JP4399230B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to a liquid crystal display device that displays an image using a liquid crystal display panel, and more particularly to a liquid crystal display device that is suitable for improving motion blur that occurs when a moving image is displayed using a liquid crystal display panel.

  In recent years, liquid crystal display (Liquid Crystal Display: hereinafter referred to as LCD) has been increased in size and definition, and displayed images mainly handle still images like liquid crystal display devices used in personal computers and word processors. Therefore, it is becoming popular in the field of handling moving images such as liquid crystal display devices used as TVs. LCDs are thinner than TVs equipped with cathode ray tubes (hereinafter referred to as CRTs) and can be installed without occupying so much space, so that they are becoming popular in ordinary households.

  In the LCD, a plurality of scanning lines formed on a first substrate and a plurality of signal lines formed on a second substrate are arranged in a lattice shape, and anisotropy is further provided between the first and second substrates. The amount of light that passes through the first and second substrates by adjusting the strength of the electric field according to the image data applied to the portion where each scanning line and the signal line intersect each other, with liquid crystal having a dielectric constant sealed By adjusting the value, a desired image is displayed. Further, when driving the liquid crystal at the portion where each scanning line and each signal line intersect, a TFT (Thin Film Transistor) which is a non-linear element (switching element) arranged in the vicinity where each scanning line and each signal line intersect. It has become mainstream to do.

  By the way, such an LCD has advantages such as being thin as described above compared with a CRT, but in displaying a moving image, image quality degradation different from that of the CRT is seen. That is, the CRT is a so-called impulse type that emits light for several milliseconds from the time when the electron beam hits the phosphor on the tube surface, whereas the LCD is the next from the time when the writing of data to the liquid crystal pixels is completed. Is a so-called hold type that holds display light for one frame period (for example, 16.7 msec in the case of 60 Hz progressive scan). In particular, in the case of a TFT-LCD, a TFT switch is provided for each dot constituting a liquid crystal pixel, and usually an auxiliary capacitor is provided for each liquid crystal pixel, so that the stored charge retention capability is extremely high. high.

  Therefore, when displaying a moving image, an impulse-type CRT displays an image instantaneously at a position corresponding to time, whereas a hold-type LCD displays a frame one frame before immediately before new writing. The image will remain. As described above, when the image one frame before remains, the image one frame before and the currently displayed image appear to overlap each other due to a visual time integration effect or the like. Such a phenomenon is generally called motion blur, and it is necessary to reduce the motion blur in order to improve image quality degradation in the display of moving images.

  In order to reduce such motion blur, as shown in FIG. 15A, a predetermined voltage that becomes black display is applied to the liquid crystal during the vertical blanking period, thereby writing to the liquid crystal pixels based on the image data. There is a way to reset the voltage. In other words, after displaying an image for one frame, black data is simultaneously inserted into all the scanning lines simultaneously through a signal line, so that an image for one frame is sequentially displayed for each scanning line and then all scanning is performed. It is to display black at the same time for the line.

  However, when the display is performed by such a method, the image display period within one frame period differs for each scanning line, so that there is a problem that a display luminance difference is generated for each scanning line as shown in FIG. is there. In other words, when displaying an image for one frame, image data is sequentially written and scanned from the top to the bottom of the liquid crystal display panel, whereas when displaying black, the entire screen is simultaneously displayed at once. This is because black data writing causes the image display period to be different between the upper scanning line and the lower scanning line of the liquid crystal display panel in one frame period. Incidentally, the image display period is proportional to the display luminance. When the image display period is short, the display luminance is low, and conversely, when the image display period is long, the display luminance is high.

As a method for solving the problem that the display luminance difference is caused by the vertical position of the liquid crystal display panel, there is a method of inserting black data between the image data of each horizontal line as disclosed in Patent Document 1. . This is because, as shown in FIG. 16 (a), an image data selection period and a black display selection period are set within a time shorter than the time required to scan one scan line, and the image data selection is performed. By displaying an image corresponding to the image data from the signal line in the period and displaying black according to the black data from the signal line in the black display selection period, the image data is displayed for each scanning line in one frame period. The write voltage to the liquid crystal pixel based on the reset is reset. According to this, since black data is sequentially inserted for each scanning line, the image display period at the vertical position of the liquid crystal display panel is compared with the above-described method of simultaneously inserting black data into all the scanning lines at the same time. Since the differences are equal, the display luminance difference caused by the location of the liquid crystal display panel is reduced as shown in FIG.
JP 2001-166280 A

  By the way, as described in Patent Document 1 described above, if black data is simply written sequentially for each scanning line, the display luminance difference caused by the vertical position of the liquid crystal display panel is reduced, but the image data and black data are reduced. Insufficient time (voltage application time) is written to the liquid crystal (reduced to about 1/2), resulting in a phenomenon in which a desired image cannot be displayed and proper black display is not performed. Resulting in. In a current general liquid crystal display panel, it is necessary to secure about 10 μsec or more as a data writing time (voltage application time).

  That is, in order to appropriately perform desired image display and black display, it is necessary to secure a sufficient time for writing image data and black data to the liquid crystal pixels (voltage application time = gate pulse width). In order to ensure a sufficient writing time (voltage application time = gate pulse width), it is necessary to simultaneously write black data to a plurality of continuous scanning lines.

  Here, the number of simultaneous black writing lines (the number of scanning lines simultaneously writing black data) x = N / 4 (N = the total number of scanning lines of the liquid crystal display panel), and the black display period (maximum black display period) is one frame period. Consider the case of a period of 50%. As shown in FIG. 17, scan lines # 1, # N / 4 + 1, # N / 2 + 1, # 3N / 4 + 1 having the maximum image display period, and scan lines # N / 4, # N / having the minimum image display period 2, # 3N / 4, and #N are different in the writing timing of the image data in the 1/4 frame period (the writing timing of the black data is the same), and the response arrival gradation of the liquid crystal pixel at the writing time of the black data is This is different for each scanning line.

  That is, as shown in FIG. 18, for example, even if the liquid crystal pixel has reached the target transmittance determined by the image data at the black writing timing at the scanning line # 1, the image data at the black writing timing at the scanning line # N / 4. The liquid crystal pixel does not reach the target transmittance determined by As described above, when the liquid crystal pixel does not reach the target transmittance, the display luminance of each liquid crystal pixel is represented by a time integral value of the liquid crystal transmittance, and therefore, scanning lines # 1, # N / 4 + 1 having the maximum image display period. , # N / 2 + 1, # 3N / 4 + 1, and scanning lines # N / 4, # N / 2, # 3N / 4, #N having the minimum image display period, the image data written to each has the same gradation Even in such a case, a difference occurs in the display gradation luminance, and as shown in FIG. 19, a non-uniform luminance distribution appears depending on the position in the vertical direction of the display screen. There was a problem of damage.

  The problem to be solved is that when black data is simultaneously written to a plurality of scanning lines in order to sufficiently secure the writing time (voltage application time) of the image data and black data to the liquid crystal pixels, each scanning is performed. Even if the image data written to the line is the same, a difference in display luminance occurs between the scanning lines.

