WO2012098904A1 - Et procédé de commande pour dispositif de visualisation d'image dispositif de visualisation d'image - Google Patents

Et procédé de commande pour dispositif de visualisation d'image dispositif de visualisation d'image Download PDF

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Publication number
WO2012098904A1
WO2012098904A1 PCT/JP2012/000337 JP2012000337W WO2012098904A1 WO 2012098904 A1 WO2012098904 A1 WO 2012098904A1 JP 2012000337 W JP2012000337 W JP 2012000337W WO 2012098904 A1 WO2012098904 A1 WO 2012098904A1
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Prior art keywords
subfield
code
gradation
value
image signal
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PCT/JP2012/000337
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English (en)
Japanese (ja)
Inventor
広史 本田
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パナソニック株式会社
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Publication of WO2012098904A1 publication Critical patent/WO2012098904A1/fr

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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/2007—Display of intermediate tones
    • G09G3/2018—Display of intermediate tones by time modulation using two or more time intervals
    • G09G3/2022—Display of intermediate tones by time modulation using two or more time intervals using sub-frames
    • G09G3/2029—Display of intermediate tones by time modulation using two or more time intervals using sub-frames the sub-frames having non-binary weights
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/28—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using luminous gas-discharge panels, e.g. plasma panels
    • G09G3/288—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using luminous gas-discharge panels, e.g. plasma panels using AC panels
    • G09G3/291—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using luminous gas-discharge panels, e.g. plasma panels using AC panels controlling the gas discharge to control a cell condition, e.g. by means of specific pulse shapes
    • G09G3/293—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using luminous gas-discharge panels, e.g. plasma panels using AC panels controlling the gas discharge to control a cell condition, e.g. by means of specific pulse shapes for address discharge
    • G09G3/2932—Addressed by writing selected cells that are in an OFF state
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
    • H04N13/30—Image reproducers
    • H04N13/332—Displays for viewing with the aid of special glasses or head-mounted displays [HMD]
    • H04N13/341—Displays for viewing with the aid of special glasses or head-mounted displays [HMD] using temporal multiplexing
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2310/00—Command of the display device
    • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
    • G09G2310/0202—Addressing of scan or signal lines
    • G09G2310/0205—Simultaneous scanning of several lines in flat panels

Definitions

  • the present invention relates to an image display device that displays an image in an image display region by combining binary control of light emission and non-light emission in a light emitting element that constitutes a pixel, and a driving method of the image display device.
  • a plasma display panel (hereinafter abbreviated as “panel”) is a typical image display device that displays an image in an image display area by combining binary control of light emission and non-light emission in a light emitting element constituting a pixel. is there.
  • a large number of discharge cells which are light-emitting elements constituting pixels, are formed between a front substrate and a rear substrate that are arranged to face each other.
  • a plurality of pairs of display electrodes composed of a pair of scan electrodes and sustain electrodes are formed on the front glass substrate in parallel with each other.
  • a dielectric layer and a protective layer are formed so as to cover the display electrode pairs.
  • the back substrate has a plurality of parallel data electrodes formed on the glass substrate on the back side, a dielectric layer is formed so as to cover the data electrodes, and a plurality of barrier ribs are formed thereon in parallel with the data electrodes. ing. And the fluorescent substance layer is formed in the surface of a dielectric material layer, and the side surface of a partition.
  • the front substrate and the rear substrate are arranged opposite to each other and sealed so that the display electrode pair and the data electrode are three-dimensionally crossed.
  • a discharge gas containing xenon at a partial pressure ratio of 5% is sealed, and a discharge cell is formed in a portion where the display electrode pair and the data electrode face each other.
  • ultraviolet rays are generated by gas discharge in each discharge cell, and the phosphors of each color of red (R), green (G) and blue (B) are excited and emitted by the ultraviolet rays. Display an image.
  • a subfield method is generally used as a method for displaying an image in an image display region by combining binary control of light emission and non-light emission in a light emitting element.
  • each discharge cell In the subfield method, one field is divided into a plurality of subfields having different emission luminances.
  • each discharge cell light emission / non-light emission of each subfield is controlled by a combination according to a desired gradation value.
  • each discharge cell emits light with the emission luminance of one field set to a desired gradation value, and an image composed of various combinations of gradation values is displayed in the image display area of the panel.
  • each subfield has an address period and a sustain period.
  • the scan pulse is sequentially applied to the scan electrodes, and the address pulse is selectively applied to the data electrodes based on the image signal to be displayed.
  • an address discharge is generated between the scan electrode and the data electrode of the discharge cell to emit light, and a wall charge is formed in the discharge cell (hereinafter, these operations are also collectively referred to as “address”). ).
  • the number of sustain pulses based on the gradation weights determined for each subfield is alternately applied to the display electrode pairs composed of the scan electrodes and the sustain electrodes.
  • a sustain discharge is generated in the discharge cell that has generated the address discharge, and the phosphor layer of the discharge cell emits light (hereinafter referred to as “lighting” that the discharge cell emits light by the sustain discharge, and “non-emitting”). Also written as “lit”.)
  • each discharge cell is made to emit light with the luminance according to the gradation weight.
  • each discharge cell of the panel is caused to emit light with a luminance corresponding to the gradation value of the image signal, and an image is displayed in the image display area of the panel.
  • the simultaneous writing operation every two lines is a driving method in which a scanning pulse is simultaneously applied to two adjacent scanning electrodes to perform the writing operation simultaneously for two lines (see, for example, Patent Document 1). If the simultaneous write operation is performed every two lines, the time spent for the write operation can be shortened and the write period can be shortened. For example, the number of subfields is increased or the time of the sustain period is increased. It becomes possible.
  • the driving method that performs the simultaneous writing operation every two lines may cause a decrease in resolution in the direction orthogonal to the scanning electrodes.
  • the direction orthogonal to the scan electrode is referred to as “vertical direction”
  • the resolution in the direction orthogonal to the scan electrode is referred to as “vertical resolution”. This is because a write operation is simultaneously performed on two adjacent scan electrodes within one field period, so that each discharge formed on the two adjacent scan electrodes in one image displayed on the panel. This is because the cells emit light in the same pattern. Therefore, the resolution of the image is reduced to half of the number of scan electrodes in the direction orthogonal to the scan electrodes (vertical direction).
  • a plasma display device as a three-dimensional (3-dimension: hereinafter referred to as “3D”) image display device.
  • a right-eye image and a left-eye image constituting a stereoscopic image (3D image) are alternately displayed on a panel, and a user uses special glasses called shutter glasses to display the images. Observe.
  • the shutter glasses include a right-eye shutter and a left-eye shutter, and the right-eye shutter is opened (a state in which visible light is transmitted) during a period in which the right-eye image is displayed on the panel, and the left-eye shutter. Is closed (a state in which visible light is blocked), and while the left-eye image is displayed, the left-eye shutter is opened and the right-eye shutter is closed.
  • the user can observe the right-eye image only with the right eye and the left-eye image with only the left eye, so that the display image can be stereoscopically viewed.
  • the plasma display device used as the 3D image display device in order to display one 3D image, two images of one right eye image and one left eye image are displayed. There must be. Therefore, a user who observes a 3D image through shutter glasses observes the number of images displayed on the panel per second as half the number of fields per second.
  • the field frequency of the image displayed on the panel is 60 Hz
  • the image is a normal image (2D image) that is not a 3D image
  • 60 images per second 60 images per second.
  • a 2D image is displayed.
  • the image is a 3D image, 30 3D images are displayed per second.
  • the field frequency in order to display 60 3D images per second, the field frequency must be set to 120 Hz, which is twice 60 Hz. In that case, the time that can be used to display one right-eye image or one left-eye image is limited to one-half of the time that can be used to display one 2D image.
  • the above-described driving method using the simultaneous writing operation every two lines is effective.
  • the vertical resolution tends to be lowered.
  • a plasma display device used as a 3D image display device smoothness of diagonal lines is prevented from being impaired when a panel is driven to display a 3D image by a driving method using a simultaneous writing operation every two lines. Therefore, it is desired to prevent deterioration of image display quality.
  • a plurality of subfields having gradation weights constitute one field, and each of the plurality of subfields is expressed using a subfield code indicating a combination of light emission and non-light emission in each of the plurality of subfields.
  • This is an image display device that controls the light emission and non-light emission, displays a gradation value based on an image signal on each of a plurality of pixels constituting the image display area, and displays an image in the image display area.
  • at least one first-type subfield that performs a line-by-line addressing operation that applies a scan pulse to each of the scan electrodes in the address period and two adjacent scan electrodes in the address period simultaneously.
  • a display code which is a subfield code for displaying a gradation value based on an image signal on a pixel, is composed of a plurality of second-type subfields that perform simultaneous writing operation every two lines to which a scan pulse is applied.
  • a drive circuit for outputting is provided.
  • the drive circuit includes a two-line average unit, a two-line difference unit, a subtraction unit, an average code conversion unit, a difference code creation unit, and a display code synthesis unit.
  • the two-line average unit calculates an average value of image signals corresponding to each pixel of a pair of pixels that are adjacent to each other in the direction orthogonal to the scanning electrode and perform the address operation simultaneously in the address period of the second type subfield.
  • the two-line difference unit calculates a difference value between the image signals corresponding to each pixel of the pair of pixels described above, and compares the difference value with the gradation weight of the first type subfield.
  • the subtraction unit subtracts a predetermined variable determined by the comparison result in the two-line difference unit from the above average value.
  • the average code conversion unit converts the output of the subtraction unit into a subfield code having a predetermined subfield determined by the comparison result of the two-line difference unit as a non-lighting subfield, and outputs the subfield code.
  • the difference code creation unit generates a subfield code for controlling a predetermined subfield based on the comparison result of the two-line difference unit.
  • the display code synthesis unit generates a display code by synthesizing the subfield code output from the average code conversion unit and the subfield code generated by the difference code creation unit.
  • the conversion from the image signal to the display code can be performed by the calculation using the calculation circuit. Therefore, even in an image display device that needs to cope with high functionality and multi-function, it is not necessary to provide a huge number of conversion tables for converting image signals into display codes. That is, it is not necessary to configure the image signal processing circuit so as to select an optimal one from a vast number of conversion tables according to various conditions. Furthermore, the time required for the writing period can be shortened while preventing the image display quality from being deteriorated in the image display device.
  • the image display device of the present invention includes a base code generation unit, a rule generation unit, an upper and lower code generation unit, and an average code selection unit in the average code conversion unit.
  • the base code generation unit selects a gradation value that is larger than the gradation value of the image signal in the target pixel pair and closest to the gradation value of the image signal in the target pixel pair from among a plurality of basic subfield codes.
  • the sub-field code having the upper gradation base code is selected.
  • the rule generation unit generates a rule for generating a new subfield code by changing the light-emitting subfield in the upper gradation base code to a non-light-emitting subfield based on the image signal in the target pixel pair.
  • the upper / lower code generation unit applies the above-described rule to the upper gradation base code and newly generates an image signal in the target pixel pair that is larger than the gradation value of the image signal in the target pixel pair.
  • the subfield code having the gradation value closest to the gradation value is selected as the upper gradation code, and is the closest to the gradation value of the image signal in the target pixel pair below the gradation value of the image signal in the target pixel pair
  • a subfield code having a gradation value is selected as the lower gradation code.
  • the average code selection unit calculates a gradation value to be displayed on the target pixel pair by adding a predetermined value to the gradation value of the image signal in the target pixel pair.
  • a subfield code having a gradation value closer to the gradation value to be displayed on the target pixel pair is selected and output.
  • the plurality of basic subfield codes described above are all subfields having the largest gradation weight among the subfields that emit light, and all having a gradation weight smaller than that subfield.
  • the sub-field is a base code that emits light, or a deleted base code that uses a predetermined sub-field determined by the comparison result of the two-line difference portion from the base code as a non-lighting sub-field.
  • the predetermined value described above is a dither value calculated by dither processing and an error generated by error diffusion processing.
  • the present invention also comprises a plurality of subfields using a subfield code indicating a combination of light emission and non-light emission in each of the plurality of subfields, with a plurality of subfields having gradation weights defined.
  • the gradation value based on the image signal is displayed on each of the plurality of pixels constituting the image display area to display the image in the image display area, and scanning in the writing period
  • At least one first-type subfield that performs a line-by-line addressing operation that applies a scan pulse to each electrode and a line-by-line simultaneous address that simultaneously applies a scan pulse to two adjacent scan electrodes in the address period
  • a plurality of second type subfields that perform the operation constitute one field, and gradation values based on image signals are displayed on the pixels.
  • a driving method of an image display device for generating a display code is a sub-field code.
  • the driving method includes calculating an average value of image signals corresponding to each pixel of a pair of pixels that are adjacent to each other in a direction orthogonal to the scanning electrode and simultaneously perform the writing operation in the writing period of the second type subfield.
  • the conversion from the image signal to the display code can be performed by the calculation using the calculation circuit. Therefore, even in an image display device that needs to cope with high functionality and multi-function, it is not necessary to provide a huge number of conversion tables for converting image signals into display codes. That is, it is not necessary to configure the image signal processing circuit so as to select an optimal one from a vast number of conversion tables according to various conditions. Furthermore, the time required for the writing period can be shortened while preventing the image display quality from being deteriorated in the image display device.
  • the driving method of the image display device includes a plurality of basic subfield codes that are larger than the gradation value of the image signal in the pixel pair of interest and the gradation value of the image signal in the pixel pair of interest. Selecting the subfield code having the gradation value closest to the upper gradation base code, and changing the light emission subfield in the upper gradation base code to the non-light emission subfield based on the image signal in the pixel pair of interest.
  • a predetermined value is added to the gradation value of the image signal in the target pixel pair to calculate a gradation value to be displayed on the target pixel pair, and the target pixel pair of the upper gradation code and the lower gradation code is calculated. Selecting a subfield code having a gradation value closer to the gradation value to be displayed.
  • FIG. 1 is an exploded perspective view showing a structure of a panel used in an image display apparatus according to an embodiment of the present invention.
  • FIG. 2 is an electrode array diagram of a panel used in the image display apparatus according to the embodiment of the present invention.
  • FIG. 3 is a diagram schematically showing drive voltage waveforms applied to the respective electrodes of the panel used in the image display device according to the embodiment of the present invention.
  • FIG. 4 is a diagram schematically showing the subfield configuration of the image display device and the opening / closing operation of the shutter glasses in the embodiment of the present invention.
  • FIG. 5 is a diagram showing an example of a code set when one field is composed of five subfields.
  • FIG. 6 is a diagram schematically showing an example of a circuit block and an image display system constituting the image display apparatus according to the embodiment of the present invention.
  • FIG. 7 is a diagram schematically showing an example of a circuit block constituting the image signal processing circuit of the image display device according to the embodiment of the present invention.
