JP4831988B2 - Display device - Google Patents

Description

  The present invention relates to a technique for driving a display panel such as a plasma display panel, and more particularly to a technique for applying a scan pulse to the display panel.

  The plasma display has a discharge space in which a discharge gas is sealed between a front glass substrate and a back substrate facing each other. A plurality of row electrode pairs composed of two strip electrodes extending in the row direction are formed on the inner surface of the front glass substrate, and a plurality of strip column electrodes extending in the column direction are formed on the inner surface of the rear substrate. ing. One display line can be constituted by each row electrode pair. A plurality of display cells (discharge cells) each having a phosphor applied therein are formed at the intersections between the row electrode pairs and the column electrodes, and divide the discharge space into a plurality of regions. When an image is displayed on such a plasma display, wall charges are selectively formed in the display cell, and a sustaining pulse is repeatedly applied to the display cell through the row electrode pair. As a result, gas discharge (sustain discharge) occurs in the display cell in which wall charges are formed, and the phosphor in the display cell is excited by the ultraviolet rays generated thereby to emit light.

In general, as a driving method of the plasma display, one field corresponding to one image is divided into a plurality of subfields, and the ratio of the light emission sustain period in each subfield is set to a power of 2, and a combination of these subfields The subfield method of performing multi-gradation display is employed. For example, the ratios of the light emission sustaining periods of eight subfields SF1, SF2,..., SF8 (ie, luminance weights) are 2 ⁰ : 2 ¹ : 2 ² : 2 ³ : 2 ⁴ : 2 ⁵ : 2 ⁶ : 2 respectively. ⁷ , that is, 1: 2: 4: 8: 16: 32: 64: 128, it is possible to realize multi-gradation display by combining these subfields. A technique related to the subfield method is disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-4606.

  Each subfield includes, for example, a reset period, an address period, and a discharge sustain period. In the reset period, an erasing discharge that erases wall charges remaining in the display cell is generated, and in the address period, An address discharge that selectively forms wall charges in the display cells is generated, and in the discharge sustain period, a rectangular wave discharge sustain pulse is repeated for all display cells to emit light in the display cells in which wall charges are selectively formed. When applied, a sustain discharge is generated.

In such a plasma display, there is a problem in that the luminance of the phosphor layer formed in each display cell varies and the luminance of the entire display panel varies due to the variation of the film thickness and the image quality deteriorates. . For example, if the thickness of the phosphor layer in one display cell is smaller than the thickness of the phosphor layer in the other display cell, address discharge is likely to occur in the other display cell, and between the two display cells. A difference in emission luminance can occur. In each address period, a scan pulse is sequentially applied to the row electrode on the display line, and an address pulse synchronized with each scan pulse is applied to the column electrode, but compared with the display line to which the scan pulse is first applied. Thus, the address discharge hardly occurs in the display cells on the display line to which the scan pulse is applied last, and this causes a problem in that a difference in emission luminance occurs between the display lines.
Japanese Patent Laid-Open No. 2004-4606

  In view of the above situation and the like, an object of the present invention is to provide a display device capable of improving variation in light emission luminance of a display panel.

In order to achieve the above object, the invention described in claim 1 includes a plurality of display lines and a plurality of column electrodes intersecting with the display lines, and a plurality of lines formed at intersections of the display lines and the column electrodes, respectively. A display panel including a display cell, a drive circuit that sequentially applies a scan pulse to the display line for each address period, while applying an address pulse synchronized with the scan pulse to the column electrode, and the scan pulse And a mode designating unit that selects at least one scanning mode from a plurality of scanning modes that are applied in different order to the display line , each of the scanning areas on the display panel being The driving circuit includes first to Nth regions (N is an integer of 2 or more) including a plurality of display lines continuously arranged. A display line to which a scan pulse is to be applied is switched between the first to Nth regions, and the scan pulse is applied to each of the first to Nth regions in the order corresponding to the scan mode selected by the mode designating unit. Are sequentially applied to the display lines .

  Hereinafter, various embodiments according to the present invention will be described.