In the liquid crystal display device according to claim 1, when the liquid crystal at a portion where a plurality of scanning lines and signal lines intersect is driven by a switching element that is turned on by sequential scanning, the gate of the switching element is turned on twice in one frame period. A liquid crystal display device for writing image data and black data from the signal line, wherein the image data is sequentially written for each scanning line to display an image, and x black (2 ≦ x ≦ N, N is a display control means for displaying black by writing to the same time for each scanning line of the total number of scanning lines), on the basis of the vertical / horizontal synchronizing signal of the image data, the image data A line detection unit for detecting a scanning line to be written, and an image display period of each scanning line based on a detection result of the line detection unit; , A enhancing conversion means for obtaining the enhancing conversion data as the liquid crystal reaches a transmittance specified by the image data, the enhancing conversion means, among the x scan lines of said successive has a maximum image display period The image data written to each scanning line is emphasized and converted so that the display luminance ratio with respect to the image data of the same gradation is 4% or less between the scanning line and the scanning line having the minimum image display period. Features.
The liquid crystal display device according to a second aspect of the present invention is characterized in that the enhancement conversion means has an enhancement conversion table in which enhancement conversion data for image data written to each scanning line is stored.
According to a third aspect of the present invention, there is provided a liquid crystal display device comprising temperature detection means for detecting an internal temperature of the apparatus, wherein the enhancement conversion means obtains the enhancement conversion data based on a detection result by the temperature detection means.
The liquid crystal display device according to a fourth aspect of the invention is characterized in that the emphasis conversion means has a temperature compensation table in which emphasis conversion data for temperature compensation with respect to image data written to each scanning line is stored.
6. The liquid crystal display device according to claim 5, wherein the frame storage means for storing the image data of the previous frame and the black display period of each scanning line based on the image data of the previous frame stored in the frame storage means. An arrival gradation predicting means for predicting the reached gradation level in the image and giving the predicted arrival gradation level to the enhancement conversion means, the enhancement conversion means based on the arrival gradation level. The enhancement conversion data for image data is obtained.
7. The liquid crystal display device according to claim 6, wherein the arrival gradation predicting means stores prediction data for predicting an arrival gradation level in the black display period of each scanning line from the image data of the previous frame. It has a reaching gradation prediction table.
The liquid crystal display device according to claim 7 is provided with a temperature detection means for detecting an internal temperature of the apparatus, and the reached gradation prediction means is based on the detection result by the temperature detection means and the image data of the previous frame. The arrival gradation level in the black display period of each scanning line is predicted, and the enhancement conversion means is configured to apply the enhancement conversion data for the image data of the current frame based on the detection result by the temperature detection means and the arrival gradation level. It is characterized by calculating | requiring.
The liquid crystal display device according to claim 8, wherein the arrival gradation prediction unit stores prediction data for predicting an arrival gradation level in a black display period of each scanning line based on a detection result by the temperature detection unit. Wherein the enhancement conversion means has a temperature compensation enhancement conversion table storing temperature compensation enhancement conversion data for image data written to each scanning line. And
In the liquid crystal display control method according to claim 9, when the liquid crystal at a portion where a plurality of scanning lines and signal lines intersect is driven by a switching element that is turned on by sequential scanning, the gate of the switching element is driven twice in one frame period. A liquid crystal display control method for turning on and writing image data and black data from the signal line, wherein the image data is sequentially written for each scanning line to display an image, and the black data is continuously written in x number. (2 ≦ x ≦ N, N is the total number of scanning lines) a step of black display by writing to the same time for each scanning line, on the basis of the vertical / horizontal synchronizing signal of the image data, the image data Based on the scanning line to be written and the detection result of the scanning line, in the image display period of each scanning line, the liquid crystal is And a step of obtaining the enhancing conversion data as to reach the transmittance established by the image data, among the x scan lines of said successive scan lines having a scan line and a minimum image display period having the maximum image display period The image data written to each of the scanning lines is subjected to emphasis conversion so that the display luminance ratio with respect to image data of the same gradation is 4% or less .
According to a tenth aspect of the present invention, there is provided a liquid crystal display control method including a step of referring to an emphasis conversion table storing emphasis conversion data for image data written to each scanning line.
The liquid crystal display control method according to an eleventh aspect includes a step of detecting an in-device temperature and a step of obtaining the enhancement conversion data based on a detection result of the in-device temperature.
According to a twelfth aspect of the present invention, there is provided a liquid crystal display control method including a step of referring to a temperature compensation table storing emphasis conversion data for temperature compensation with respect to image data written to each scanning line.
14. The liquid crystal display control method according to claim 13, wherein the image data of the previous frame is stored, and the reached gradation level in the black display period of each scanning line based on the stored image data of the previous frame. And providing the predicted arrival gradation level, and obtaining the enhancement conversion data for the image data of the current frame based on the arrival gradation level.
The liquid crystal display control method according to claim 14 refers to a reaching gradation prediction table in which prediction data for predicting a reaching gradation level in the black display period of each scanning line is stored from the image data of the previous frame. It has the process to perform.
The liquid crystal display control method according to claim 15, wherein an arrival floor in the black display period of each scanning line is based on the step of detecting the temperature in the device, the detection result of the temperature in the device, and the image data of the previous frame. A step of predicting a tone level, and a step of obtaining the enhancement conversion data for the image data of the current frame based on the detection result of the temperature in the apparatus and the reached gradation level.
The liquid crystal display control method according to claim 16, wherein an arrival gradation prediction table storing prediction data for predicting an arrival gradation level in a black display period of each scanning line based on a detection result of the temperature in the apparatus. And a step of referring to a temperature compensation enhancement conversion table storing temperature compensation enhancement conversion data for the image data written to each scanning line.
The liquid crystal display device of the present invention detects a scanning line in which the image data is written based on the vertical / horizontal synchronization signal of the image data by the line detection unit, and based on the detection result of the line detection unit by the enhancement conversion unit, By obtaining enhancement conversion data such that the liquid crystal reaches the transmittance determined by the image data during the image display period of the scan line, the display brightness in each scan line can be made substantially the same.

  In the liquid crystal display device of the present invention, when black data is simultaneously written to a plurality of scanning lines in order to sufficiently secure a data writing time (voltage application time) to the liquid crystal pixels, each scanning line (display line) is written. In the meantime, the input image data is emphasized and supplied to the liquid crystal display panel so that the display gradation luminance for the image data of the same gradation is substantially the same (luminance ratio is 4% or less). Therefore, a high-quality moving image display without uneven brightness can be realized.

  In the liquid crystal display device of the present invention, in order to sufficiently secure the writing time (voltage application time) of image data and black data to the liquid crystal pixels in one frame period (for example, 16.7 msec in the case of 60 Hz progressive scan). In addition, the image data is sequentially written for each scanning line of the liquid crystal display panel, and the black data is simultaneously written to a plurality of continuous scanning lines. At this time, since the image display period in each scanning line is different, The display gradation luminance (liquid crystal) for the image data of the same gradation between the respective scanning lines (display lines) is obtained by performing appropriate enhancement conversion on the image data written to each scanning line corresponding to the image display period. (Time integral value of transmittance) is made substantially the same (luminance ratio is 4% or less).

(Embodiment 1)
FIG. 1 is a diagram for explaining a first embodiment of a liquid crystal display device of the present invention, FIGS. 2 and 3 are timing charts showing writing timing of image data and black data in the liquid crystal display device of FIG. 1, and FIG. FIG. 5 is a diagram for explaining a case where correction voltage data for each scanning line is obtained from correction voltage data obtained by referring to the emphasis conversion table (ROM) with a single emphasis conversion table (ROM). FIG. 6 to FIG. 8 are diagrams for explaining response waveforms of liquid crystal pixels based on enhancement conversion data by the enhancement conversion unit in FIG. 1, and FIGS. 6 to 8 show the same gradation in each scanning line (display line) by enhancement conversion by the enhancement conversion unit in FIG. It is a figure for demonstrating that the display gradation brightness | luminance with respect to this image data is substantially the same (luminance ratio is 4% or less of range). In the following description, terms such as scanning lines G1 to GN and scanning lines # 1 to #N are used, but scanning lines # 1 to #N correspond to the scanning lines G1 to GN, They shall be used properly according to the contents of the explanation. In the following description, it is assumed that the scanning line corresponds to the display line.

  The liquid crystal display device shown in FIG. 1 is predetermined after, for example, a ½ frame period (= 8.3 msec) from the image data writing timing within one frame period (for example, 16.7 msec in the case of 60 Hz progressive scan). A series of operations of simultaneously selecting a predetermined number of scanning lines and writing black data is performed in one frame cycle. In the following description, in order to sufficiently secure the data writing time (voltage application time = gate pulse width), the number x of scanning lines to which black data is simultaneously written is referred to as the number of simultaneous black writing lines. The number x of simultaneous black writing lines can be arbitrarily set within the range of not more than the total number of scanning lines N of the liquid crystal display panel and not less than 2.

  FIG. 2 shows the gate driver output when the number of simultaneous black writing lines x = 4, for example. Further, among the scanning lines G1 to GN, for example, the image display periods of the scanning lines G1 to G4 are T1 to T4 (T1> T2> T3> T4), respectively. Further, for example, black display periods in the scanning lines G1 to G4 are B1 to B4 (B1 <B2 <B3 <B4), respectively. Here, since each of the image display periods T1 to T4 is proportional to the display luminance as described above, a display luminance difference occurs between the scanning lines G1 to G4.

  That is, as shown in FIG. 3, when image data is sequentially written for each scan line and black data is simultaneously written for a plurality of scan lines, the scan line having the maximum image display period and the minimum image display period are set. A scanning line having the same exists. Further, since the display brightness is proportional to the image display period in each scan line, it can be seen that the display brightness differs between the scan line having the maximum image display period and the scan line having the minimum image display period.

Here, as a result of an experiment conducted by the present applicant regarding an identification limit of a display luminance difference in an area where a scanning line having the maximum image display period and a scanning line having the minimum image display period are adjacent to each other, for example, the display luminance is 400 cd / m. The luminance ratio at the discrimination limit in ² was 3.5%. The identification limit is a limit area where the difference in display luminance is not discernible to the viewer, but in actual display under various environmental conditions, the discriminating limit is not recognized by the viewer if the luminance ratio is 4% or less at maximum. As a result of the experiment, I found out.

  Therefore, in the present embodiment, the number of simultaneous black writing lines x is set in consideration of the period required for data writing, and each scanning line Gn to Gn + (x−1) (where n = 1, x + 1). 2x + 1, 3x + 1,...)), And appropriate enhancement conversion is performed on each of the image data written to each scanning line so that the liquid crystal pixels have the transmittance determined by the input image data. The liquid crystal display panel 7 is supplied to prevent a display luminance difference from occurring for each scanning line. As a result, the display gradation luminance (time integration value of the liquid crystal transmittance) for the image data of the same gradation is made substantially the same (the luminance ratio is 4% or less) between the scanning lines (display lines). Details of the enhancement conversion will be described later.

