JPH05119733A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To provide a small-sized liquid crystal display device whose constitution is simple and where the linear relation between a video signal and transmissivity is obtained regardless of the change of the ambient temperature of a liquid crystal panel. CONSTITUTION:Impressed voltage-transmissivity correction curves in accordance with impressed voltage-transmissivity characteristic owned by the liquid crystal panel are somewhat different according to the ambient temperature, but they are nearly superposed by being moved in parallel. The differential coefficients are also somewhat different but they coincide by being multiplied by a certain value. The temperature is compensated based on such an idea. Correction data on a certain temperature is stored in a video signal conversion table 4. Then, the level of a video signal before and after conversion by the table 4 is shifted in accordance with the ambient temperature of the liquid crystal panel detected by a temperature detector 8(3, 6). Gain adjustment is performed to the video signal before and after conversion by the table 4 in accordance with the detected ambient temperature of the liquid crystal panel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device having a liquid crystal panel such as a liquid crystal display or a liquid crystal projector, and more particularly to a temperature compensation structure.

[0002]

2. Description of the Related Art In a liquid crystal display device, by making a video signal and a light transmittance (light transmittance) have a linear relationship,
The linear gradation of the video signal is maintained, and the display quality of the video signal can be made appropriate. However, in the active matrix type liquid crystal panel, the applied voltage and the transmittance are not in a linear relationship. Therefore, the applied voltage of the liquid crystal panel −
The video signal is corrected in advance according to the transmittance characteristic so that the video signal before correction and the transmittance have a linear relationship.
Hereinafter, such correction will be referred to as applied voltage-transmittance correction. In addition, in the image pickup system, it is assumed that a CRT in which the light emission luminance is proportional to the γth power of the input voltage (that is, the light emission luminance and the input voltage are non-linear) is used in the display system. Correction of the power of / γ (so-called γ correction) is performed. However, γ
Since the correction is for the cathode ray tube, the γ correction is unnecessary in the liquid crystal display device. Therefore, in the liquid crystal display device, reverse correction (hereinafter, referred to as reverse γ correction) to γ correction performed in the image pickup system is performed on the video signal.

However, even if such applied voltage-transmittance correction or inverse γ correction is performed, the video signal and the light transmittance may not have a linear relationship. That is, the transmittance of the liquid crystal panel changes depending on the ambient temperature even if the applied voltage is the same.

Therefore, a temperature compensation structure for a liquid crystal panel has already been proposed. For example, JP-A-63-68822, JP-A-63-265228 and JP-A-63-
No. 306426, Japanese Patent Laid-Open No. 2-212813,
It has already been proposed in Japanese Utility Model Publication No. 63-200819. These are common in that the drive reference voltage in the drive unit of the liquid crystal panel is adjusted by the detected temperature.

[0005]

However, it is the video signal that is required to have a linear relationship with the transmittance, and the temperature compensation by the adjustment of the driving reference voltage as described above provides a fine temperature compensation. I can't. In addition, a temperature compensation structure is provided for the drive unit of the liquid crystal panel, which increases the occupied area including the periphery of the liquid crystal panel,
This causes a problem that the device becomes large and complicated.

Therefore, it has been proposed to correct the transmittance change due to the temperature of the liquid crystal panel by correcting the video signal according to the ambient temperature of the liquid crystal panel. For example, JP-A-63-231423 and JP-A-2-271390.
It is disclosed in Japanese Patent Laid-Open No. 3-18823. In these methods, the applied voltage-transmittance correction for the video signal is performed by using a look-up table, and as many such tables as the number corresponding to the ambient temperature of the liquid crystal panel are prepared. Selected table and execute the applied voltage-transmittance correction,
It is intended to satisfy the linear relationship between the video signal and the transmittance regardless of the temperature change.

However, a large amount of conversion data corresponding to the variable range of the applied voltage must be stored in one table itself, and many such tables are necessary in the case of careful temperature compensation. Therefore, there is a problem that the amount of data to be stored becomes large, the configuration becomes complicated, and the size becomes large.

