JP4096197B2 - Liquid crystal module and backlight adjustment device - Google Patents

Description

  The present invention relates to a liquid crystal module and a backlight adjustment device, and more particularly to a liquid crystal module and a backlight adjustment device using a plurality of backlights.

  Conventionally, as a liquid crystal module using a plurality of backlights of this type, a light source switching unit that switches between an internal light source and an external light source, a white balance sensor that outputs a signal for white balance adjustment, and a light source switching unit are externally provided. A display device is known that includes an LCD drive circuit that drives an LCD at a color temperature matched to an external light source based on the output of a white balance sensor when switched to a light source (see, for example, Patent Document 1).

In the above display device, when the backlight is switched to the internal light source by the light source switching means, the LCD driving circuit drives the LCD with a hue set in advance corresponding to the color temperature of the internal light source. On the other hand, when the backlight is switched to the external light source, the LCD drive circuit performs correction processing for matching the hue of the LCD with the color temperature of the external light source based on the output of the white balance sensor.
JP-A-5-91376

  The display device described in Patent Document 1 described above discloses a technique for driving an LCD with a hue suitable for the color temperature of an internal light source or external light source selected as a backlight. Here, the display apparatus described in Patent Document 1 irradiates the LCD panel using only the selected internal or external light source as a backlight. Therefore, there is a problem that the color temperature of the light transmitted through the LCD panel greatly depends on the color temperature of the selected internal light source or external light source. In particular, when the LCD is driven with an internal light source selected as the backlight, the color temperature of the light transmitted through the LCD panel will vary from product to product unless the color temperature characteristics of the lamp of the internal light source for each product are constant. There was a problem.

  The present invention has been made in view of the above problems, and provides a liquid crystal module and a backlight adjustment device capable of easily adjusting the color temperature of light transmitted through a liquid crystal panel using a plurality of backlights. For the purpose.

In order to achieve the above object, an invention according to claim 1 is a liquid crystal panel composed of a plurality of pixels corresponding to RGB, and a liquid crystal panel that receives a predetermined digital video signal and displays an image based on the digital video signal. A liquid crystal panel drive unit to be displayed on, a backlight unit that irradiates the liquid crystal panel from the back side, an inverter that supplies an alternating voltage to the backlight unit and lights the backlight unit with a predetermined luminance, and the inverter The backlight unit includes a plurality of fluorescent tubes having different color temperatures, and the microcomputer is supplied to each of the fluorescent tubes and the fluorescent tubes. It is equipped with a memory that stores a table that defines the correspondence relationship with the duty ratio of the AC voltage for each country of the liquid crystal module. A control signal indicating the duty ratio of each of the one fluorescent tubes corresponding to one of the destination country acquired from Bull, sends the same inverter, according to a control signal for each said respective fluorescent tubes in the inverter, the respective by varying the duty ratio of the AC voltage supplied to the fluorescent tube, by varying the intensity for each of the respective fluorescent tubes, it is constituted to adjust the color temperature of the illumination light the backlight unit irradiates.

  In the invention according to claim 1 configured as described above, the liquid crystal panel driving unit inputs a predetermined digital video signal and causes the liquid crystal panel to display an image based on the digital video signal. The liquid crystal panel is composed of a plurality of pixels corresponding to RGB. On the other hand, the backlight unit is supplied with an AC voltage from the inverter and lights up with a predetermined luminance, and irradiates the liquid crystal panel from the back side. The microcomputer performs predetermined control processing by connecting to the inverter. In such a configuration, the color temperature of the light transmitted through the liquid crystal panel greatly depends on the color temperature of the irradiation light irradiated by the backlight unit.