  The liquid crystal display device shown in FIG. 1 includes a line detection unit 1, a control CPU 2, an emphasis conversion unit 3, emphasis conversion tables (ROM) 4 a to 4 d, a black data supply unit 5, a liquid crystal controller 6, and a liquid crystal display panel 7. ing. The line detection unit 1 serving as a line detection unit detects a scanning line in which the image data is written based on a vertical / horizontal synchronization signal of image data (here, 60 Hz progressive data, for example). The control CPU 2 controls the enhancement conversion by the enhancement conversion unit 3, controls the black data supply by the black data supply unit 5, or the liquid crystal display panel 7 by the liquid crystal controller 6 according to the detection result from the line detection unit 1. To control the drive.

  The enhancement conversion unit 3 as enhancement conversion means refers to any one of the enhancement conversion tables (ROM) 4a to 4d that are switched and selected in accordance with the detection result of the line detection unit 1, and performs liquid crystal in the image display period of each scanning line. Correction voltage data (enhancement conversion data) is read so that the pixel has the transmittance determined by the input image data, and is output to the liquid crystal controller 6. Thereby, the display gradation luminance for the image data of the same gradation is made substantially the same (the luminance ratio is in the range of 4% or less) between the scanning lines (display lines).

  The emphasis conversion tables (ROM) 4a to 4d are provided corresponding to the case where the number of simultaneous black writing lines x is, for example, four. The enhancement conversion tables (ROM) 4a to 4d store correction voltage data (emphasis conversion data) that allows the liquid crystal pixels to reach the transmittance determined by the input image data within the image display period of each scanning line. Has been.

  Here, the enhancement conversion table (ROM) 4a is a scan line n LUT (lookup table), and the enhancement conversion table (ROM) 4b is a scan line n + 1 LUT (lookup table). ) 4c is a scan line n + 2 LUT (lookup table), and the enhancement conversion table (ROM) 4d is a scan line n + 3 LUT (lookup table). However, n = 1, 5, 9, 13... (When x = 4).

  In the enhancement conversion table (ROM) 4a, correction voltage data is stored such that the liquid crystal pixels have the transmittance determined by the input image data within the image display period in the scanning line n. In the enhancement conversion table (ROM) 4b, correction voltage data is stored such that the liquid crystal pixels have the transmittance determined by the input image data within the image display period in the scanning line n + 1. In the enhancement conversion table (ROM) 4c, correction voltage data is stored so that the liquid crystal pixels have the transmittance determined by the input image data within the image display period in the scanning line n + 2. In the enhancement conversion table (ROM) 4d, correction voltage data is stored such that the liquid crystal pixels have the transmittance determined by the input image data within the image display period in the scanning line n + 3.

  The correction voltage data in each of the enhancement conversion tables (ROM) 4a to 4d is obtained in advance from actual measurement values of the optical response characteristics of the liquid crystal display panel 7. Each of the emphasis conversion tables (ROM) 4a to 4d may have correction voltage data for all 256 gradations when the image data is 8-bit 256 gradations, for example, 32 gradation gradations. Only the correction voltage data for the nine representative gradations may be provided, and the other correction voltage data may be obtained from the above actual measurement values by calculation such as linear interpolation. If the correction voltage data is reduced, the capacity of each emphasis conversion table (ROM) 4a to 4d can be reduced.

  Further, the emphasis conversion tables (ROMs) 4a to 4d are set to four corresponding to the case where the number of simultaneous black writing lines x is four, but not limited to this, the number of simultaneous black writing lines x depends on the number x of simultaneous black writing lines. Should be provided. That is, for example, when the number of simultaneous black writing lines x is 3, a total of three tables of the scanning line n enhancement conversion table, the scanning line n + 1 enhancement conversion table, and the scanning line n + 2 enhancement conversion table are switched and referenced. Thus, the image data supplied to each scanning line may be configured to perform enhancement conversion. In this case, however, n = 1, 4, 7, 10,.

  For example, when the number of simultaneous black writing lines x is 5, the scanning line n enhancement conversion table, the scanning line n + 1 enhancement conversion table, the scanning line n + 2 enhancement conversion table, the scanning line n + 3 enhancement conversion table, and the scanning A configuration may be adopted in which enhancement conversion of image data supplied to each scanning line is performed by switching and referring to a total of five tables of line n + 4 enhancement conversion tables. In this case, however, n = 1, 6, 11, 16,. Therefore, when the number of simultaneous black writing lines is x, the scanning line n enhancement conversion table, the scanning line n + 1 enhancement conversion table, the scanning line n + 2 enhancement conversion table,..., For the scanning line n + (x−1). It may be configured to perform enhancement conversion of image data supplied to each scanning line by switching and referring to a total of x tables of enhancement conversion tables. In this case, however, n = 1, x + 1, 2x-1, 3x + 1.

  Furthermore, here, for example, the number of enhancement conversion tables (ROM) corresponding to the number x of simultaneous black writing lines is provided so as to realize the same display luminance in all of the scanning lines n, n + 1, n + 2, and n + 3. However, it is not always necessary to provide x tables. That is, as is apparent from the principle, the display luminance difference appears remarkably between the nth scanning line and the n + (x−1) th scanning line, and adjacent scanning lines. The luminance ratio visually recognized by the viewer is 4% or more. Therefore, it is only necessary to perform enhancement conversion on image data so that a display luminance difference with respect to image data of the same gradation is not visually recognized at least between these scanning lines.

  That is, for example, x / 2 emphasis conversion tables corresponding to every two consecutive scan lines may be provided, or x / 3 emphasis conversion tables corresponding to every three consecutive scan lines. It is good also as a structure. As described above, if the enhancement conversion table is shared for a plurality of continuous scanning lines, the capacity of the table memory can be suppressed.

  Further, when the enhancement conversion table (ROM) is shared by a plurality of continuous scanning lines, each scanning line is obtained by performing an operation such as linear interpolation on the correction voltage data read from the enhancement conversion table (ROM). You may make it obtain | require correction voltage data for every.

  Further, for example, as shown in FIG. 4, only the scanning line n enhancement conversion table (ROM) 4 is provided, and the correction voltage data read from the enhancement conversion table (ROM) 4 differs for each scanning line. The correction voltage data for each scanning line may be obtained by multiplying by a coefficient α (α ≧ 1). In this case, the correction voltage data read from the emphasis conversion table (ROM) 4 by the subtractor 3a is subtracted from the input image data, and the scanning line in which the image data is written into the subtracted data by the multiplier 3b. The correction voltage data (enhancement conversion data) to be output to the liquid crystal controller 6 is obtained by multiplying the coefficient α according to the above and the added data by the adder 3c and the input image data. it can.

  The black data supply unit 5 supplies black data for causing the liquid crystal display panel 7 to perform black display to the liquid crystal controller 6. The black data may be stored in the liquid crystal controller 6 in advance. In this case, the black data supply unit 5 can be omitted.

  The liquid crystal controller 6 drives the gate driver 8 and the source driver 9 of the liquid crystal display panel 7 as shown in FIG. 2 under the control of the control CPU 2 described above. That is, the gate driver 8 sequentially selects the scanning lines G1, G2, G3, G4,..., GN shown in FIG. 2 in one frame period (for example, 16.7 msec in the case of 60 Hz progressive scan). The image data is written, and after the writing of the image data, for example, after ½ frame period (= 8.3 msec), G1 to G4, G5 to G8,.. A series of operations of writing black data is performed in one frame cycle. The source driver 9 outputs corresponding image data in accordance with the sequential scanning of the scanning lines G1, G2, G3, G4,. At this time, image data is written using the enhanced conversion data enhanced by the enhancement conversion unit 3.

  Next, a liquid crystal display control method based on enhancement conversion of image data in the above-described embodiment will be described. In the following description, it is assumed that the liquid crystal pixel reaches and responds to black (0 gradation) within the black display period immediately before the image data is written. For the sake of simplicity, a case where the number of simultaneous black writing lines x is four will be described.

  First, when image data (here, 60 Hz progressive data, for example) is input, the line detection unit 1 performs line detection of the image data. Here, when image data to be written on the scanning line G1 is detected, the control CPU 2 selects and refers to the enhancement conversion table (ROM) 4a for the scanning line n with respect to the enhancement conversion unit 3, and enhances the image data. You are instructed to perform the conversion process. Here, in the enhancement conversion table (ROM) 4a, as described above, correction voltage data is stored such that the liquid crystal pixels have the transmittance determined by the image data within the image display period T1 in the scanning line G1. The correction voltage data is output to the liquid crystal controller 6 so that the luminance display determined by the image data can be performed on the scanning line G1.

  Next, when the image data written on the scanning line G2 is detected by the line detection unit 1, the control CPU 2 selects and refers to the enhancement conversion table (ROM) 4b for the scanning line n + 1 with respect to the enhancement conversion unit 3, An instruction is given to perform enhancement conversion processing of the image data. Here, in the enhancement conversion table (ROM) 4b, as described above, correction voltage data is stored such that the liquid crystal pixels have the transmittance determined by the image data within the image display period T2 in the scanning line G2. The correction voltage data is output to the liquid crystal controller 6 so that the luminance display determined by the image data can be performed on the scanning line G2.