The present invention has been made in consideration of the above points, and by correcting the video signal, a linear relationship between the video signal and the transmittance can be obtained despite the temperature change of the liquid crystal panel. It is an object of the present invention to provide a small-sized liquid crystal display device that has a simple structure and is capable of being manufactured.

[0009]

In order to solve such a problem, in the present invention of claim 1, an applied voltage-transmittance correction according to an applied voltage-transmittance characteristic of a liquid crystal panel is performed on a video signal. In a liquid crystal display device provided with at least a video signal conversion table, a temperature detection means for detecting an ambient temperature of a liquid crystal panel, a shift amount generation means for outputting a level shift amount signal according to the detected temperature, and a video signal conversion table. And a level shift unit that shifts the level of the video signal before reaching according to the level shift amount signal from the shift amount generation unit.

According to the present invention of claim 2, in addition to the structure of claim 1, before reaching the video signal conversion table, a gain instruction means for outputting a gain control signal according to the temperature detected by the temperature detecting means. And an amplifying means for amplifying the image signal of (1) according to the gain control signal from the gain instructing means.

According to the present invention of claim 3, in a liquid crystal display device provided with a video signal conversion table for performing at least an applied voltage-transmittance correction on a video signal according to an applied voltage-transmittance characteristic of the liquid crystal panel. A temperature detecting means for detecting the ambient temperature of the liquid crystal panel, a shift amount generating means for outputting a level shift amount signal according to the detected temperature,
A level shift means for shifting the level of the video signal output from the video signal conversion table according to the level shift amount signal from the shift amount generation means is provided.

According to the present invention of claim 4, in addition to the configuration of claim 3, the gain instruction means for outputting a gain control signal according to the temperature detected by the temperature detecting means, and the output from the video signal conversion table And an amplifying means for amplifying the image signal of (1) according to the gain control signal from the gain instructing means.

According to a fifth aspect of the present invention, there is provided a liquid crystal display device having a video signal conversion table for performing at least an applied voltage-transmittance correction on a video signal according to an applied voltage-transmittance characteristic of a liquid crystal panel. , A temperature detecting means for detecting the ambient temperature of the liquid crystal panel, a parameter generating means for outputting a parameter for specifying an applied voltage-transmittance correction curve according to the detected temperature, and a video signal conversion table using this parameter Table data calculating means for calculating the output data to be stored and updating the contents stored in the video signal conversion table.

[0014]

The applied voltage-transmittance correction curve according to the applied voltage-transmittance characteristic of the liquid crystal panel is slightly different depending on the ambient temperature, but can be superposed on each other by moving in parallel. Conversely, if the applied voltage-transmittance correction curve at a certain temperature is moved in parallel, the applied voltage-transmittance correction curve at another temperature can be obtained. Since the applied voltage-transmittance correction is performed on the video signal,
The movement of applied voltage-transmittance correction is equivalent to the level shift of the video signal.

The present invention according to claim 1 is based on the above concept. That is, the correction data for a certain temperature is stored in the video signal conversion table. Then, according to the ambient temperature of the liquid crystal panel detected by the temperature detecting means, the shift amount generating means outputs a level shift amount signal, and the level shift means shifts the level of the video signal before reaching the video signal conversion table by this level shift. The temperature is compensated by shifting according to the quantity signal.

The present invention of claim 3 is also based on the above-mentioned concept. While the present invention according to claim 1 shifts the level of the video signal before reaching the video signal conversion table according to the detected temperature, the present invention according to claim 3 outputs from the video signal conversion table. The difference is that the level of the subsequent video signal is shifted according to the detected temperature.

The inventions of claims 1 and 3 can be used together.

As described above, when the applied voltage-transmittance correction curve at a certain temperature is moved in parallel, the applied voltage-transmittance correction curve at another temperature can be obtained. Somewhat different. Therefore, when trying to compensate the temperature more meticulously, it is necessary not only to perform the moving process but also to align the differential coefficients. The process of changing the differential coefficient is to amplify the video signal.

According to the present invention of claim 2, in addition to the structure of claim 1, a gain instruction means for outputting a gain control signal according to the temperature detected by the temperature detecting means, and a video signal before reaching the video signal conversion table. By providing an amplifying means for amplifying in accordance with the gain control signal from the gain instructing means,
The temperature compensation according to this idea is realized.

