LEDU31 and LEDU32 is controlled based on the detection output of the light amount sensor section LS3a provided on the right end face of the light detecting light introducing plate LGP3. Meanwhile, the light amount balance of the light emitting diode units LEDU33 and LEDU34 is controlled based on the detection output of the light amount sensor section LS3b provided on the left end face of the light detecting light introducing plate LGP3.
Furthermore, the light amount balance of the light emitting diode units LEDU41 and LEDU42 is controlled based on the detection output of the light amount sensor section LS4a provided on the right end face of the light detecting light introducing plate LGP4. Meanwhile, the light amount balance of the light emitting diode units LEDU43 and LEDU44 is controlled based on the detection output of the light amount sensor section LS4b l provided on the left end face of the light detecting light introducing plate LGP4.
It is to be noted that, since the light fluxes of the colors picked up through the light pickup portions W are attenuated when they pass a light detecting light introducing plate LGP in the form of an elongated plate, in order to detect the light amounts at a high sensitivity and control the light amount balance, it is preferable to provide light amount sensor sections LSa and LSb at the opposite end portions of the light detecting light introducing plate LGP as seen in
In particular, the backlight driving control section 250 controls the light amount sensors of the light amount sensor sections LSa and LSb provided at the opposite ends of the light detecting light introducing plate LGP in the longitudinal direction so that each of the light amount sensors detects light fluxes emitted from those of the light emitting diode units LEDUa1 to LEDUa4 and LEDUb1 to LEDUb4 which correspond to those of divisional portions obtained by dividing the light detecting light introducing plate LGP equally into two portions in the longitudinal direction which are positioned on the near side from the light amount sensor, that is, light fluxes from optical regions Aa1 to Aa4 and Ab1 to Ab4 grouped for each arbitrary number of monochromatic light sources, thereby to successively detect the light fluxes emitted from the optical regions Aa1 to Aa4 and Ab1 to Ab4 by means of the light amount sensors of the colors at the light amount sensor sections LSa and LSb, and then controls the light amount balances of the light fluxes to be emitted from the monochromatic light sources grouped individually for the optical regions Aa1 to Aa4 and Ab1 to Ab4 based on the detection outputs of the light amount sensor sections. By this, light amount can be performed and the light amount balance can be controlled in high sensitivity.
Further, since the detection sensitivity of the light amount sensor sections LSa and LSb to light fluxes emitted individually from the light emitting diode units LEDUa1 to LEDUa4 and LEDUb1 to LEDUb4, that is, to light fluxes emitted from the optical regions Aa1 to Aa4 and Ab1 to Ab4 grouped for each arbitrary number of monochromatic light sources, varies depending upon the distance from the light amount sensor sections LSa and LSb to the optical regions Aa1 to Aa4 and Ab1 to Ab4, light pickup portions Wa1 to Wa4 and Wb1 to Wb4 whose light pickup efficiency increases as the distance from the light amount sensor sections LSa and LSb increases should be provided for the individual optical regions Aa1 to Aa4 and Ab1 to Ab4. By this, the detection sensitivity can be made fixed to control the light amount balance uniformly.
The light pickup efficiency of the light pickup portions Wa1 to Wa4 and Wb1 to Wb4 can be varied by varying the shape of the light pickup portions such as the size of the light pickup portions, the depth of the light pickup portions where the light pickup portions have a concave shape or the height of the light pickup portions where the light pickup portions have a convex shape, the number of such light pickup portions or the like.
The detection sensitivity can be made uniform, for example, by providing such light pickup portions Wa1 to Wa4 and Wb1 to Wb4 whose size is varied among the optical regions Aa1 to Aa4 and Ab1 to Ab4 as seen in
Here, a result of actual measurement of the intensity of light where light is picked up from N optical regions through light pickup portions and introduced to a light amount sensor section through a light detecting light introducing plate so that it is detected by the light amount sensor section is illustrated in
Also where such light pickup portions Wa1 to Wa4 and Wb1 to Wb4 whose light pickup efficiencies are made different from each other by changing the number of light pickup portions among the different optical regions Aa1 to Aa4 and Ab1 to Ab4 as seen in
While a preferred embodiment of the present invention has been described using specific terms, such description is for illustrative purpose only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| P2006-150415 | May 2006 | JP | national |
| P2007-108501 | Apr 2007 | JP | national |