  FIG. 1 is a block diagram schematically showing a configuration of a plasma display (display device) 1 according to an embodiment of the present invention. The plasma display 1 includes a display panel (plasma display panel) 2 and address electrode drivers 16 and sustain electrode drivers 17A and 17B for supplying various drive pulses to display cells (discharge cells) CL,. And. The plasma display 1 further includes a drive data generation unit 13, a memory circuit 14, and a controller 21. The controller 21 controls the operation of the processing blocks 13, 14, 16, 17 </ b> A, and 17 </ b> B using a synchronization signal (including a horizontal synchronization signal and a vertical synchronization signal) and a clock signal supplied from the outside.

The drive data generation unit 13 generates a drive data signal GD from the digital video signal PD and supplies it to the memory circuit 14. The memory circuit 14 temporarily stores the supplied drive data signal GD in an internal buffer memory (not shown), while reading the drive data signal stored in the buffer memory in units of subfields. 16 is supplied. Address electrode driver 16, an address pulse generated based from the memory circuit 14 to the supplied field data signals SD, and applies these address pulses to the address electrodes D ₁ to D _r at the specified timing by the controller 21.

The display panel 2 includes a plurality of display cells CL, CL,... Arranged in a plane and in a matrix, and r address electrodes (r is an integer of 2 or more) extending from the address electrode driver 16 in the Y direction. D _1, D _2, ..., D _r and, from the first sustain electrode driver 17A, the sustain electrodes L ₁ band of the n extending in the X direction perpendicular to the Y-direction (n is an integer of 2 or more), L ₂ ,..., L _n, and n strip-shaped sustain electrodes S ₁ , S ₂ , S _n extending in the −X direction from the second sustain electrode driver 17B. In this embodiment, one address electrode D _p (p is an integer of 1 to r) constitutes one column electrode, and two sustain electrodes L _q and sustain electrodes S _q (q is 1 to n). An integer) forms one row electrode pair, and one display line is formed along each row electrode pair. The address electrode _Dp and the row electrode pair are separated from each other in the thickness direction of the substrate (not shown) of the display panel 2. Address electrodes D _1, ..., D _r and each of the intersections display cells CL of the row electrode pairs, ..., CL are formed. Each display cell CL includes a phosphor having a predetermined emission color, with a discharge space between the row electrode pairs and the address electrodes D _p. A plurality of these display cells CL,... Constitute one pixel cell.

The controller 21 performs light emission drive control according to a predetermined light emission drive sequence. FIG. 2 schematically shows an example of the light emission drive sequence. Referring to FIG. 2, the display period of one field of the video signal is a period (subfield period) of M (M is an integer of 2 or more) subfields SF _{1 to} SF _M arranged continuously in the display order. Each of the subfields SF _{1 to} SF _M has an address period Tw and a sustain period Ti. Only the _first subfield SF ₁ has a reset period Tr before the address period Tw. Subfields SF _1, SF _2, SF _3, ..., the SF _M, respectively, 2 ^0, 2 ^{1, 2} 2, ..., light emission sustain period Ti proportional to the weight of the 2 ^M, Ti, Ti, ..., Ti Is assigned.

In the reset period Tr of the subfield SF ₁ , gas discharge is caused in all the display cells CL,..., And wall charges are accumulated in all the display cells CL,. In the subsequent address period Tw, the sustain electrode driver 17A sequentially applies the scan pulse to the sustain electrodes L _{1 to} L _n , while the address electrode driver 16 applies the address pulse synchronized with the scan pulse to the address electrodes D ₁ ,. _Apply to _r . As a result, gas discharge (erase address discharge) occurs selectively in the display cells CL,..., And wall charges are selectively erased. The display cell CL in which the wall charges are stored without being erased is caused to emit light in the next sustain period Ti. In the sustain period Ti, the sustain electrode driver 17A and 17B are, respectively, the sustain electrodes L _1, ..., L _n and sustain electrodes S _1, ..., a S _n, repetition number of times assigned polarities different sustaining pulse to each other Apply. As a result, the sustain discharge repeatedly occurs in the display cell CL in which the wall charges are accumulated, and the phosphor in the display cell CL is excited to emit light. In each of the subsequent subfields SF _{2 to} SF _M , in the address period Tw, gas discharge (erase address discharge) is selectively generated in the display cells CL,... And wall charges are selectively erased. Further, in the sustain period Ti, the sustain discharge of the number of times assigned to the subfield is repeatedly generated in the display cell CL in which the wall charges are accumulated. With such a light emission driving sequence, M + 1 gradation display is possible.