Therefore, the microcomputer causes the inverter to change the brightness of the plurality of fluorescent tubes for each fluorescent tube. Therefore, the correspondence relationship between the fluorescent tubes and the duty ratio of the AC voltage supplied to the fluorescent tube is determined by the destination country of the liquid crystal module. A memory storing a separately defined table is mounted, and a control signal indicating the duty ratio for each fluorescent tube corresponding to one of the destination countries acquired from the table is transmitted to the inverter . The inverter that receives the control signal changes the brightness of the plurality of fluorescent tubes for each fluorescent tube based on the control signal. That is, since the ratio of the lighting time and the non-lighting time of each fluorescent tube is determined based on the duty ratio of the AC voltage supplied to each fluorescent tube, if the duty ratio of the AC voltage is changed based on the control signal, The brightness of each fluorescent tube can be changed.

  When the duty ratio of the AC voltage supplied to multiple fluorescent tubes with different color temperatures is varied, the multiple fluorescent tubes with different color temperatures are lit with different brightness, so the color of the light emitted from the backlight unit The temperature can be adjusted. Here, the backlight unit includes a plurality of fluorescent tubes including a fluorescent tube having a high color temperature and a fluorescent tube having a low color temperature. A fluorescent tube with a high color temperature has a bluish white illumination light, and a fluorescent tube with a low color temperature has a reddish white illumination light. Therefore, based on the same control signal from the microcomputer, the inverter changes the luminance of the fluorescent tube with a high color temperature and the fluorescent tube with a low color temperature, so that the backlight unit irradiates the liquid crystal panel. The color temperature of the light can be adjusted between bluish white and reddish white. As a result, the color temperature of light transmitted through the liquid crystal panel can be adjusted.

Needless to say, the above-described technical idea is not limited to a liquid crystal module that is a specific product device, but can be realized as a backlight adjustment device that adjusts the color temperature of light emitted from the backlight unit. Accordingly, the invention according to claim 2 includes a backlight unit having a plurality of backlights having different color temperatures and disposed at a predetermined position around the liquid crystal panel to irradiate the liquid crystal panel from the back side, and the backlight. An inverter that supplies an AC voltage to the light unit to light each backlight of the backlight unit with a predetermined luminance, and a predetermined control signal is transmitted to the inverter, and each of the above-described inverters based on the control signal is transmitted to the inverter. An inverter control unit that adjusts the color temperature of the irradiation light emitted from the backlight unit by changing the luminance of the backlight for each backlight, and the backlight control unit, the inverter control unit Is a table that defines the correspondence between each backlight and the duty ratio of the AC voltage supplied to the backlight for each country of destination. A control signal indicating the duty ratio for each backlight corresponding to one of the destination countries obtained from the table is transmitted to the inverter, and the control for each backlight is transmitted to the inverter. The luminance of each backlight is changed by changing the duty ratio of the AC voltage supplied to each backlight based on the signal .

In the invention according to claim 2 configured as described above, the backlight unit includes a plurality of backlights having different color temperatures. Further, in order to irradiate the liquid crystal panel from the back side, the backlight unit is disposed at a predetermined position around the liquid crystal panel.
The backlight adjustment unit changes the luminance of a plurality of backlights having different color temperatures in the backlight unit for each backlight. Therefore, it is possible to adjust the color temperature of the irradiation light that the backlight unit irradiates the liquid crystal panel, and as a result, it is possible to adjust the color temperature of the light that passes through the liquid crystal panel.

Upper Symbol backlight unit may be configured to a high color temperature backlight and color temperature of the low backlight.

In the above configuration , the backlight section includes a backlight having a high color temperature and a backlight having a low color temperature. By changing the brightness of the backlight with a high color temperature and the backlight with a low color temperature, the color temperature of the irradiation light that the backlight unit illuminates the liquid crystal panel is changed between bluish white and reddish white. Can be adjusted. That is, if the luminance of the backlight having a high color temperature is increased and the luminance of the backlight having a low color temperature is decreased, the irradiation light from the backlight portion becomes white light with strong bluishness. Conversely, if the luminance of the backlight having a low color temperature is increased and the luminance of the backlight having a high color temperature is decreased, the irradiation light from the backlight portion becomes white light with strong redness. Therefore, the color temperature of light transmitted through the liquid crystal panel is also adjusted between bluish white and reddish white.

According to a third aspect of the present invention, in the backlight adjustment device according to the second aspect of the present invention, the backlight unit is arranged at a substantially side surface position of the liquid crystal panel.