  • FIG. 8A is a diagram schematically showing an example of a writing operation in the image signal processing circuit of the image display device according to the embodiment of the present invention.
  • FIG. 8B is a diagram schematically showing another example of the writing operation in the image signal processing circuit of the image display device according to the embodiment of the present invention.
  • FIG. 8C is a diagram schematically showing another example of the write operation in the image signal processing circuit of the image display device according to the embodiment of the present invention.
  • FIG. 8A is a diagram schematically showing an example of a writing operation in the image signal processing circuit of the image display device according to the embodiment of the present invention.
  • FIG. 8B is a diagram schematically showing another example of the writing operation
  • FIG. 8D is a diagram schematically showing another example of the writing operation in the image signal processing circuit of the image display device according to the embodiment of the present invention.
  • FIG. 8E is a diagram schematically showing another example of the writing operation in the image signal processing circuit of the image display device according to the embodiment of the present invention.
  • FIG. 8F is a diagram schematically showing another example of the writing operation in the image signal processing circuit of the image display device according to the embodiment of the present invention.
  • FIG. 8G is a diagram schematically showing another example of the writing operation in the image signal processing circuit of the image display device according to the embodiment of the present invention.
  • FIG. 9 is a diagram schematically showing an example of a circuit block constituting the average code conversion unit of the image display device according to the embodiment of the present invention.
  • FIG. 10A is a diagram illustrating an example of a base code set used in the image display device according to the embodiment of the present invention.
  • FIG. 10B is a diagram showing an example of a deleted base code set used in the image display device according to the embodiment of the present invention.
  • FIG. 11A is a diagram illustrating an example of an intermediate code set generated by the intermediate code generation unit of the image display device according to the embodiment of the present invention.
  • FIG. 11B is a diagram showing another example of the intermediate code set generated by the intermediate code generation unit of the image display device according to the embodiment of the present invention.
  • FIG. 11C is a diagram illustrating another example of the intermediate code set generated by the intermediate code generation unit of the image display device according to the embodiment of the present invention.
  • FIG. 11A is a diagram illustrating an example of a base code set used in the image display device according to the embodiment of the present invention.
  • FIG. 10B is a diagram showing an example of a deleted base code set used in the image display device according to the embodiment of the
  • FIG. 12A is a diagram illustrating an example of a dither pattern used in the image display device according to the embodiment of the present invention.
  • FIG. 12B is a diagram showing another example of the dither pattern used in the image display device according to the embodiment of the present invention.
  • FIG. 13 is a diagram showing the error diffusion coefficient of the error diffusion unit of the image display device according to the embodiment of the present invention.
  • FIG. 14 is a flowchart showing the operation of the image signal processing circuit of the image display device according to the embodiment of the present invention.
  • FIG. 15 is a diagram schematically showing another example of a drive voltage waveform applied to each electrode of the panel used in the image display device according to the embodiment of the present invention.
  • FIG. 16A is a diagram illustrating an example of a base code set used in the image display device according to the embodiment of the present invention.
  • FIG. 16B is a diagram showing another example of the deleted base code set used in the image display device according to the embodiment of the present invention.
  • FIG. 16C is a diagram showing another example of the deleted base code set used in the image display device according to the embodiment of the present invention.
  • FIG. 1 is an exploded perspective view showing the structure of panel 10 used in the image display apparatus according to the embodiment of the present invention.
  • a plurality of display electrode pairs 14 each including a scanning electrode 12 and a sustaining electrode 13 are formed on a glass front substrate 11.
  • a dielectric layer 15 is formed so as to cover the scan electrode 12 and the sustain electrode 13, and a protective layer 16 is formed on the dielectric layer 15.
  • This protective layer 16 has been used as a panel material in order to lower the discharge start voltage in the discharge cell, and has a large secondary electron emission coefficient and durability when neon (Ne) and xenon (Xe) gas is sealed. It is made of a material mainly composed of magnesium oxide (MgO).
  • the protective layer 16 may be composed of a single layer or may be composed of a plurality of layers. Moreover, the structure which particle
  • a plurality of data electrodes 22 are formed on the rear substrate 21, a dielectric layer 23 is formed so as to cover the data electrodes 22, and a grid-like partition wall 24 is further formed thereon.
  • a phosphor layer 25R that emits red (R)
  • a phosphor layer 25G that emits green (G)
  • a phosphor layer 25B that emits blue (B).
  • the phosphor layer 25R, the phosphor layer 25G, and the phosphor layer 25B are collectively referred to as a phosphor layer 25.
  • the front substrate 11 and the rear substrate 21 are arranged to face each other so that the display electrode pair 14 and the data electrode 22 intersect each other with a minute space therebetween, and a discharge space is provided in the gap between the front substrate 11 and the rear substrate 21.
  • the outer peripheral part is sealed with sealing materials, such as glass frit.
  • sealing materials such as glass frit.
  • a mixed gas of neon and xenon is sealed in the discharge space as a discharge gas.
  • the discharge space is partitioned into a plurality of sections by the barrier ribs 24, and discharge cells, which are light-emitting elements constituting the pixels, are formed at the intersections between the display electrode pairs 14 and the data electrodes 22.
  • one pixel is composed of three consecutive discharge cells arranged in the direction in which the display electrode pair 14 extends.
  • the three discharge cells are a discharge cell having a phosphor layer 25R and emitting red (R) (red discharge cell), and a discharge cell having a phosphor layer 25G and emitting green (G) (green). And a discharge cell having a phosphor layer 25B and emitting blue (B) light (blue discharge cell).
  • the structure of the panel 10 is not limited to the above-described structure, and may be, for example, provided with a stripe-shaped partition wall.
  • FIG. 2 is an electrode array diagram of panel 10 used in the plasma display device according to one embodiment of the present invention.
  • the panel 10 includes n scan electrodes SC1 to SCn (scan electrode 12 in FIG. 1) extended in the horizontal direction (row direction and line direction) and n sustain electrodes SU1 to SUn (FIG. 1).
  • the sustain electrodes 13) are arranged, and m data electrodes D1 to Dm (data electrodes 22 in FIG. 1) extending in the vertical direction (column direction) are arranged.
  • m discharge cells are formed on one pair of display electrodes 14 and m / 3 pixels are formed.
  • the cell is coated with a green phosphor as a phosphor layer 25G, and the discharge cell having the data electrode Dp + 2 is coated with a blue phosphor as a phosphor layer 25B.
  • the plasma display device in the present embodiment drives the panel 10 by the subfield method.
  • the subfield method one field of an image signal is divided into a plurality of subfields on the time axis, and a gradation weight is set for each subfield. Therefore, each field has a plurality of subfields having different gradation weights.
  • the image signal input to the image display device is a 3D image signal.
  • the 3D image signal is a stereoscopic image signal in which a right-eye image signal and a left-eye image signal are alternately repeated for each field.
  • the right-eye field for displaying the right-eye image signal on the panel 10 and the left-eye field for displaying the left-eye image signal on the panel 10 are alternately repeated, and the panel 10 includes the stereoscopic image including the right-eye image and the left-eye image.
  • the stereoscopic image (3D image) displayed on the panel 10 is observed by the user through shutter glasses that open and close the right-eye shutter and the left-eye shutter in synchronization with the right-eye field and the left-eye field, respectively. To do. Thereby, the user can stereoscopically view the 3D image displayed on the panel 10.
  • the right-eye field and the left-eye field differ only in the image signal to be displayed, and the field configuration is the same, such as the number of subfields constituting one field, the gradation weight of each subfield, and the arrangement of subfields. is there.
  • the configuration of one field and the drive voltage waveform applied to each electrode will be described.
  • the field frequency (the number of fields generated per second) is set to twice the normal frequency (for example, 120 Hz) so that the user can smoothly observe a 3D moving image. ing.
  • Each field has a plurality of subfields, and each subfield has an initialization period, an address period, and a sustain period.
  • an initializing operation is performed in which initializing discharge is generated in the discharge cells and wall charges necessary for the address discharge in the subsequent address period are formed on each electrode.
  • Initialization operation includes “forced initialization operation” that forcibly generates an initializing discharge in all discharge cells regardless of the operation of the immediately preceding subfield and an addressing discharge that occurs in the addressing period of the immediately preceding subfield.
  • the forced initializing operation the rising ramp waveform voltage and the falling ramp waveform voltage are applied to the scan electrode 12 to generate an initializing discharge in the discharge cell.
  • the forced initializing operation is performed in all discharge cells in the initializing period of one subfield, and all the discharge cells are selected in the initializing period of the other subfield. Perform initialization.
  • force initialization period the initialization period in which the forced initialization operation is performed
  • subfield having the forced initialization period is referred to as “forced initialization subfield”.
  • An initialization period for performing the selective initialization operation is referred to as a “selective initialization period”
  • a subfield having the selective initialization period is referred to as a “selective initialization subfield”.
  • subfield SF1 is a forced initialization subfield
  • the other subfields are selected initialization subfields.
  • the present invention is not limited to the above-described subfields as subfields for forced initialization subfields and subfields for selective initialization subfields.
  • the structure which switches a subfield structure based on an image signal etc. may be sufficient.
  • a scan pulse is applied to the scan electrode 12 and an address pulse is selectively applied to the data electrode 22 to selectively generate an address discharge in the discharge cells to emit light. Then, an address operation is performed to form wall charges in the discharge cells for generating a sustain discharge in the subsequent sustain period.
  • either the simultaneous writing operation for every two lines or the writing operation for every one line is performed in the writing period.
  • the simultaneous writing operation for every two lines is an addressing operation in which a scanning pulse is simultaneously applied to two adjacent scanning electrodes 12 and a writing pulse is selectively applied to the data electrodes 22.
  • the simultaneous address operation for every two lines the address discharge is simultaneously generated in the discharge cells in which the sustain discharge is to be generated.
  • the address operation for each line is an address operation in which a scan pulse is sequentially applied to each of scan electrode SC1 to scan electrode SCn and an address pulse is selectively applied to data electrode 22.
  • an address discharge is generated for each line in a discharge cell in which a sustain discharge is to be generated.
  • the length of the writing period can be shortened as compared with the writing period in which the writing operation is performed every line.
  • a subfield that performs a write operation for each line in the write period is referred to as a “first type subfield”. Further, a subfield that performs the simultaneous writing operation every two lines during the writing period is referred to as a “second type subfield”.
  • the first type subfield and the second type subfield are mixed in one field. That is, in the present embodiment, one field includes at least one first type subfield and a plurality of second type subfields.
  • the above-mentioned 1 line is a row
  • sustain pulses of the number obtained by multiplying the gradation weight set in each subfield by a predetermined proportional constant are alternately applied to the scan electrode 12 and the sustain electrode 13 to generate an address discharge in the immediately preceding address period.
  • a sustain discharge is generated in the discharged discharge cell, and a sustain operation for emitting light from the discharge cell is performed.
  • This proportionality constant is a luminance multiple.
  • the gradation weight represents the ratio of the magnitude of the luminance displayed in each subfield, and the number of sustain pulses corresponding to the gradation weight is generated in the sustain period in each subfield. Therefore, for example, the subfield with the gradation weight “8” emits light with a luminance about eight times that of the subfield with the gradation weight “1”, and about four times as high as the subfield with the gradation weight “2”. Emits light. Therefore, for example, if the subfield with the gradation weight “8” and the subfield with the gradation weight “2” are emitted, the discharge cell can emit light with a luminance corresponding to the gradation value “10”.
  • each discharge cell emits light with various gradation values by selectively emitting light in each subfield by controlling light emission / non-light emission of each discharge cell for each subfield in a combination according to the image signal. That is, a gradation value corresponding to an image signal can be displayed on each discharge cell, and an image based on the image signal can be displayed on the panel 10.
  • one pixel includes three consecutive discharge cells arranged in the direction in which the display electrode pair 14 extends, that is, a red discharge cell, a green discharge cell, and a blue discharge.
  • a red discharge cell is also referred to as a “red pixel”, a green discharge cell as a “green pixel”, and a blue discharge cell as a “blue pixel”.
  • the right-eye field and the left-eye field are each composed of five subfields (subfield SF1, subfield SF2, subfield SF3, subfield SF4, subfield SF5), and subfield SF1.
  • subfield SF1, subfield SF2, subfield SF3, subfield SF4, subfield SF5 are set to each subfield of subfield SF5.
  • the subfield SF1, the subfield SF3, the subfield SF4, and the subfield SF5 are the second type subfield
  • the subfield SF2 is the first type subfield.
  • the subfields that are the first type subfield and the subfields that are the second type subfield are not limited to the subfields described above.
  • the number of subfields constituting one field and the gradation weight set in each subfield are not limited to the above-described subfield configuration. They are preferably set optimally according to the specifications of the image display device.
  • FIG. 3 is a diagram schematically showing drive voltage waveforms applied to the respective electrodes of panel 10 used in the plasma display device according to one embodiment of the present invention.
  • FIG. 3 shows data electrode D1 to data electrode Dm, scan electrode SC1 that performs the address operation first in the address period, scan electrode SCn that performs the address operation last in the address period (for example, scan electrode SC1080), sustain electrode SU1 to The drive voltage waveform applied to each of the sustain electrodes SUn is shown.
  • Scan electrode SCi, sustain electrode SUi, and data electrode Dk in the following represent electrodes selected based on image data (data indicating light emission / non-light emission for each subfield) from among the electrodes.
  • FIG. 3 also shows a subfield SF1 that is a forced initialization subfield and the second type subfield, a subfield SF2 that is a selective initialization subfield and the first type subfield, and a selective initialization subfield.
  • the subfield SF3 which is the second type subfield.
  • the subfield SF1, the subfield SF2, and the subfield SF3 have different waveform shapes of the drive voltage applied to the scan electrode 12 in the initialization period.
  • the subfield SF1, the subfield SF3, and the subfield SF2 have different write operations in the write period.
  • each subfield after subfield SF4 is a selective initialization subfield and is a second type subfield, and therefore generates substantially the same drive voltage waveform as subfield SF3 except for the number of sustain pulses.
  • the voltage 0 (V) is applied to the data electrode D1 to the data electrode Dm and the sustain electrode SU1 to the sustain electrode SUn.
  • a voltage Vi1 is applied to scan electrode SC1 through scan electrode SCn after voltage 0 (V) is applied, and a ramp waveform voltage that gradually rises from voltage Vi1 to voltage Vi2 (hereinafter referred to as an “upward ramp waveform voltage”). ) Is applied.
  • voltage Vi1 is set to a voltage lower than the discharge start voltage for sustain electrode SU1 to sustain electrode SUn
  • voltage Vi2 is set to a voltage exceeding the discharge start voltage for sustain electrode SU1 to sustain electrode SUn.
  • the wall voltage on the electrode represents a voltage generated by wall charges accumulated on the dielectric layer covering the electrode, the protective layer, the phosphor layer, and the like.
