JP3766042B2 - Rear light source for display device and liquid crystal display device - Google Patents

Rear light source for display device and liquid crystal display device Download PDF

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Publication number
JP3766042B2
JP3766042B2 JP2002181682A JP2002181682A JP3766042B2 JP 3766042 B2 JP3766042 B2 JP 3766042B2 JP 2002181682 A JP2002181682 A JP 2002181682A JP 2002181682 A JP2002181682 A JP 2002181682A JP 3766042 B2 JP3766042 B2 JP 3766042B2
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current
control signal
end
light emitting
semiconductor light
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JP2004029141A (en
Inventor
昌彦 小澤
博明 杉浦
英之 金子
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三菱電機株式会社
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Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a back light source used for a liquid crystal display device (for example, a display monitor or a liquid crystal television).
[0002]
[Prior art]
As a backlight (back light source) for a liquid crystal display monitor, a cold cathode fluorescent discharge tube (CCFL) that is a fluorescent lamp is generally used.
[0003]
Recently, it has been reported that white LED lamps can be used as backlight lamps. For example, Japanese Patent Laid-Open No. 2001-272938 discloses a backlight for an LCD using two or more LED lamps, and this publication proposes a technique for uniformly adjusting the color tone of each LED lamp. Has been. This technique provides a backlight that emits standard white light. Here, the “white LED lamp” has a structure composed of InGaN that emits blue light and a color conversion member that emits white light (the member includes a fluorescent material).
[0004]
[Problems to be solved by the invention]
In the xy-chromaticity diagram which is the CIE 1931 standard color system, the current color reproduction range is red (R), green (G) and blue (B) realized by a CRT display monitor which is a conventional representative display device. It is within the range of a triangle obtained by connecting each color coordinate (chromaticity point). For example, in EBU (European Broadcasting Union), which is one of the standards for the color reproduction range, the triangular area of the color reproduction range (hereinafter simply referred to as the color reproduction range) is 0.1134, which is also one of the standards, IEC61966. -2-1 sRGB has a color reproduction range of 0.1121, but the CRT display monitor has a color reproduction range of 0.11413, which satisfies both the above standards.
[0005]
In the natural world, there are many colors located outside the color reproduction range determined by the standard RGB signal. For example, 60% of the colors of the paint are located outside the color reproduction range of the CRT display monitor. For this reason, it is demanded by the printing plate making related industry, the movie industry / broadcasting industry, etc. that more colors can be expressed on a display monitor. To that end, it is urgent to expand the color reproduction range (0.11) that could not be expanded for about 40 years. By expanding the color reproduction range, development of bit stream video distribution using the Internet, development of stream broadcasting, and the like can be developed.
[0006]
However, the color reproduction range of a CCFL backlight liquid crystal display monitor, which is a typical example of a flat display monitor, is 0.1108, for example, which is smaller than that of a CRT display monitor. Similarly, the color reproduction range of a liquid crystal display monitor using a white LED lamp as a backlight is also inferior to that of a CRT display monitor. Therefore, the color reproduction range (0.11) cannot be expanded depending on the current liquid crystal display monitor.
[0007]
Further, even in an organic EL display monitor that has recently attracted attention as a flat display monitor, the color reproduction range is, for example, 0.1141, and therefore the monitor cannot expand the current color reproduction range (0.11).
[0008]
The present invention has been made in view of such recognition of the present situation, and an object of the present invention is to realize a liquid crystal display device capable of expanding the current color reproduction range (0.11) and to obtain uniform brightness as described later. It is in the point which realizes the back light source.
[0009]
[Means for Solving the Problems]
  The subject of the present invention is a back light source for a display device, comprising a plurality of semiconductor light emitting element blocks, a plurality of current adjustment control circuits, a data collection control circuit, the data collection control circuit, and the plurality of current adjustment control circuits. Each of the plurality of semiconductor light emitting element blocks includes a first power supply terminal, a second power supply terminal, a first end, a second end, and a third end. A first current driving circuit for passing a current having a first current amount according to a first control signal applied to the third end between the first end and the second end, and the first power source Between the terminal and the second power supply terminal, red monochromatic light is connected in series with the first current driving circuit and has a light amount corresponding to the first current amount applied by the first current driving circuit. A first semiconductor light emitting element emitting, a first end, a second And a second current drive circuit that has a third end, and causes a second current amount corresponding to a second control signal applied to the third end to flow between the first end and the second end. The first power supply terminal and the second power supply terminal are connected in series with the second current drive circuit, and have a light amount corresponding to the second current amount applied by the second current drive circuit. A second semiconductor light emitting element emitting green monochromatic light; a first end; a second end; and a third end; a third current amount corresponding to a third control signal applied to the third end A third current driving circuit for flowing the current between the first end and the second end; and the third current driving circuit connected in series between the first power supply terminal and the second power supply terminal; A first monochromatic light emitting light having a light quantity corresponding to the third current amount applied by the third current driving circuit; A semiconductor light emitting device, a first photodetector for detecting the amount of red monochromatic light emitted from the first semiconductor light emitting device, and a second light detection for detecting the amount of green monochromatic light emitted from the second semiconductor light emitting device. And a third photodetector for detecting the amount of the blue monochromatic light emitted from the third semiconductor light emitting element, and each of the plurality of current adjustment control circuits includes a plurality of semiconductor light emitting element blocks. Further, each of the plurality of current adjustment control circuits is provided in each of the third ends of the first current drive circuit in the semiconductor light emitting element block corresponding to the current adjustment control circuit. A first control signal output terminal, a second control signal output terminal, and a third control signal output terminal connected to the third terminal of the second current driver circuit and the third terminal of the third current driver circuit, respectively; The data collection The collector control circuit collects first, second, and third light quantity data signals from the first, second, and third photodetectors belonging to each of the plurality of semiconductor light emitting element blocks, and The first, second, and third light quantity data signals are transmitted to the corresponding current adjustment control circuit via the bus, and each of the plurality of current adjustment control circuits includes a predetermined standard value relating to color temperature, A storage unit that stores a predetermined luminance value of white light determined in advance for each current adjustment control circuit, and the first light amount data signal in the semiconductor light emitting element block corresponding to the current adjustment control circuit, Based on the second light quantity data signal and the third light quantity data signal, the calculation part for calculating the color temperature of the white light and the brightness of the white light after adjusting the color temperature is calculated by the calculation part. The color temperature The first control signal, the second control signal, and the third control signal are individually set based on a comparison process between the calculated value and the predetermined standard value relating to the color temperature. An individual current adjustment control unit, and an individual comparison process between the calculated value of the luminance of the white light calculated in the calculation part and the predetermined luminance value of the white light predetermined for the current adjustment control circuit. Based on the current adjustment control circuit, a common current increase / decrease ratio adjustment control unit that sets the first control signal, the second control signal, and the third control signal after adjustment of the color temperature as a common signal; And the individual current adjustment control unit in each of the plurality of current adjustment control circuits emits the first semiconductor light emitting element to the corresponding semiconductor light emitting element block. The color temperature of the white light obtained by mixing the red monochromatic light, the green monochromatic light emitted from the second semiconductor light emitting element, and the blue monochromatic light emitted from the third semiconductor light emitting element is applied to the current adjustment control circuit. The first control signal for controlling the first current amount is output from the first control signal output terminal to the first current driving circuit so as to be the predetermined standard value in the first current driving circuit, and further the second The second control signal for controlling the amount of current is output from the second control signal output terminal to the second current driving circuit, and the third control signal for controlling the third amount of current is further outputted. 3 From the control signal output end, the third While outputting to the current drive circuit, the common current increase / decrease ratio adjustment control unit in each of the plurality of current adjustment control circuits, for the corresponding semiconductor light emitting element block, in the current adjustment control circuit, The first control signal for instructing to increase / decrease all of the first current amount, the second current amount, and the third current amount after adjustment of the color temperature with a common current increase / decrease rate, The control signal and the third control signal are respectively sent from the first control signal output terminal, the second control signal output terminal, and the third control signal output terminal to the first current driving circuit, the second current driving circuit, and the Output to the third current drive circuitIt is characterized by that.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
<Monitor configuration>
FIG. 1 is a longitudinal sectional view schematically showing the configuration of the liquid crystal display monitor according to the present embodiment, and FIG. 2 is a plan view when the monitor is viewed from the direction of arrow A1 in FIG.