  The controller 21 has a drive control unit 24 that controls the light emission drive sequence as described above. Here, the address electrode driver 16, the sustain electrode drivers 17 </ b> A and 17 </ b> B, and the drive control unit 24 may constitute the drive circuit of the present invention. The drive control unit 24 holds, in an internal nonvolatile memory (not shown), a data set of a plurality of types of scanning modes having different orders in which scanning pulses are applied to the row electrodes. The mode designating unit 23 selects at least one scanning mode from the plurality of types of scanning modes, and instructs the drive control unit 24 about the selected scanning mode. The drive control unit 24 reads the scan mode data corresponding to the instruction from the internal memory, generates a control signal so that the sustain electrode driver 17A sequentially applies the scan pulse to the row electrodes according to the scan mode, and generates the sustain electrode driver 17A. To supply.

3A and 3B are diagrams for explaining various scanning modes in one address period. In each figure, scan pulses 30A and 30B sequentially applied to scan electrodes (sustain electrodes) L ₁ , L ₂ ,..., L _n on the first to nth display lines are shown. 3A shows a scanning mode in which a scanning pulse 30A is sequentially applied from the first display line at the upper end of the display panel 2 to the n-th display line at the lower end. In FIG. A scanning mode in which scanning pulses 30B are sequentially applied from the nth display line at the lower end of the display panel 2 toward the first display line at the upper end is shown.

  FIGS. 4A, 4B, 4C, 4D, 4E, and 4F are diagrams for explaining other examples of various scanning modes in one address period. The scanning area of the display panel 2 includes a first scanning area including an m-th display line (m is an integer of 2 to n−1) at a substantially central position from the first display line at the upper end of the display panel 2, and the display panel 2. It is divided into the second scanning region including the (m + 1) th display line at the substantially central position and the nth display line at the lower end.

  In the scanning mode of FIG. 4A, the scanning pulse 31A is sequentially applied from the first display line at the upper end of the first scanning area toward the mth display line at the lower end, and the nth display line at the lower end of the second scanning area. A scanning pulse 31B is sequentially applied from the uppermost line toward the uppermost m + 1th display line. Here, each time one scanning pulse is applied to the display line, the display line to which the scanning pulse is to be applied is switched between the first scanning region and the second scanning region. The specific scanning order is as follows: first display line (first scanning region), nth display line (second scanning region), second display line (first scanning region), n−1th display line. (Second scanning region)..., M-th display line (first scanning region), and m + 1-th display line (second scanning region).

  In the scanning mode of FIG. 4B, the scanning pulse 32B is sequentially applied from the first display line at the upper end of the first scanning area toward the mth display line at the lower end, and the nth display line at the lower end of the second scanning area. A scanning pulse 32A is sequentially applied from the uppermost line toward the uppermost m + 1th display line. This scan mode is the same as the scan mode in FIG. 4A except that the display line to which the scan pulse is applied starts from the nth display line in the second scan region. The specific scanning order is as follows: nth display line (second scanning region), first display line (first scanning region), n−1th display line (second scanning region), second display line. (First scanning region),..., M + 1th display line (second scanning region), and mth display line (first scanning region).

  In the scanning mode of FIG. 4C, the scanning pulse 33A is sequentially applied from the m-th display line at the lower end of the first scanning area toward the first display line at the upper end, and the m + 1-th display line at the upper end of the second scanning area. A scanning pulse 33B is sequentially applied from the bottom toward the nth display line at the bottom. Here, each time one scanning pulse is applied to the display line, the display line to which the scanning pulse is to be applied is switched between the first scanning region and the second scanning region. The specific scanning order is as follows: m-th display line (first scanning region), m + 1-th display line (second scanning region), m-1-th display line (first scanning region), and m + 2-th display line. (Second scanning region)... The first display line (first scanning region) and the nth display line (second scanning region).