  • the positive voltage Ve is applied to the sustain electrodes SU1 to SUn, and the voltage 0 (V) is applied to the data electrodes D1 to Dm.
  • a scan waveform SC1 to scan electrode SCn are applied with a ramp waveform voltage that gently falls from voltage Vi3 to negative voltage Vi4 (hereinafter referred to as “down ramp waveform voltage”).
  • Voltage Vi3 is set to a voltage lower than the discharge start voltage with respect to sustain electrode SU1 through sustain electrode SUn
  • voltage Vi4 is set to a voltage exceeding the discharge start voltage with respect to sustain electrode SU1 through sustain electrode SUn.
  • the above voltage waveform is a forced initializing waveform that generates an initializing discharge in the discharge cell regardless of the operation of the immediately preceding subfield.
  • the operation for applying the forced initialization waveform to the scan electrode 12 is the forced initialization operation.
  • the forced initialization operation in the initialization period Ti1 of the forced initialization subfield ends.
  • initializing discharge is forcibly generated in all the discharge cells in the image display area of the panel 10.
  • the simultaneous writing operation every two lines, scan electrode SC1 and scan electrode SC2, scan electrode SC3 and scan electrode SC4, scan electrode SC5 and scan electrode SC6,..., Scan electrode SCn-1 and scan electrode SCn are adjacent in this order.
  • a scanning pulse is simultaneously applied to the two scanning electrodes 12 to be performed. That is, the two-line simultaneous write operation is a write operation in which scan pulses are sequentially applied to two adjacent scan electrodes 12 in the order in which the scan electrodes 12 are arranged on the panel 10.
  • the scan pulse is applied to each scan electrode 12 in the order of scan electrode SC1, scan electrode SC2, scan electrode SC3, scan electrode SC4,..., Scan electrode SCn-1, and scan electrode SCn.
  • the line-by-line address operation is an address operation in which scan pulses are sequentially applied to each of the scan electrodes 12 in the order in which the scan electrodes 12 are arranged on the panel 10.
  • the voltage Ve is applied to the sustain electrode SU1 to the sustain electrode SUn, and the voltage 0 (V) is applied to the data electrode D1 to the data electrode Dm.
  • Voltage Vc is applied to scan electrode SC1 through scan electrode SCn.
  • a negative scan pulse with a negative voltage Va is applied to the first (first line) scan electrode SC1 and the second (second line) scan electrode SC2 from the top in terms of arrangement.
  • a positive address pulse having a positive voltage Vd is applied to the data electrodes Dk of the discharge cells that should emit light in the first and second lines of the data electrodes D1 to Dm.
  • the voltage difference between data electrode Dk and scan electrode SC2 exceeds the discharge start voltage, and discharge occurs between data electrode Dk and scan electrode SC1, and between data electrode Dk and scan electrode SC2.
  • sustain electrode SU1 in a region intersecting data electrode Dk is induced by a discharge generated between data electrode Dk and scan electrode SC1. Discharge also occurs between scan electrode SC1 and scan electrode SC1. Similarly, a discharge is also generated between sustain electrode SU2 and scan electrode SC2 in a region intersecting data electrode Dk, induced by a discharge generated between data electrode Dk and scan electrode SC2.
  • address discharge is generated in the discharge cells (discharge cells to emit light) to which the scan pulse voltage Va and the address pulse voltage Vd are simultaneously applied.
  • the address operation in the first-line discharge cells and the second-line discharge cells is completed.
  • the discharge cell having the data electrode Dh to which the address pulse is not applied the data electrode Dh is the data electrode D1 to the data electrode Dm excluding the data electrode Dk
  • the intersection of the data electrode Dh and the scan electrode SC1 Since the voltage at the portion and the voltage at the intersection between the data electrode Dh and the scan electrode SC2 do not exceed the discharge start voltage, the address discharge does not occur and the wall voltage after the end of the initialization period Ti1 is maintained.
  • a scan pulse of voltage Va is applied to the third (third line) scan electrode SC3 and the fourth (fourth line) scan electrode SC4 from the top, and the third and fourth lines are arranged.
  • An address pulse of voltage Vd is applied to the data electrode Dk corresponding to the discharge cell that should emit light to the eye.
  • address discharge occurs in the discharge cells of the third line and the discharge cells of the fourth line to which the scan pulse and the address pulse are simultaneously applied.
  • the address operation is performed in the discharge cells of the third line and the fourth line.
  • the same addressing operation is sequentially performed in the order of scan electrode SC5 and scan electrode SC6, scan electrode SC7 and scan electrode SC8,..., Scan electrode SCn-1 and scan electrode SCn up to the discharge cell in the nth row.
  • An address discharge is selectively generated in the discharge cell to emit light, and a wall charge for sustain discharge is formed in the discharge cell.
  • the writing period Tw1 of the subfield SF1 ends.
  • the time required for the writing period for performing the simultaneous writing operation for every two lines is reduced to about half of the time required for the writing period for performing the writing operation for every one line.
  • the simultaneous write operation for every two lines is not limited to the write operation in which the scan pulse is simultaneously applied to the scan electrode SCp of the odd line and the scan electrode SCp + 1 of the next even line.
  • an address operation may be performed in which a scan pulse is simultaneously applied to the even-numbered scan electrode SCp + 1 and the next odd-numbered scan electrode SCp + 2.
  • the order in which the scan pulse is applied to the scan electrode 12 is not limited to the order described above. What is necessary is just to set arbitrarily the order which applies a scanning pulse to the scanning electrode 12 according to the specification etc. in an image display apparatus.
  • voltage Ve applied to sustain electrode SU1 through sustain electrode SUn in the second half of initialization period Ti1 and voltage Ve applied to sustain electrode SU1 through sustain electrode SUn in address period Tw1 may have different voltage values. .
  • the voltage 0 (V) is applied to the sustain electrodes SU1 to SUn. Then, sustain pulse of positive voltage Vs is applied to scan electrode SC1 through scan electrode SCn.
  • the voltage difference between the scan electrode SCi and the sustain electrode SUi exceeds the discharge start voltage, and is maintained between the scan electrode SCi and the sustain electrode SUi. Discharge occurs.
  • the phosphor layer 25 of the discharge cell in which the sustain discharge has occurred emits light by the ultraviolet rays generated by the sustain discharge.
  • a negative wall voltage is accumulated on scan electrode SCi
  • a positive wall voltage is accumulated on sustain electrode SUi.
  • a positive wall voltage is also accumulated on the data electrode Dk.
  • the sustain discharge does not occur in the discharge cells in which the address discharge has not occurred in the address period Tw1.
  • the sustain pulses of the number obtained by multiplying the gradation weight by a predetermined luminance multiple are alternately applied to scan electrode SC1 through scan electrode SCn and sustain electrode SU1 through sustain electrode SUn.
  • the discharge cells that have generated the address discharge in the address period generate the sustain discharges the number of times corresponding to the gradation weight, and emit light with the luminance corresponding to the gradation weight.
  • scan electrode SC1 to scan are performed while voltage 0 (V) is applied to sustain electrode SU1 to sustain electrode SUn and data electrode D1 to data electrode Dm.
  • An upward ramp waveform voltage that gradually rises from voltage 0 (V) to voltage Vr is applied to electrode SCn.
  • the sustain of the discharge cell that has generated the sustain discharge is maintained while the rising ramp waveform voltage applied to scan electrode SC1 through scan electrode SCn exceeds the discharge start voltage.
  • a weak discharge (erase discharge) is continuously generated between the electrode SUi and the scan electrode SCi.
  • the charged particles generated by this weak discharge are accumulated as wall charges on the sustain electrode SUi and the scan electrode SCi so as to reduce the voltage difference between the sustain electrode SUi and the scan electrode SCi.
  • the wall voltage on scan electrode SCi and the wall voltage on sustain electrode SUi are weakened while the positive wall voltage on data electrode Dk remains.
  • unnecessary wall charges in the discharge cell are erased.
  • the voltage 0 (V) is applied to the data electrodes D1 to Dm, and the positive voltage Ve is applied to the sustain electrodes SU1 to SUn.
  • Scan electrode SC1 to scan electrode SCn decrease from a voltage lower than the discharge start voltage (for example, voltage 0 (V)) toward negative voltage Vi4 at the same gradient as the downward ramp waveform voltage generated in initialization period Ti1. Apply a downward ramp waveform voltage.
  • the voltage Vi4 is set to a voltage exceeding the discharge start voltage.
  • the negative wall voltage on scan electrode SCi and the positive wall voltage on sustain electrode SUi are weakened.
  • an excessive portion of the positive wall voltage on the data electrode Dk is discharged.
  • the wall voltage in the discharge cell is adjusted to a wall voltage suitable for the address operation in the address period Tw2.
  • the voltage waveform described above is a selective initialization waveform in which an initializing discharge is selectively generated in a discharge cell that has performed an address operation in the address period (here, address period Tw1) of the immediately preceding subfield.
  • the operation of applying the selective initialization waveform to the scan electrode 12 is the selective initialization operation.
  • the voltage Ve is applied to the sustain electrode SU1 to the sustain electrode SUn, and the voltage 0 (to the data electrode D1 to the data electrode Dm, as in the address period Tw1. V) is applied, and voltage Vc is applied to scan electrode SC1 through scan electrode SCn.
  • a negative scan pulse having a negative voltage Va is applied to the first (first line) scan electrode SC1 in terms of arrangement.
  • a positive address pulse of a positive voltage Vd is applied to the data electrode Dk of the discharge cell that should emit light in the first line among the data electrodes D1 to Dm.
  • the voltage difference between the data electrode Dk and the scan electrode SC1 determines the discharge start voltage.
  • the address discharge occurs between the data electrode Dk and the scan electrode SC1 and between the sustain electrode SU1 and the scan electrode SC1 in the region intersecting with the data electrode Dk.
  • a positive wall voltage is accumulated on the scan electrode SC1
  • a negative wall voltage is accumulated on the sustain electrode SU1
  • a negative wall voltage is also accumulated on the data electrode Dk.
  • the address operation in the discharge cell on the first line is completed.
  • the discharge cell having the data electrode Dh to which the address pulse is not applied the data electrode Dh is the data electrode D1 to the data electrode Dm excluding the data electrode Dk
  • the intersection of the data electrode Dh and the scan electrode SC1 Since the voltage of the part does not exceed the discharge start voltage, the address discharge does not occur, and the wall voltage after the end of the initialization period Ti2 is maintained.
  • a scan pulse of the voltage Va is applied to the second (second line) scan electrode SC2 from the top, and the voltage Vd is applied to the data electrode Dk corresponding to the discharge cell that should emit light on the second line. Apply the write pulse. As a result, an address discharge is generated in the discharge cells of the second line to which the scan pulse and the address pulse are simultaneously applied. Thus, the write operation in the second line is performed.
  • the same addressing operation is sequentially performed in the order of scan electrode SC3, scan electrode SC4,..., Scan electrode SCn-1, and scan electrode SCn up to the discharge cell in the nth row, and is selected as a discharge cell to emit light. Address discharge is generated, and wall charges for sustain discharge are formed in the discharge cells. Thus, the writing period Tw2 of the subfield SF2 ends.
  • the address operation is performed for each line in which the scan pulse is sequentially applied to each of the scan electrodes SC1 to SCn.
  • sustain period Ts2 of subfield SF2 As in sustain period Ts1 of subfield SF1, the number of sustain pulses corresponding to the gradation weights are alternately applied to scan electrode SC1 through scan electrode SCn and sustain electrode SU1 through sustain electrode SUn. Apply.
  • a driving voltage waveform for performing a selective initialization operation is applied to each electrode in the same manner as in the initialization period Ti1 of the subfield SF2.
  • a driving voltage waveform for performing the simultaneous writing operation for every two lines is applied to each electrode as in the writing period Tw1 of the subfield SF1.
  • sustain period Ts3 of subfield SF3 as in sustain period Ts2 of subfield SF2, the number of sustain pulses corresponding to the gradation weights are alternately applied to scan electrode SC1 through scan electrode SCn and sustain electrode SU1 through sustain electrode SUn. Apply.
  • each subfield after subfield SF4 the same drive voltage waveform as in subfield SF3 is applied to each electrode except for the number of sustain pulses generated in the sustain period. That is, in each subfield after subfield SF4, the selective initialization operation is performed in the initialization period, and the simultaneous writing operation is performed every two lines in the writing period.
  • Voltage Va ⁇ 180 (V)
  • voltage Vc ⁇ 30 (V)
  • voltage Vs 190 (V)
  • voltage Vr 190 (V)
  • voltage Ve 120 (V)
  • voltage Vd 60 (V)
  • the gradient of the rising ramp waveform voltage generated in the initialization period Ti1 is about 1.3 V / ⁇ sec
  • the gradient of the rising ramp waveform voltage generated in each sustain period is about 10 V / ⁇ sec.
  • the gradient of the generated downward ramp waveform voltage is about ⁇ 1.5 V / ⁇ sec.
  • the specific numerical values such as the voltage value and the gradient described above are merely examples, and the present invention is not limited to the numerical values described above for each voltage value and the gradient.
  • Each voltage value, gradient, and the like are preferably set optimally based on the discharge characteristics of the panel and the specifications of the plasma display device.
  • subfield SF1 is a forced initialization subfield for performing a forced initialization operation
  • other subfields are a selective initialization subfield for performing a selective initialization operation
  • the present invention is not limited to this configuration.
  • the subfield SF1 may be a selective initialization subfield and other subfields may be forced initialization subfields, or a plurality of subfields may be forced initialization subfields.
  • FIG. 4 is a diagram schematically showing the subfield configuration of the image display device and the opening / closing operation of the shutter glasses in the embodiment of the present invention.
  • FIG. 4 shows scan electrode SC1 that performs the address operation first in the address period, scan electrode SCn that performs the address operation last in the address period, sustain electrode SU1 to sustain electrode SUn, and data electrode D1 to data electrode Dm.
  • the drive voltage waveform to be applied and the opening / closing operation of the right-eye shutter and the left-eye shutter are shown.
  • FIG. 4 shows three fields (field F1 to field F3).
  • a right eye field and a left eye field are alternately generated.
  • the field F1 and the field F3 are right-eye fields, and the field F2 is a left-eye field. Therefore, the right eye image signal is displayed on the panel 10 in the field F1 and the field F3, and the left eye image signal is displayed on the panel 10 in the field F2.
  • an image (right-eye image and left-eye image) displayed in two fields is recognized as one 3D image. Therefore, the number of images displayed on the panel 10 per second is observed by the user as half the number of fields displayed per second.
  • the field frequency of the 3D image displayed on the panel (the number of fields generated per second) is 60 Hz, the user will observe 30 3D images per second. Therefore, in order to display 60 3D images per second, the field frequency must be set to 120 Hz, which is twice 60 Hz.