  Next, when the image data written on the scanning line G3 is detected by the line detection unit 1, the control CPU 2 selects and refers to the enhancement conversion table (ROM) 4c for the scanning line n + 2 with respect to the enhancement conversion unit 3. An instruction is given to perform enhancement conversion processing of the image data. Here, in the enhancement conversion table (ROM) 4c, as described above, correction voltage data is stored such that the liquid crystal pixels have the transmittance of the liquid crystal pixels determined by the image data within the image display period T3 in the scanning line G3. The correction voltage data is output to the liquid crystal controller 6, so that the luminance display determined by the image data can be performed on the scanning line G3.

  Next, when the image data to be written on the scanning line G4 is detected by the line detection unit 1, the control CPU 2 selects and refers to the enhancement conversion table (ROM) 4d for the scanning line n + 3 with respect to the enhancement conversion unit 3, and An instruction is given to perform enhancement conversion processing of the image data. Here, in the enhancement conversion table (ROM) 4d, as described above, correction voltage data is stored such that the liquid crystal pixels have the transmittance of the liquid crystal pixels determined by the image data within the image display period T4 in the scanning line G4. The correction voltage data is output to the liquid crystal controller 6 so that the luminance display determined by the image data can be performed on the scanning line G4.

  In this manner, the correction voltage data corresponding to the image display period of each scanning line is output to the liquid crystal controller 6, thereby displaying an image for one frame. At this time, for example, after a half frame period (= 8.3 msec) from the writing of the image data, the scanning lines are simultaneously selected for every x lines and the black data is written again. In the image display period immediately before the image is written, the liquid crystal pixels reach and respond to a desired transmittance corresponding to the input image data, so that there is no display luminance difference between the scanning lines, and there is no luminance unevenness. A high-quality image can be displayed.

  That is, as shown in FIG. 2, even if the image display periods T1 to T4 in the scanning lines G1 to G4 are T1> T2> T3> T4, the display luminances in the scanning lines G1 to G4 are the same. In addition, since optimum enhancement conversion is performed on the image data supplied to each of the scanning lines G1 to G4, no difference in display luminance occurs even if the image display period is different for each scanning line. Further, according to the detection result of the line detection unit 1, the enhancement conversion unit 3 refers to the enhancement conversion tables (ROM) 4a to 4d corresponding to the respective scanning lines G1 to G4, and corresponds to each image display period T1 to T4. By outputting the correction voltage data to the liquid crystal controller 6, a desired halftone can be displayed on each of the scanning lines G1 to G4.

  As a result, for example, as shown in FIG. 5, the black display period is set in the second half frame period (= 8.3 msec) of one frame period, and the liquid crystal pixels are always displayed in the black display period immediately before the image data is written. Is assumed to have reached and responded to black (0 gradation), for example, when image data of 64 gradations is input in a certain frame, a predetermined image is referred to by referring to the enhancement conversion tables (ROM) 4a to 4d. By supplying to the liquid crystal display panel 7 correction voltage data (emphasis conversion data) of 72 gradations for causing the liquid crystal pixels to respond to the target gradation (64 gradations) within the display period, the gradation brightness of 64 gradations. Can be displayed. Similarly, when 96 gradation image data is input in the next frame, the liquid crystal pixels are set to the target gradation (96th floor) within a predetermined image display period with reference to the enhancement conversion tables (ROM) 4a to 4d. By supplying correction voltage data (enhanced conversion data) of 108 gradations for responding to (tone) to the liquid crystal display panel 7, it is possible to display gradation gradations of 96 gradations.

  Here, the number of simultaneous black writing lines (the number of scanning lines for simultaneously writing black data) x = N / 4 (N = total number of scanning lines of the liquid crystal display panel), and the black display period (= maximum black display period) is one frame. Consider the case of 50% of the period.

  That is, as shown in FIG. 6, scanning lines # 1, # N / 4 + 1, # N / 2 + 1, # 3N / 4 + 1 having the maximum image display period, and scanning lines # N / 4, #N having the minimum image display period In N / 2, # 3N / 4, and #N, the writing timing of image data is also different in the 1/4 frame period (the writing timing of black data is the same), and the response of the liquid crystal pixel at the writing time of black data The reached gradation is different for each scanning line. Therefore, for example, for image data written (supplied) to scanning lines # 1, # N / 4 + 1, # N / 2 + 1, # 3N / 4 + 1, within an image display period (1/2 frame period), Write image data (enhancement conversion data) that causes the liquid crystal pixels to reach and respond to the target arrival gradation (transmittance) determined by the input image data is obtained from the above-described enhancement conversion table (ROM) 4a, and the subsequent stage liquid crystal controller 6 is output. For example, for data written (supplied) to the scanning lines # N / 4, # N / 2, # 3N / 4, and #N, the liquid crystal is displayed within the image display period (¼ frame period). Written image data (enhanced conversion data) is obtained from the above-described enhancement conversion table (ROM) 4d so that the pixel reaches and reaches the target arrival gradation (transmittance) determined by the input image data, and the subsequent stage liquid crystal controller 6 is obtained. Is output.

  In this case, even if the image data has the same gradation, scanning is performed in comparison with the writing image data (enhancement conversion data) supplied to the scanning lines # 1, # N / 4 + 1, # N / 2 + 1, and # 3N / 4 + 1. Write image data (enhancement conversion data) written to lines # N / 4, # N / 2, # 3N / 4, and #N is larger (the degree of emphasis conversion is greater).

  Thereby, even if the image display period in each scanning line is different, as shown in FIG. 7, it becomes possible for the liquid crystal pixels to reach the transmittance determined by the input image data within each image display period, as shown in FIG. The display gradation luminance for the image data of the same gradation can be made substantially the same (the luminance ratio is in the range of 4% or less), and the luminance distribution at the vertical position of the display screen is made uniform as shown in FIG. Therefore, the quality of the display image is improved.

However, strictly speaking, just by making the liquid crystal transmittance just before writing black data in each scanning line the same, the display luminance (time integrated value of the liquid crystal transmittance) between the scanning lines does not become the same,
Display luminance (time integral value of liquid crystal transmittance) = liquid crystal transmittance immediately before writing black data × (image display period + black display period) / 2
By controlling the enhancement conversion process for the input image data so that the liquid crystal pixels reach the transmittance determined by the input image data within the image display period in each scan line, The display luminance difference between the lines (display lines) can be suppressed to a range that is not visually recognized by the viewer (luminance ratio of 4% or less).

  In the present embodiment, the case where the liquid crystal pixel always reaches the black level in response during the black display period has been described. However, the liquid crystal pixel does not necessarily reach the black level within the black display period (which differs for each scanning line). The present invention can be applied even when the response does not reach. This will be described later.

  As described above, in this embodiment, based on the vertical / horizontal synchronization signal of the image data, the scanning line to which the image data is written is detected, and the liquid crystal has a transmittance determined by the image data in the image display period of each scanning line. Since the emphasis conversion data that arrives is obtained and supplied to the liquid crystal display panel 7, the display gradation luminance for the image data of the same gradation is substantially the same between the scanning lines (display lines). (The luminance ratio is suppressed to 4% or less), and high-quality image display without luminance unevenness can be realized.

(Embodiment 2)
FIG. 9 is a diagram illustrating a second embodiment of the liquid crystal display device in consideration of an improvement in response speed due to the temperature dependence of the liquid crystal, and FIG. 10 is a diagram illustrating an example of the temperature compensation table in FIG. Note that, in the drawings described below, the same reference numerals are given to portions common to those in FIG. 1 and overlapping descriptions are omitted.

  In the liquid crystal display device shown in FIG. 9, according to the temperature of the liquid crystal display panel 7, the liquid crystal pixels can reach the transmittance determined by the input image data within the image display period of each scanning line detected by the line detection unit 1. The liquid crystal display panel 7 is driven using such temperature compensation data (emphasis conversion data). The temperature compensation data (enhancement conversion data) takes into account the response speed improvement due to the temperature dependence of the liquid crystal, details of which will be described later. Further, in order to compensate the temperature dependence of the liquid crystal, temperature detection data (detection result) from the temperature sensor 11 as temperature detection means is used. Although it is desirable to provide the temperature sensor 11 in the liquid crystal display panel 7 for its original purpose, this is difficult in terms of structure, so it may be installed as close to the liquid crystal display panel 7 as possible.

  In the liquid crystal display device shown in FIG. 9, a temperature compensation table having temperature compensation data (emphasis conversion data) for temperature compensation as shown in FIG. 10 instead of the emphasis conversion tables (ROM) 4a to 4d shown in FIG. (ROM) 10a to 10d are provided. Here, the temperature compensation table (ROM) 10a is a scan line n LUT (lookup table), the temperature compensation table (ROM) 10b is a scan line n + 1 LUT (lookup table), and the temperature compensation table (ROM) 10c is scanned. The line n + 2 LUT (lookup table) and temperature compensation table (ROM) 10d are the scan line n + 3 LUT (lookup table). However, n = 1, 5, 9, 13,... (When x = 4).