According to a fourth aspect of the present invention, similarly, in addition to the configuration of the third aspect, the gain instruction means for outputting a gain control signal according to the temperature detected by the temperature detecting means and the video signal conversion table are outputted. The temperature compensation according to this concept is realized by providing an amplifying unit that amplifies the video signal after being processed according to the gain control signal from the gain instructing unit.

Therefore, the present invention according to claims 1 to 4 requires only one video signal conversion table, and realizes downsizing and simplification of the configuration.

The present invention according to claim 5 also considers that the number of necessary video signal conversion tables is one. However, the method of realizing the temperature compensation is different from that of the present invention described above. That is, the contents stored in one video signal conversion table are updated in accordance with the ambient temperature of the liquid crystal panel, thereby creating a state similar to the case where the video signal conversion table for each temperature is provided to perform temperature compensation. Is. Therefore, a temperature detection unit that detects the ambient temperature of the liquid crystal panel, a parameter generation unit that outputs a parameter that specifies the applied voltage-transmittance correction curve according to the detected temperature, and a video signal conversion table using this parameter. A table data calculating means for calculating the output data to be stored and updating the stored contents of the video signal conversion table is provided.

[0023]

【Example】

(A) First Embodiment Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. Here, FIG. 1 is a block diagram showing the configuration of the first embodiment. Further, FIG. 1 shows a processing system for any of the three primary color signals R, G, B, and the processing systems for the other two primary color signals also have the same configuration.

The input primary color analog signal is converted into a digital signal in the analog / digital conversion circuit 1. This primary color digital signal is multiplied by a coefficient α described later by a first multiplier (amplification means) 2 for temperature compensation, and further level-shifted by a shift amount β described later by a first adder (level shift means) 3. And is provided to a video signal conversion table (which should be called a primary color signal conversion table to be exact, but this term will be used hereinafter) 4.

The video signal conversion table 4 receives the primary color digital signal from the first adder 3 as an address and outputs the stored data as a corrected primary color digital signal. The video signal conversion table 4 of this embodiment is
As a conversion curve in which an input signal (address) and an output signal (stored data) are associated with each other, a combined correction curve in which an applied voltage-transmittance correction curve and an inverse γ correction curve are combined is adopted (Japanese Patent Application No. 2). -408806 specification and drawings). The video signal conversion table 4 also stores, for example, data related to a conversion curve corresponding to an average ambient temperature of a liquid crystal panel (not shown).

The primary color digital signal subjected to the applied voltage-transmittance correction and the inverse γ correction by the video signal conversion table 4 is multiplied by a coefficient γ described later by the second multiplier (amplifying means) 5 for temperature compensation. Further, it is level-shifted by a second adder (level shift means) 6 by a shift amount δ which will be described later and applied to the digital / analog conversion circuit 7.

The digital / analog conversion circuit 7 converts the primary color digital signal, which has been subjected to the applied voltage-transmittance correction, the inverse γ correction and the temperature compensation, into an analog signal by the above-mentioned processing, and an AC drive circuit (not shown) is formed. To a horizontal driver (not shown). Thus, the liquid crystal panel (not shown) performs the display operation.

The liquid crystal panel (not shown) is provided with a temperature detector 8 for detecting the ambient temperature of the liquid crystal panel. The temperature detector 8 uses, for example, the average value of the detection information from the temperature sensors provided at the four vertexes of the rectangular liquid crystal panel as the output detection temperature.

This output detection temperature signal (analog signal)
Are converted into digital signals by the analog / digital conversion circuit 9, and then are converted into a first temperature-gain coefficient conversion table 10, a first temperature-shift amount conversion table 11, and a second temperature-shift amount conversion table 11.
Temperature-gain coefficient conversion table 12 and second temperature-
It is given to the shift amount conversion table 13. Each table 1
0, 11, 12, and 13 respectively receive the output detection temperature signal (digital signal) as an address, and correspond to the coefficient data α, the shift amount data β, the coefficient data γ, and the shift amount data δ stored at the address. To the first multiplier 2, the first adder 3, the second multiplier 5, and the second adder 6.