[0019]
The liquid crystal display monitors shown in FIGS. 1 and 2 are roughly composed of a liquid crystal panel LCDP and a backlight (back light source).
[0020]
Among these, the liquid crystal panel LCDP has a front surface FS which is a display surface and a back surface BS facing the front surface FS, and an array substrate (not shown) for sealing a liquid crystal material therein, And an RGB color filter and two polarizing plates (both not shown) and an array substrate drive circuit (not shown).
[0021]
On the other hand, the backlight configuration includes a sidelight system in which the light source is disposed on the side surface side of the liquid crystal panel and a direct light system in which the light source is disposed directly under the liquid crystal panel. It is disposed above and below the back surface BS of the liquid crystal panel LCDP and corresponds to a sidelight type backlight. Therefore, the backlight includes a white light source WLS disposed above and below the back surface BS, and a light guide plate that can diffuse the white light emitted from the white light source WLS and directly propagate the light to just below the back surface BS. And LGP. 1 and 2, a reflector for the white light source WLS, a reflection sheet disposed along the back surface of the light guide plate LGP, a diffusion sheet disposed on the front surface side of the light guide plate LGP, and the like are illustrated. Bake is omitted.
[0022]
  The feature point of this embodiment is the configuration of the white light source WLS. That is, the white light source WLS has a plurality ofSemiconductor light emitting deviceIt consists of only block LEDBL (here, for convenience, it consists of six diode blocks LEDBL (BL1 to BL6)). And eachSemiconductor light emitting deviceBlock LEDBL is1)For at least one red that emits red monochromatic lightSemiconductor light emitting deviceLEDR,2)For at least one green emitting green monochromatic lightSemiconductor light emitting deviceLEDG,3)For at least one blue emitting blue monochromatic lightSemiconductor light emitting deviceIt consists of LEDB. eachSemiconductor light emitting deviceFor block LEDBL, for redSemiconductor light emitting deviceFor red light emitted from LEDR and greenSemiconductor light emitting deviceFor green light emitted from LEDG and blue lightSemiconductor light emitting deviceThe white light is mixed with the blue light emitted from the LEDB, and the generated white light enters the light guide plate LGP.
[0023]
  As described above, the backlight (back light source) according to the present embodiment is replaced with a general CCFL backlight, instead of RGB monochromatic light.Semiconductor light emitting deviceAt least one consisting of onlySemiconductor light emitting deviceIt consists of block LEDs BL.
[0024]
  Note that the backlight according to this embodiment may be configured with a direct-type backlight instead of the sidelight-type backlight. Such a schematic example is shown in the longitudinal sectional view of FIG. In the backlight WLSM by this method, the light guide plate is unnecessary, and not only the upper and lower positions of the back surface BS, but also a large number not only under the back surface BS.Semiconductor light emitting deviceA block LEDBL is arranged.
[0025]
  <Expansion of color reproduction range>
  Next, the verification of the point of focus and the effect that led to such a backlight will be described. That is, the inventor of the present application says that the half width of the emission spectrum is relatively small.Semiconductor light emitting device (Light emitting diode)According to the characteristics ofSemiconductor light emitting deviceWe focused on the point that the light emitted from the slab is close to monochromatic light and the purity of the emitted color is relatively high. If this point is utilized, the inventors of the present application thought that the purity of the three primary colors of RGB forming white light can be increased, and as a result, the color reproduction range may be expanded.
[0026]
Based on such an idea, the inventor of the present application simulated the color reproduction range of the RGB-LED backlight liquid crystal display monitor illustrated in FIGS. 1 and 2. The result is shown in the xy-chromaticity diagram (C.I.E. Chromaticity Diagram) of FIG. In FIG. 4, a curve C0 is a chromaticity diagram of a horseshoe shape defined by the CIE (Commission Internationale de l'Eclairage), and all the light existing in nature is in this horseshoe shape C0. It can be expressed by coordinate values. Triangles C1 and C3 give the color reproduction ranges in the standards sRGB and EBU, respectively. On the other hand, a triangle C2 obtained by connecting RGB chromaticity points represented by x marks indicates a color reproduction range in the RGB-LED backlight liquid crystal panel exemplified in FIGS. FIG. 4 shows that the color reproduction range given by the triangle C2 can be expanded by 50% of the standard color reproduction range. As a result, the RGB-LED backlight liquid crystal panel illustrated in FIGS. 1 and 2 reproduces as much of the color existing in the region surrounded by the horseshoe shape C0 and the triangle C1 or C3 indicated by sRGB or EBU. I can do it.