In the invention according to claim 3 configured as described above, the backlight portion is disposed at a substantially side position of the liquid crystal panel. That is, by disposing the liquid crystal panel on the substantially side surface position rather than on the back side, the entire apparatus in which the backlight adjustment device is accommodated can be thinly formed.

Here, various light emitters used as the backlight are conceivable. For example, a fluorescent tube may be adopted as the backlight. Therefore, according to a fourth aspect of the present invention, in the backlight adjustment device according to the second or third aspect , the plurality of backlights of the backlight unit are fluorescent tubes.

In the invention concerning Claim 4 comprised as mentioned above, the fluorescent tube is employ | adopted as the some backlight of the said backlight part. In this application, since a plurality of fluorescent tubes having different color temperatures are used as the backlight, when one fluorescent tube is used as the backlight, the color temperature of the light transmitted through the liquid crystal panel is the color temperature of the single fluorescent tube. The adverse effect of depending on characteristics is eliminated.

Upper Symbol backlight adjustment unit sends an inverter for lighting a predetermined brightness a plurality of the backlight of the backlight unit by supplying an AC voltage to the backlight unit, a predetermined control signal to the inverter, The inverter may include an inverter control unit that changes the luminance of a plurality of backlights for each backlight based on the control signal .

In the above configuration , the backlight adjustment unit includes an inverter and an inverter control unit. Here, the inverter control unit transmits a predetermined control signal for changing the luminance of the plurality of backlights of the backlight unit for each backlight to the inverter. The inverter functions to supply an alternating voltage to the backlight unit and turn on the backlight unit with a predetermined brightness. When the inverter receives the control signal from the inverter control unit, the inverter operates based on the control signal. The brightness of the plurality of backlights is changed for each backlight. In other words, the inverter that has received the control signal lights each backlight with the brightness changed for each backlight based on the control signal.

Upper Symbol inverter control unit may control signals the inverter changes the duty ratio of the AC voltage supplied to the backlight unit configured so as to transmit to the inverter.

In the above configuration , the inverter control unit transmits a control signal for changing a duty ratio of an AC voltage supplied from the inverter to the backlight unit to the inverter. The inverter that has received the control signal changes the duty ratio of the AC voltage supplied to the backlight unit based on the control signal, and supplies the AC voltage having the changed duty ratio to the backlight unit. The luminance of each backlight is changed by receiving the supply of an alternating voltage whose duty ratio is changed, and each backlight is turned on by the changed luminance. That is, by changing the duty ratio of the AC voltage supplied to the plurality of backlights having different color temperatures for each backlight, the plurality of backlights having different color temperatures are lit with different luminances. As a result, the color temperature of the irradiation light from the backlight unit can be adjusted.

Upper Symbol inverter control unit, the inverter has in advance as data the degree of changing the duty ratio of the AC voltage supplied to the backlight unit, also a control signal based on the data as a configuration to be transmitted to the inverter Good.

In the above configuration , the inverter control unit has in advance a degree of change in the duty ratio of the AC voltage supplied from the inverter to the backlight unit as data in a predetermined storage area. And when adjusting the color temperature of the irradiation light irradiated from a backlight part by changing the brightness | luminance of each backlight, an inverter control part transmits the control signal based on the said data to an inverter. The inverter that receives the control signal changes the duty ratio of the AC voltage supplied to the backlight unit based on the control signal, and changes the luminance for each backlight.

As described above, according to the first aspect of the present invention, the color temperature of the irradiation light from the backlight unit is adjusted between the bluish white and the reddish white so that the light transmitted through the liquid crystal panel can be adjusted. A liquid crystal module capable of easily adjusting the color temperature can be provided.
According to the second aspect of the present invention, the backlight adjustment device capable of easily adjusting the color temperature of the light transmitted through the liquid crystal panel by adjusting the color temperature of the light emitted from the backlight unit. Can be provided.
Further, according to the first and second aspects, it is possible to easily adjust to an optimum color temperature according to the destination country.
Furthermore, it can be adjusted between a white color temperature of light transmitted through the liquid crystal panel, reddish and bluish white.
Furthermore, according to the invention concerning Claim 3 , the whole apparatus in which a backlight adjustment apparatus is accommodated can be shape | molded thinly.
Furthermore, according to the invention concerning Claim 4 , a suitable example of the light-emitting body used as a backlight can be shown.