Therefore, in the first embodiment, the applied voltage-transmittance correction and the inverse γ correction are carried out through the video signal conversion table 4, and the first primary color digital signal to the video signal conversion table 4 is subjected to the first correction. Amplification processing and level shift processing by the multiplier 2 and the first adder 3, and amplification processing and level by the second multiplier 5 and the second adder 6 for the output primary color digital signal from the video signal conversion table 4. Temperature compensation is performed by shift processing.

Next, it will be explained that temperature compensation is performed by amplification and level shift of the video signal.

FIG. 2 shows that the ambient temperature of the liquid crystal panel is 20 degrees,
Applied voltage-transmittance characteristic T1 at 40 degrees and 60 degrees,
It shows T2 and T3. Actually, the dynamic range of the video signal is not associated with 0% to 100% of the transmittance, but the range of the intermediate transmittance is used for display. In such a range, as shown in FIG. 2, the applied voltage-transmittance characteristics T1, T2, and T3 have similar shapes, and the shapes can be almost overlapped by shifting in the applied voltage direction, for example. .. Conversely, by shifting the applied voltage-transmittance characteristic at a certain temperature, the applied voltage-transmittance characteristic at another temperature can be created. Further, although the differential coefficients have similar values, the differential coefficients of the shapes can be made more consistent by performing amplification processing.

Although the applied voltage-transmittance correction curve is not shown in the figure, it has an inverse characteristic of the applied voltage-transmittance characteristic curve. Therefore, the shapes of a plurality of applied voltage-transmittance correction curves corresponding to the ambient temperature of the liquid crystal panel can be overlapped by shifting and amplifying. The inverse γ correction curve is not related to temperature, but since the applied voltage-transmittance correction curve differs depending on the temperature, the combined correction curve obtained by combining the applied voltage-transmittance correction curve and the inverse γ correction curve also differs depending on temperature. .. However, since the inverse γ correction curve is not related to temperature, the difference in the combined correction curve for each temperature is the same as the difference in the applied voltage-transmittance correction curve for each temperature. Therefore, the shapes of a plurality of combined correction curves corresponding to the ambient temperature of the liquid crystal panel can be overlapped by shifting and amplifying.

That is, the temperature compensation can be performed by shifting and amplifying the input primary color signals to the video signal conversion table 4 and / or by shifting and amplifying the output primary color signals from the video signal conversion table 4.

In the first embodiment, the temperature compensation by the level shift and amplification of the video signal before the composite correction process and the temperature compensation by the level shift and amplification of the video signal after the composite correction process are used together.

Therefore, according to the first embodiment, since the temperature compensation is performed by the level shift processing and the amplification processing of the video signals before and after the composite correction processing, the structure around the driving unit of the liquid crystal panel can be simplified and the temperature can be simplified. The compensation can be performed more finely. Here, since the conversion table for the video signal only needs to be for a certain temperature, the memory capacity is small, and the configuration can be simple and compact. Certainly, the first temperature-gain coefficient conversion table 10, the first temperature-
The shift amount conversion table 11, the second temperature-gain coefficient conversion table 12, and the second temperature-shift amount conversion table 13 are required, but the memory capacity is significantly smaller than when a video signal conversion table for each temperature is provided. Complete.

(B) Second Embodiment Next, a second embodiment of the present invention will be described in detail with reference to FIG. The second embodiment is different from the first embodiment in that the level shift processing and the amplification processing of the video signal before and after the composite correction processing are performed on the video signal in the analog signal stage.

In FIG. 3, which corresponds to FIG. 1 and in which the same parts are denoted by the same reference numerals, one of the input primary color analog signals is converted into a coefficient α1 described later by the first amplifier circuit 20 for temperature compensation. And a shift amount β described later by the first bias circuit (level shift means) 21.
The signal is level-shifted by 1 and supplied to the analog / digital conversion circuit 22. In the case of this embodiment, since the amplification process and the level shift process are executed before being applied to the analog / digital conversion circuit 22, any one of the input primary color analog signals is processed by a pedestal clamp, a sync tip clamp, or the like. It needs to be clamped. Incidentally, in the case of analog / digital conversion of the video signal, analog / digital conversion is often performed so that the pedestal level or the like in the input video analog signal becomes the reference data value. In the case of the second embodiment, analog / digital conversion is performed.
Since the amplification process and the level shift process are performed before the digital conversion, it is necessary that the input signal is clamped.