  In the scanning mode of FIG. 4D, the scanning pulse 34B is sequentially applied from the m-th display line at the lower end of the first scanning area toward the first display line at the upper end, and the m + 1-th display line at the upper end of the second scanning area. A scan pulse 34A is sequentially applied from the first to the nth display line at the lower end. This scan mode is the same as the scan mode in FIG. 4C except that the display line to which the scan pulse is applied starts from the (m + 1) th display line in the second scan region. The specific scanning order is as follows: m + 1th display line (second scanning region), mth display line (first scanning region), m + 2nd display line (second scanning region), m−1th display line. (First scanning region),..., The nth display line (second scanning region), and the first display line (first scanning region).

  In the scanning mode of FIG. 4E, the scanning pulse 35A is sequentially applied from the m-th display line at the lower end of the first scanning area toward the first display line at the upper end, and the n-th display line at the lower end of the second scanning area. A scanning pulse 35B is sequentially applied from the uppermost line toward the uppermost m + 1 display line. Here, each time one scanning pulse is applied to the display line, the display line to which the scanning pulse is to be applied is switched between the first scanning region and the second scanning region. The specific scanning order is as follows: m-th display line (first scanning region), n-th display line (second scanning region), m-1st display line (first scanning region), n-1th. A display line (second scanning region),..., A first display line (first scanning region), and an m + 1th display line (second scanning region).

  In the scanning mode of FIG. 4F, the scanning pulse 36A is sequentially applied from the first display line at the upper end of the first scanning area to the m-th display line at the lower end, and the (m + 1) th display line at the upper end of the second scanning area. A scanning pulse 36B is sequentially applied from the bottom toward the nth display line at the bottom. Here, each time one scanning pulse is applied to the display line, the display line to which the scanning pulse is to be applied is switched between the first scanning region and the second scanning region. The specific scanning order is as follows: first display line (first scanning region), m + 1th display line (second scanning region), second display line (first scanning region), m + 2nd display line (first scanning region). 2 scanning regions),..., M-th display line (first scanning region), and n-th display line (second scanning region).

  4A to 4F, the scanning area on the display panel 2 is divided into two areas, but the present invention is not limited to this. For example, the scanning area on the display panel 2 can be divided into first to Nth areas (N is an integer of 3 or more). The display line to which the scan pulse is to be applied may be switched between the first to Nth regions every time the scan pulse is applied.

  Further, FIGS. 5A, 5B, 5C, 5D, 5E, and 5F are diagrams for explaining still another example of various scanning modes in one address period. . The address period is divided into a first half period T1 and a second half period T2, and different scanning modes are assigned to the first half period T1 and the second half period T2. That is, in FIG. 5A, in the first half period T1, the scanning pulse 41A is directed from the first display line at the upper end of the display panel 2 toward the mth display line (m is an integer of 2 to n-1) at a substantially central position. Are sequentially applied, and in the second half period T2, the scan mode in which the scan pulse 44A is sequentially applied from the nth display line at the lower end of the display panel 2 toward the m + 1st display line at a substantially central position is provided. It is shown.

  FIG. 5B shows a scanning mode in which the scanning pulse 42A is sequentially applied from the nth display line at the lower end of the display panel 2 toward the m + 1st display line at a substantially central position in the first half period T1. In T2, a scanning mode in which the scanning pulse 43A is sequentially applied from the first display line at the upper end of the display panel 2 toward the m-th display line at a substantially central position is shown.

  FIG. 5C shows a scanning mode in which the scanning pulse 41B is sequentially applied from the mth display line at the substantially central position of the display panel 2 toward the first display line at the upper end in the first half period T1. In T2, a scanning mode in which the scanning pulse 44B is sequentially applied from the (m + 1) th display line at the substantially central position of the display panel 2 to the nth display line at the lower end is shown.

  FIG. 5D shows a scanning mode in which the scanning pulse 42B is sequentially applied from the (m + 1) th display line at the substantially center position of the display panel 2 toward the nth display line at the lower end in the first half period T1. In T2, a scanning mode in which the scanning pulse 43B is sequentially applied from the m-th display line at the substantially center position of the display panel 2 toward the first display line at the upper end is shown.

  FIG. 5E shows a scanning mode in which the scanning pulse 41A is sequentially applied from the m-th display line at the substantially central position of the display panel 2 toward the first display line at the upper end in the first half period T1. In T2, a scanning mode in which a scanning pulse 44B is sequentially applied from the nth display line at the lower end of the display panel 2 to the m + 1st display line at a substantially central position is shown.