Furthermore, it is possible to change the brightness of each backlight by a control signal inverter control unit sends to the inverter.
Furthermore , the luminance of each backlight can be changed by changing the ratio of the lighting time and non-lighting time of each backlight.
Furthermore, based on the predetermined data inverter control unit has previously, the inverter control unit can easily transmit a predetermined control signal to the inverter.

FIG. 1 is a diagram showing a schematic configuration of a liquid crystal display device using a liquid crystal module according to an embodiment of the present invention.
In FIG. 1, a liquid crystal display device 10 is roughly composed of a tuner 11, an A / D conversion circuit 12, a Y / C separation circuit 13, an image quality adjustment circuit 14, a color demodulation circuit 15, a matrix circuit 16, It consists of a synchronization circuit 17 and a liquid crystal module 20. The liquid crystal module 20 includes a liquid crystal driver circuit 21, a liquid crystal panel 22, a backlight unit 23, an inverter 24, and a microcomputer 25. The microcomputer 25 is connected to the inverter 24, and transmits a predetermined control signal when the inverter 24 lights the backlight unit 23.

  The tuner 11 receives a television broadcast signal via the antenna 11a under the control of the microcomputer 25. The tuner 11 outputs a video composite signal as an analog video signal based on the television broadcast signal. The video composite signal is input to the A / D conversion circuit 12, and the A / D conversion circuit 12 converts the video composite signal into a digital signal according to the signal level of the analog video signal. The digital video signal is output to the Y / C separation circuit 13. In the Y / C separation circuit 13, separation into a luminance signal and a chroma signal is performed based on the digitized video signal. The separated luminance signal is input to the image quality adjustment circuit 14, and after predetermined image quality adjustment is performed in the image quality adjustment circuit 14, the luminance signal is output to the matrix circuit 16. On the other hand, the separated chroma signal is demodulated by the color demodulation circuit 15 into RY and BY color difference signals and then output to the matrix circuit 16. In the matrix circuit 16, matrix conversion processing is performed based on the input luminance signal and color difference signal, and an RGB signal is generated.

  The video signal converted into a digital signal is also input to the synchronization circuit 17. In the synchronization circuit 17, a synchronization signal is extracted from the digital video signal, and the synchronization signal is output to the liquid crystal driver circuit 21. The liquid crystal driver circuit 21 includes a scaler, a control circuit, a horizontal scanning circuit, a vertical scanning circuit, and the like (not shown). The scaler performs a scaling process on the RGB signal input from the matrix circuit 16 to generate an RGB signal for one screen displayed on the liquid crystal panel 22.

  On the other hand, the synchronization signal input from the synchronization circuit 17 to the liquid crystal driver circuit 21 is input to the control circuit. The control circuit generates a control signal voltage based on the synchronization signal and outputs the control signal voltage to the horizontal scanning circuit and the vertical scanning circuit. Then, the horizontal scanning circuit acquires the RGB signal output from the scaler and the control signal voltage, and displays the image of each pixel while synchronizing the display timing of each pixel in the horizontal direction of the liquid crystal panel 22. The vertical scanning circuit drives the vertical scanning line of the liquid crystal panel 22 based on the control signal voltage.

  The backlight unit 23 serves as a light source that irradiates the back surface of the liquid crystal panel 22 and is connected to the inverter 24. The inverter 24 converts the DC voltage into an AC voltage, and then applies the AC voltage to the backlight unit 23 to light the backlight unit 23. The inverter 24 is connected to the microcomputer 25, receives a predetermined control signal from the microcomputer 25, and changes the duty ratio of the AC voltage applied to the backlight unit 23 based on the control signal. When an alternating voltage whose duty ratio is changed based on the control signal is applied to the backlight unit 23, the color temperature of the irradiation light of the backlight unit 23 is adjusted as will be described later.