  • the field frequency (the number of fields generated per second) is set to twice the normal frequency (for example, 120 Hz) so that the user can smoothly observe the 3D moving image. ing. Therefore, the time that can be used to display one right-eye image or one left-eye image is the time that can be used to display one 2D image (a normal image that is not a 3D image) with a field frequency of 60 Hz. Is limited to one-half of.
  • the opening / closing operation of the shutter for the right eye and the shutter for the left eye of the shutter glasses is controlled based on on / off of a shutter opening / closing timing signal.
  • the right-eye shutter opens in synchronization with the start of the writing period of the first subfield (subfield SF1) of the right-eye field (for example, field F1), and starts the left-eye field (for example, field F2).
  • the subfield (subfield SF1) is closed in synchronization with the start of the writing period.
  • the left-eye shutter opens in synchronization with the start of the writing period of the first subfield (subfield SF1) of the left-eye field (eg, field F2), and the first subfield (subfield) of the right-eye field (eg, field F3) Closed in synchronization with the start of the writing period of SF1).
  • one field is composed of a plurality of subfields in which gradation weights are determined in advance. Then, by combining a subfield that is lit (lighting subfield) and a subfield that is not lit (non-lighting subfield), each discharge cell emits light with a light emission luminance corresponding to the magnitude of the gradation value based on the image signal. .
  • subfield code a combination of a lighting subfield and a non-lighting subfield
  • code set a set of a plurality of subfield codes
  • a subfield code is selected from a plurality of subfield codes constituting a code set according to a gradation value. Then, light emission / non-light emission of each subfield is controlled based on the subfield code, and the discharge cell is caused to emit light with a luminance corresponding to the magnitude of the gradation value, and an image is displayed on the panel 10.
  • the gradation value when displaying black (the gradation value when no sustain discharge occurs) is assumed to be “0”.
  • a gradation value corresponding to the gradation weight “N” is expressed as a gradation value “N”.
  • the gradation value displayed by the discharge cells that emit light only in the subfield SF1 having the gradation weight “1” is the gradation value “1”.
  • FIG. 5 is a diagram showing an example of a code set when one field is composed of five subfields.
  • the numerical value written immediately below the notation indicating each subfield represents the gradation weight of each subfield.
  • one field includes five subfields from subfield SF1 to subfield SF5, and each subfield is “1”, “10”, “6”, “3”, “2”. ”Indicates a code set having a tone weight of“. ”
  • “1” indicates a light-emitting subfield
  • a blank field indicates a non-light-emitting subfield
  • the leftmost column indicates a gradation value to be displayed in each subfield code.
  • the subfield code corresponding to the gradation value “1” is “10000”.
  • subfield code it is assumed that 0 or 1 data is arranged in the order of subfield SF1, subfield SF2, subfield SF3, subfield SF4, and subfield SF5 from the left. In the following description, it is assumed that binary numerical values shown as subfield codes are arranged in the order of subfield SF1, subfield SF2, subfield SF3,.
  • the subfield code corresponding to the gradation value “10” is “10110”. Accordingly, in the discharge cell displaying the gradation value “10”, the subfield SF1, the subfield SF3, and the subfield SF4 emit light.
  • FIG. 6 is a diagram schematically showing an example of a circuit block and an image display system constituting the image display device 30 according to the embodiment of the present invention.
  • the image display system shown in the present embodiment includes an image display device 30 and shutter glasses 38 as constituent elements.
  • the image display device 30 includes a panel 10, a drive circuit that drives the panel 10, and a power supply circuit (not shown) that supplies power necessary for each circuit block.
  • the drive circuit includes an image signal processing circuit 31, a data electrode drive circuit 32, a scan electrode drive circuit 33, a sustain electrode drive circuit 34, and a timing generation circuit 35.
  • the drive circuit included in the image display device 30 includes one field including a first-type subfield that performs a writing operation for each line and a second-type subfield that performs a simultaneous writing operation for every two lines. Each drive voltage is generated and applied to each electrode.
  • the image signals input to the image signal processing circuit 31 are a red image signal, a green image signal, and a blue image signal. Based on the red image signal, the green image signal, and the blue image signal, the image signal processing circuit 31 sets each gradation value of red, green, and blue (a gradation value expressed by one field) to each discharge cell. To do.
  • the input image signal includes a luminance signal (Y signal) and a saturation signal (C signal, or RY signal and BY signal, or u signal and v signal, etc.).
  • a red image signal, a green image signal, and a blue image signal are calculated based on the luminance signal and the saturation signal, and then, each gradation value of red, green, and blue is set in each discharge cell.
  • the red, green, and blue gradation values set for each discharge cell are subfield codes indicating lighting / non-lighting for each subfield (light emission / non-light emission corresponds to digital signals “1” and “0”).
  • the subfield code is output as a display code. That is, the image signal processing circuit 31 converts the red image signal, the green image signal, and the blue image signal into a red display code, a green display code, and a blue display code and outputs the converted signals.
  • the image signal input to the image display device 30 is a 3D image signal having a right-eye image signal and a left-eye image signal.
  • the image signal processing circuit 31 converts the right-eye image signal into a right-eye display code (red right-eye display code, green right-eye display code, blue right-eye display code), and converts the left-eye image signal to the left-eye.
  • Display code red left eye display code, green left eye display code, blue left eye display code
  • the image signal processing circuit 31 does not convert an image signal into a subfield code using a conversion table, but converts the image signal into a subfield code by a logical operation. Details of this will be described later.
  • the timing generation circuit 35 generates various timing signals for controlling the operation of each circuit block based on the horizontal synchronization signal and the vertical synchronization signal.
  • the generated timing signal is supplied to each circuit block (data electrode drive circuit 32, scan electrode drive circuit 33, sustain electrode drive circuit 34, image signal processing circuit 31, etc.).
  • Scan electrode drive circuit 33 includes a ramp waveform generation unit, a sustain pulse generation unit, and a scan pulse generation unit (not shown in FIG. 6), and generates a drive voltage waveform based on a timing signal supplied from timing generation circuit 35. Then, the voltage is applied to each of scan electrode SC1 to scan electrode SCn.
  • the ramp waveform generator generates a forced initialization waveform and a selective initialization waveform to be applied to scan electrode SC1 through scan electrode SCn during the initialization period based on the timing signal.
  • the sustain pulse generator generates a sustain pulse to be applied to scan electrode SC1 through scan electrode SCn during the sustain period based on the timing signal.
  • the scan pulse generator includes a plurality of scan electrode drive ICs (scan ICs), and generates scan pulses to be applied to scan electrode SC1 through scan electrode SCn during the address period based on the timing signal.
  • the scanning electrode drive circuit 33 sequentially applies scanning pulses to two adjacent scanning electrodes 12 in the order in which the scanning electrodes 12 are arranged on the panel 10 in the address period in which the simultaneous writing operation is performed every two lines. .
  • the scan pulse is sequentially applied to each of the scan electrodes SC1 to SCn in the order in which the scan electrodes 12 are arranged on the panel 10.
  • Sustain electrode drive circuit 34 includes a sustain pulse generation unit and a circuit (not shown in FIG. 5) for generating voltage Ve, and generates and maintains a drive voltage waveform based on the timing signal supplied from timing generation circuit 35.
  • the voltage is applied to each of electrode SU1 through sustain electrode SUn.
  • a sustain pulse is generated based on the timing signal and applied to sustain electrode SU1 through sustain electrode SUn.
  • voltage Ve is generated based on the timing signal and applied to sustain electrode SU1 through sustain electrode SUn.
  • the data electrode drive circuit 32 is based on the right eye display code and the left eye display code of each color output from the image signal processing circuit 31 and the timing signal supplied from the timing generation circuit 35. A write pulse corresponding to is generated. Then, the data electrode drive circuit 32 applies the address pulse to the data electrodes D1 to Dm during the address period.
  • the purpose of the image signal processing circuit 31 in the present embodiment is to reduce the time required for the writing period while preventing the image display quality in the image display device 30 from deteriorating.
  • the distinction between the image signal for the right eye and the image signal for the left eye is not mentioned, and they are collectively referred to as an image signal.
  • the value of the image signal is assumed to be equal to the gradation value to be displayed on the target pixel.
  • the pixel of interest is a pixel that is an object of calculation at that time.
  • FIG. 7 is a diagram schematically showing an example of a circuit block constituting the image signal processing circuit 31 of the image display device 30 according to an embodiment of the present invention.
  • the image signal processing circuit 31 includes a one horizontal period delay unit 41, a line average unit 42, a two line difference unit 43, a subtraction unit 44, an average code conversion unit 45, a difference code creation unit 91, and a display code synthesis unit 92.
  • the one horizontal period delay unit 41 is abbreviated as “1H delay unit 41”.
  • the 1H delay unit 41 delays the image signal input to the image signal processing circuit 31 by one horizontal period. Therefore, the image signal output from the 1H delay unit 41 is an image signal one line before the target pixel, and is an image signal of a pixel adjacent to the target pixel. That is, if the image signal of the pixel of interest is the image signal of the pixel on the (p + 1) line, the image signal output from the 1H delay unit 41 is the image signal of the pixel on the p line.
  • pixels continuously arranged on one data electrode 22 are referred to as “vertically continuous pixels”.
  • pixels continuously arranged on one display electrode pair 14 are referred to as “horizontal pixels”. Therefore, the pixels adjacent above and below the pixel of interest are pixels adjacent to the pixel of interest on one data electrode 22.
  • the pixels adjacent to the left and right of the target pixel are pixels adjacent to the target pixel on one display electrode pair 14.
  • the vertical direction is a direction in which the data electrode 22 extends
  • the horizontal direction is a direction in which the display electrode pair 14 extends.
  • the two-line averaging unit 42 is two pixels adjacent in the vertical direction (two pixels adjacent in the direction orthogonal to the scanning electrode 12), and the writing operation is performed simultaneously when performing the simultaneous writing operation every two lines. An average value of the image signals corresponding to each of the two pixels is calculated. Hereinafter, these two pixels are also referred to as “a pair of pixels”. That is, the 2-line average unit 42 calculates an average value of the image signal corresponding to the pixel on the p-th line and the image signal corresponding to the pixel on the (p + 1) -th line. Hereinafter, this average value is referred to as an “average image signal”. Therefore, the output of the 2-line averaging unit 42 is an average image signal of pixels on the p-th line and the (p + 1) -th line. Note that p is an odd number.
  • the two-line difference unit 43 is two pixels adjacent in the vertical direction (two pixels adjacent in the direction orthogonal to the scanning electrode 12), and performs a write operation simultaneously when performing a two-line simultaneous write operation.
  • the difference value of the image signal corresponding to each of the two pixels (a pair of pixels) is calculated.
  • the two-line difference unit 43 compares the difference value with the gradation weight of the first type subfield.
  • the 2-line difference unit 43 subtracts the image signal corresponding to the pixel on the (p + 1) line from the image signal corresponding to the pixel on the p line to calculate a difference value. Then, the two-line difference unit 43 compares the calculated difference value with the gradation weight Wth of the first type subfield (subfield SF2 in the present embodiment).
  • the gradation weight Wth of the first type subfield (subfield SF2 in the present embodiment) is referred to as “gradation threshold Wth”.
  • the two-line difference unit 43 outputs “1” if the difference value is equal to or greater than the gradation threshold value Wth.
  • the 2-line difference unit 43 outputs “ ⁇ 1” if the difference value is equal to or less than ( ⁇ 1) ⁇ (tone threshold Wth).
  • the 2-line difference unit 43 outputs “0” if the difference value is larger than ( ⁇ 1) ⁇ (gradation threshold value Wth) and less than the gradation threshold value Wth.
  • the two-line difference unit 43 performs the following three operations. 1) When Wth ⁇ (difference value), “1” is output. 2) When -Wth ⁇ (difference value) ⁇ Wth, “0” is output. 3) When (difference value) ⁇ ⁇ Wth, “ ⁇ 1” is output.
  • the subtracting unit 44 subtracts a predetermined variable determined based on the output of the two-line difference unit 43 from the output of the two-line averaging unit 42. That is, the subtracting unit 44 subtracts a predetermined variable determined by the difference value of the image signal of the pair of pixels from the average image signal of the pair of pixels.
  • this predetermined variable is set to “1/2 of the gradation threshold value Wth”. If the output of the 2-line difference unit 43 is “0”, the predetermined variable is set to “0”.
  • the subtraction unit 44 subtracts 1 ⁇ 2 of the gradation threshold value Wth from the average image signal output from the 2-line average unit 42. To do. Then, the subtraction result is output as an image signal of a pixel on the p-th line and a pixel on the (p + 1) -th line (a pair of pixels on the p-th line and the (p + 1) -th line).
  • the subtracting unit 44 uses the average image signal output from the two-line averaging unit 42 as it is as the pixel on the p-th line and the pixel on the (p + 1) -th line. This is output as an image signal (a pair of pixels on the p-th line and the (p + 1) -th line).
  • the average code conversion unit 45 converts the image signal output from the subtraction unit 44 into a subfield code having a predetermined subfield as a non-lighting subfield.
  • This predetermined subfield is a subfield determined by the output of the 2-line difference unit 43 (comparison result in the 2-line difference unit 43).
  • the average code conversion unit 45 converts the image signal of the pair of pixels on the p-th line and the (p + 1) -th line output from the subtraction unit 44 into a subfield code. At this time, if the output of the two-line difference unit 43 is “1” or “ ⁇ 1”, the average code conversion unit 45 in the present embodiment performs the first type subfield (subfield SF2 in the present embodiment). ) To the non-lit subfield.
  • the subfield code output from the average code conversion unit 45 is “X0XXX”.
  • This subfield code represents a lighting subfield as “1” and a non-lighting subfield as “0”, and “X” represents either “0” or “1”. .
  • subfield SF1 subfield SF2
  • subfield SF3 subfield SF4
  • subfield SF5 subfield SF5
  • the difference code creation unit 91 generates a subfield code for controlling the first type subfield (subfield SF2 in the present embodiment), which is a predetermined subfield, based on the output of the two-line difference unit 43.
  • the difference code creation unit 91 sets the subfield code “ -1 ---- "is output. Further, for the image signal of the pixel on the (p + 1) -th line, a subfield code “ ⁇ 0 ⁇ ” is output that sets the subfield SF2 to a non-lighting subfield.
  • the difference code creation unit 91 sets the subfield SF2 as a non-lighting subfield for the image signal of the pixel on the p-th line.
  • the code “ ⁇ 0 ⁇ ” is output.
  • the subfield code “ ⁇ 1 ⁇ ” which outputs the subfield SF2 as the lighting subfield is output.
  • the difference code creation unit 91 applies the subfield SF2 to the image signal of the pixel on the p-th line and the image signal of the pixel on the (p + 1) -th line.
  • the sub-field code “-----” that does not control is output.
  • subfields that are not subject to control are represented by “-”.