  FIG. 5F shows a scanning mode in which the scanning pulse 42B is sequentially applied from the (m + 1) th display line at the substantially central position of the display panel 2 toward the nth display line at the lower end in the first half period T1. In T2, a scanning mode in which the scanning pulse 43A is sequentially applied from the first display line at the upper end of the display panel 2 toward the m-th display line at a substantially central position is shown.

  The mode designating unit 23 is shown in FIG. 3 (A), (B), FIG. 4 (A), (B), (C), (D), (E), (F) and FIG. ), (C), (D), (E), (F), any one of the scanning modes can be selected for each address period. Further, the user can select any one scanning mode by operating the input unit 22 before or after the plasma display 1 is shipped. Therefore, by appropriately selecting a scanning mode that is optimal for variations in the light emission characteristics of the display panel 2 and changes over time, it is possible to improve variations in light emission luminance and improve image quality.

  Next, another embodiment according to the present invention will be described. FIG. 6 is a block diagram schematically showing a configuration of a plasma display 1A which is another embodiment. The components denoted by the same reference numerals in FIG. 1 and FIG. 6 have the same functions and will not be described in detail.

  The display panel 2 of the plasma display 1A includes a first area composed of display lines from the first top to the m-th display at a substantially central position among all the first to n-th display lines, and a (m + 1) -th display position from a substantially central position. And a second region composed of the display lines up to the nth lower end.

The plasma display 1A includes an address electrode driver 16A that supplies address pulses to the display cells CL,... Formed in the first region, and an address electrode driver that supplies address pulses to the display cells CL,. And an output circuit 15 for supplying the field data signal SD supplied from the memory circuit 14 to the first address electrode driver 16A and the second address electrode driver 16B. A field data signal SD corresponding to the upper half of the image is supplied to the first address electrode driver 16A, and a field data signal SD corresponding to the lower half of the image is supplied to the second address electrode driver 16B. The display panel 2 is formed with _r address electrodes D ₁ , D ₂ ,..., Dr that extend from the first address electrode driver 16A in the + Y direction (r is an integer of 2 or more). M address electrodes K ₁ , K ₂ ,..., K _r extending in the −Y direction from the two address electrode drivers 16B are formed.

FIGS. 7A and 7B are diagrams for explaining an example of various scanning modes in one address period. In each figure, scanning pulses 50A, 51A, 50B, 51B sequentially applied to the scanning electrodes (sustain electrodes) L ₁ , L ₂ ,..., L _n on the first to nth display lines are shown. FIG. 7A shows a scanning mode in which the scanning pulse 50A is sequentially applied from the first display line at the upper end to the m-th display line at a substantially central position in the first region, and the lower end in the second region. The scanning mode in which the scanning pulse 51A is sequentially applied from the nth display line to the (m + 1) th display line at a substantially central position is shown. FIG. 7B shows a scanning mode in which the scanning pulse 50B is sequentially applied from the m-th display line at the substantially central position toward the first display line at the upper end in the first region. The scanning mode in which the scanning pulse 51B is sequentially applied from the (m + 1) th display line at the substantially central position to the nth display line at the lower end is shown.

FIGS. 7C and 7D are diagrams for explaining other examples of various scanning modes in one address period. In each figure, scan pulses 52A, 53A, 52B, and 53B sequentially applied to scan electrodes (sustain electrodes) L ₁ , L ₂ ,..., L _n on the nth to first display lines are shown. This example is an example where the order of the display lines is reversed from the order of FIGS. 7A and 7B, in other words, the display panel 2 is upside down. FIG. 7C shows a scanning mode in which the scanning pulse 52A is sequentially applied from the nth display line at the upper end to the (m + 1) th display line at the substantially central position in the second region. The scanning mode in which the scanning pulse 53A is sequentially applied from the first display line to the mth display line at a substantially central position is shown. FIG. 7D shows a scanning mode in which the scanning pulse 52B is sequentially applied from the (m + 1) th display line at the substantially central position to the nth display line at the upper end in the second region. A scanning mode is shown in which scanning pulses 53B are sequentially applied from the mth display line at the center position toward the first display line at the lower end.