[0027]
In order to further confirm this advantage, the inventor of the present application prototyped an RGB-LED backlight liquid crystal display monitor exemplified in FIGS. 1 and 2 and actually measured the color reproduction range of the prototype. FIG. 5 is a plot of the actual measurement data, and triangles C21 and C22 in the figure indicate the actual color reproduction ranges of the prototype No. 1 and the prototype No. 2, respectively. For comparison, FIG. 5 also illustrates a CIE horseshoe shape C0, a color reproduction range C1 defined by the standard sRGB, and a color reproduction range C20 of the RGB-LED backlight alone. In FIG. 5, for the R coordinate value of prototype No. 1, x is 0.6685, y is 0.3093, G coordinate value is x 0.2343, y is 0.6700, and B coordinate value is X is 0.1475 and y is 0.0573. For the R coordinate value of prototype No. 2, x is 0.6751, y is 0.2927, G coordinate value is x 0.2474, y is 0.6762, and B coordinate value is x is 0.1547 and y is 0.0491. Therefore, when the two-dimensional area surrounded by the RGB coordinates is calculated as the value of the color reproduction range, the color reproduction range of the CCFL backlight LCD monitor is 0.110787, whereas the color reproduction range of the prototype No. 1 is The color reproduction range of prototype No. 2 is 0.151866. Therefore, prototype No. 1 and prototype No. 2 achieve a color reproduction range corresponding to 1.4 to 1.5 times the color reproduction range of the CCFL backlight liquid crystal display monitor.
[0028]
  As described above, the RGB-LED backlight liquid crystal display monitor according to the present embodiment can expand the color reproduction range that has not been expanded for the past 40 years to about 1.5 times the color reproduction range. Exactly, this advantage has been realized through research activities by the inventors of the present invention.Semiconductor light emitting deviceTherefore, it has a real value or significance.
[0029]
  <New issues>
  Semiconductor light emitting deviceThe brightness (light quantity) of the light emitted from the light beam varies due to variations in manufacturing characteristics (electric-light conversion efficiency). Therefore, as illustrated in FIG. 1 and FIG. 2 or FIG. 3, the block LEDBL of the white light source for backlight is composed of at least three semiconductor light emitting elements that respectively emit red, green, and blue light. In some cases, the light obtained by mixing red, green, and blue light is colored either red, green, blue, or an intermediate color due to variations in brightness among individual semiconductor light emitting devices. At the same time, the brightness of the mixed color light also varies. Accordingly, when the liquid crystal display device illustrated in FIG. 1, FIG. 2, or FIG. 3 is configured without adjusting such variations, color irregularities that cannot be ignored appear on the screen of the liquid crystal panel. A new problem is revealed. For this reason, it is newly required to eliminate the occurrence of such color unevenness.
[0030]
Accordingly, the present inventor has developed a white balance (color temperature) / luminance adjustment technique in an RGB-LED backlight to overcome such a new problem. The newly developed RGB-LED backlight is described below.
[0031]
(Embodiment 2)
The present embodiment relates to a color temperature / luminance adjustment technique for an RGB-LED backlight based on an analog system. The points (basic concept) of the white balance / brightness adjustment technology adopted by the present invention are as follows: (1) The current flowing through each semiconductor light emitting element belonging to the semiconductor light emitting element block of the back light source is individually controlled, so that The color temperature of white light obtained by mixing monochromatic light emitted from the light emitting element is adjusted to be equal to a predetermined standard value, and (2) while maintaining the adjusted color temperature, that is, The brightness (brightness) of white light is controlled by controlling the increase or decrease of the current flowing in all the semiconductor light emitting elements in the block at the same rate while maintaining the intensity ratio of the monochromatic light emitted from the semiconductor light emitting element. The point is that the adjustment is made to be equal to a predetermined desired value. Hereinafter, the feature points will be described in detail with reference to the drawings.
[0032]
<Back light source block configuration>
FIG. 6 is a block diagram schematically showing the electrical configuration of the back light source according to the present embodiment.
[0033]
In FIG. 6, a power source (not shown) of a power source voltage Vcc is connected to a high potential side power source terminal (also referred to as a first power source terminal) 20. The power source may be provided exclusively for the rear light source, or may be shared by the rear light source and a display monitor and / or a liquid crystal panel control circuit.
[0034]
A first variable constant current drive circuit (also simply referred to as a first current drive circuit) 4 has a grounded first end 5, a second end 6, and a third end, and is applied to the third end. A first current having a first current amount corresponding to the voltage of the first control signal V <b> 1 is passed between the second end 6 and the first end 5. The first semiconductor light emitting element (also referred to as red light emitting diode) 1 has an anode connected to the power supply terminal 20 and a cathode connected to the second end 6 of the first current driving circuit 4. The first current driving circuit 4 emits red monochromatic light R having a light amount corresponding to the first current amount applied or injected.
[0035]
A second variable constant current drive circuit (also simply referred to as a second current drive circuit) 10 has a grounded first end 11, a second end 14, and a third end, and is applied to the third end. A second current having a second current amount corresponding to the voltage of the second control signal V <b> 2 is caused to flow between the second end 14 and the first end 11. The second semiconductor light emitting element (also referred to as green light emitting diode) 2 has an anode connected to the power supply terminal 20 and a cathode connected to the second end 14 of the second current driving circuit 10. Then, green monochromatic light G having a light amount corresponding to the second current amount applied or injected by the second current driving circuit 10 is emitted.
[0036]
A third variable constant current drive circuit (also simply referred to as a third current drive circuit) 17 has a grounded first end 16, a second end 15, and a third end, and is applied to the third end. A third current amount of current corresponding to the voltage of the third control signal V <b> 3 is caused to flow between the second end 15 and the first end 16. The third semiconductor light emitting element (also referred to as blue light emitting diode) 3 has an anode connected to the power supply terminal 20 and a cathode connected to the second end 15 of the third current drive circuit 17. Then, blue single-color light B having a light amount corresponding to the third current amount applied or injected by the third current driving circuit 17 is emitted.
[0037]
Note that the power supply terminals connected to the first ends 5, 11, 16 (also referred to as low-potential side second power supply terminals) are connected to a power supply having a negative power supply voltage in place of the ground terminal in FIG. It may be replaced with a power terminal. This also holds true for Embodiments 3 and 4 to be described later.
[0038]
For these components, the control circuit CC that forms the core of the present embodiment includes a first control circuit 7, a second control circuit 12, and a third control circuit 18.