  The temperature compensation table (ROM) 10a has temperature compensation data corresponding to the temperature detection data from the temperature sensor 11 such that the liquid crystal pixels have a transmittance determined by the input image data within the image display period in the scanning line n. Stored. In the temperature compensation table (ROM) 10b, there is temperature compensation data corresponding to the temperature detection data from the temperature sensor 11 such that the liquid crystal pixels have the transmittance determined by the input image data within the image display period in the scanning line n + 1. Stored. In the temperature compensation table (ROM) 10c, temperature compensation data corresponding to the temperature detection data from the temperature sensor 11 is set so that the liquid crystal pixels have the transmittance determined by the input image data within the image display period in the scanning line n + 2. Stored. The temperature compensation table (ROM) 10d has temperature compensation data corresponding to the temperature detection data from the temperature sensor 11 such that the liquid crystal pixels have the transmittance determined by the input image data within the image display period in the scanning line n + 3. Stored.

  Further, as shown in FIG. 10, each temperature compensation table 10a to 10d includes a table area that is referenced when the temperature detected by the temperature sensor 11 is T1 to T2, a table area that is referenced when T2 to T3, and T3 to T3. Each has a table area referred to at T4 and a table area referred to at T4 to T5. These table areas are switched and selected by the control CPU 2 that receives the temperature detection data (detection result) of the temperature sensor 11. Further, these table areas may be provided as separate table memories, and may be switched and referred to by the temperature detected by the temperature sensor 11.

  Note that the temperature compensation data in each temperature compensation table (ROM) 10a to 10d is obtained in advance from measured values of the optical response characteristics of the liquid crystal display panel 7 under each temperature condition, as described above. In addition, each of the temperature compensation tables (ROM) 10a to 10d may have temperature compensation data for all 256 gradations as in the case where the image data is 8-bit 256 gradations. Only the temperature compensation data for nine representative gradations of 32 gradations may be provided, and the other temperature compensation data may be obtained from the above actual measurement values by calculation such as linear interpolation. If the temperature compensation data is reduced, the capacity of each temperature compensation table (ROM) 10a to 10d can be reduced.

  Further, each temperature compensation table (ROM) 10a to 10d has four simultaneous black writing lines corresponding to the case where the number of simultaneous black writing lines x is four, but this is not restrictive. What is necessary is just to provide according to the number x of lines. Further, the temperature compensation table (ROM) may be shared by a plurality of continuous scanning lines as described above. In this case, the temperature compensation data for each scanning line may be obtained by performing an operation such as linear interpolation on the temperature compensation data read from the temperature compensation table (ROM).

  In such a configuration, as described above, it is assumed that the liquid crystal pixel reaches black (0 gradation) within the black display period immediately before the image data is written, and the number of simultaneous black writing lines x is 4. If it is a book, the line detection unit 1 performs line detection of image data (here, 60 Hz progressive data, for example). Here, when the image data written to the scanning line G1 is detected and the temperature detection data from the temperature sensor 11 is obtained, the temperature compensation table (ROM) for the scanning line n is given to the enhancement conversion unit 3 by the control CPU 2. By selecting and referring to 10a, an instruction is given to perform enhancement conversion processing of the image data. At this time, when the temperature detected by the temperature sensor 11 is, for example, T1 to T2, the enhancement conversion unit 3 is instructed to refer to the table area of T1 to T2. When the temperature detected by the temperature sensor 11 is T2 to T3, T3 to T4, and T4 to T5, the same instruction is given.

  Here, in the temperature compensation table (ROM) 10a, temperature compensation data is stored such that the liquid crystal pixels have the transmittance determined by the image data within the image display period T1 in the scanning line G1 for each temperature condition. By outputting the temperature compensation data to the liquid crystal controller 6, it is possible to perform luminance display determined by the input image data on the scanning line G1 at any operating environment temperature.

  Similarly, when image data written to the scanning line G2 is detected and temperature detection data from the temperature sensor 11 is obtained, the temperature compensation table (ROM) 10b for the scanning line n + 1 is selected and referred to, and the image is detected. It is instructed to perform data enhancement conversion processing. At this time, when the temperature detected by the temperature sensor 11 is, for example, T1 to T2, the enhancement conversion unit 3 is instructed to refer to the table area of T1 to T2. When the temperature detected by the temperature sensor 11 is T2 to T3, T3 to T4, and T4 to T5, the same instruction is given. The temperature compensation data is output to the liquid crystal controller 6 so that the luminance display determined by the input image data can be performed on the scanning line G2 at any operating environment temperature.

  Similarly, when image data written to the scanning line G3 is detected and temperature detection data from the temperature sensor 11 is obtained, the temperature compensation table (ROM) 10c for the scanning line n + 2 is selected and referred to, and the image data is read. It is instructed to perform data enhancement conversion processing. At this time, when the temperature detected by the temperature sensor 11 is, for example, T1 to T2, the enhancement conversion unit 3 is instructed to refer to the table area of T1 to T2. When the temperature detected by the temperature sensor 11 is T2 to T3, T3 to T4, and T4 to T5, the same instruction is given. The temperature compensation data is output to the liquid crystal controller 6 so that the luminance display determined by the input image data can be performed on the scanning line G3 at any operating environment temperature.

  Similarly, when the image data written to the scanning line G4 is detected and the temperature detection data from the temperature sensor 11 is obtained, the temperature compensation table (ROM) 10d for the scanning line n + 3 is selected and referred to, and the image is detected. It is instructed to perform data enhancement conversion processing. At this time, when the temperature detected by the temperature sensor 11 is, for example, T1 to T2, the enhancement conversion unit 3 is instructed to refer to the table area of T1 to T2. When the temperature detected by the temperature sensor 11 is T2 to T3, T3 to T4, and T4 to T5, the same instruction is given. The temperature compensation data is output to the liquid crystal controller 6 so that the luminance display determined by the input image data can be performed on the scanning line G4 at any operating environment temperature.

  In this way, the temperature compensation data corresponding to each scanning line is output to the liquid crystal controller 6, thereby displaying an image for one frame. At this time, for example, after a half frame period (= 8.3 msec) from the writing of the image data, the scanning lines are simultaneously selected for every x lines and the black data is written again. In the image display period immediately before the image is written, the liquid crystal pixels reach and respond to a desired transmittance corresponding to the image data according to the temperature detected by the temperature sensor 11, so that the display luminance difference between the scanning lines is different. It is possible to display a high-quality image with no luminance unevenness without occurring.

  As described with reference to FIGS. 6 to 8, the image display period is applied to the image data written (supplied) to the scanning lines # 1, # N / 4 + 1, # N / 2 + 1, # 3N / 4 + 1. Write image data (enhancement conversion data) such that the liquid crystal pixels reach and respond to the target arrival gradation (transmittance) defined by the input image data within (1/2 frame period) is the temperature compensation table (ROM) 10a described above. Is output to the liquid crystal controller 6 at the subsequent stage. For image data written (supplied) to the scanning lines # N / 4, # N / 2, # 3N / 4, and #N, the liquid crystal is displayed within the image display period (1/4 frame period). Write image data (enhancement conversion data) such that the pixel reaches and responds to the target arrival gradation (transmittance) determined by the input image data is obtained from the temperature compensation table (ROM) 10d described above, and is sent to the liquid crystal controller 6 at the subsequent stage. Is output.

  In this case, as described above, the write image data (emphasis conversion data) supplied to the scanning lines # 1, # N / 4 + 1, # N / 2 + 1, # 3N / 4 + 1 with respect to the input image data of the same gradation. Compared to the above, the writing image data (enhancement conversion data) written to the scanning lines # N / 4, # N / 2, # 3N / 4, and #N is larger (enhancement conversion degree is greater), so that the same as above. In addition, the display gradation luminance for the image data of the same gradation between the scanning lines (display lines) can be made substantially the same (the luminance ratio is 4% or less).

  As described above, in the present embodiment, image data enhancement conversion is performed using the temperature compensation data (emphasis conversion data) of the temperature compensation tables (ROM) 10a to 10d. It is possible to achieve an improvement in response speed due to the temperature dependence.

(Embodiment 3)
FIG. 11 is a diagram showing a third embodiment of the liquid crystal display device improved in the case where the liquid crystal pixels do not reach black (0 gradation) in the black display period immediately before the image data is written, and FIG. FIG. 13 is a diagram illustrating an example of the temperature compensation table in FIG. 11, and FIG. 14 is a diagram for explaining the response waveform of the liquid crystal pixel based on the enhancement conversion data by the enhancement conversion unit in FIG. FIG.

  The liquid crystal display device shown in FIG. 11 adds a frame memory (FM) 12, a reached tone prediction unit 13, and reached tone prediction tables (ROM) 14a to 14d to the configuration of the liquid crystal display device shown in FIG. Yes. Further, temperature compensation tables (ROM) 15a to 15d are provided instead of the temperature compensation tables (ROM) 10a to 10d in FIG.

  A frame memory (FM) 12 as a frame storage means can store image data for one frame, and stores image data of one frame before the image data to be displayed. .

  The reached gradation prediction unit 13 is based on the temperature detection data from the temperature sensor 11 obtained via the control CPU 2 and the image data of the previous frame stored in the frame memory (FM) 12. With reference to the prediction tables (ROM) 14a to 14d, the reached gradation level in the black display period of each scanning line is predicted for each scanning line, and the predicted reaching gradation level is given to the emphasis conversion unit 3.