  • the image signal processing circuit 31 in the present embodiment synthesizes the output of the average code conversion unit 45 and the output of the difference code creation unit 91 by a logical sum operation in the display code synthesis unit 92. Therefore, the differential code creation unit 91 outputs the bit corresponding to “ ⁇ ” replaced with “0” in consideration of the logical OR operation performed in the subsequent stage.
  • bit is data constituting a subfield code, and a numerical value of 1 or 0 represented by each bit represents lighting or non-lighting in each subfield.
  • the display code synthesis unit 92 creates a display code by synthesizing the subfield code output from the average code conversion unit 45 and the subfield code output from the difference code creation unit 91.
  • the display code synthesis unit 92 includes a subfield code corresponding to the p-th pixel output from the average code conversion unit 45, and a subfield code corresponding to the p-th pixel output from the difference code creation unit 91. Is ORed for each bit. Then, the result of the logical sum operation is output to the data electrode driving circuit 32 as a display code of the pixel on the p-th line.
  • the display code is a subfield code actually used for image display.
  • the display code synthesis unit 92 applies the subfield code corresponding to the (p + 1) line pixel output from the average code conversion unit 45 and the (p + 1) line pixel output from the difference code creation unit 91.
  • the corresponding subfield code is ORed for each bit. Then, the result of the logical sum operation is output to the data electrode driving circuit 32 as the display code of the pixel on the (p + 1) line.
  • the display is performed on the panel 10 even when the simultaneous writing operation is performed every two lines in the writing period in order to shorten the writing period. It is possible to suppress a decrease in the vertical resolution of the image to be displayed.
  • the image signal processing circuit 31 for performing the simultaneous writing operation every two lines with the odd-numbered scan electrode SCp and the next even-numbered scan electrode SCp + 1 as one pair in the write period.
  • the operation of 31 has been described, the present invention is not limited to this configuration.
  • the image signal processing circuit 31 performs the operation on the scan electrode SCp + 1. It is assumed that the same operation as described above is performed with the pixel and the pixel on the scan electrode SCp + 1 as a pair of pixels.
  • FIG. 8A is a diagram schematically showing an example of a write operation in the image signal processing circuit 31 of the image display device 30 according to the embodiment of the present invention.
  • FIG. 8B is a diagram schematically showing another example of the writing operation in the image signal processing circuit 31 of the image display device 30 according to the embodiment of the present invention.
  • FIG. 8C is a diagram schematically showing another example of the writing operation in the image signal processing circuit 31 of the image display device 30 according to the embodiment of the present invention.
  • FIG. 8D is a diagram schematically showing another example of the writing operation in the image signal processing circuit 31 of the image display device 30 according to the embodiment of the present invention.
  • FIG. 8E is a diagram schematically showing another example of the writing operation in the image signal processing circuit 31 of the image display device 30 according to the embodiment of the present invention.
  • FIG. 8F is a diagram schematically showing another example of the writing operation in the image signal processing circuit 31 of the image display device 30 according to the embodiment of the present invention.
  • FIG. 8G is a diagram schematically showing another example of the writing operation in the image signal processing circuit 31 of the image display device 30 according to the embodiment of the present invention.
  • FIG. 8A is a diagram schematically illustrating an example of an image signal input to the image signal processing circuit 31.
  • FIG. 8B is a diagram schematically illustrating an example of an image displayed on the panel 10 when it is assumed that the simultaneous writing operation is performed every two lines in the writing period of all the subfields.
  • FIG. 8C is a diagram schematically illustrating an example of an average image signal output from the two-line average unit 42.
  • FIG. 8D is a diagram schematically illustrating an example of an image signal output from the subtracting unit 44.
  • FIG. 8E is a diagram schematically illustrating an example of the output of the 2-line difference unit 43.
  • FIG. 8F is a diagram schematically showing lighting / non-lighting of the first type subfield based on the subfield code output from the difference code creating unit 91.
  • FIG. 8G is a diagram schematically showing an example of a display image based on the subfield code output from the display code synthesis unit 92.
  • 8A to 8G one column represents one pixel.
  • 8A to 8G (excluding FIG. 8E), white columns represent pixels that are lit, and black columns represent pixels that are not lit.
  • 8E shows the output (“1” or “ ⁇ 1”) of the 2-line difference unit 43, and the output “0” of the 2-line difference unit 43 is indicated by a blank.
  • the 2-line average unit 42 is a circuit block provided to prevent such information loss.
  • the two-line averaging unit 42 calculates an average value of the image signal of the pixel on the p-th line and the image signal of the pixel on the (p + 1) -th line, and outputs them as image signals for the p-th line and the (p + 1) -th line. To do. Thereby, as shown to FIG. 8C, it can prevent that the information which should be displayed on the panel 10 is missing.
  • the first type subfield (in this embodiment, subfield SF2) for performing the writing operation for each line is provided in one field. .
  • the image signal processing circuit 31 includes a two-line difference unit 43 and a difference code creation unit 91.
  • the two-line difference unit 43 is a circuit block for detecting a pixel that should compensate for the decrease in vertical resolution
  • the difference code creation unit 91 is a first-type subfield (this embodiment) for compensating for the decrease in vertical resolution.
  • the circuit block for generating a subfield code for controlling the subfield SF2).
  • the image signal processing circuit 31 includes a subtraction unit 44 and a display code synthesis unit 92.
  • the subtraction unit 44 and the display code synthesis unit 92 are circuit blocks for generating a display code based on the subfield code created by the difference code creation unit 91.
  • the two-line difference unit 43 changes the gradation value to be equal to or higher than the gradation threshold Wth between the image signal of the pixel on the p-th line and the image signal of the pixel on the (p + 1) -th line.
  • Wth the gradation threshold
  • the difference code creation unit 91 turns on the first type subfield (subfield SF2 in the present embodiment) with the pixels marked with “1” in FIG. 8E and does not light up with the pixels marked with “ ⁇ 1”. Create a subfield code. As a result, each pixel is turned on or off in the first type subfield (subfield SF2 in this embodiment) as shown in FIG. 8F. In FIG. 8F, each pixel not shown in the column represents lighting or non-lighting based on the image signal.
  • the subtracting unit 44 uses a pixel in which the output of the two-line difference unit 43 is “1” or “ ⁇ 1” (for example, a pixel marked “1” or “ ⁇ 1” in FIG. 8E) 2), 1/2 of the gradation threshold value Wth is subtracted from the average image signal output from the two-line average unit 42.
  • the average code conversion unit 45 converts the image signal output from the subtraction unit 44 into a subfield code.
  • the first type subfield in this embodiment, the sub-field The field SF2
  • the second type subfield in this embodiment, the subfield excluding the subfield SF2
  • the average code conversion unit 45 converts all the subfields into subfield codes based on the image signal output from the subtraction unit 44 for the other pixels (pixels whose output from the two-line difference unit 43 is “0”). To do.
  • the display code synthesis unit 92 synthesizes the subfield code output from the average code conversion unit 45 and the subfield code output from the difference code creation unit 91 by a logical sum operation, and actually displays the image on the image display.
  • a display code to be used is output to the data electrode drive circuit 32.
  • the image signal processing circuit 31 in the present exemplary embodiment displays an image in which the vertical resolution is prevented from lowering compared to the original image signal (for example, the image shown in FIG. 8A). 10 can be displayed. That is, the image signal processing circuit 31 in the present embodiment has a vertical resolution compared to an image (for example, the image shown in FIG. 8B) when performing the simultaneous writing operation every two lines in the writing period of all subfields. It is possible to improve and display an image of a smooth diagonal line on the panel 10.
  • FIG. 9 is a diagram schematically showing an example of a circuit block constituting the average code conversion unit 45 of the image display device 30 according to the embodiment of the present invention.
  • the average code conversion unit 45 includes an attribute detection unit 49, a base code generation unit 50, a rule generation unit 61, an upper and lower code generation unit 70, and an average code selection unit 80.
  • the attribute detection unit 49 specifies the relationship between the image signal and the position of the pixel displaying the image signal.
  • the time differentiation of the image signal corresponding to each pixel determines whether each pixel is in the moving image area or the still image area. Detect if there is any.
  • a change in brightness is detected by spatial differentiation of the image signal (detecting a change in the image signal between adjacent pixels), and it is detected whether or not each pixel corresponds to the contour portion of the image. Then, those detection results are output as attributes of the image signal corresponding to each pixel.
  • a subfield code that is basic in subsequent signal processing is referred to as a “basic code”, and a code set including the base code is referred to as a “basic code set”.
  • the base code is a subfield code generated by lighting one by one or two in order from the subfield having the smallest gradation weight. Therefore, the base code is a subfield code in which a subfield having the largest gradation weight among the subfields to emit light and all subfields having a gradation weight smaller than that subfield emit light.
  • “deleted base code” is set based on the base code set.
  • the deleted base code is a subfield code in which a predetermined subfield determined by the output of the two-line difference unit 43 among the lighting subfields of the base code is a non-lighting subfield.
  • a subfield code set in which a predetermined subfield determined by the output of the two-line difference unit 43 is a non-lighting subfield is referred to as a “deleted base code set”.
  • the base code generation unit 50 selects “base code set” or “deleted base code set” based on the tone value of the image signal output from the subtraction unit 44 (hereinafter referred to as “input tone”). Select "Upper gradation basis code”.
  • the upper tone base code is a base code or a deleted base code having a tone value larger than the input tone and having a tone value closest to the input tone.
  • the base code generation unit 50 selects a base code having a gradation value larger than the input gradation and closest to the input gradation in the base code set as the upper gradation base code, Output.
  • the base code generation unit 50 selects a deleted base code having a gradation value larger than the input gradation and closest to the input gradation as the upper gradation base code in the deleted base code set, Output it.
  • FIG. 10A is a diagram illustrating an example of a base code set used in the image display device 30 according to an embodiment of the present invention.
  • FIG. 10B is a diagram showing an example of a deleted base code set used in the image display device 30 according to the embodiment of the present invention.
  • the light-emitting subfield is “1”
  • the non-light-emitting subfield is blank
  • each subfield code (base code or deleted) is displayed in the second column from the left.
  • base code represents a gradation value to be displayed in (base code).
  • the numerical value written immediately below the notation indicating each subfield in each code set represents the gradation weight of each subfield.
  • FIG. 10A shows a base code set used when the output of the 2-line difference unit 43 is “0”.
  • one field is composed of five subfields, and each subfield is “1”, “10”, “6”, “3”, “3” in order from the subfield SF1. 2 "gradation weight.
  • the first subfield (subfield SF1) of one field is the subfield having the smallest gradation weight
  • the second subfield (subfield SF2) is the subfield having the largest gradation weight.
  • the subfields are arranged so that the gradation weights are sequentially reduced. And it is set as a lighting subfield one by one in an order from the subfield with the smallest gradation weight. Therefore, the number of base codes included in this base code set is (the number of subfields constituting one field + 1). For example, in the example of the base code set shown in FIG. 10A, the number of base codes is 6.
  • FIG. 10B shows a deleted base code set used when the output of the 2-line difference unit 43 is “1” or “ ⁇ 1”.
  • the deleted base code set shown in FIG. 10B is a subfield code set generated from the base code set shown in FIG. 10A with a predetermined subfield determined by the output of the two-line difference unit 43 as a non-lighting subfield. is there.
  • this predetermined subfield is a first type subfield (in this embodiment, subfield SF2). Therefore, the deleted base code set shown in FIG. 10B is a subfield code set in which the subfield SF2 is a non-lighting subfield from the base code set shown in FIG. 10A.
  • the subfield SF2 is a subfield having the largest gradation weight. Therefore, the deleted base code set shown in FIG. 10B is equal to the code set obtained by removing the base code “11111” having the gradation value “22” from the base code set shown in FIG. 10A.
  • the image display device 30 in the present embodiment generates a new code set based on the code set as described above, and converts the input gradation into a subfield code using the code set.
  • the base code generation unit 50 includes a base code set selection unit 52 and a base code selection unit 54.
  • the base code set selection unit 52 stores the base code set and gradation values of a plurality of base codes constituting the base code set. In addition, the base code set selection unit 52 stores the gradation values of the deleted base code set and the plurality of deleted base codes constituting the deleted base code set. Each base code and each gradation value of the base code are stored in the base code set selection unit 52 in association with each other.
  • This base code set is, for example, the base code set shown in FIG. 10A.
  • Each deleted base code and each gradation value of the deleted base code are stored in the base code set selection unit 52 in association with each other.
  • This deleted base code set is, for example, the deleted base code set shown in FIG. 10B.
  • the base code set selection unit 52 selects a base code set (for example, the base code set shown in FIG. If the output is “1” or “ ⁇ 1”, the deleted base code set (for example, the deleted base code set shown in FIG. 10B) is selected.
  • the base code selection unit 54 includes a subfield code (a base code constituting the base code set or a deleted base code constituting the deleted base code set) constituting the code set selected by the base code set selection unit 52. Code) and the input gradation are compared. Then, a subfield code (base code or deleted base code) having a gradation value larger than the input gradation and closest to the input gradation is selected. Then, the selected subfield code is output as the upper gradation base code.
  • a subfield code a base code constituting the base code set or a deleted base code constituting the deleted base code set
  • the base code generation unit 50 selects a base code (or a deleted base code) having a gradation value larger than the input gradation and closest to the input gradation, and uses the selected base code as the upper gradation base. Output as code.
  • a new subfield code not included in the base code set is obtained by changing the lighting subfield in the upper gradation base code to the non-lighting subfield based on the image signal output from the subtracting unit 44. Is generated.
  • the rule generation unit 61 generates a rule for generating this new subfield code.
  • the rule generation unit 61 increases the number of subfield codes used for image display, the image signal output from the subtraction unit 44, and the attribute detected by the attribute detection unit 49 (the attribute associated with the image signal). ) To generate a rule for changing the lighting subfield in the upper gradation base code selected by the base code generation unit 50 to the non-lighting subfield.
  • the rule generated by the rule generation unit 61 defines a rule for changing the lighting subfield in the upper gradation base code to the non-lighting subfield.
  • the rule generated by the rule generation unit 61 restricts subfields to be changed from lighting to non-lighting in the upper gradation base code. This is because the gradation value of the new subfield code created by changing the lighting subfield to the non-lighting subfield in the upper gradation basis code is smaller than the upper gradation basis code (or the deleted basis). This is so that it does not fall below the gradation value of (code).
  • the upper gradation base code allows unlimited subfields to change from lighting to non-lighting, all lighting subfields become non-lighting subfields, and subfield codes with a gradation value of “0” are generated. This is because there is a possibility that it may occur.
  • the rule generation unit 61 generates a rule so that the subfield code generated based on the rule has the next gradation value.
  • the “lower gradation base code” is a base code (or a deleted base code) having a gradation value that is equal to or lower than the input gradation and closest to the input gradation.
