CA2010267A1 - Image display apparatus for controlling lighting of a plurality of discharge paths in time divisional manner - Google Patents
Image display apparatus for controlling lighting of a plurality of discharge paths in time divisional mannerInfo
- Publication number
- CA2010267A1 CA2010267A1 CA002010267A CA2010267A CA2010267A1 CA 2010267 A1 CA2010267 A1 CA 2010267A1 CA 002010267 A CA002010267 A CA 002010267A CA 2010267 A CA2010267 A CA 2010267A CA 2010267 A1 CA2010267 A1 CA 2010267A1
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- discharge
- display
- lighting
- discharge paths
- display control
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- 238000007599 discharging Methods 0.000 claims description 14
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- 230000001276 controlling effect Effects 0.000 claims 5
- 238000010586 diagram Methods 0.000 description 12
- 230000003287 optical effect Effects 0.000 description 9
- 230000003213 activating effect Effects 0.000 description 3
- 238000005286 illumination Methods 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000003079 width control Methods 0.000 description 3
- 241000282320 Panthera leo Species 0.000 description 2
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- 238000006243 chemical reaction Methods 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- 101100186820 Drosophila melanogaster sicily gene Proteins 0.000 description 1
- 240000002989 Euphorbia neriifolia Species 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
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Classifications
-
- 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
- G09G3/2003—Display of colours
-
- 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
-
- 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
- G09G3/2014—Display of intermediate tones by modulation of the duration of a single pulse during which the logic level remains constant
-
- 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
- G09G3/282—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 DC panels
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2300/00—Aspects of the constitution of display devices
- G09G2300/04—Structural and physical details of display devices
- G09G2300/0439—Pixel structures
- G09G2300/0452—Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2320/00—Control of display operating conditions
- G09G2320/02—Improving the quality of display appearance
- G09G2320/0242—Compensation of deficiencies in the appearance of colours
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- General Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Plasma & Fusion (AREA)
- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
Abstract
Abstract of the Disclosure An image display apparatus has a signal generator for generating an electric signal corresponding to an image to be displayed. This electric signal is con-verted into a predetermined color image signal by an image processor. This color image signal is sent over to a display controller in a display section and is subjected to pulse width modulation control by the display controller. The color image signal controlled by this controller is displayed on a display panel having a plurality of discharge paths two-dimensionally arranged. Each discharge path displays one of a plurality of predetermined colors. The display controller permits those discharge paths of the same color of the display panel to be connected to the same ballast, and performs lighting control through time-division of a lighting time of these discharge paths of the same color.
Description
The present invention generally relates to an image display apparatus which has a plurality of discharge paths arranged in matrix form and performs illumination control of the discharge paths to thereby display an image, and, more particularly, to an image display apparatus which controls time-divisional lighting of the discharge paths.
Conventionally, large image display apparatuses or large color image display apparatuses such as large lo displays called color display panels have been used at stadiums, such as baseball fields or race tracks.
Such a large color image display apparatus has many discharge lamps arranged in matrix form on its display surface, and each discharge lamp has a color filter provided at the front, which permits only one of three colors, red (R), green (G) and blue (B), to pass through. Passing each filter, the R, G or B light provides a display of one of the primary colors (R, G
and B). Each discharge lamp is driven by PAM (pulse Width Modulation) for its illumination and lighting control to thereby provide a display of the desired color image.
There is another image display apparatus known which uses a discharge tube of a tricolor single tube type to cope with a smaller display surface. AS its name clearly implies, this discharge tube has three discharge lamps for three colors incorporated into a single tube. In using this type of discharge tube in the aforementioned large color image display apparatus, in order to reduce the size of electric circuits, the ballasts such as inductances provided for the respective discharge lamps are shared by the discharge lamps (for three colors) of one discharge tube and the individual discharge lamps are subjected to a time-divisional lighting control. In this case, the discharge lamp G
which most includes luminance data included in one image signal, are separated into two lamps, Go and Go, to improve the resolution. This measure is taken because of the necessity to increase the luminance (which will be described later) as large color image display Papa-fetuses are generally used outdoors, of easier arrange-mint of the discharge tube, or of the number of scanning lines appearing to increase.
In a case where four discharge lamps R, Go, Go and B are connected to the same ballast, discharge currents (lamp currents) of the individual discharge lamps all become the same and display luminance vary color by color. In order to provide the white balance, there-fore, it is still necessary to control the lighting time (pulse width) for each color or adjust the trays-motivity of each filter for the associated color.