The primary color digital video signal output from the analog / digital conversion circuit 22 is applied to the video signal conversion table 4. The video signal conversion table 4 is the same as that of the first embodiment, and the analog / digital conversion circuit 22
It receives a primary color digital signal (video signal) from the above as an address and outputs the stored data to the digital / analog conversion circuit 23 as a corrected primary color digital signal.

The digital / analog conversion circuit 23 converts this primary color digital signal into an analog signal and supplies it to the second amplifier circuit 24 for temperature compensation. The second amplifier circuit 24 is
This primary color analog signal is multiplied by a coefficient γ1 described later and applied to the second bias circuit (level shift means) 25, and the second bias circuit 25 level-shifts by a shift amount δ1 described later.

The primary-color analog signal output from the second bias circuit 25 in this manner and subjected to the applied voltage-transmittance correction, inverse γ correction, and temperature compensation is illustrated via an AC driving circuit (not shown). Not given to horizontal drivers. Thus, the liquid crystal panel (not shown) performs the display operation.

Also in the second embodiment, the liquid crystal panel (not shown) is provided with a temperature detector 8 for detecting the ambient temperature of the liquid crystal panel. The output detection temperature signal (analog signal) from the temperature detector 8 is converted into a digital signal by the analog / digital conversion circuit 9,
It is given to the first temperature-gain coefficient conversion table 10, the first temperature-shift amount conversion table 11, the second temperature-gain coefficient conversion table 12, and the second temperature-shift amount conversion table 13. Each table 10, 11, 12, 1
3 receives the output detection temperature signal (digital signal) as an address, and the coefficient data, the shift amount data, the coefficient data, and the shift amount data stored at the address are corresponding to digital / analog conversion circuits 26, 27, Two
Give to 8, 29.

The digital / analog converter circuit 26 converts the supplied coefficient data into an analog signal α1 and supplies it to the above-mentioned amplifier circuit 20 as a gain control signal. The digital / analog conversion circuit 27 converts the given shift amount data into an analog signal β1 and gives it to the above-mentioned bias circuit 21 as a bias level shift amount command signal. The digital / analog conversion circuit 28 converts the supplied coefficient data into an analog signal γ1 and supplies it to the above-mentioned amplification circuit 24 as a gain control signal. The digital / analog conversion circuit 29 converts the applied shift amount data into an analog signal δ1 and applies it to the above-mentioned bias circuit 25 as a bias level shift amount command signal.

Therefore, in the second embodiment, the applied voltage-transmittance correction and the inverse .gamma. Correction are performed through the video signal conversion table 4, and the first primary color analog signal before input to the video signal conversion table 4 is performed. Amplification and level shift by the first amplification circuit 20 and the first bias circuit 21, and the second amplification circuit 24 and the second amplification circuit 24 for the primary color analog signal output from the video signal conversion table 4.
The temperature compensation is performed by amplification and level shift by the bias circuit 25 of FIG.

Also according to the second embodiment, the video signal conversion table for each temperature is not prepared and only the video signal conversion table 4 for a certain temperature is used for temperature compensation by the video signal amplification processing and the level shift processing. Since this is performed, highly accurate temperature compensation can be performed with a simple and compact structure.

(C) Third Embodiment Next, a third embodiment of the present invention will be described in detail with reference to the drawings. Here, FIG. 4 is a block diagram showing the configuration of the third embodiment. This FIG. 4 also shows a processing system for any of the three primary color signals R, G, and B, and the processing system for the other two primary color signals has the same configuration.

The input primary color analog signal is applied to the analog / digital conversion circuit 30 and converted into a digital signal. This primary color digital signal is given to the video signal conversion table 31.