[0039]
The first control circuit 7 includes a first input terminal connected to the first individual current adjustment input terminal 8, a second input terminal connected to the common current increase / decrease ratio input terminal 9, and a first control signal output. And an output terminal corresponding to the end. The circuit 7 is (1) a color temperature of white light generated by mixing three monochromatic lights R, G, and B in accordance with a first voltage signal applied to the first individual current adjustment input terminal 8. A first control signal V1 for adjustment is generated and output. The first control signal V1 is a voltage signal that can control the increase and decrease of the first current amount of the first current. Further, the circuit 7 generates and outputs a first control signal V1 for brightness adjustment of white light performed after color temperature adjustment according to a common voltage signal applied to the common current increase / decrease ratio input terminal 9. . The increase / decrease rate of the first current amount commanded by the first control signal V1 at this time is equal to the increase / decrease rate of the current amount commanded by second and third control signals V2 and V3 described later.
[0040]
The second control circuit 12 includes a first input terminal connected to the second individual current adjustment input terminal 13, a second input terminal connected to the common current increase / decrease ratio input terminal 9, and a second control signal output terminal. And an output terminal corresponding to the above. Similarly, the circuit 12 (1) changes the color temperature in accordance with a second voltage signal (a signal generated separately from the first voltage signal) applied to the second individual current adjustment input terminal 13. A second control signal V2 for adjustment is generated and output. The second control signal V2 is a voltage signal that can individually control the increase and decrease of the second current amount of the second current. Further, the circuit 7 generates and outputs a second control signal V2 for brightness adjustment of white light performed after color temperature adjustment according to the common voltage signal applied to the common current increase / decrease rate input terminal 9. . The command content of the second control signal V2 at this time corresponds to that of the first control signal V1 as described above (the increase / decrease rate of the first current amount and the increase / decrease rate of the second current amount are equal to each other).
[0041]
The third control circuit 18 includes a first input terminal connected to the third individual current adjustment input terminal 19, a second input terminal connected to the common current increase / decrease ratio input terminal 9, and a third control signal output terminal. And an output terminal corresponding to the above. The circuit 18 includes (1) a third voltage signal applied to the third individual current adjustment input terminal 19 (the third voltage signal is a signal generated separately from the first and second voltage signals). The third control signal V3 for color temperature adjustment is generated and output in response to The third control signal V3 is a voltage signal that can individually control the increase and decrease of the third current amount of the third current. Further, the circuit 7 generates and outputs a third control signal V3 for brightness adjustment of white light performed after color temperature adjustment in accordance with (2) the common voltage signal applied to the common current increase / decrease ratio input terminal 9. . The command contents of the third control signal V3 at this time correspond to those of the first and second control signals V1 and V2 as described above (the increase / decrease rate of the third current amount is the first and second current amounts). Is equal to the increase or decrease rate of
[0042]
Next, the operation of each part in FIG. 6 will be described.
[0043]
  <Adjustment of color temperature>
  The multiple white light sources that make up the back light sourceSemiconductor light emitting deviceWhen the color temperatures of the blocks are different from each other, color unevenness occurs on the display screen of the panel as shown on the left side of FIG. Note that D55, D65, and D95 in FIG. 7 are standard values of the color temperature, and in the example of FIG.Semiconductor light emitting deviceA state is shown in which the color temperature of the block is unified to the standard value D65. Therefore, in order to prevent such color unevenness,Semiconductor light emitting deviceIt is necessary to individually adjust the light amounts of all the semiconductor light emitting elements belonging to the block so that the color temperature of the block becomes equal to a predetermined standard value.
[0044]
For this purpose, the first, second and third voltage signals are individually applied to the terminals 8, 13 and 19 in FIG. 6, respectively, and the control circuits 7, 12, and 18 are in response to the first, second and third, respectively. First, second, and third control signals V1, V2, and V3 that specify the third current amount are individually output. As a result, the first, second, and third current amounts injected into the semiconductor light emitting elements 1, 2, and 3 are increased / decreased, and the amounts of the monochromatic lights R, G, and B are adjusted separately. Such adjustment of the amount of light is continued until the color temperature of the white light reaches a predetermined standard value. Here, the operator who individually adjusts each current manually sets the first, second and third voltage signals so as to eliminate color unevenness on the display screen while observing the display screen of the panel. Alternatively, the first, second and third voltage signals may be manually set and adjusted individually based on the measurement result while measuring the color temperature of white light.
[0045]
<Adjusting the brightness of white light>
Even if the color temperature of each semiconductor light emitting element block is adjusted to a predetermined standard value (for example, D65), if the luminance of white light generated by each block varies, as shown on the right side of FIG. Light and dark (brightness unevenness) occurs on the display screen. Therefore, in order to make the brightness of the entire display screen of the panel uniform, the current adjustment for making the brightness of the white light generated by each block in the back light source uniform is further performed while maintaining the adjusted color temperature. Necessary.
[0046]
Therefore, after the color temperature adjustment is completed, the common voltage is applied to the terminal 9 in FIG. 6 after fixing the levels of the first, second, and third voltage signals applied to the terminals 8, 13, and 19. To do. In response to this application, the control circuits 7, 12, 18 control signals V1, V2 for instructing the rate of increase / decrease of the current injected into each of the semiconductor light emitting elements 1, 2, 3 to be the same rate. , V3 is generated and output. As a result, the first, second and third currents both increase / decrease at the same (common) ratio, and the ratio of the light quantity of the red light R, the light quantity of the green light G and the light quantity of the blue light B. The brightness of white light obtained by mixing is increased / decreased while maintaining At that time, the operator manually sets and adjusts the common voltage signal individually while visually observing the brightness of the display screen of the panel or measuring the brightness of white light.
[0047]
With the above configuration, the control circuit CC of FIG. 6 has the following functions. That is, (1) The circuit CC includes a red monochromatic light R emitted from the first semiconductor light emitting element 1, a green monochromatic light G emitted from the second semiconductor light emitting element 2, and a blue monochromatic light B emitted from the third semiconductor light emitting element 3. The first control signal V1 for controlling the first current amount is output from the first control signal output terminal to the first current drive circuit 4 so that the color temperature of the white light obtained by mixing becomes a predetermined standard value. Further, a second control signal V2 for controlling the second current amount is outputted from the second control signal output terminal to the second current driving circuit 10, and a third control signal V3 for further controlling the third current amount is outputted. Output from the third control signal output terminal to the third current drive circuit 17. (2) Next, the circuit CC instructs the first current amount, the second current amount, and the third current amount after completion of the color temperature adjustment to be increased or decreased at a common current increase / decrease rate. The first control signal V1, the second control signal V2, and the third control signal V3 are output to the first current drive circuit 4, the second current drive circuit 10, and the third current drive circuit 17, respectively.