FIG. 2 is a perspective view showing the liquid crystal panel 22 and the backlight unit 23.
In the present embodiment, two fluorescent tubes, a fluorescent tube 23 a having a high color temperature and a fluorescent tube 23 b having a low color temperature, are used as the backlight unit 23. The fluorescent tube 23a having a high color temperature is irradiated with bluish white light, and the fluorescent tube 23b having a low color temperature is irradiated with reddish white light. The liquid crystal panel 22 includes a polarizing plate 22a, a glass substrate 22b, a liquid crystal 22c, a light guide plate 22d, a reflection plate 22e, and the like as a thin plate layer. Here, the light guide plate 22d serves to guide the irradiation light from the fluorescent tubes 23a and 23b to the entire liquid crystal panel 22. Further, as shown in the figure, the fluorescent tubes 23a and 23b are disposed on the upper and lower side surfaces of the light guide plate 22d. Thus, by arranging the fluorescent tubes 23a and 23b on the upper and lower side portions of the light guide plate 22d, the entire shape of the liquid crystal display device 10 that houses the liquid crystal module 20 according to the present invention can be formed thin.

  Here, in general, the color temperature of the irradiation light of the fluorescent tube is determined by various factors such as the fluorescent material applied inside the fluorescent tube, the gas sealed inside, and the pressure of the gas. Therefore, a great amount of labor and cost are required to perfectly match the color temperatures of each fluorescent tube. Further, since the liquid crystal itself does not emit light, the color temperature of the liquid crystal panel greatly depends on the color temperature of the irradiation light of the backlight that passes through the liquid crystal panel from the back side. Therefore, when a single fluorescent tube is used as the backlight, the color temperature of the liquid crystal panel greatly depends on the color temperature of the fluorescent tube, and the color temperature of the liquid crystal panel is different for each product of the liquid crystal module. There was a problem of being slightly different.

  Therefore, in the present embodiment, two fluorescent tubes, a fluorescent tube 23a having a high color temperature and a fluorescent tube 23b having a low color temperature, are used as the backlight unit 23, so that the liquid crystal panel 22 has a single color temperature. This prevents the dependence on the color temperature characteristics of the tube. Further, the color temperature of white light transmitted through the liquid crystal panel 22 can be freely adjusted between bluish white and reddish white. In particular, even when the color temperature of white light preferred by the destination country of the liquid crystal display device 10 is different, by adopting the configuration of the backlight unit 23 in the present embodiment, the white light preferred in any destination country. It is possible to match the color temperature. Hereinafter, the process for adjusting the color temperature of the white light of the liquid crystal panel 22 in the present embodiment will be described.

FIG. 3 is a block diagram showing the backlight unit 23, the inverter 24, and the microcomputer 25. The microcomputer 25 is equipped with a memory 25a.
In the figure, an inverter 24 includes an oscillation circuit 24a, a waveform synthesis circuit 24b, and a switching circuit 24c. Further, the inverter 24 acquires a DC voltage through the connection line 24d. The DC voltage is supplied from a power supply circuit (not shown), and the power supply circuit converts commercial AC power into DC voltage in order to drive the entire liquid crystal display device 10. The DC voltage is synthesized with an oscillation signal having a predetermined frequency generated by the oscillation circuit 24a and the waveform synthesis circuit 24b, and then outputted to the switching circuit 24c. The switching circuit 24 c converts the input DC voltage into an AC voltage and outputs the AC voltage to the backlight unit 23.

  That is, an alternating voltage is taken out to the output side by alternately switching the switching elements 24c1 and 24c2 on and off with respect to the direct current input to the switching circuit 24c. The output from the switching circuit 24c becomes a drive pulse signal, which is applied to the electrodes of the fluorescent tubes 23a and 23b constituting the backlight unit 23, thereby lighting the fluorescent tubes 23a and 23b. The driving pulse signal generated by switching the switching element 24c1 is supplied to the fluorescent tube 23a, and the driving pulse signal generated by switching the switching element 24c2 is supplied to the fluorescent tube 23b.