This lighting time control requires different gradation/lighting time conversion ROMs for the respect live colors. In addition, there may be an adverse influence on reddening which causes high display luminance with thy same current or, in some case, the resolution of brightness due to the lighting time being too short. Further, adjusting the transmittivity of a color filter reduces general brightness or efficiency, thus adversely influencing the saturation, hue and so forth.
There is another type of a large color image display apparatus which, as different from the one with the above-described structure, employs a single tube multicolor or single tube monochromatic display element (e.g., mercury discharge lamp) at each point on this display face. The "single tube multicolor display element" is designed to display different colors simultaneously or individually for a plurality of discharge paths in one lamp. This display element alone can serve as a plurality of display elements, whereas the single tube monochromatic display element displays one color with one lamp.
As a lighting device for such a display element, for example, a single tube multicolor lamp has an anode R for forming a discharge path for displaying red, green display discharge lamps Go and Go, blue display discharge lamp B, a common cathode and an activating auxiliary electrode. A switching transistor for supplying a current to the discharge path for each color display is connected for each color. These transistors
Conventionally, large image display apparatuses or large color image display apparatuses such as large lo displays called color display panels have been used at stadiums, such as baseball fields or race tracks.
Such a large color image display apparatus has many discharge lamps arranged in matrix form on its display surface, and each discharge lamp has a color filter provided at the front, which permits only one of three colors, red (R), green (G) and blue (B), to pass through. Passing each filter, the R, G or B light provides a display of one of the primary colors (R, G
and B). Each discharge lamp is driven by PAM (pulse Width Modulation) for its illumination and lighting control to thereby provide a display of the desired color image.
There is another image display apparatus known which uses a discharge tube of a tricolor single tube type to cope with a smaller display surface. AS its name clearly implies, this discharge tube has three discharge lamps for three colors incorporated into a single tube. In using this type of discharge tube in the aforementioned large color image display apparatus, in order to reduce the size of electric circuits, the ballasts such as inductances provided for the respective discharge lamps are shared by the discharge lamps (for three colors) of one discharge tube and the individual discharge lamps are subjected to a time-divisional lighting control. In this case, the discharge lamp G
which most includes luminance data included in one image signal, are separated into two lamps, Go and Go, to improve the resolution. This measure is taken because of the necessity to increase the luminance (which will be described later) as large color image display Papa-fetuses are generally used outdoors, of easier arrange-mint of the discharge tube, or of the number of scanning lines appearing to increase.
In a case where four discharge lamps R, Go, Go and B are connected to the same ballast, discharge currents (lamp currents) of the individual discharge lamps all become the same and display luminance vary color by color. In order to provide the white balance, there-fore, it is still necessary to control the lighting time (pulse width) for each color or adjust the trays-motivity of each filter for the associated color.
This lighting time control requires different gradation/lighting time conversion ROMs for the respect live colors. In addition, there may be an adverse influence on reddening which causes high display luminance with thy same current or, in some case, the resolution of brightness due to the lighting time being too short. Further, adjusting the transmittivity of a color filter reduces general brightness or efficiency, thus adversely influencing the saturation, hue and so forth.
There is another type of a large color image display apparatus which, as different from the one with the above-described structure, employs a single tube multicolor or single tube monochromatic display element (e.g., mercury discharge lamp) at each point on this display face. The "single tube multicolor display element" is designed to display different colors simultaneously or individually for a plurality of discharge paths in one lamp. This display element alone can serve as a plurality of display elements, whereas the single tube monochromatic display element displays one color with one lamp.
As a lighting device for such a display element, for example, a single tube multicolor lamp has an anode R for forming a discharge path for displaying red, green display discharge lamps Go and Go, blue display discharge lamp B, a common cathode and an activating auxiliary electrode. A switching transistor for supplying a current to the discharge path for each color display is connected for each color. These transistors
2~r3~ 7 each have their base supplied with a pulse lighting control signal from a controller. Based on this control signal, the transistors are turned on or off to supply a current to the discharge lamps for the individual colors, thus switching its dots (pixels) on or off-This type of lighting apparatus needs adjusting brightness of the dots for each color. That is, even if a current with the same value is rendered to flow through a blue dot and a green dot for the same period of time, the luminance is low for blue and high for green. If similar control is executed for each color, therefore, luminance balance cannot be attained for individual colors so that the brightness of dots for each color needs to be preadjusted.