  That is, as shown in FIG. 14, even if a voltage corresponding to, for example, a display gradation of 64 to black (0 gradation) corresponding to the image data of one frame before is applied to the liquid crystal pixel, the liquid crystal display panel Due to the optical response characteristic of No. 7, there are cases where, for example, only 16 gradations are reached within the black display period of 50% in the latter half of one frame period. Similarly, even if a voltage corresponding to, for example, a display gradation from 96 gradations to black (0 gradation) is applied to the liquid crystal pixels, 50% of the latter half of one frame period due to the optical response characteristics of the liquid crystal display panel 7. For example, only up to 8 gradations may be reached within the black display period.

  In this case, when the image display of the next frame is performed even though the black (0 gradation) level has not reached in the black display period, the start gradation (gradation before transition) is emphasized as 0 gradation. When the conversion is performed, an error occurs in the actual display gradation luminance with respect to the target arrival gradation, and there is a possibility that such an error may be gradually expanded. Therefore, in the present embodiment, the reached gradation level (the gradation level that has not reached black) in the immediately preceding black display period is set so that the liquid crystal reaches and responds accurately to the target gradation luminance within the image display period. Prediction is performed, and this is used as a start gradation (gradation before transition) to perform enhancement conversion of image data.

  The arrival tone prediction table (ROM) 14a is a scan line n LUT (lookup table), the arrival tone prediction table (ROM) 14b is a scan line n + 1 LUT (lookup table), and a reach tone prediction table (ROM). Reference numeral 14c denotes a scan line n + 2 LUT (lookup table), and a reached gradation prediction table (ROM) 14d denotes a scan line n + 3 LUT (lookup table). However, n = 1, 5, 9, 13... (When x = 4).

  In the arrival gradation prediction table (ROM) 14a, the voltage corresponding to the black (0 gradation) from the gradation of the image data of the previous frame in the scanning line n corresponding to the temperature detection data from the temperature sensor 11. Stored is prediction data for predicting the reached gradation level (level not reached to black (0 gradation)) when is applied to the liquid crystal pixel. In the arrival gradation prediction table (ROM) 14b, the voltage corresponding to the black (0 gradation) from the gradation of the image data of the previous frame in the scanning line n + 1 corresponding to the temperature detection data from the temperature sensor 11. Stored is prediction data for predicting the reached gradation level (level not reached to black (0 gradation)) when is applied to the liquid crystal pixel.

  In the arrival gradation prediction table (ROM) 14c, a voltage corresponding to black (0 gradation) from the gradation of the image data of the previous frame in the scanning line n + 2 corresponding to the temperature detection data from the temperature sensor 11. Stored is prediction data for predicting the reached gradation level (level not reached to black (0 gradation)) when is applied to the liquid crystal pixel. In the arrival gradation prediction table (ROM) 14d, a voltage corresponding to black (0 gradation) from the gradation of the image data of the previous frame in the scanning line n + 3 corresponding to the temperature detection data from the temperature sensor 11. Stored is prediction data for predicting the reached gradation level (level not reached to black (0 gradation)) when is applied to the liquid crystal pixel.

  FIG. 12 shows an example of each of the reached gradation prediction tables (ROM) 14a to 14d. Similarly to the above, table areas T2 to T3 to be referred to when the temperature detected by the temperature sensor 11 is T1 to T2. Each table area includes a table area referred to at times, a table area referred to at times T3 to T4, and a table area referred to at times T4 to T5. These table areas are switched and selected by the control CPU 2 that has received the temperature detection data of the temperature sensor 11 as described above. In addition, these table areas may be provided as separate table memories as described above, and may be switched and referenced according to the temperature detected by the temperature sensor 11.

  Note that the prediction data in each of the arrival gradation prediction tables (ROM) 14a to 14d is obtained in advance from the actually measured values of the optical response characteristics of the liquid crystal display panel 7 as described above. Each of the reached gradation prediction tables (ROM) 14a to 14d may have temperature compensation data for all 256 gradations as described above when the image data has 256 gradations of 8 bits. For example, only the temperature compensation data for nine representative gradations of 32 gradations may be provided, and the other temperature compensation data may be obtained by calculation such as linear interpolation from the above measured values. If the temperature compensation data is reduced, the capacities of the reached gradation prediction tables (ROM) 14a to 14d can be reduced.

  In addition, each of the reached gradation prediction tables (ROM) 14a to 14d is set to four corresponding to the case where the number of simultaneous black writing lines x is four, but this is not restrictive. It may be provided according to the number x of black writing lines. Further, each of the reached gradation prediction tables (ROM) 14a to 14d may be shared by a plurality of continuous scanning lines as described above. In this case, prediction data for each scanning line may be obtained by performing operations such as linear interpolation on the prediction data read from the arrival gradation prediction table (ROM).

  The temperature compensation table (ROM) 15a is a scan line n LUT (lookup table), the temperature compensation table (ROM) 15b is a scan line n + 1 LUT (lookup table), and the temperature compensation table (ROM) 15c is a scan line n + 2. An LUT (look-up table) and a temperature compensation table (ROM) 15d are scanning line n + 3 LUTs (look-up tables). However, n = 1, 5, 9, 13,... (When x = 4).

  The temperature compensation table (ROM) 15a includes a scanning line n based on the temperature detection data from the temperature sensor 11, the arrival gradation level from the arrival gradation prediction unit 13, and the gradation level of the input image data of the current frame. Temperature compensation data is stored such that the liquid crystal pixels have the transmittance determined by the input image data within the image display period. The enhancement conversion table (ROM) 15b is a scan specified by the temperature detection data from the temperature sensor 11, the arrival gradation level from the arrival gradation prediction unit 13, and the gradation level of the input image data of the current frame. Temperature compensation data is stored such that the liquid crystal pixels have the transmittance determined by the input image data within the image display period on line n + 1.

  In the enhancement conversion table (ROM) 15c, a scanning line specified from the temperature detection data from the temperature sensor 11, the arrival gradation level from the arrival gradation prediction unit 13, and the gradation level of the input image data of the current frame. Temperature compensation data is stored such that the liquid crystal pixels have the transmittance determined by the input image data within the image display period at n + 2. The enhancement conversion table (ROM) 15d includes a scanning line specified from the temperature detection data from the temperature sensor 11, the arrival gradation level from the arrival gradation prediction unit 13, and the gradation level of the input image data of the current frame. Temperature compensation data is stored such that the liquid crystal pixels have the transmittance determined by the input image data within the image display period at n + 3.

  FIG. 13 shows an example of each of the temperature compensation tables (ROM) 15a to 15d. Similarly to the above, when the temperature detected by the temperature sensor 11 is T1 to T2, the table area is referred to, and when the temperature is T2 to T3. Each has a table area to be referred to, a table area to be referred to at T3 to T4, and a table area to be referred to at T4 to T5. Further, the temperature compensation data of each table area is liquid crystal within the image display period in each scanning line obtained from the reached gradation level (predicted data) from the reached gradation predicting unit 13 and the input image data of the current frame. The data is such that the pixel has the transmittance determined by the image data.

  These table areas are switched and selected by the control CPU 2 that has received the temperature detection data of the temperature sensor 11 as described above. In addition, these table areas may be provided as separate table memories as described above, and may be switched and referenced according to the temperature detected by the temperature sensor 11.

  Note that the temperature compensation data (emphasis conversion data) in each temperature compensation table (ROM) 15a to 15d is obtained in advance from an actual measurement value of the optical response characteristic of the liquid crystal display panel 7, as described above. In addition, each of the temperature compensation tables (ROM) 15a to 15d may have temperature compensation data for all 256 gradations as described above when the image data has 8-bit 256 gradations. Only the temperature compensation data for nine representative gradations of 32 gradations may be provided, and the other temperature compensation data may be obtained from the above actual measurement values by calculation such as linear interpolation. If the temperature compensation data is reduced, the capacity of each temperature compensation table (ROM) 15a to 15d can be reduced.

  Each temperature compensation table (ROM) 15a to 15d has four simultaneous black writing lines corresponding to the case where the number of simultaneous black writing lines x is four. However, the present invention is not limited to this. What is necessary is just to provide according to the number x of lines. Further, each of the temperature compensation tables (ROM) 15a to 15d may be shared between a plurality of continuous scanning lines as described above. In this case, the temperature compensation data for each scanning line may be obtained by performing an operation such as linear interpolation on the temperature compensation data read from the temperature compensation table (ROM).

  In such a configuration, as described above, when the number of simultaneous black writing lines x is 4, the image data of one frame before (here, 60 Hz progressive data, for example) is stored in the frame memory (FM) 12. Then, the arrival gradation prediction unit 13 predicts the arrival gradation level in the black display period following the image display period one frame before, for each scanning line. In this case, when the line detection unit 1 detects that the image data is to be written to the scanning line n, the control CPU 2 causes the arrival gradation prediction unit 13 to reach the arrival gradation prediction table (ROM) for the scanning line n. ) 14a is selected and instructed to output the reached gradation level in the immediately preceding black display period.

  At this time, when the temperature detected by the temperature sensor 11 is, for example, T1 to T2, the arrival gradation predicting unit 13 is instructed to refer to the table area of T1 to T2. When the temperature detected by the temperature sensor 11 is T2 to T3, T3 to T4, and T4 to T5, the same instruction is given.