[0048]
<Specific configuration example of back light source>
FIG. 8 is a diagram illustrating an example of the implementation of FIG. In FIG. 8, the first current driving circuit 4 includes a first NPN bipolar transistor T1 and a first fixed resistor, and the first control circuit 7 includes a first variable resistor VR1 (potentiometer or the like) and a first resistor. And a rectifier diode. Therefore, the resistance adjustment terminal of the first variable resistor VR1 forms the terminal 8 of FIG. In FIG. 8, the second current driving circuit 10 includes a second NPN bipolar transistor T2 and a second fixed resistor, and the second control circuit 12 includes a second variable resistor VR2 (potentiometer or the like). And a second rectifier diode. Therefore, the resistance adjustment terminal of the second variable resistor VR2 forms the terminal 13 in FIG. Further, in FIG. 8, the third current drive circuit 17 is composed of a third NPN bipolar transistor T3 and a third fixed resistor, and the third control circuit 18 includes a third variable resistor VR3 (potentiometer or the like). And a third rectifier diode. Therefore, the resistance adjusting terminal of the third variable resistor VR3 forms the terminal 19 in FIG.
[0049]
In FIG. 8, the resistance values of the variable resistors VR1, VR2, and VR3 are individually adjusted. The base potentials of the bipolar transistors T1, T2, and T3 change according to the adjustment of the resistance values of the variable resistors VR1, VR2, and VR3, and the first, second, and third current amounts are adjusted. By such adjustment, the color temperature of white light is adjusted to a predetermined standard value. At that time, a constant voltage is applied to the terminal 9.
[0050]
In FIG. 8, the output of an external common potentiometer (not shown) is applied to the terminal 9. Therefore, by adjusting the common potentiometer with the resistance values of the variable resistors VR1, VR2, and VR3 fixed, the base potentials of the bipolar transistors T1, T2, and T3 are increased / decreased at the same rate. This makes it possible to set the luminance of white light to a predetermined desired value while maintaining the adjusted color temperature.
[0051]
<Advantages of this embodiment>
According to this configuration, the current amount of each of the semiconductor light emitting elements 1, 2, 3 can be individually changed, and the current amount of each of the semiconductor light emitting elements 1, 2, 3 can be increased or decreased at a common rate. It becomes. Accordingly, the white balance is adjusted by the individual current adjustment of the red, green, and blue semiconductor light-emitting elements 1, 2, 3, and subsequently, the respective semiconductor light-emitting elements 1, 2, based on the common increase / decrease rate. With the current increase / decrease adjustment of 3, it is possible to adjust the brightness of the white light while maintaining the white balance. As a result, an operator at the time of manufacturing the back light source or a user who purchased a liquid crystal display device incorporating the back light source (for example, a designer in the printing plate making field) performs a desired predetermined process by executing the above adjustment method. A back light source having a standard color temperature and uniform predetermined brightness can be obtained, and color irregularities are generated on the display screen of a liquid crystal display device incorporating the back light source after such adjustment. It is possible not to let it.
[0052]
<Modification of Embodiment 2>
At least one of the first semiconductor light emitting element, the second semiconductor light emitting element, and the third semiconductor light emitting element in the semiconductor light emitting element block may include a plurality of light emitting diodes. In such a modification, the same effect as in the first embodiment can be obtained.
[0053]
One such example is shown in the block diagram of FIG. In FIG. 9, the blue semiconductor light emitting element 3 (FIG. 6) is composed of first and second blue light emitting diodes 3A and 3B, and the blue light BA and BB emitted from the respective light emitting diodes 3A and 3B. By mixing, blue light B to be adjusted is obtained.
[0054]
For reference, an example of the implementation of FIG. 9 is indicated by a broken line in FIG. In this example, the drive circuit 17 includes two drive circuits 17A and 17B.
[0055]
(Embodiment 3)
The present embodiment relates to a color temperature / luminance adjustment technique for an RGB-LED backlight based on a digital method. However, the white balance / brightness adjustment method in the present embodiment is basically the same as that described in the first embodiment. The main difference is that all the functions of the control circuit (circuit CC in FIG. 6) in the first embodiment are automatically performed by a microcomputer chip (IC) (hereinafter simply referred to as a microcomputer chip). The feature points will be described below based on the drawings.
[0056]
FIG. 10 is a block diagram showing the configuration of the back light source according to the present embodiment. 10, components having the same reference numerals as those in FIG. 6 are the same as those described in the first embodiment.
[0057]
The first current driving circuit 4 includes a first transistor T1 (bipolar transistor or MOS transistor), a first fixed resistor, a first D / A converter 21, and a first buffer amplifier 22. Similarly, the second current drive circuit 10 includes a second transistor T2 (bipolar transistor or MOS transistor), a second fixed resistor, a second D / A converter 23, and a second buffer amplifier 24. Similarly, the third current driving circuit 17 includes a third transistor T3 (bipolar transistor or MOS transistor), a third fixed resistor, a third D / A converter 25, and a third buffer amplifier 26.
[0058]
Further, the back light source has first, second and third photodetectors PD1, PD2, PD3 (for example, these photodetectors are composed of photodiodes). That is, an opening (not shown) is formed in each part facing the semiconductor light emitting elements 1, 2, and 3 in the back surface BS (reference symbol FS is the front surface) of the liquid crystal display module LCDM incorporating the back light source. Corresponding photodetectors PD1, PD2, and PD3 are attached to the openings and the periphery thereof. Each of the photodetectors PD1, PD2, and PD3 is controlled by a microcomputer chip (control circuit) 30 so that the monochromatic light R emitted from the first, second, and third semiconductor light emitting elements 1, 2, 3, respectively. The light amounts of G and B are detected, and the measurement results are transmitted to the microcomputer chip 30 as first, second and third light amount data signals VQ1, VQ2 and VQ3, respectively.
[0059]
On the other hand, the microcomputer chip 30 is a circuit unit having the same function as the control circuit CC of FIG. 6 and includes a storage circuit or storage unit 30M, a calculation unit, an individual current adjustment control unit, and a common current increase / decrease ratio adjustment control unit.
[0060]
That is, the storage circuit 30M stores a predetermined standard value relating to the color temperature and a predetermined luminance value of white light as table values. This table value can be arbitrarily rewritten by the operator.