  • the rule generated by the rule generation unit 61 is composed of one or more of the following three rules. 1) A rule for setting the first subfield to be changed from the lighting subfield to the non-lighting subfield. 2) A rule for setting the second subfield to be changed from the lighting subfield to the non-lighting subfield. 3) A rule for setting a sub-field that prohibits non-lighting.
  • the upper / lower code generation unit 70 applies the rule generated by the rule generation unit 61 to the upper gradation base code output from the base code generation unit 50 to generate an upper gradation code and a lower gradation code.
  • the upper gradation code is a sub-field code that can be newly generated based on the rule generated by the rule generation unit 61 and has a gradation value larger than the input gradation and closest to the input gradation. It is a field code.
  • the lower gradation code has a gradation value that is equal to or lower than the input gradation and closest to the input gradation among subfield codes that can be newly generated based on the rule generated by the rule generation unit 61. It is a subfield code.
  • the upper / lower code generation unit 70 includes an intermediate code generation unit 72 and an upper / lower code selection unit 74.
  • the intermediate code generation unit 72 changes the lighting subfield in the upper gradation base code to the non-lighting subfield and generates a new subfield code.
  • the newly generated subfield code is referred to as “intermediate code”.
  • a set obtained by adding the original upper tone base code to these intermediate codes is referred to as an “intermediate code set”.
  • FIG. 11A is a diagram illustrating an example of an intermediate code set generated by the intermediate code generation unit 72 of the image display device 30 according to the embodiment of the present invention.
  • FIG. 11B is a diagram illustrating another example of the intermediate code set generated by the intermediate code generation unit 72 of the image display device 30 according to the embodiment of the present invention.
  • FIG. 11C is a diagram illustrating another example of the intermediate code set generated by the intermediate code generation unit 72 of the image display device 30 according to the embodiment of the present invention.
  • the light emitting subfield is indicated by “1”
  • the non-light emitting subfield is indicated by a blank
  • each subfield code (intermediate) is indicated in the second column from the left.
  • Code) represents the gradation value to be displayed.
  • the numerical value written immediately below the notation indicating each subfield in each intermediate code set represents the gradation weight of each subfield.
  • one field includes five subfields, and each subfield is “1”, “10”, and “6” in order from the subfield SF1. , “3” and “2”.
  • FIG. 11A as an example of the intermediate code set, “1) Rules for setting the first subfield to be changed from the lighting subfield to the non-lighting subfield” are shown in FIGS. 10A and 10B.
  • rule 1 This “1) rule for setting the first subfield to be changed from a lighting subfield to a non-lighting subfield” is a rule that “one of the lighting subfields is changed to a non-lighting subfield”. (Hereinafter referred to as “rule 1”).
  • the subfield SF1 and four subfields from the subfield SF3 to the subfield SF5 are lit. It becomes a subfield.
  • the subfield code “10011” obtained by changing the subfield SF3 to the non-lighting subfield is the base code (or the deleted base code) of the gradation value “6” shown in FIG. 10A (or FIG. 10B) (No. It is equal to 4). Accordingly, three subfield codes excluding the subfield code “10011” are newly generated intermediate codes.
  • FIG. 11B as an example of the intermediate code set, in addition to the above-described rule 1, “2) a rule for setting the second subfield to be changed from the lighting subfield to the non-lighting subfield” is shown in FIG.
  • Rule 2 for setting the second subfield to be changed from the lighting subfield to the non-lighting subfield is “the subfield code having the smallest gradation value among the newly generated intermediate codes”.
  • the sub-field SF5 is a non-lighting sub-field ”(hereinafter referred to as“ rule 2 ”).
  • rule 1 By applying rule 1 to the base code of gradation value “12” shown in FIG. 10A (or the deleted base code of gradation value “12” shown in FIG. 10B) “10111” (No. 5). As shown in FIG. 11A, three new subfield codes are generated. Of these three subfield codes, the “subfield code with the smallest gradation value among the newly generated intermediate codes” is the subfield code “10101” with the gradation value “9”.
  • rule 1 and rule 2 are applied to the base code of the gradation value “12” shown in FIG. 10A (or the deleted base code of the gradation value “12” shown in FIG. 10B) “10111”. Then, four new subfield codes can be generated as intermediate codes.
  • FIG. 9C as an example of the intermediate code set, in addition to the above-described rule 1, “3) a rule for setting a subfield that prohibits non-lighting” is shown in the gradation value ““3 a rule for setting a subfield that prohibits non-lighting” is shown in the gradation value “3 a rule for setting a subfield that prohibits non-lighting” is shown in the gradation value “3 a rule for setting a subfield that prohibits non-lighting” is shown in the gradation value “ The intermediate code set generated by applying to the base code of “12” (or the deleted base code of the gradation value “12” shown in FIG. 10B) “10111” is shown.
  • rule 3 This “3) rule for setting a subfield that prohibits non-lighting” is a rule that “subfield SF1 is prohibited from being a non-lighting subfield” (hereinafter referred to as “rule 3”). ).
  • rule 1 By applying rule 1 to the base code of gradation value “12” shown in FIG. 10A (or the deleted base code of gradation value “12” shown in FIG. 10B) “10111” (No. 5). As shown in FIG. 11A, three new subfield codes are generated. Of these three subfield codes, the “subfield code whose subfield SF1 is a non-lighting subfield” is a subfield code “00111” having a gradation value of “11”.
  • rule 1 and rule 3 described above are applied to the base code of the gradation value “12” shown in FIG. 10A (or the deleted base code of the gradation value “12” shown in FIG. 10B) “10111”. Then, two new subfield codes can be generated as intermediate codes.
  • the intermediate code generation unit 72 applies the rule generated by the rule generation unit 61 to the upper gradation base code output from the base code generation unit 50 to generate an intermediate code, and the intermediate code set Is generated.
  • rule 1 and rule 3 are used when generating intermediate code.
  • rule 2 may be added when generating intermediate code.
  • the image display device 30 displays an image with relatively low power consumption, or when an image with relatively little occurrence of moving image pseudo contour is displayed, the number of intermediate codes generated can be increased. It is. Then, by increasing the number of intermediate codes generated, an image can be displayed with a smoother gradation change.
  • the upper / lower code selection unit 74 compares each gradation value of the subfield code constituting the intermediate code set generated by the intermediate code generation unit 72 with the input gradation. Then, the upper / lower code selection unit 74 selects a subfield code having a gradation value larger than the input gradation and closest to the input gradation, and outputs it as an upper gradation code. In addition, the upper / lower code selection unit 74 selects a subfield code having a gradation value equal to or lower than the input gradation and closest to the input gradation, and outputs it as a lower gradation code.
  • the average code selection unit 80 adds a predetermined value to the input gradation and calculates a gradation value to be displayed on the pixel pair of interest. Then, the average code selection unit 80 selects one of the upper gradation code and the lower gradation code that has a gradation value closer to the gradation value to be displayed on the target pixel pair, and outputs it.
  • the pixel-of-interest pair is a pair of pixels that are the targets of gradation value calculation at that time.
  • the above-described predetermined value added to the input gradation is an error diffused by the error diffusion process and a dither value calculated by the dither process. Therefore, the average code selection unit 80 adds the error and the dither value to the input gradation, calculates the gradation value to be displayed on the pixel pair of interest, and selects the attention value of the upper gradation code and the lower gradation code. The one having a gradation value closer to the gradation value to be displayed on the pixel pair is selected.
  • the average code selection unit 80 calculates the difference between the gradation value to be displayed on the target pixel pair and the selected gradation value, and diffuses the difference as an error to surrounding pixels.
  • the average code selection unit 80 includes a dither selection unit 82, an error diffusion unit 84, and an average code determination unit 86.
  • the dither selection unit 82 stores a plurality of dither patterns. Then, one dither pattern based on the image signal output from the subtraction unit 44 (hereinafter simply referred to as “image signal”) and the attribute detected by the attribute detection unit 49 from among the plurality of stored dither patterns. Select.
  • the dither selection unit 82 selects a dither element corresponding to the position of the pixel from the selected dither pattern based on the position of the pixel displaying the image signal. Further, the dither selection unit 82 calculates the dither value by multiplying the selected dither element by the difference between the gradation value of the upper gradation code and the gradation value of the lower gradation code.
  • the same dither element is given to each of a pair of pixels that simultaneously perform the write operation in the second type subfield.
  • FIG. 12A is a diagram showing an example of a dither pattern used in the image display device 30 according to the embodiment of the present invention.
  • FIG. 12B is a diagram showing another example of the dither pattern used in the image display device 30 according to the embodiment of the present invention.
  • one column represents one pixel.
  • FIG. 12A shows the simplest binary dither.
  • “+0.25” and “ ⁇ 0.25” are arranged in a checkered pattern as dither elements.
  • FIG. 12B is a diagram showing an example of a quaternary dither. In FIG. 12B, dither elements “+0.375”, “+0.125”, “ ⁇ 0.375” and “ ⁇ 0.125” are arranged.
  • the error diffusion unit 84 outputs an error to be added to the target pixel pair to the average code determination unit 86 and diffuses the error output from the average code determination unit 86 to the peripheral pixels of the target pixel pair.
  • the error diffusion unit 84 diffuses the same error to each of a pair of pixels that simultaneously perform the write operation in the second type subfield.
  • the dither selection unit 82 stores, for example, the two types of dither patterns shown in FIGS. 12A and 12B, and selects one of the dither patterns based on the attributes detected by the image signal and the attribute detection unit 49. .
  • the dither pattern shown in FIG. 12A is selected, the dither element is either “+0.25” or “ ⁇ 0.25”.
  • the dither element shown in FIG. 12B is selected, the dither element is “+0”. .375 ”,“ +0.125 ”,“ ⁇ 0.375 ”, and“ ⁇ 0.125 ”.
  • the dither selection unit 82 selects any one of these dither elements based on the position of the pixel displaying the image signal. Further, the dither value is calculated by multiplying the selected dither element by the difference between the tone value of the upper tone code and the tone value of the lower tone code. Then, the calculated dither value is added to the input gradation in the average code selection unit 80.
  • FIG. 13 is a diagram showing error diffusion coefficients of the error diffusion unit 84 of the image display device 30 according to the embodiment of the present invention.
  • one column represents one pixel.
  • the middle column in FIG. 13 represents a pair of pixels (target pixel pair) that are to be subjected to error diffusion processing.
  • the error diffusion unit 84 diffuses (adds) a value obtained by multiplying the error generated in the pair of pixels arranged at the upper left of the target pixel pair by the diffusion coefficient k1 to the target pixel pair. Further, the error diffusion unit 84 diffuses (adds) a value obtained by multiplying the error generated in the pair of pixels arranged on the target pixel pair by the diffusion coefficient k2 to the target pixel pair. Further, the error diffusion unit 84 diffuses (adds) a value obtained by multiplying the error generated in the pair of pixels arranged at the upper right of the target pixel pair by the diffusion coefficient k3 to the target pixel pair. Further, the error diffusion unit 84 diffuses (adds) a value obtained by multiplying an error generated in a pair of pixels arranged on the left of the target pixel pair by a diffusion coefficient k4.
  • the error diffusion unit 84 diffuses (adds) a value obtained by multiplying the error generated in the target pixel pair by the diffusion coefficient k4 to a pair of pixels arranged to the right of the target pixel pair. In addition, the error diffusion unit 84 diffuses (adds) a value obtained by multiplying the error generated in the target pixel pair by the diffusion coefficient k3 to a pair of pixels arranged at the lower left of the target pixel pair. Further, the error diffusion unit 84 diffuses (adds) a value obtained by multiplying the error generated in the target pixel pair by the diffusion coefficient k2 to a pair of pixels arranged below the target pixel pair. In addition, the error diffusion unit 84 diffuses (adds) a value obtained by multiplying the error generated in the target pixel pair by the diffusion coefficient k1 to a pair of pixels arranged at the lower right of the target pixel pair.
  • which diffusion coefficient is selected is determined using a random number generated by a random number generator (not shown).
  • the average code determination unit 86 converts the subfield code output to the subsequent stage into the upper tone code or the lower tone code. Determine one of the gradation codes.
  • the average code determination unit 86 adds a dither value and an error to the input gradation, and calculates a gradation value to be displayed on the target pixel pair. Then, of the upper gradation code and the lower gradation code, the one having the gradation value closer to the gradation value to be displayed on the target pixel pair is selected as the subfield code to be output to the subsequent stage.
  • the average code determination unit 86 calculates a difference between the gradation value to be displayed on the target pixel pair and the gradation value of the selected subfield code, and uses the difference as a newly generated error. Output to.
  • FIG. 14 is a flowchart showing the operation of the image signal processing circuit 31 of the image display device 30 according to the embodiment of the present invention.
  • the image signal processing circuit 31 executes the following series of steps.
  • Step S42 The 2-line averaging unit 42 calculates an average value of the image signal corresponding to the target pixel on the p-th line and the image signal corresponding to the target pixel on the (p + 1) -th line. Then, the calculation result is output as an average image signal of the target pixel pair on the p-th line and the (p + 1) -th line.
  • the line average unit 42 outputs “11.5” as the gradation value of the average image signal of the target pixel pair in the p-th line and the (p + 1) -th line.
  • Step S43 The two-line difference unit 43 calculates a difference value by subtracting the image signal corresponding to the target pixel on the (p + 1) line from the image signal corresponding to the target pixel on the p-th line. Then, the difference value is compared with the gradation threshold value Wth, and the comparison result is output.
  • the two-line difference unit 43 outputs “1” if the difference value is equal to or greater than the gradation threshold Wth, and “ ⁇ 1” if the difference value is equal to or less than ( ⁇ 1) ⁇ (gradation threshold Wth). Is output, and if the difference value is larger than ( ⁇ 1) ⁇ (tone threshold Wth) and less than the tone threshold Wth, “0” is output.
  • the gradation threshold value Wth is a numerical value equal to the gradation weight of the first type subfield (subfield SF2 in the present embodiment). Therefore, for example, if the gradation weight of the subfield SF2 is “10”, the gradation threshold value Wth is “10”. At this time, the difference value “ ⁇ 13” is equal to or less than ( ⁇ 1) ⁇ (tone threshold Wth). Therefore, the two-line difference unit 43 outputs “ ⁇ 1”.
  • Step S44 If the output of the two-line difference unit 43 is “1” or “ ⁇ 1”, the subtraction unit 44 subtracts 1 ⁇ 2 ⁇ tone threshold Wth from the average image signal of the target pixel pair, and the result is p-line It outputs as an image signal of the target pixel pair of the eye and the (p + 1) -th line. If the output of the two-line difference unit 43 is “0”, the subtracting unit 44 outputs the average image signal of the target pixel pair as it is.
  • the subtracting unit 44 outputs “6.5” as the gradation value of the target pixel pair on the p-th line and the (p + 1) -th line.
  • the attribute detection unit 49 of the average code conversion unit 45 receives the image signal (input gradation) of the target pixel pair on the p-th line and the (p + 1) -th line output from the subtraction unit 44.