The video signal conversion table 31 can update the stored data value corresponding to the address as described later, and receives the primary color digital signal (video signal) from the analog / digital conversion circuit 30 as an address. The stored data at that time is output as a corrected primary color digital signal. The video signal conversion table 31 of this embodiment is also a conversion curve in which an input signal (address) and an output signal (stored data) are associated with each other.
A combined correction curve obtained by combining the correction curve and the correction curve is used (see Japanese Patent Application No. 2-408806 and drawings).

With this video signal conversion table 31,
The primary color digital signal subjected to the applied voltage-transmittance correction, inverse γ correction, and temperature compensation (which will be described later regarding temperature compensation by conversion using a table) is a digital / digital signal.
It is given to the analog conversion circuit 32. The digital / analog conversion circuit 32 converts the input primary color digital signal into an analog signal and supplies it to a horizontal driver (not shown) via an AC drive circuit (not shown). Thus, the liquid crystal panel (not shown) performs the display operation.

The liquid crystal panel (not shown) is provided with a temperature detector 33 for detecting the ambient temperature of the liquid crystal panel. The temperature detector 33 uses, for example, the average value of the detection information from the temperature sensors provided at the positions of the four vertices of the rectangular liquid crystal panel as the output detection temperature.

This output detection temperature signal (analog signal)
Is converted into a digital signal by the analog / digital conversion circuit 34 and then given to the temperature-correction curve parameter conversion table 35. The temperature-correction curve parameter conversion table 35 has an output detection temperature signal (digital signal).
Is given as an address, and parameter data for specifying the combined correction curve stored at that address is given to the correction curve output data calculation unit 36.

The correction curve output data calculation unit 36 creates all data on the output side according to the combined correction curve at the detected temperature based on the given parameter data, and gives it to the above-mentioned video signal conversion table 31 and stores it. Update the data value. As a result, the video signal conversion table 31 stores optimum data according to the ambient temperature at that time.

Next, the parameter data for specifying the combined correction curve and the fact that the data according to the combined correction curve can be created using this parameter data will be described in detail (for details, see Japanese Patent Application No. 2-408806 and See drawings).

It is difficult to approximate the combined correction curve with one function, but when divided into a plurality of parts, each can be approximated according to a certain function.
When function approximation is performed by dividing into a plurality of parts in this way, the function for each part can be specified by a small number of parameters. That is, it is possible to specify the function of the part by giving the parameter, and it is possible to specify the entire composite correction curve by giving the parameter to all the parts.

Although the shape of the composite correction curve is slightly different depending on each temperature, if the number of divisions into parts and the kind of function applied to each part are the same, the value of the parameter itself is different depending on the temperature, but the composite correction curve is different. The types of parameters required to specify the same are the same regardless of temperature.

Such parameters for each temperature are stored in the temperature-correction curve parameter conversion table 35 as described above, parameters corresponding to the temperature at that time are output, and the correction curve output is performed by using this parameter. Data according to the combined correction curve can be obtained by the data calculation unit 36 performing the calculation process.

It takes time to update the data stored in the video signal conversion table 31 with the data obtained by such an operation, but in the case of a video signal, there is a horizontal synchronization period or a vertical synchronization period, so By using the non-display time, it is possible to prevent the deterioration of the image quality at the time of updating.

Therefore, according to the third embodiment, a memory having a capacity capable of storing data about a certain temperature is used as the video signal conversion table 31, and the stored contents are updated according to the detected temperature. According to this, it is possible to realize the same fine temperature compensation as that provided with the video signal conversion table for each temperature. That is, it is possible to realize fine temperature compensation with less memory than the conventional one. Certainly, a table that stores parameters is required, but the required memory capacity is significantly smaller than when a video signal conversion table for each temperature is provided.

(D) Other Embodiments In the above-described embodiments, the video signal conversion table performs both the applied voltage-transmittance correction and the inverse γ correction, but only the applied voltage-transmittance correction is performed. It may be done. For example, when the video signal is used as an output device of an information processing apparatus, inverse γ correction is not necessary because the video signal has not been γ corrected.

In the first and second embodiments, the video signal before input to the video signal conversion table is subjected to amplification processing and level shift processing, and the video signal after output from the video signal conversion table is processed. On the other hand, the case where the amplification process and the level shift process are performed is shown, but the method of temperature compensation is not limited to this, and there are various methods as follows.