[0061]
The calculation part calculates the color temperature of the white light and the luminance of the white light after the color temperature adjustment based on the first light quantity data signal VQ1, the second light quantity data signal VQ2, and the third light quantity data signal VQ3. .
[0062]
  Further, the individual current adjustment control unit performs the first adjustment at the time of color temperature adjustment based on a comparison process between the calculated value of the color temperature obtained by the operation of the calculation part and the table value (predetermined standard value regarding the color temperature). Control signal V1, second control signal V2, and second3The level of the control signal V3 is set individually and output to the circuits 4, 10, and 17.
[0063]
Further, the common current increase / decrease ratio adjustment control unit performs the first control after the color temperature adjustment is completed based on a comparison process between the calculated luminance value obtained by the operation of the calculation part and the table value (predetermined luminance value). The levels of the signal V1, the second control signal V2, and the third control signal V3 are set and output as common signals to the circuits 4, 10, and 17.
[0064]
With this configuration, the microcomputer chip 30 is (1) based on the comparison processing between the color temperature calculated from the light quantity data signals VQ1, VQ2, and VQ3 and the table value, and should be applied to the bases of the transistors T1, T2, and T3. The levels of the control signals V1, V2, and V3 are individually set and adjusted to appropriate values automatically, thereby adjusting the color temperature of white light to a predetermined standard value. Subsequently, the chip 30 (2) based on the comparison processing between the luminance calculated from the light quantity data signals VQ1, VQ2, and VQ3 and the table value, shares all the first, second, and third currents. The level of each control signal V1, V2, V3 for increasing / decreasing at (increase / decrease rate) is automatically set and output. Thereby, the brightness | luminance of the white light obtained by mixing monochromatic light R, G, B is match | combined with a predetermined | prescribed brightness value. Therefore, an operator (manufacturer or user) can automatically obtain a back light source having a desired color temperature and desired brightness simply by setting the table value of the microcomputer chip 30. As described above, in order to prevent color unevenness from occurring on the display screen of the liquid crystal display device, it is possible to automatically perform an adjustment operation for making the brightness of the back light source uniform.
[0065]
In FIG. 10, the first, second, and third current amounts are controlled by controlling the base potentials of the transistors T1, T2, and T3. Instead, a pulse signal is sent from the microcomputer chip 30. By applying to the base of each transistor T1, T2, T3 and controlling the pulse width of each pulse signal, and thus by controlling the duty factor of each pulse signal, the first, second and third current quantities are obtained. It may be controlled. In this case, a pulse width modulator is provided in place of the D / A converter and the buffer amplifier in each of the drive circuits 4, 10, and 17, but instead of this configuration, the microcomputer chip 30 itself is provided therein. It is also possible to adopt a configuration in which after the pulse width modulation is performed, the modulated pulse signal is output as a control signal.
[0066]
Also in the present embodiment, the power source and / or the microcomputer chip 30 having the voltage Vcc at the power terminal 20 may be provided exclusively for the rear light source, or the rear light source and display monitor and / or liquid crystal. It may be shared with the control circuit of the panel.
[0067]
(Embodiment 4)
In the present embodiment, the back light source includes (1) a plurality of semiconductor light emitting element blocks, (2) a current adjustment control circuit (microcomputer chip) provided for each semiconductor light emitting element block, and (3) each current. The first, second, and third light quantity data signals from the R, G, B photodetectors in each semiconductor light emitting element block are collected and connected to the adjustment control circuit via the data bus. By providing a data collection control circuit (microcomputer chip) that transmits a light amount data signal to a corresponding current adjustment control circuit via a data bus, for each semiconductor light emitting element block, white light generated by the block is generated. Adjust the color temperature and brightness to appropriate values. Thereby, for each semiconductor light emitting element block, it is possible to automatically adjust variation in characteristics of each of the red, green, and blue semiconductor light emitting elements constituting the block. Here, the configuration of each semiconductor light emitting element block and the corresponding current adjustment control circuit (microcomputer chip) is the same as the corresponding one in the third embodiment (FIG. 10). Accordingly, each semiconductor light emitting element block includes a first power supply terminal 20, a second power supply terminal (here, a ground terminal), the first semiconductor light emitting element 1, the first current driving circuit 4, and the second semiconductor light emitting element 2. A second current driving circuit 10, a third semiconductor light emitting element 3, a third current driving circuit 17, a first photodetector PD1, a second photodetector PD2, and a third photodetector PD3. I have. Each control circuit (microcomputer chip) similarly includes the storage unit, the calculation unit, the individual current adjustment control unit, and the common current increase / decrease ratio adjustment control unit described above. Hereinafter, an example of the back light source according to the present embodiment will be described with reference to the drawings.
[0068]
FIG. 11 is a block diagram illustrating a configuration example of the back light source according to the present embodiment. Here, for the sake of convenience, the white light source part of the back light source is assumed to be composed of three semiconductor light emitting element blocks BL1, BL2, and BL3. The block diagram of FIG. 12 shows the internal configuration of the first LED block BL1 as a representative example of the semiconductor light emitting element block, and also includes a first block control circuit (microcomputer chip) CC1 and a data collection control circuit (microcomputer chip) CC0. And a collecting function of each light amount data signal in the data collection control circuit (microcomputer chip) CC0 is also illustrated. Note that the rewritable memory circuits (for example, RAMs) M1, M2, and M3 included in the control circuits CC1, CC2, and CC3 correspond to the memory circuit 30M in FIG. 10, and are set to the white color set for each block. The standard value of the color temperature and the predetermined brightness value of the white color are held as table values.
[0069]
11 and 12, DL is a data line for transmitting a light quantity data signal, and CL is a clock line for transmitting a clock signal for each block. DLT is a data line terminal, CLT1, CLT2, and CLT3 are clock line terminals that receive the first, second, and third block clock signals, DT is an input terminal that receives the light quantity data signal, and CLT is a clock. An input terminal for receiving a signal. OT1, OT2, and OT3 are terminals that output the first, second, and third control signals, respectively. IT1, IT2, and IT3 are terminals that receive the first, second, and third control signals, respectively. is there.