  Here, the luminance of the fluorescent tubes 23a and 23b that are turned on upon receiving the drive pulse signal is determined by the duty ratio of the drive pulse signal. The fluorescent tubes 23a and 23b are lit when the signal level of the drive pulse signal is H level, and are not lit when the signal level is L level. Accordingly, the luminance of the fluorescent tubes 23a and 23b is determined by the ratio between the H level and the L level of the supplied driving pulse signal, and the higher the ratio of the H level in one cycle of the driving pulse signal, that is, the higher the duty ratio, the higher the luminance. To do. Conversely, the lower the H level ratio in one cycle of the drive pulse signal, the lower the luminance.

  As described above, since the luminance of the fluorescent tubes 23a and 23b is determined by the duty ratio of the drive pulse signal supplied to the fluorescent tubes 23a and 23b, in order to change the luminance of each fluorescent tube 23a and 23b individually, What is necessary is just to change individually the duty ratio of the drive pulse signal supplied to fluorescent tube 23a, 23b. Therefore, the microcomputer 25 transmits a control signal for individually changing the duty ratio of the drive pulse signal supplied to each of the fluorescent tubes 23 a and 23 b to the switching circuit 24 c of the inverter 24. Specifically, the switching circuit 24c transmits a control signal for changing the timing for switching the switching element 24c1, and a control signal for changing the timing for switching the switching element 24c2.

  The switching circuit 24c that has received the control signal changes the ratio between the time when the switching element 24c1 is on and the time when the switching element 24c1 is off based on the control signal that changes the timing for switching the switching element 24c1. Based on the control signal for changing the timing for switching 24c2, the ratio between the time when the switching element 24c2 is on and the time when it is off is changed. Then, the ratio between the H level and the L level of the drive pulse signal output from the switching circuit 24c to the fluorescent tube 23a and the fluorescent tube 23b individually changes. The fluorescent tubes 23a and 23b that are supplied with the drive pulse signal with the changed duty ratio change the ratio between the lighting time and the non-lighting time, respectively, and as a result, the luminance changes individually.

FIG. 4 is a table 30 that defines data for generating a control signal that the microcomputer 25 transmits to the switching circuit 24c. The table 30 is stored in advance in a memory 25 a mounted on the microcomputer 25.
In the figure, A, B, and C in the right column represent different destination countries of the liquid crystal display device 10. In the middle row, a1, b1, and c1 are data that determine the duty ratio of the fluorescent lamp 23a having a high color temperature, which is obtained when the products are for A, B, and C countries, respectively. On the other hand, a2, b2, and c2 in the left column are data defining the duty ratio of the fluorescent lamp 23b having a low color temperature, which is obtained when the product is for A, B, and C countries, respectively.

  Here, when the destination country of the liquid crystal display device 10 is, for example, country A, the microcomputer 25 acquires data a1 and a2 from the table 30 stored in the memory 25a, and is based on the data a1 and a2. The control signal is transmitted to the switching circuit 24c of the inverter 24. In the switching circuit 24c, the ON / OFF time ratio of the switching element 24c1 is changed by the control signal based on the data a1. Similarly, the on / off time ratio of the switching element 24c2 is changed by the control signal based on the data a2. As a result, the duty ratio of the drive pulse signal supplied from the switching circuit 24 to the fluorescent tube 23a is a1, and the fluorescent tube 23a is turned on by the brightness changed based on the change in the duty ratio. In addition, the duty ratio of the drive pulse signal supplied to the fluorescent tube 23b is a2, and the fluorescent tube 23b is lit by the brightness changed based on the change in the duty ratio.