  Here, the arrival gradation prediction table (ROM) 14a corresponds to the temperature detection data from the temperature sensor 11, and from the display gradation of the image data of the previous frame on the scanning line n to black (0 gradation). Since the prediction data for predicting the reached gradation level (the unreachable level to black (0 gradation)) when a voltage corresponding to is applied to the liquid crystal pixel is stored, the temperature sensor obtained via the control CPU 2 11 and the reached gradation prediction table (ROM) 14a on the basis of the temperature detection data from 11 and the image data of the previous frame stored in the frame memory (FM) 12, and the reached gradation in the black display period The level (prediction data) is predicted, and the predicted reached gradation level is given to the enhancement conversion unit 3.

  Similarly, when the line detection unit 1 detects that the image data is to be written to the scanning line n + 1, the control CPU 2 causes the arrival gradation prediction unit 13 to reach the arrival gradation prediction table (for the scanning line n + 1). (ROM) 14b is selected and instructed to predict the reached gradation level of the image data. Based on the temperature detection data from the temperature sensor 11 obtained by the arrival gradation prediction unit 13 via the control CPU 2 and the image data of the previous frame stored in the frame memory (FM) 12, the arrival gradation prediction is performed. With reference to the table (ROM) 14b, the reached gradation level (prediction data) in the black display period is predicted, and the predicted arrival gradation level is given to the enhancement conversion unit 3.

  Similarly, when the line detection unit 1 detects that the image data is to be written to the scanning line n + 2, the control CPU 2 causes the arrival gradation prediction unit 13 to reach the arrival gradation prediction table (for the scanning line n + 2). ROM) 14c is selected and referred to, and an instruction is given to predict the reached gradation level of the image data. Based on the temperature detection data from the temperature sensor 11 obtained by the arrival gradation prediction unit 13 via the control CPU 2 and the image data of the previous frame stored in the frame memory (FM) 12, the arrival gradation prediction is performed. With reference to the table (ROM) 14c, the reached gradation level (prediction data) in the black display period is predicted, and the predicted arrival gradation level is given to the enhancement conversion unit 3.

  Similarly, when the line detection unit 1 detects that the image data is to be written to the scanning line n + 3, the control CPU 2 causes the arrival gradation prediction unit 13 to reach the arrival gradation prediction table (for the scanning line n + 3). (ROM) 14d is selected and instructed to predict the reached gradation level of the image data. Based on the temperature detection data from the temperature sensor 11 obtained by the arrival gradation prediction unit 13 via the control CPU 2 and the image data of the previous frame stored in the frame memory (FM) 12, the arrival gradation prediction is performed. With reference to the table (ROM) 14d, the reached gradation level (prediction data) in the black display period is predicted, and the predicted arrival gradation level is given to the enhancement conversion unit 3.

  At this time, as described above, the line detection unit 1 performs line detection of image data (here, 60 Hz progressive data, for example), detects image data written to the scanning line G1, and further detects the temperature from the temperature sensor 11. When the detected data and the reached gradation level from the reached gradation predicting unit 13 are obtained, the control CPU 2 selects and refers to the temperature compensation table (ROM) 15a for the scanning line n with respect to the enhancement conversion unit 3, and An instruction is given to perform enhancement conversion processing of image data. At this time, the emphasis conversion unit 3 is instructed to refer to the table area of T1 to T2 when the temperature detected by the temperature sensor 11 is T1 to T2, for example. When the temperature detected by the temperature sensor 11 is T2 to T3, T3 to T4, and T4 to T5, the same instruction is given.

  Here, in the temperature compensation table (ROM) 15a, the temperature detection data from the temperature sensor 11 and the arrival gradation level from the arrival gradation prediction unit 13 are set as the start gradation (the gradation before transition), and the scanning line n Temperature compensation data is stored such that the liquid crystal pixels have a transmittance determined by the image data of the current frame within the image display period, and the temperature compensation data is output to the liquid crystal controller 6, so that any use environment Even at the temperature, the luminance display determined by the input image data can be performed on the scanning line G1.

  Similarly, when the image data written to the scanning line G2 is detected and the temperature detection data from the temperature sensor 11 is obtained, the temperature compensation table (ROM) 15b for the scanning line n + 1 is selected and referred to, and the image is detected. It is instructed to perform data enhancement conversion processing. At this time, when the temperature detected by the temperature sensor 11 is, for example, T1 to T2, the enhancement conversion unit 3 is instructed to refer to the table area of T1 to T2. When the temperature detected by the temperature sensor 11 is T2 to T3, T3 to T4, and T4 to T5, the same instruction is given. Then, by outputting the temperature compensation data to the liquid crystal controller 6, it is possible to perform luminance display determined by the input image data on the scanning line G2 at any operating environment temperature.

  Similarly, when the image data written to the scanning line G3 is detected and the temperature detection data from the temperature sensor 11 is obtained, the temperature compensation table (ROM) 15c for the scanning line n + 2 is selected and referred to, and the image is detected. It is instructed to perform data enhancement conversion processing. At this time, when the temperature detected by the temperature sensor 11 is, for example, T1 to T2, the enhancement conversion unit 3 is instructed to refer to the table area of T1 to T2. When the temperature detected by the temperature sensor 11 is T2 to T3, T3 to T4, and T4 to T5, the same instruction is given. Then, by outputting the temperature compensation data to the liquid crystal controller 6, it is possible to perform luminance display determined by the input image data on the scanning line G3 at any operating environment temperature.

  Similarly, when image data written to the scanning line G4 is detected and further temperature detection data is obtained from the temperature sensor 11, the temperature compensation table (ROM) 15d for the scanning line n + 3 is selected and referred to, and the image data is read. It is instructed to perform data enhancement conversion processing. At this time, when the temperature detected by the temperature sensor 11 is, for example, T1 to T2, the enhancement conversion unit 3 is instructed to refer to the table area of T1 to T2. When the temperature detected by the temperature sensor 11 is T2 to T3, T3 to T4, and T4 to T5, the same instruction is given. Then, by outputting the temperature compensation data to the liquid crystal controller 6, it is possible to perform luminance display determined by the input image data on the scanning line G4 at any operating environment temperature.

  In this way, temperature compensation data corresponding to the reached gradation level in the immediately preceding black display period in each scanning line, the input image data of the current frame, and the temperature detected by the temperature sensor 11 is output to the liquid crystal controller 6. Thus, image display for one frame is performed. At this time, for example, after a half frame period (= 8.3 msec) from the writing of the image data, the scanning lines are simultaneously selected for every x lines and the black data is written again. In the image display period immediately before the image is written, the liquid crystal reaches and responds to a desired transmittance corresponding to the image data in accordance with the temperature detected by the temperature sensor 11, so that a display luminance difference occurs between the scanning lines. Therefore, a high-quality image display without luminance unevenness can be achieved.

  As described with reference to FIGS. 6 to 8, the image display period is applied to the image data written (supplied) to the scanning lines # 1, # N / 4 + 1, # N / 2 + 1, # 3N / 4 + 1. Write image data (enhancement conversion data) such that the liquid crystal pixels reach and respond to the target arrival gradation (transmittance) defined by the input image data within (1/2 frame period) is the temperature compensation table (ROM) 10a described above. Is output to the liquid crystal controller 6 at the subsequent stage. For image data written (supplied) to the scanning lines # N / 4, # N / 2, # 3N / 4, and #N, the liquid crystal is displayed within the image display period (1/4 frame period). Write image data (enhancement conversion data) such that the pixel reaches and responds to the target arrival gradation (transmittance) determined by the input image data is obtained from the temperature compensation table (ROM) 10d described above, and is sent to the liquid crystal controller 6 at the subsequent stage. Is output.

  In this case, as described above, the write image data (emphasis conversion data) supplied to the scanning lines # 1, # N / 4 + 1, # N / 2 + 1, # 3N / 4 + 1 with respect to the input image data of the same gradation. Compared to the above, the writing image data (enhancement conversion data) written to the scanning lines # N / 4, # N / 2, # 3N / 4, and #N is larger (enhancement conversion degree is greater), so that the same as above. In addition, the display gradation luminance for the image data of the same gradation between the scanning lines (display lines) can be made substantially the same (the luminance ratio is 4% or less).

  As described above, in the present embodiment, the arrival gradation predicting unit 13 arrives based on the temperature detection data from the temperature sensor 11 and the image data of the previous frame stored in the frame memory (FM) 12. The gradation prediction tables (ROM) 14a to 14d are referred to, and the reached gradation level (prediction data) in the black display period of each scanning line is predicted for each scanning line. By using the arrival gradation level from the arrival gradation prediction unit 13 and the temperature detection data from the temperature sensor 11, the emphasis conversion unit 3 refers to the temperature compensation tables (ROM) 15a to 15d and scans each of them. Since the temperature compensation data such that the liquid crystal pixels have the transmittance determined by the input image data is output to the liquid crystal controller 6 within the image display period in the line, in addition to the above-described effects, the black display of each scanning line is performed. Even if the arrival response to the black (0 gradation) level cannot be achieved within the period, the unreachable gradation level is predicted and used to perform enhancement conversion on the image data of the current frame. It is possible to realize high-quality image display while suppressing the occurrence of luminance errors.