  • the attribute detection unit 49 detects an attribute associated with the image signal.
  • the image signal corresponding to the pixel pair of interest has a gradation value (input gradation) of “6.5”, and the attribute attached to the image signal corresponding to the pixel pair of interest in the attribute detection unit 49 is a moving image.
  • the description will be made assuming that the detection result of the contour portion is obtained.
  • the base code set selection unit 52 of the average code conversion unit 45 is either a base code set stored in the base code set selection unit 52 or a deleted base code set. Select. If the output of the 2-line difference unit 43 is “0”, the base code set selection unit 52 selects a base code set (for example, the base code set shown in FIG. 10A), and the output of the 2-line difference unit 43 is If it is “1” or “ ⁇ 1”, the deleted base code set (for example, the deleted base code set shown in FIG. 10B) is selected.
  • Step S54 The base code selection unit 54 of the average code conversion unit 45 selects the upper tone base code for the input tone.
  • step S54 the gradation that is larger than the gradation value (input gradation) of the image signal in the pixel pair of interest and is closest to the input gradation from the code set selected by the base code set selection unit 52.
  • a subfield code having a value is selected as the upper gradation base code.
  • the base code selection unit 54 sets each gradation value of the base code constituting the base code set stored in the base code set selection unit 52 (or the deleted base code constituting the deleted base code set). Are compared with the input gradation. Then, a base code (or a deleted base code) having a gradation value larger than the input gradation and closest to the input gradation is selected, and is output as an upper gradation base code.
  • the base code set selection unit 52 selects the deleted base code set shown in FIG. 10B. . Then, the base code selection unit 54 has a gradation value that is larger than the gradation value “6.5” and closest to the gradation value “6.5” in the deleted base code set shown in FIG. 10B. Select the deleted base code. At this time, the deleted base code “10111” having the gradation value “12” is the deleted base code having the gradation value larger than the gradation value “6.5” and having the gradation value closest to the gradation value “6.5”. Is. Therefore, the base code selection unit 54 selects the deleted base code “10111” and outputs it as the upper gradation base code.
  • Step S61 The rule generation unit 61 of the average code conversion unit 45 generates a rule for generating an intermediate code set.
  • step S61 a rule for generating a new subfield code by changing the light emitting subfield in the upper gradation base code to a non-light emitting subfield is generated based on the image signal in the pixel pair of interest.
  • the rule generation unit 61 performs a basic rule (rule 1) “change any one of the lighting subfields to the non-lighting subfield” if the attribute attached to the image signal is a still image. ) Is generated.
  • the rule generation unit 61 restricts the subfield codes that can be used for displaying the image in order to suppress the moving image pseudo contour.
  • the subfield codes include those that have a high effect of suppressing moving image pseudo contours and those that do not.
  • the subfield codes shown in FIGS. 10A and 10B are subfield codes that have a high effect of suppressing the moving image pseudo contour.
  • the appearance of the moving image pseudo contour depends on the subfield code that can be used to display the image, and the image is displayed using the subfield code that is highly effective in suppressing the moving image pseudo contour.
  • the moving image pseudo contour can be suppressed.
  • the subfield code that can be used for displaying an image is limited as compared with the case where the suppression of the moving image pseudo contour is unnecessary. This is the reason why the rule generation unit 61 restricts the subfield codes that can be used for image display in order to suppress the moving image pseudo contour.
  • the rule generating unit 61 sets “a subfield that prohibits non-lighting” in the basic rule 1 in order to suppress the moving image pseudo contour. Add “When the rule”.
  • This additional rule is, for example, the rule 3 described with reference to FIG. 11C, which is “prohibiting the subfield SF1 from being a non-lighting subfield”.
  • the rule generation unit 61 limits the subfield codes that can be used for displaying an image.
  • the rule generated by the rule generation unit 61 is that the attribute attached to the image signal is a still image.
  • the rule generation unit 61 includes a rule generated when the image signal in the pixel pair of interest is a still image.
  • Step S72 The intermediate code generation unit 72 of the average code conversion unit 45 generates an intermediate code set.
  • the intermediate code generation unit 72 generates an intermediate code from the upper gradation base code based on the rules generated by the rule generation unit 61, and generates an intermediate code set.
  • the code generation unit 72 applies the rules 1 and 3 generated by the rule generation unit 61 to the base code “10111” to generate a new intermediate code.
  • subfield SF1 and subfield SF3 to subfield SF5 which are lighting subfields of the deleted base code “10111”
  • the subfield (from subfield SF3 to subfield SF1 is excluded based on rule 3).
  • the subfield SF5) is to be replaced with a non-lighting subfield.
  • the subfields SF3 to SF5 are set to non-lighting subfields.
  • the intermediate code generating unit 72 generates three intermediate codes “10011”, “10101”, and “10110”.
  • the intermediate code set thus obtained is, for example, the intermediate code set shown in FIG. 11C.
  • Step S74 The upper / lower code selection unit 74 of the average code conversion unit 45 selects an upper gradation code and a lower gradation code.
  • step S74 the gradation of the image signal in the target pixel pair is larger than the gradation value of the image signal in the target pixel pair from the intermediate code set generated by applying the above-described rule to the upper gradation base code.
  • the subfield code having the gradation value closest to the value is selected as the upper gradation code, and the gradation closest to the gradation value of the image signal in the target pixel pair is equal to or smaller than the gradation value of the image signal in the target pixel pair
  • a subfield code having a value is selected as a lower gradation code.
  • the upper / lower code selection unit 74 compares each gradation value of the subfield code constituting the intermediate code set with the input gradation. Then, a subfield code having a gradation value larger than the input gradation and closest to the input gradation is selected and output as an upper gradation code. Also, a subfield code having a gradation value that is equal to or lower than the input gradation and closest to the input gradation is selected, and is output as a lower gradation code.
  • the subfield code corresponding to the upper gradation code is This is a subfield code of gradation value “9”.
  • the subfield code corresponding to the lower gradation code is a subfield code having a gradation value “6”. Therefore, the upper / lower code selection unit 74 selects the subfield code “10101” having the gradation value “9” as the upper gradation code and the subfield code “10011” having the gradation value “6” as the lower gradation code. ”Is selected.
  • Step S82 The dither selection unit 82 of the average code conversion unit 45 selects a dither element based on the attribute of the image signal.
  • the dither selection unit 82 uses the attribute detected by the image signal and attribute detection unit 49. Based on the above, one of the dither patterns is selected.
  • the dither pattern shown in FIG. 12A is selected. If the attribute attached to the image signal is not a contour portion, the dither pattern shown in FIG. 12B is selected. If the selection unit 82 is set, when the attribute attached to the image signal is a contour portion, the dither selection unit 82 selects the dither pattern shown in FIG. 12A. Then, the dither selection unit 82 selects one of the dither elements set in the dither pattern based on the position of the target pixel pair. For example, the dither selection unit 82 selects “0.25” as the dither element based on the dither pattern shown in FIG. 2A.
  • Step S83 The dither selector 82 calculates a dither value.
  • the dither selection unit 82 calculates the dither value by multiplying the selected dither element by the difference between the tone value of the upper tone code and the tone value of the lower tone code.
  • the upper gradation code selected in step S74 is the gradation value “9”
  • the gradation value of the lower gradation code selected in step S74 is “6”
  • the dither selected in step S82 If the element is “0.25”, the dither selector 82 multiplies the difference “3” between the gradation value of the upper gradation code and the gradation value of the lower gradation code by the dither element “0.25”. Then, the dither value “0.75” is calculated.
  • Step S86 The average code determination unit 86 of the average code conversion unit 45 calculates a gradation value to be displayed on the target pixel pair.
  • step S86 a predetermined value is added to the gradation value of the image signal in the target pixel pair to calculate the gradation value to be displayed on the target pixel pair.
  • the average code determination unit 86 adds the dither value calculated in step S83 to the input gradation, and further adds the error output from the error diffusion unit 84 based on the calculation result in step S88.
  • the gradation value to be displayed on the target pixel pair is calculated. Therefore, the predetermined value is a numerical value obtained by adding the dither value output from the dither selection unit 82 and the error output from the error diffusion unit 84.
  • the input gradation is the gradation value “6.5”
  • the dither value calculated in step S83 is “0.75”
  • Step S87 The average code determination unit 86 determines a subfield code to be used when displaying a gradation value on the target pixel pair.
  • step S87 the one having the gradation value closer to the gradation value to be displayed on the target pixel pair among the upper gradation code and the lower gradation code is selected as the subfield code to be output to the subsequent stage.
  • the average code determination unit 86 compares the gradation value to be displayed on the target pixel pair with the gradation value of the upper gradation code and the gradation value of the lower gradation code. If the tone value to be displayed on the target pixel pair is closer to the tone value of the upper tone code than the tone value of the lower tone code, it is used to display the tone value on the target pixel pair.
  • the upper gradation code is selected as the subfield code to be output, and is output.
  • the gradation value to be displayed on the target pixel pair is closer to the lower gradation code gradation value than the upper gradation code gradation value, the gradation value is displayed on the attention pixel pair.
  • a lower gradation code is selected as a subfield code to be used, and is output.
  • the gradation value of the upper gradation code is “9”, the gradation value of the lower gradation code is “6”, and the gradation value to be displayed on the target pixel pair is “7.15”.
  • the difference between the gradation value of the upper gradation code and the gradation value to be displayed on the target pixel pair is “1.85”, and the gradation value to be displayed on the lower pixel code and the target pixel pair The difference from the value is “1.15”. Therefore, in this case, the average code determination unit 86 selects the lower gradation code “10011” having the gradation value “6” and outputs it to the subsequent stage.
  • Step S88 The average code determination unit 86 calculates a newly generated error and outputs it to the error diffusion unit 84.
  • the average code determination unit 86 subtracts the gradation value of the subfield code selected for output to the subsequent stage from the gradation value to be displayed on the pixel pair of interest, and the subtraction result is error diffusion as a newly generated error. To the unit 84.
  • the average code determination unit 86 outputs “1.15” to the error diffusion unit 84 as a newly generated error.
  • Step S91 Based on the output of the two-line difference unit 43, the difference code creation unit 91 generates a subfield code for controlling the first type subfield (subfield SF2 in the present embodiment) that performs the write operation for each line during the write period. Generate.
  • the difference code creation unit 91 sets the first type subfield to the lighting subfield for the image signal of the pixel of interest on the p-th line. And a subfield code for making the first type subfield a non-lighting subfield is output for the image signal of the target pixel on the (p + 1) -th line.
  • the difference code creation unit 91 sets the first type subfield to the non-lighting subfield for the image signal of the target pixel on the p-th line. And outputs a subfield code for setting the first type subfield to the lighting subfield for the image signal of the target pixel on the (p + 1) -th line.
  • the difference code creation unit 91 applies the first to the image signal of the target pixel of the p-th line and the image signal of the target pixel of the (p + 1) -th line. A subfield code that does not control one type of subfield is output.
  • the difference code creation unit 91 does not process the image signal of the pixel of interest on the p-th line.
  • a subfield code “ ⁇ 1 ⁇ ” that outputs the subfield SF2 as a lighting subfield is output.
  • a subfield that is not subject to control is represented by “ ⁇ ”.
  • “ ⁇ ” is set to “0” in consideration of a logical operation in a later stage. Yes. Therefore, the difference code creation unit 91 outputs the above-described subfield code “ ⁇ 0 ⁇ ” as the subfield code “00000”, and outputs the above subfield code “ ⁇ 1 ⁇ ” as the subfield code “01000”. "Is output.
  • Step S92 The display code synthesis unit 92 synthesizes the subfield code output from the average code conversion unit 45 and the subfield code output from the difference code creation unit 91 to create a display code.
  • the display code synthesis unit 92 includes the sub-field code corresponding to the p-th pixel of interest output from the average code converter 45 and the p-th pixel of interest output from the difference code creation unit 91.
  • the sub-field code corresponding to is ORed for each bit. Then, the result of the logical sum operation is output to the data electrode drive circuit 32 as a display code of the pixel of interest on the p-th line.
  • the display code synthesis unit 92 also outputs the subfield code corresponding to the pixel of interest on the (p + 1) th line output from the average code conversion unit 45 and the target of the (p + 1) th line output from the difference code creation unit 91.
  • the subfield code corresponding to the pixel is ORed for each bit. Then, the result of the logical sum operation is output to the data electrode driving circuit 32 as the display code of the pixel on the (p + 1) line.
  • the display code is a subfield code actually used for image display.
  • the display code synthesis unit 92 “10011” is output as the display code of the pixel of interest on the line.
  • the display code synthesis unit 92 “11011” is output as the display code of the pixel of interest on the (p + 1) -th line.
  • step S92 ends, the process returns to step S42. In this way, a series of steps from step S42 to step S92 is repeatedly executed.
  • one field is constituted by the first type subfield that performs the write operation for each line during the write period and the second type subfield that performs the simultaneous write operation for every two lines during the write period. To do.
  • the difference value of the image signal corresponding to a pair of pixels (target pixel pair) performing the write operation at the same time in the second type subfield is smaller than the gradation weight of the first type subfield, it corresponds to the target pixel pair.
  • the average value of the image signal to be converted is converted into a display code.
  • the time required for the writing period can be shortened while preventing the image display quality in the image display device 30 from deteriorating.
  • conversion from an image signal to a display code is performed using a conversion table including a number of subfield codes. Rather than doing so, it can be done by an arithmetic circuit.
  • conversion from an image signal to a display code can be performed by calculation using an arithmetic circuit. Therefore, even in such an image display device, it is not necessary to provide a huge number of conversion tables, but a necessary minimum table (for example, the base code set shown in FIG. 10A and the deleted base code shown in FIG. 10B). Set) and an arithmetic circuit for converting the image signal into the display code.
  • the conversion from the image signal to the subfield code can be performed by the logical operation, which is necessary for the writing period while preventing the image display quality from being deteriorated. Time can be shortened.
  • subfield SF2 in the present embodiment only the subfield having the largest gradation weight (subfield SF2 in the present embodiment) is the first type subfield, and the other subfields are the second type subfield.
  • the present invention is not limited to this configuration.
  • FIG. 15 is a diagram schematically showing another example of a drive voltage waveform applied to each electrode of panel 10 used in image display device 30 in one embodiment of the present invention.
  • FIG. 15 shows data electrode D1 to data electrode Dm, scan electrode SC1 that performs the address operation first in the address period, scan electrode SCn that performs the address operation last in the address period (for example, scan electrode SC1080), sustain electrode SU1 to The drive voltage waveform applied to each of the sustain electrodes SUn is shown.
  • one field is composed of five subfields (subfield SF1, subfield SF2, subfield SF3, subfield SF4, subfield SF5), and subfield SF1 to subfield SF5 It is assumed that gradation weights of (1, 10, 6, 3, 2) are set in each subfield.
  • subfield SF1 is a forced initialization subfield and is a second type subfield.