[0070]
For example, when adjusting the color temperature and luminance of white light generated by the first LED block BL1, the data collection control circuit (microcomputer chip) CC0 controls the photodetectors PD1, PD2, and PD3 belonging to the block BL1, A light quantity data signal is acquired and stored in an internal memory. The circuit CC0 generates a first clock signal designating the first block control circuit CC1, and outputs the collected light amount data signal for the first LED block BL1 to the IIC bus in synchronization with the first clock signal. . Thus, the first block control circuit CC1 acquires the measured light amount data signal in synchronization with the first clock signal. Subsequent adjustment operations performed by the circuit CC1 are as described in the third embodiment. Then, the data collection control circuit CC0 performs the same operation on the other LED blocks BL2 and BL3, and accordingly, the control circuits CC2 and CC3 perform the white balance as described in the third embodiment. And automatically adjust the brightness.
[0071]
According to the present embodiment, white balance and brightness can be automatically adjusted for each semiconductor light emitting element block, so that a back light source having a more uniform brightness can be realized and color unevenness in a liquid crystal display device can be achieved. It is possible to more reliably prevent the occurrence of.
[0072]
Each control circuit (microcomputer chip) CC1, CC2, CC3 may be realized by a single microcomputer chip. Also in the present embodiment, the power supply of the voltage Vcc at the power supply terminal 20 and / or each microcomputer chip. CC1, CC2, and CC3 may be provided exclusively for the rear light source, or may be shared by the rear light source and a display monitor and / or a liquid crystal panel control circuit.
[0073]
<Modification of Embodiment 4>
Depending on the arrangement order of the red LED, the green LED, and the blue LED constituting each semiconductor light emitting element block, a situation may occur where the screen peripheral portion of the liquid crystal display device becomes darker than the screen central portion. To solve this problem, the luminance table value in each block control circuit may be changed for each block. As a result, the brightness of the white light can be changed for each location on the screen corresponding to the position of each block while maintaining the adjusted color temperature of each block. By making the periphery of the screen relatively bright while making it dark, it becomes possible to make the brightness of the entire screen uniform.
[0074]
FIG. 13 shows an example of such a method of changing the brightness table value, and shows the calculation coefficient for each block. In FIG. 13, 58, 60 and 62 are block location identification numbers, and 59, 61 and 63 are calculation coefficients for each location.
[0075]
In the method illustrated in FIG. 13, a value obtained by multiplying a predetermined luminance table value set in each storage circuit M1, M2, and M3 by a calculation coefficient determined according to the location of the corresponding block is used for each block. The brightness adjustment target value is set at. Such a calculation coefficient is appropriately determined by an operator such as a user and set in a corresponding storage circuit.
[0076]
For example, in the example shown in FIG. 13, the calculation coefficient 59 is set for the storage circuit of the block located at the screen end 58, and the calculation coefficient 61 is set for the storage circuit of the block located at the adjacent point 60. Set.
[0077]
Such a configuration of setting the calculation coefficient can be similarly applied to a case where the number of blocks exceeds three.
[0078]
According to this modification, it is possible to compensate for a decrease in brightness at the periphery of the screen.
[0079]
<Modification common to Embodiment 2-4>
You may make it reverse the arrangement | positioning relationship between each semiconductor light-emitting device and the current drive circuit corresponding to it. Even in such a modification, the actions and effects described in the respective embodiments can be obtained similarly.
[0080]
FIG. 14 and FIG. 15 show such an example, the former is the one in which this modification is applied to the circuit configuration of FIG. 6, and the latter is the one in which this modification is applied to the circuit configuration in FIG. is there. As shown in FIGS. 14 and 15, the second end and the first end of each of the current driving circuits 4, 10, and 17 are respectively the first power supply terminal 20 on the high potential side and the corresponding semiconductor light emitting elements 1, 2, 3, and the cathode electrodes of the respective semiconductor light emitting elements 1, 2, 3 are connected to a second power supply terminal (described as a ground terminal here) on the low potential side.
[0081]
The arrangement relationship between the current driving circuit and the semiconductor light emitting element will be described based on the configurations disclosed in FIGS. 6, 10, 14 and 15 as follows: “Each current driving circuit 4, 10, 17 and corresponding to it. It can be said that the semiconductor light emitting elements 1, 2, and 3 that are connected are connected in series between the first power supply terminal 20 and the second power supply terminal.
[0082]
(Appendix)
While the embodiments of the present invention have been disclosed and described in detail above, the above description exemplifies aspects to which the present invention can be applied, and the present invention is not limited thereto. In other words, various modifications and variations to the described aspects can be considered without departing from the scope of the present invention.
[0083]
【The invention's effect】
  Claim1And claims2According to each of the inventions, the brightness of each of the semiconductor light emitting elements for red, green, and blue can be adjusted independently, and the brightness of the three colors can be adjusted at the same ratio. A back light source having no color unevenness and uniform brightness can be realized.
[0084]
  Especially claims2According to the invention, by providing the calculation coefficient, there is an effect that it is possible to compensate for a decrease in brightness at the periphery of the screen.
[0085]
  ClaimThreeAccording to the invention, there is an effect that the color reproduction range can be expanded to about 1.5 times the conventional one.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view schematically showing a configuration of a liquid crystal display device according to Embodiment 1 of the present invention.
FIG. 2 is a plan view schematically showing a configuration of a liquid crystal display device according to Embodiment 1 of the present invention.
3 is a longitudinal sectional view schematically showing a configuration of a liquid crystal display device according to a modification of the first embodiment. FIG.
4 is a chromaticity diagram showing a simulation result of a color reproduction range of the liquid crystal display device according to Embodiment 1. FIG.
5 is a chromaticity diagram showing an actual measurement result of a color reproduction range of the liquid crystal display device according to Embodiment 1. FIG.
FIG. 6 is a block diagram schematically showing the configuration of an LCD back light source according to Embodiment 2 of the present invention.
FIG. 7 is a diagram schematically showing white light adjustment of a back light source for LCD in the present invention.
FIG. 8 is a diagram showing a specific circuit configuration example of an LCD back light source according to Embodiment 2 of the present invention.
FIG. 9 is a block diagram schematically showing a configuration of a back light source for LCD according to a modification of the second embodiment.
FIG. 10 is a block diagram schematically showing the configuration of an LCD back light source according to Embodiment 3 of the present invention.
FIG. 11 is a block diagram schematically showing a configuration of a back light source for LCD according to Embodiment 4 of the present invention.
FIG. 12 is a block diagram schematically showing a configuration of a back light source for LCD according to Embodiment 4 of the present invention.
FIG. 13 is a diagram schematically showing calculation coefficients in a modification of the fourth embodiment.
14 is a block diagram schematically showing a modification of the back light source for LCD shown in FIG. 6. FIG.