  Any hold-type display device may be used. For example, the present invention can also be applied to an electrophoretic display using a microlens array structure. Also, any device equipped with a flat panel type liquid crystal display panel 7 may be used, and is applicable not only to familiar devices such as personal computers and television receivers, but also to measuring devices, medical devices, general industrial devices, etc. It is.

It is a figure for demonstrating Embodiment 1 of the liquid crystal display device of this invention. 3 is a timing chart showing the writing timing of image data and black data in the liquid crystal display device of FIG. 1. FIG. 2 is an explanatory diagram showing writing timing of image data and black data in the liquid crystal display device of FIG. 1. A configuration example in the case where the enhancement conversion table (ROM) of FIG. 1 is used as a single unit and correction voltage data for each scanning line is obtained from correction voltage data obtained by referring to the enhancement conversion table (ROM). FIG. It is a figure for demonstrating the response waveform of the liquid crystal pixel by the emphasis conversion data of the emphasis conversion part of FIG. FIG. 2 is a diagram for explaining writing timing of image data and black data in the liquid crystal display device of FIG. 1. In order to explain that the display luminance with respect to the image data of the same gradation between the scanning lines (display lines) is substantially the same (the luminance ratio is in the range of 4% or less) by the enhancement conversion data of the enhancement conversion unit in FIG. It is a figure which shows the response waveform of this liquid crystal pixel. In order to explain that the display luminance with respect to the image data of the same gradation between the scanning lines (display lines) is substantially the same (the luminance ratio is in the range of 4% or less) by the enhancement conversion data of the enhancement conversion unit in FIG. It is a figure which shows the screen luminance distribution. It is a figure which shows Embodiment 2 of a liquid crystal display device at the time of considering the improvement of the response speed by the temperature dependence of a liquid crystal pixel. It is a figure which shows an example of the temperature compensation table of FIG. FIG. 10 is a diagram illustrating a third embodiment of the liquid crystal display device improved in a case where the liquid crystal pixel does not reach black (0 gradation) in black display immediately before image data is written and does not respond. It is a figure which shows an example of the arrival gradation prediction table of FIG. It is a figure which shows an example of the temperature compensation table of FIG. It is a figure for demonstrating the response waveform of the liquid crystal pixel by the emphasis conversion data of the emphasis conversion part of FIG. It is a figure which shows an example of the reduction method of the motion blur in the display of the conventional moving image. It is a figure which shows the other example of the reduction method of the motion blur in the display of the conventional moving image. It is a figure for demonstrating the write-in timing of the image data in the conventional liquid crystal display device, and black data. It is a figure which shows the response waveform of the liquid crystal pixel for demonstrating the difference of the display luminance by the response arrival gradation of the liquid crystal pixel at the time of the conventional black data writing differing in each scanning line. It is a figure which shows the screen luminance distribution for demonstrating the difference of the display luminance by the response arrival gradation of the liquid crystal pixel at the time of the writing of the conventional black data differing in each scanning line.

Explanation of symbols

1 Line detector (line detector)
2 Control CPU
3 Emphasis conversion part (enhancement conversion means)
4a to 4d Emphasis conversion table (ROM)
5 Black data supply unit 6 Liquid crystal controller (display control means)
7 Liquid crystal display panels 10a to 10d Temperature compensation table (ROM)
12 frame memory (FM: frame storage means)
13 Achievable tone prediction unit (Achieved tone prediction means)
14a to 14d Reaching tone prediction table (ROM)
15a to 15d Temperature compensation table (ROM)
G1-GN scan line

Claims (16)

When driving a liquid crystal at a portion where a plurality of scanning lines and signal lines intersect with a switching element that is turned on by sequential scanning, the gate of the switching element is turned on twice in one frame period, and image data from the signal line And a liquid crystal display device for writing black data,
Causes the image display by writing sequentially the image data for each scan line, the black data x book successive (2 ≦ x ≦ N, N is the total number of scanning lines)-out written at the same time for each scanning line of Display control means for displaying black by inserting,
Line detection means for detecting a scanning line in which the image data is written based on a vertical / horizontal synchronization signal of the image data;
Emphasis conversion means for obtaining enhancement conversion data such that the liquid crystal reaches the transmittance determined by the image data in the image display period of each scanning line based on the detection result of the line detection means,
The enhancement conversion means has a display luminance ratio with respect to image data of the same gradation between the scanning line having the maximum image display period and the scanning line having the minimum image display period among the continuous x scanning lines. A liquid crystal display device characterized in that image data written to each of the scanning lines is enhanced and converted so as to be 4% or less .   2. The liquid crystal display device according to claim 1, wherein the enhancement conversion means has an enhancement conversion table in which enhancement conversion data for image data written to each scanning line is stored. A temperature detecting means for detecting the temperature in the apparatus;
The liquid crystal display device according to claim 1, wherein the enhancement conversion unit obtains the enhancement conversion data based on a detection result of the temperature detection unit.   4. The liquid crystal display device according to claim 3, wherein the enhancement conversion means has a temperature compensation table in which enhancement conversion data for temperature compensation for image data written to each scanning line is stored. Frame storage means for storing image data of one frame before;
Based on the image data of the previous frame stored in the frame storage means, the arrival gradation level in the black display period of each scanning line is predicted, and the predicted arrival gradation level is given to the enhancement conversion means. Gradation prediction means,
The liquid crystal display device according to claim 1, wherein the enhancement conversion unit obtains the enhancement conversion data for the image data of the current frame based on the reached gradation level.   The arrival gradation prediction means has an arrival gradation prediction table storing prediction data for predicting the arrival gradation level in the black display period of each scanning line from the image data of the previous frame. The liquid crystal display device according to claim 5. A temperature detecting means for detecting the temperature in the apparatus;
The arrival gradation prediction means predicts an arrival gradation level in the black display period of each scanning line based on the detection result by the temperature detection means and the image data of the previous frame,
The liquid crystal according to claim 5 or 6, wherein the enhancement conversion means obtains the enhancement conversion data for the image data of the current frame based on a detection result by the temperature detection means and the reached gradation level. Display device. The arrival gradation prediction means has an arrival gradation prediction table storing prediction data for predicting the arrival gradation level in the black display period of each scanning line based on the detection result by the temperature detection means. And
The liquid crystal display device according to claim 7, wherein the enhancement conversion unit includes a temperature compensation enhancement conversion table in which temperature compensation enhancement conversion data for image data written to each scanning line is stored. . When driving a liquid crystal at a portion where a plurality of scanning lines and signal lines intersect with a switching element that is turned on by sequential scanning, the gate of the switching element is turned on twice in one frame period, and image data from the signal line A liquid crystal display control method for writing black and black data,
Causes the image display by writing sequentially the image data for each scan line, the black data x book successive (2 ≦ x ≦ N, N is the total number of scanning lines)-out written at the same time for each scanning line of The process of displaying black by
Detecting a scan line in which the image data is written based on a vertical / horizontal synchronization signal of the image data;
Obtaining enhanced conversion data such that the liquid crystal reaches the transmittance determined by the image data in the image display period of each scan line based on the detection result of the scan line;
Of the continuous x scanning lines, a display luminance ratio for image data of the same gradation is 4% or less between a scanning line having the maximum image display period and a scanning line having the minimum image display period. In addition, the liquid crystal display control method is characterized in that image data written to each scanning line is enhanced and converted .   10. The liquid crystal display control method according to claim 9, further comprising a step of referring to an enhancement conversion table in which enhancement conversion data for image data written to each scanning line is stored. Detecting the temperature in the apparatus;
The liquid crystal display control method according to claim 9, further comprising: obtaining the enhancement conversion data based on a detection result of the temperature in the apparatus.   12. The liquid crystal display control method according to claim 11, further comprising a step of referring to a temperature compensation table in which emphasis conversion data for temperature compensation with respect to image data written to each scanning line is stored. A step of storing image data of one frame before;
Predicting the reached gradation level in the black display period of each scanning line based on the stored image data of one frame before, and giving the predicted reached gradation level;
The liquid crystal display control method according to claim 9, further comprising: obtaining the enhancement conversion data for the image data of the current frame based on the reached gradation level.   The method includes a step of referring to an arrival gradation prediction table storing prediction data for predicting the arrival gradation level in the black display period of each scanning line from the image data of the previous frame. Item 14. A liquid crystal display control method according to Item 13. Detecting the temperature in the apparatus;
Predicting the reached gradation level in the black display period of each scanning line based on the detection result of the temperature in the apparatus and the image data of the previous frame;
The liquid crystal display control according to claim 13, further comprising: obtaining the enhancement conversion data for the image data of the current frame based on the detection result of the internal temperature and the reached gradation level. Method. Referring to a reaching gradation prediction table storing prediction data for predicting the reaching gradation level in the black display period of each scanning line based on the detection result of the internal temperature of the apparatus;
16. The liquid crystal display control method according to claim 15, further comprising a step of referring to a temperature compensation enhancement conversion table storing temperature compensation enhancement conversion data for image data written to each scanning line. .

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