  As described above, the color temperature of the irradiation light of the backlight unit 23 can be adjusted by changing the luminance of the fluorescent tubes 23a and 23b. For example, when the white light color temperature of the liquid crystal panel 22 is preferred in country A, the data a1 in the table 30 may be set to a low duty ratio and the data a2 may be set to a high duty ratio. That's fine. If the microcomputer 25 transmits a control signal based on the data a1 and a2 to the inverter 24 to change the duty ratio of the drive pulse signal supplied to the fluorescent tubes 23a and 23b, the luminance of the fluorescent tube 23a is lowered. The brightness of the fluorescent tube 23b is increased. Therefore, the color temperature of the irradiation light of the entire backlight unit 23, which is a mixed light of the irradiation light of the fluorescent tube 23a and the irradiation light of the fluorescent tube 23b, becomes reddish white.

  As a result, the color temperature of the white light of the liquid crystal panel 22 that transmits the irradiation light of the backlight unit 23 from the back surface also becomes reddish white. That is, by storing in the table 30 the duty ratios that determine the luminance of the fluorescent tubes 23a and 23b corresponding to the color temperature of white light preferred for each destination country, the liquid crystal panel 22 for each destination country is stored. The liquid crystal module 20 in which the color temperature of white light is appropriately adjusted can be produced efficiently.

  In the above description, the data for generating the control signal transmitted from the microcomputer 25 to the inverter 24 is stored in the memory 25 a of the microcomputer 25 as the table 30. However, the color temperature of the backlight unit 23 may be adjusted without having the table 30 in the memory 25a of the microcomputer 25. That is, the adjuster inputs an arbitrary duty ratio to the microcomputer 25, causes the control signal based on the duty ratio to be transmitted to the inverter 24, and changes the duty ratio of the drive pulse signal supplied to the backlight unit 23. Also good. In this way, if the duty ratio of the drive pulse signal supplied to the backlight unit 23 is changed at an arbitrary ratio, the color temperature of the backlight unit 23 can be adjusted more finely.

In addition to the useful effects described above, the present invention has the following effects.
Conventionally, the color temperature of light transmitted through a liquid crystal panel is adjusted using a color filter laminated in the liquid crystal panel. However, since the color temperature of the light transmitted through the liquid crystal panel greatly depends on the color temperature of the irradiation light of the backlight, there is a limit to the adjustment of the color temperature using the color filter. That is, a product whose backlight color temperature is different from the other products by a predetermined range or more cannot be adjusted to a desired color temperature even by a color filter, and such a product has been excluded from the shipment target. Here, the liquid crystal module 20 according to the present embodiment adjusts the color temperature of the backlight unit 23 by changing the luminance of the two fluorescent tubes 23a and 23b having different color temperatures. Therefore, compared with the conventional color temperature adjustment of the liquid crystal panel using a combination of a backlight with a fixed color temperature and a color filter, the color temperature can be adjusted to a desired color temperature more accurately. As a result, the number of products that are not shipped can be extremely reduced.

  Another effect is a reduction in production costs. In the present embodiment, the irradiation light of the backlight unit 23 is a mixed light of the irradiation light of the two fluorescent tubes 23a and 23b, and the color temperature of the backlight unit 23 is the ratio of the luminance of the fluorescent tubes 23a and 23b. Can be adjusted by. Therefore, compared with the consistency of the color temperature of the fluorescent tube between products required when using one fluorescent tube as a backlight, the consistency of the color temperature of the fluorescent tubes 23a between products, and between the fluorescent tubes 23b The color temperature consistency is not required with high accuracy, leading to a reduction in production costs.

  Furthermore, since the color temperature of the white light of the liquid crystal panel 22 can be adjusted to the color temperature preferred in any destination country, the color temperature of white light preferred in the country for each destination country where the product is shipped. There is no need to prepare a backlight to be lit. That is, since the same liquid crystal module 20 having the fluorescent tube 23a having a high color temperature and the fluorescent tube 23b having a low color temperature as the backlight unit 23 may be produced for the total number of shipments, it is mass-produced for a plurality of destination countries. Production cost can be greatly reduced.