15 is a block diagram schematically showing a modification of the back light source for LCD shown in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 1st semiconductor light-emitting device, 2 2nd semiconductor light-emitting device, 3rd 3rd semiconductor light-emitting device, 4 1st current drive circuit, 10 2nd current drive circuit, 17 3rd current drive circuit, CC, CC0, CC1, CC2, CC3 control circuit, 20 power supply terminal, 30 control circuit, 30M storage circuit, PD1 first photo detector, PD2 second photo detector, PD3 third photo detector, VQ1 first light quantity data signal, VQ2 second light quantity data signal , VQ3 Third light quantity data signal, BL1, BL2, BL3 LED block.

Claims (3)

  1. A rear light source for a display device,
    A plurality of semiconductor light emitting element blocks;
    A plurality of current adjustment control circuits;
    A data collection control circuit;
    Bus and the Bei Eteori for connecting the each of the said data acquisition control circuit a plurality of current adjustment control circuit,
    Each of the plurality of semiconductor light emitting element blocks includes:
    A first power terminal;
    A second power supply terminal;
    A first end, a second end, and a third end. A current having a first current amount corresponding to a first control signal applied to the third end is supplied to the first end and the second end. A first current drive circuit for passing between;
    A red color connected between the first power supply terminal and the second power supply terminal in series with the first current drive circuit and having a light amount corresponding to the first current amount applied by the first current drive circuit. A first semiconductor light emitting device emitting monochromatic light of
    A first end, a second end, and a third end, and a second current amount corresponding to a second control signal applied to the third end is transmitted between the first end and the second end. A second current drive circuit for flowing through
    A green light connected between the first power supply terminal and the second power supply terminal in series with the second current drive circuit and having a light amount corresponding to the second current amount applied by the second current drive circuit. A second semiconductor light emitting device emitting monochromatic light of
    A first end, a second end, and a third end, and a third current amount corresponding to a third control signal applied to the third end is transmitted between the first end and the second end. A third current drive circuit for flowing through
    A blue color connected between the first power supply terminal and the second power supply terminal in series with the third current drive circuit and having a light amount corresponding to the third current amount applied by the third current drive circuit A third semiconductor light emitting device emitting monochromatic light of
    A first photodetector for detecting a light amount of the red monochromatic light emitted by the first semiconductor light emitting element;
    A second photodetector for detecting the amount of the green monochromatic light emitted by the second semiconductor light emitting element;
    A third photodetector for detecting the amount of the blue monochromatic light emitted by the third semiconductor light emitting element ,
    Each of the plurality of current adjustment control circuits is provided for each of the plurality of semiconductor light emitting element blocks, and each of the plurality of current adjustment control circuits is a semiconductor light emitting device corresponding to the current adjustment control circuit. First control signals connected to the third end of the first current driving circuit, the third end of the second current driving circuit, and the third end of the third current driving circuit, respectively, in the element block An output end, a second control signal output end, and a third control signal output end;
    Wherein the data collection control circuit, said first belonging to each of the plurality of semiconductor light-emitting element block, the second and third optical detectors or et first collects second and third light quantity data signals, each of the semiconductor light-emitting Sending the first, second and third light quantity data signals of the element block to the corresponding current adjustment control circuit via the bus ;
    Each of the plurality of current adjustment control circuits includes:
    A storage unit that stores a predetermined standard value relating to the color temperature and a predetermined luminance value of white light determined in advance for each current adjustment control circuit;
    Based on the first light amount data signal, the second light amount data signal, and the third light amount data signal in the semiconductor light emitting element block corresponding to the current adjustment control circuit, the color temperature of the white light and the A calculation part for calculating the brightness of the white light after adjusting the color temperature;
    The first control signal, the second control signal at the time of adjusting the color temperature, based on a comparison process between the calculated value of the color temperature calculated in the calculation part and the predetermined standard value related to the color temperature, And an individual current adjustment control unit for individually setting the third control signal,
    The current adjustment control circuit based on an individual comparison process between the calculated value of the luminance of the white light calculated in the calculation part and the predetermined luminance value of the white light predetermined for the current adjustment control circuit. relating the first control signal after the adjustment of the color temperature, the second control signals, and further comprising a common current decrease ratio adjustment control unit that sets the third control signal as a common signal,
    The individual current adjustment control unit in each of the plurality of current adjustment control circuits is configured such that the red single-color light emitted from the first semiconductor light emitting element and the second semiconductor light emitting element correspond to a corresponding semiconductor light emitting element block. The color temperature of the white light obtained by mixing the green monochromatic light emitted and the blue monochromatic light emitted by the third semiconductor light emitting element becomes the predetermined standard value in the current adjustment control circuit. The first control signal for controlling the first current amount is output from the first control signal output terminal to the first current driving circuit, and further the second control signal for controlling the second current amount. Is output from the second control signal output terminal to the second current driving circuit, and further, the third control signal for controlling the third current amount is output from the third control signal output terminal to the third current driving circuit. Output to ,
    The common current increase / decrease ratio adjustment control unit in each of the plurality of current adjustment control circuits is configured to adjust the color temperature after the color temperature adjustment in the current adjustment control circuit to the corresponding semiconductor light emitting element block. The first control signal, the second control signal, and the third control signal that command to increase / decrease all of one current amount, the second current amount, and the third current amount with a common current increase / decrease rate. Are output from the first control signal output terminal, the second control signal output terminal, and the third control signal output terminal to the first current drive circuit, the second current drive circuit, and the third current drive circuit, respectively. It is characterized by
    Rear light source for display devices.
  2. A back light source for a display device according to claim 1 ,
    The storage unit included in each of the plurality of current adjustment control circuits is an operation for multiplying the predetermined luminance value of the white light , which is determined according to the location of the semiconductor light emitting element block corresponding to the current adjustment control circuit. I also remember the coefficients ,
    In each current adjustment control circuit, the value obtained by multiplying the predetermined luminance value of the corresponding white light by the calculation coefficient corresponds to the luminance adjustment target value in the semiconductor light emitting element block corresponding to each current adjustment control circuit. The common current increase / decrease ratio adjustment control unit set in each current adjustment control circuit performs a comparison process between the calculated value of the luminance of the white light calculated in the corresponding calculation part and the adjustment target value of the luminance. It is characterized by
    Rear light source for display devices.
  3. A liquid crystal panel having a front surface as a display surface and a back surface facing the front surface;
    Characterized in that it comprises a said back light source for a display device according to any of the said rear claim 1 or disposed side 2 of the liquid crystal panel,
    Liquid crystal display device.
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