  The mode designating unit 23 can select any one of the scanning modes shown in FIGS. 7A, 7B, 7C, and 7D for each address period. Further, the user can select any one scanning mode by operating the input unit 22 before or after the plasma display 1 is shipped. Therefore, by appropriately selecting an optimal scanning mode according to variations in the light emission characteristics of the display panel 2 and changes with time, it is possible to improve variations in light emission luminance and improve image quality.

It is a block diagram which shows roughly the structure of the plasma display (display apparatus) which is one Example which concerns on this invention. It is a figure which shows an example of the light emission drive sequence roughly. It is a figure for demonstrating the example of the various scanning modes in one address period. It is a figure for demonstrating the other example of the various scanning modes in one address period. It is a figure for demonstrating the further another example of the various scanning modes in one address period. It is a block diagram which shows roughly the structure of the plasma display 1A which is another Example which concerns on this invention. It is a figure for demonstrating the example of the various scanning modes in one address period.

Explanation of symbols

1,1A Plasma display (display device)
2 Display Panel 13 Drive Data Generation Unit 14 Memory Circuit 15 Output Circuit 16, 16A, 16B Address Electrode Driver 17A, 17B Sustain Electrode Driver 21 Controller 22 Input Unit 23 Mode Designation Unit 24 Drive Control Unit

Claims (5)

A display panel including a plurality of display cells and a plurality of column electrodes intersecting with the display lines, and a plurality of display cells respectively formed at intersections of the display lines and the column electrodes;
A drive circuit for sequentially applying a scan pulse to the display line for each address period, while applying an address pulse synchronized with the scan pulse to the column electrode;
A mode specifying unit that selects at least one scanning mode from a plurality of types of scanning modes in which the order of applying the scanning pulse to the display line is different from each other,
The scanning area on the display panel includes first to Nth areas (N is an integer of 2 or more) each including a plurality of display lines arranged continuously.
The drive circuit switches the display line to which the scan pulse is to be applied between the first to Nth areas every time the scan pulse is applied, and an order corresponding to the scan mode selected by the mode designating unit. In the display device, the scan pulse is sequentially applied to the display line in each of the first to Nth regions. The scanning region on the display panel includes the first region including a display line from the upper end of the display panel to a substantially central position, and the second region including a display line from the lower end of the display panel to a substantially central position. Consisting of areas,
The drive circuit sequentially applies the scan pulse from the uppermost display line of the first region toward the lowermost display line, and from the lowermost display line of the second region toward the uppermost display line. 2. The display device according to claim 1, wherein a scanning pulse is sequentially applied, and a display line to which the scanning pulse is applied is switched between the first and second regions every time the scanning pulse is applied. The scanning region on the display panel, before Symbol said first region including a display line to the substantially central position from the upper end of the display panel, the second containing the display lines from the bottom of the display panel to substantially the center position Consisting of
The driving circuit sequentially applies the scan pulse from the lower end display line of the first region toward the upper end display line, and from the upper end display line of the second region toward the lower end display line. 2. The display device according to claim 1, wherein a scanning pulse is sequentially applied, and a display line to which the scanning pulse is applied is switched between the first and second regions every time the scanning pulse is applied. The scanning region on the display panel, before Symbol said first region including a display line to the substantially central position from the upper end of the display panel, the second containing the display lines from the bottom of the display panel to substantially the center position Consisting of
The driving circuit sequentially applies the scanning pulse from the upper display line of the first region toward the lower display line, and from the upper display line of the second region toward the lower display line. 2. The display device according to claim 1, wherein a scanning pulse is sequentially applied, and a display line to which the scanning pulse is applied is switched between the first and second regions every time the scanning pulse is applied. The scanning region on the display panel, before Symbol said first region including a display line to the substantially central position from the upper end of the display panel, the second containing the display lines from the bottom of the display panel to substantially the center position Consisting of
The driving circuit sequentially applies the scanning pulse from the lower end display line of the first region toward the upper end display line, and from the lower end display line of the second region toward the upper end display line. 2. The display device according to claim 1, wherein a scanning pulse is sequentially applied, and a display line to which the scanning pulse is applied is switched between the first and second regions every time the scanning pulse is applied.

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