(1) Level shift processing is performed only on the video signal before being input to the video signal conversion table. (2) Amplification processing and level shift processing are performed only on the video signal before being input to the video signal conversion table. (3) Level shift processing is performed only on the video signal output from the video signal conversion table.

(4) The amplification process and the level shift process are performed only on the video signal output from the video signal conversion table. (5) Level shift processing is performed on the video signal before input to the video signal conversion table, and level shift processing is also performed on the video signal output from the video signal conversion table. (6) Amplification processing and level shift processing are performed on the video signal before input to the video signal conversion table, and level shift processing is performed on the video signal output from the video signal conversion table. (7) Level shift processing is performed on the video signal before input to the video signal conversion table, and amplification processing and level shift processing are performed on the video signal output from the video signal conversion table.

The present invention is not limited to the color liquid crystal display device, but can be applied to a monochrome liquid crystal display device.

[0064]

As described above, according to the present invention, the temperature compensation according to the ambient temperature of the liquid crystal panel is performed by using one video signal conversion table, so that the temperature change of the liquid crystal panel can be prevented. It is possible to realize a small-sized liquid crystal display device having a simple structure, which can obtain a linear relationship between the video signal and the transmittance regardless of the above.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment.

FIG. 2 is a characteristic curve diagram showing a relationship between an ambient temperature of a liquid crystal panel and an applied voltage-transmittance characteristic.

FIG. 3 is a block diagram showing a configuration of a second embodiment.

FIG. 4 is a block diagram showing a configuration of a third embodiment.

[Explanation of symbols]

2, 5 ... Multiplier (amplifying means), 3, 6 ... Adder (level shift means), 4, 31 ... Video signal conversion table, 8, 33 ... Temperature detector, 10, 12 ... Temperature -Gain coefficient conversion table (gain instruction means), 11, 13 ... Temperature-shift amount conversion table (shift amount generation means), 20, 24 ... Amplification circuit, 21, 25 ... Bias circuit (level shift means), 35 ... Temperature-correction curve parameter conversion table (parameter generating means), 36 ... Correction curve output data calculation unit.

Claims (5)

[Claims] 1. A liquid crystal display device comprising a video signal conversion table for at least applying voltage-transmittance correction according to the applied voltage-transmittance characteristic of the liquid crystal panel to a video signal. Temperature detecting means for detecting the level, a shift amount generating means for outputting a level shift amount signal according to the detected temperature, a level of the video signal before reaching the video signal conversion table, and a level shift from the shift amount generating means. A liquid crystal display device, comprising: a level shift means for shifting in accordance with a quantity signal. 2. A gain instructing means for outputting a gain control signal according to the temperature detected by the temperature detecting means, and a video signal before reaching the video signal conversion table in accordance with the gain control signal from the gain instructing means. The liquid crystal display device according to claim 1, further comprising an amplifying unit for amplifying the liquid crystal. 3. A liquid crystal display device comprising a video signal conversion table for at least applying voltage-transmittance correction according to the applied voltage-transmittance characteristic of the liquid crystal panel to a video signal, wherein the ambient temperature of the liquid crystal panel is Temperature detecting means for detecting, a shift amount generating means for outputting a level shift amount signal according to the detected temperature, and a level of the video signal output from the video signal conversion table from the shift amount generating means. A liquid crystal display device comprising: a level shift unit that shifts according to a level shift amount signal. 4. A gain control means for outputting a gain control signal according to a temperature detected by the temperature detection means, and a video signal output from the video signal conversion table, the gain control signal from the gain control means. 4. An amplifying means for amplifying in accordance with
The liquid crystal display device according to item 1. 5. A liquid crystal display device comprising a video signal conversion table for performing at least applied voltage-transmittance correction according to the applied voltage-transmittance characteristic of the liquid crystal panel on a video signal, wherein the ambient temperature of the liquid crystal panel. Temperature detecting means for detecting, a parameter generating means for outputting a parameter for specifying an applied voltage-transmittance correction curve according to the detected temperature, and output data stored in the video signal conversion table using this parameter. And a table data calculation unit for updating the stored contents of the video signal conversion table.