  • the subfield SF2 and the subfield SF3 are selective initialization subfields and are type 1 subfields.
  • Each subfield after subfield SF4 is a selective initialization subfield and is a second type subfield.
  • a subfield having the largest gradation weight for example, subfield SF2
  • a subfield having the second largest gradation weight for example, subfield SF3
  • the first type subfield that performs each write operation may be used, and the other subfield may be the second type subfield that performs the simultaneous write operation every two lines during the write period.
  • the gradation weight Wth of the first type subfield (subfield SF2 in FIG. 15) having the largest gradation weight is set to the first gradation threshold Wth1, and the gradation weight is the second.
  • the gradation weight Wth of the large first type subfield (subfield SF3 in FIG. 15) is set as the second gradation threshold Wth2.
  • the two-line difference unit 43 compares the calculated difference value (difference value of the image signal corresponding to each pixel of the target pixel pair) with the first gradation threshold Wth1 and the second gradation threshold Wth2.
  • the 2-line difference unit 43 outputs “2” if the difference value is equal to or greater than the first gradation threshold Wth1.
  • the two-line difference unit 43 outputs “1” if the difference value is less than the first gradation threshold value Wth1 and greater than or equal to the second gradation threshold value Wth2.
  • the 2-line difference unit 43 outputs “0” if the difference value is less than the second gradation threshold Wth2 and greater than ( ⁇ 1) ⁇ (second gradation threshold Wth2).
  • the two-line difference unit 43 outputs “ ⁇ 1” if the difference value is equal to or smaller than ( ⁇ 1) ⁇ (second gradation threshold Wth2) and is larger than ( ⁇ 1) ⁇ (first gradation threshold Wth1). To do.
  • the 2-line difference unit 43 outputs “ ⁇ 2” if the difference value is equal to or less than ( ⁇ 1) ⁇ (first gradation threshold Wth1).
  • the 2-line difference unit 43 performs the following five operations. 1) When Wth1 ⁇ (difference value), “2” is output. 2) When Wth2 ⁇ (difference value) ⁇ Wth1, “1” is output. 3) When -Wth2 ⁇ (difference value) ⁇ Wth2, “0” is output. 4) When -Wth1 ⁇ (difference value) ⁇ Wth2, “ ⁇ 1” is output. 5) When (difference value) ⁇ ⁇ Wth1, “ ⁇ 2” is output.
  • the subtracting unit 44 subtracts a predetermined variable determined based on the output of the two-line difference unit 43 from the average image signal output from the two-line averaging unit 42. That is, the subtracting unit 44 subtracts a predetermined variable determined by the difference value of the image signal of the pair of pixels from the average image signal of the pair of pixels.
  • the subtraction unit 44 sets this predetermined variable to “1 ⁇ 2 of the first gradation threshold value Wth1”. If the output of the two-line difference unit 43 is “1” or “ ⁇ 1”, the subtracting unit 44 sets the predetermined variable to “1 ⁇ 2 of the second gradation threshold value Wth2”. The subtractor 44 sets the predetermined variable to “0” if the output of the two-line difference unit 43 is “0”.
  • the subtracting unit 44 uses the average image signal output from the two-line averaging unit 42 to 1 ⁇ 2 the first gradation threshold value Wth1. Is output as an image signal of a pixel on the p-th line and a pixel on the (p + 1) -th line (a pair of pixels on the p-th line and the (p + 1) -th line).
  • the subtracting unit 44 calculates 1 ⁇ 2 of the second gradation threshold Wth2 from the average image signal output from the two-line averaging unit 42. Is output as an image signal of a pixel on the p-th line and a pixel on the (p + 1) -th line (a pair of pixels on the p-th line and the (p + 1) -th line).
  • the subtracting unit 44 uses the average image signal output from the two-line averaging unit 42 as it is as the pixel on the p-th line and the pixel on the (p + 1) -th line. This is output as an image signal (a pair of pixels on the p-th line and the (p + 1) -th line).
  • the average code conversion unit 45 converts the image signal output from the subtraction unit 44 into a subfield code having a predetermined subfield as a non-lighting subfield.
  • This predetermined subfield is a subfield determined by the output of the 2-line difference unit 43 (comparison result in the 2-line difference unit 43).
  • the average code conversion unit 45 converts the image signal of the target pixel pair on the p-th line and the (p + 1) -th line output from the subtraction unit 44 into a subfield code. At this time, if the output of the two-line difference unit 43 is “2” or “ ⁇ 2”, the average code conversion unit 45 in the present embodiment has the first type subfield having the largest gradation weight (in this embodiment). In the embodiment, the subfield SF2) is a non-lighting subfield.
  • the subfield code output from the average code conversion unit 45 is “X0XXX”.
  • the average code conversion unit 45 in the present embodiment has the second largest tone weight.
  • One type of subfield (in this embodiment, subfield SF3) is set as a non-lighting subfield.
  • the subfield code output from the average code conversion unit 45 is “XX0XX”.
  • This subfield code represents a lighting subfield as “1” and a non-lighting subfield as “0”, and “X” represents either “0” or “1”. .
  • subfield SF1 subfield SF2
  • subfield SF3 subfield SF4
  • subfield SF5 subfield SF5
  • the base code set selection unit 52 of the average code conversion unit 45 may be configured as follows.
  • FIG. 16A is a diagram showing another example of the base code set used in the image display device 30 according to the embodiment of the present invention.
  • FIG. 16B is a diagram showing another example of the deleted base code set used in the image display device 30 according to the embodiment of the present invention.
  • FIG. 16C is a diagram showing another example of the deleted base code set used in the image display device 30 according to the embodiment of the present invention.
  • the light-emitting subfield is “1”
  • the non-light-emitting subfield is blank
  • each subfield code (base code) is displayed in the second column from the left. (Or a deleted base code) represents a gradation value to be displayed. Further, the numerical value written immediately below the notation indicating each subfield in each code set represents the gradation weight of each subfield.
  • FIG. 16A shows a base code set used when the output of the 2-line difference unit 43 is “0”.
  • one field is composed of five subfields, and each subfield is “1”, “10”, “6”, “3”, “3” in order from the subfield SF1. 2 "gradation weight.
  • the base code set shown in FIG. 16A is the same base code set as the base code set shown in FIG. 10A, and is set to the lighting subfield one by one in order from the subfield having the smallest gradation weight. Therefore, the number of base codes included in this base code set is six.
  • FIG. 16B shows a deleted base code set used when the output of the 2-line difference unit 43 is “2” or “ ⁇ 2”.
  • the deleted base code set shown in FIG. 16B is a subfield code set generated from the base code set shown in FIG. 16A with a predetermined subfield determined by the output of the two-line difference unit 43 as a non-lighting subfield. is there.
  • this predetermined subfield is a first type subfield (in this embodiment, subfield SF2) having the largest gradation weight.
  • the deleted base code set shown in FIG. 16B is a sub-field code set in which the sub-field SF2 is a non-lighting sub-field from the base code set shown in FIG. 16A.
  • the subfield SF2 is a subfield having the largest gradation weight. Therefore, the deleted base code set shown in FIG. 16B is equal to the code set obtained by removing the base code “11111” having the gradation value “22” from the base code set shown in FIG. 16A.
  • FIG. 16C shows a deleted base code set used when the output of the two-line difference unit 43 is “1” or “ ⁇ 1”.
  • the deleted base code set shown in FIG. 16C is a sub-field code set generated from the base code set shown in FIG. 16A using a predetermined sub-field determined by the output of the two-line difference unit 43 as a non-lighting sub-field. is there.
  • this predetermined subfield is the first type subfield having the second largest gradation weight (subfield SF3 in the present embodiment). Therefore, the deleted base code set shown in FIG. 16C is a subfield code set in which the subfield SF3 is set as a non-lighting subfield from the base code set shown in FIG. 16A.
  • the base code set selection unit 52 stores the base code set and gradation values of a plurality of base codes constituting the base code set. In addition, the base code set selection unit 52 stores the gradation values of the deleted base code set and the plurality of deleted base codes constituting the deleted base code set. Each base code and each gradation value of the base code are stored in the base code set selection unit 52 in association with each other.
  • This base code set is, for example, the base code set shown in FIG. 16A.
  • Each deleted base code and each gradation value of the deleted base code are stored in the base code set selection unit 52 in association with each other.
  • This deleted base code set is, for example, the deleted base code set shown in FIGS. 16B and 16C.
  • the base code set selection unit 52 selects a base code set (for example, the base code set shown in FIG. 16A). If the output of the 2-line difference unit 43 is “2” or “ ⁇ 2”, the base code set selection unit 52 deletes the base code that has been deleted by setting the first type subfield having the highest gradation weight as a non-lighting subfield. A set (eg, a deleted base code set shown in FIG. 16B) is selected. Then, if the output of the two-line difference unit 43 is “1” or “ ⁇ 1”, the base code set selection unit 52 sets the second-type first subfield with the second largest gradation weight as a non-lighting subfield. A deleted base code set (for example, the deleted base code set shown in FIG. 16C) is selected.
  • the base code selection unit 54 compares each gradation value of the subfield code constituting the code set selected by the base code set selection unit 52 with the input gradation, and forms a subfield that becomes an upper gradation base code. Select a code.
  • the image signal processing circuit 31 may be configured as described above.
  • the base code generation unit 50 includes a base code set selection unit 52, and the base code set selection unit 52 stores the base code set and the deleted base code set in advance.
  • the present invention is not limited to this configuration.
  • a configuration may be adopted in which a rule for generating a base code or a deleted base code is determined in advance, and the base code or the deleted base code is generated based on the rule.
  • the upper / lower code generation unit 70 selects the upper gradation code and the lower gradation code by the upper / lower code selection unit 74 after the intermediate code set is generated by the intermediate code generation unit 72.
  • the present invention is not limited to this configuration.
  • an intermediate code is generated in order of increasing gradation value, and at the same time, the intermediate code and the input gradation are sequentially compared to select the upper gradation code and the lower gradation code.
  • dither processing and error diffusion processing are performed after setting a subfield for prohibiting the write operation. Therefore, even in the image display device 30 that generates display codes from an intermediate code set having a limited number of subfield codes and uses them for image display, it is possible to prevent image display quality from being deteriorated.
  • the configuration in which the average code selection unit 80 includes the dither selection unit 82 and the error diffusion unit 84 has been described.
  • the present invention is not necessarily limited to this configuration.
  • the dither selection unit 82 may be omitted.
  • the error diffusion unit 84 may be omitted when the error diffusion process is not performed.
  • a common error and a common dither element are used for the p-line target pixel and the (p + 1) -line target pixel, and the output of the average code selection unit 80 is the p-line target pixel.
  • the common subfield code is used for the target pixel in the (p + 1) -th line.
  • the present invention is not limited to this configuration. For example, the following configuration may be used. First, the difference between the upper gradation code and the lower gradation code selected by the upper / lower code selection unit 74 is calculated.
  • the output of the average code selection unit 80 is set to a different subfield code for the target pixel on the p-th line and the target pixel on the (p + 1) -th line.
  • a different subfield code for the target pixel on the p-th line and the target pixel on the (p + 1) -th line.
  • the number of subfields constituting one field, the subfields that are forced initialization subfields, the gradation weights of each subfield, and the like are not limited to the above-described numerical values. Moreover, the structure which switches a subfield structure based on an image signal etc. may be sufficient.
  • drive voltage waveforms shown in FIGS. 3, 4, and 15 are merely examples in the embodiment of the present invention, and the present invention is not limited to these drive voltage waveforms.
  • circuit configurations shown in FIGS. 6, 7, and 9 are merely examples in the embodiment of the present invention, and the present invention is not limited to these circuit configurations.
  • each circuit block shown in the embodiment of the present invention may be configured as an electric circuit that performs each operation shown in the embodiment, or a microcomputer that is programmed to perform the same operation. May be used.
  • the number of subfields constituting one field is not limited to the above number.
  • the number of gradations that can be displayed on the panel 10 can be further increased.
  • the time required for driving panel 10 can be shortened by reducing the number of subfields.
  • one pixel is constituted by discharge cells of three colors of red, green, and blue.
  • a panel in which one pixel is constituted by discharge cells of four colors or more has been described.
  • the specific numerical values shown in the embodiment of the present invention are set based on the characteristics of the panel 10 having a screen size of 50 inches and the number of display electrode pairs 14 of 1024. It is just an example.
  • the present invention is not limited to these numerical values, and each numerical value is desirably set optimally in accordance with panel specifications, panel characteristics, plasma display device specifications, and the like. Each of these numerical values is allowed to vary within a range where the above-described effect can be obtained.
  • the number of subfields constituting one field, the gradation weight of each subfield, and the like are not limited to the values shown in the embodiment of the present invention, and the subfield configuration is based on an image signal or the like. May be configured to switch.
  • the present invention since conversion from an image signal to a subfield code can be performed by calculation, it is not necessary to use a conversion table composed of a large number of subfield codes, and the writing period is prevented while preventing a decrease in image display quality.
  • the time required for the image display device can be shortened, so that it is useful as an image display device that displays an image in an image display region by combining binary control of light emission and non-light emission in a light emitting element that constitutes a pixel, and an image display device driving method It is.

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Abstract

Selon l'invention, pour réduire le temps requis pour une période d'écriture dans un dispositif de visualisation d'image, ce dernier comprend une unité de moyennage à 2 lignes (42) pour calculer une valeur moyenne d'un signal d'image en relation avec un pixel d'intérêt; une unité de calcul de différence à 2 lignes (43) pour calculer une différence de valeur du signal d'image en relation avec le pixel d'intérêt, et comparer la différence de valeur au poids de gradient d'un premier type de sous-champ; une unité de soustraction (44) pour soustraire un coefficient prescrit déterminé par le résultat de la comparaison obtenu par l'unité de calcul de différence à 2 lignes à partir de la valeur moyenne; une unité de conversion de code moyen (45) pour convertir le résultat issu de l'unité de soustraction en un code de sous-champ dont un sous-champ prescrit est défini comme sous-champ non-émetteur, et produire ce code; une unité de génération de code de différence (91) pour générer un code de sous-champ et contrôler le sous-champ prescrit en fonction du résultat de la comparaison produit par l'unité de calcul de différence à 2 lignes; et une unité de synthèse de code d'affichage (92) pour synthétiser le code de sous-champ produit par l'unité de conversion de code moyen et le code de sous-champ généré par l'unité de génération de code de différence, et générer un code d'affichage.
PCT/JP2012/000337 2011-01-20 2012-01-20 Et procédé de commande pour dispositif de visualisation d'image dispositif de visualisation d'image WO2012098904A1 (fr)

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WO2011074242A1 (fr) * 2009-12-14 2011-06-23 パナソニック株式会社 Procédé de pilotage de dispositif d'affichage à plasma, dispositif d'affichage à plasma et système d'affichage à plasma
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