  Thus, the duty ratio of the drive pulse signal supplied to the fluorescent tube 23a having a high color temperature and the fluorescent tube 23b having a low color temperature is individually changed by the control signal transmitted from the microcomputer 25 to the inverter 24. The color temperature of the irradiation light irradiated on the entire backlight unit 23 is freely adjusted between bluish white and reddish white. Therefore, the color temperature of the white light transmitted through the liquid crystal panel 22 is also adjusted between the bluish white and the reddish white, and the color temperature of the white light of the liquid crystal panel 22 is adjusted to an appropriate color temperature according to the destination country. It can be adjusted easily.

It is a schematic block diagram of the liquid crystal display device using the liquid crystal module concerning one Embodiment of this invention. FIG. 3 is a perspective view showing a liquid crystal panel 22 and a backlight unit 23. It is the block diagram which showed the backlight, the inverter, and the microcomputer. It is a block diagram of the table which defined the data for producing | generating a control signal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Liquid crystal display device 11 ... Tuner 12 ... A / D conversion circuit 13 ... Y / C separation circuit 14 ... Image quality adjustment circuit 15 ... Color demodulation circuit 16 ... Matrix circuit 17 ... Synchronization circuit 20 ... Liquid crystal module 21 ... Liquid crystal driver circuit 22 ... Liquid crystal panel 22a ... Polarizing plate 22b ... Glass substrate 22c ... Liquid crystal 22d ... Light guide plate 22e ... Reflecting plate 23 ... Backlight parts 23a, 23b ... Fluorescent tube 24 ... Inverter 24a ... Oscillation circuit 24b ... Waveform synthesis circuit 24c ... Switching circuit 24c1 , 24c2 ... switching element 24d ... connection line 25 ... microcomputer 25a ... memory 30 ... table

Claims (4)

A liquid crystal panel composed of a plurality of pixels corresponding to RGB, a liquid crystal panel drive unit that inputs a predetermined digital video signal and displays an image based on the digital video signal on the liquid crystal panel, and the liquid crystal panel on the back side A liquid crystal display comprising: a backlight unit for irradiating from the inverter; an inverter for supplying an alternating voltage to the backlight unit for lighting the backlight unit with a predetermined brightness; and a microcomputer for performing a predetermined control process connected to the inverter. In the module
The backlight unit includes a plurality of fluorescent tubes having different color temperatures,
The microcomputer is equipped with a memory storing a table that defines the correspondence relationship between each fluorescent tube and the duty ratio of the AC voltage supplied to the fluorescent tube for each country of the liquid crystal module, and any one of the obtained from the table. exchanges a control signal indicating the duty ratio of the respective fluorescent tubes each corresponding to the destination country, and sent to the inverter, based on the control signals for each said respective fluorescent tubes in the inverter, supplied to the respective fluorescent tubes by varying the duty ratio of the voltage, the liquid crystal module, characterized in that by varying the intensity at the each fluorescent tube, adjust the color temperature of the illumination light the backlight unit irradiates. A backlight unit having a plurality of backlights having different color temperatures and arranged at a predetermined position around the liquid crystal panel to irradiate the liquid crystal panel from the back side;
An inverter that supplies an alternating voltage to the backlight unit to turn on each backlight of the backlight unit with a predetermined brightness, a predetermined control signal is transmitted to the inverter, and the inverter is based on the control signal. A backlight adjustment unit comprising: an inverter control unit that adjusts the color temperature of irradiation light emitted from the backlight unit by changing the luminance of each backlight for each backlight; and
The inverter control unit is equipped with a memory storing a table that defines the correspondence between each backlight and the duty ratio of the AC voltage supplied to the backlight for each country of destination of the device, and any of the acquired from the table The control signal indicating the duty ratio for each backlight corresponding to the destination country is transmitted to the inverter, and the AC voltage supplied to the backlight based on the control signal for each backlight is transmitted to the inverter. A backlight adjustment device that changes the luminance of each of the backlights by changing the duty ratio of the backlight. The backlight adjustment device according to claim 2 , wherein the backlight unit is disposed at a substantially side position of the liquid crystal panel. A plurality of backlight of the backlight unit, a backlight controller according to claim 2 or claim 3 characterized in that it is a fluorescent tube.

Images