To adjust the brightness of each dot, convent tonally, the section to supply a current to a dot for luminance adjustment is controlled or the ballast resistance is changed for each dot to alter the value of the current through pulse width control. For instance, if one discharge path (lamp) is to initiate in white lighting, when lighting power is supplied from a power source, dots for the individual colors are switched on in the order of, for example, from B
to Go to R to Go. By repeating the lighting of the individual dots at such a timing in time divisional manner, the discharge path us lit white. on view of - 5 - my the aforementioned low/high relation of luminance, the pulse width of the lighting control signal for B is set long and that for G is set short. As R generally falls within the intermediate range, its pulse width is - 5 shorter than that of B and longer than that of G.
According to the type which controls the lighting time of each dot by altering each pulse width under the pulse width control, it is always necessary to perform this control dot by dot when white lighting is into-axed, thus complicating the control system. Part-ocularly, in executing gradation control, the pulse width of the lighting control signal is segmented into, for example, 64 sections, and a pulse having the same pulse width as the width of the desired one of the 64 US segments is given as a control signal, thus ensuring expression of 64 different gradations. Since the pulse width at the time of providing white lighting differs color by color, the segmented pulse widths also vary for each color. The control system therefore becomes further complicated. Provided that the pulse width for given dots consisting Go and Go are a half that for blue, making such a narrow pulse width even narrower to be 1/256 (8 bits causes the pulse width for one gradation to be too narrow to activate or turn on the lamp.
Further, there is a system in which a ballast resistance is provided for each dot or each color so that luminance can be controlled by altering the value of the ballast resistance and thus changing the value of a current flowing through each dot. This system however requires different ballast resistances with different values for the individual dots, which increases the cost. In a particular case where a transformer, not a resistance, is used as a ballast, many different types of transformers are necessary, which also increases the cost.
Accordingly, it is a primary object of this invent lion to provide an image display apparatus which permits one ballast to be shared by a plurality of discharge paths for time divisional lighting of the individual discharge lamps to reduce the number of required ballasts and can adjust color balance such as white balance without adjusting the lighting time and filter transmittivity.
It is another object of this invention to provide an image display apparatus which adjusts the brightness for each display element not by pulse width control and eliminates the need to provide a ballast for each element.
According to one aspect of the present invention, there is provided an image display apparatus comprising:
so B at generating means for generating an electric signal corresponding to an image to be displayed image processing means for converting the electric signal generated by the signal generating means into a prude-termined color image signal; display control means for executing pulse width modulation control to display the color image signal processed by the image processing means; and display means for displaying the color image signal controlled by the display control means, the display means having a plurality of discharge paths two-dimensionally arranged each for displaying one of a plurality of predetermined colors, the display means having ballast means connected to the discharge paths, wherein the display control means permits a plurality of discharge paths of the same color of the display means to be coupled to the same ballast means to thereby time-divide a lighting time of the plurality of discharge paths for lighting control.
According to another aspect of the present invent lion, there is provided an image display apparatus comprising: signal generating means for generating an electric signal corresponding to an image to be disk played; image processing means for converting the electric signal generated by the signal generating means : into a predetermined color image signal; display control means for executing pulse width modulation control to display the color image signal processed by the image processing means; and display means for displaying the color image signal controlled by the display control means, the display means having a plurality of discharge paths two-dimensionally arranged each for displaying one of a plurality of predetermined colors, the display means having power supply means connected to the disk charge paths, wherein the display control means permits a plurality of discharge paths of the swamp color of the display means to be coupled to the same power supply means to thereby time-divide a lighting time of the plurality of discharge paths for lighting control.
According to still another aspect of the present lo invention, there is provided a light circuit for an image display apparatus, comprising: control means for executing pulse width modulation control of an image signal corresponding to an image to be displayed; a plurality of discharging means for displaying the image signal controlled by the control means and each disk playing one of a plurality of predetermined colors; and a plurality of ballast means for supplying power to those of the plurality of discharging means which supply current with the same current value, wherein the control means permits a plurality of discharge elect troves of the same color of the discharging means to be coupled to same ballast means to thereby time-divide a lighting lime of the plurality of discharge electrodes of the same color for lighting control.
: Additional objects and advantages of the invention ;: will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
The accompanying drawings, which are incorporated in and constitute a part of the specification, thus-trades presently preferred embodiments of the invention and, together with the general description given above and the detailed description of the preferred embody-mints given below, serve to explain the principles of the invention.
This invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which:
Fig. 1 is a block diagram schematically thus-treating an image display apparatus according to the first embodiment of this invention;
Fig. 2 is a circuit diagram illustrating a controller and a lighting circuit of the image display apparatus shown in Fig. 1;
Figs. PA through ED are timing charts for explain-in the controller shown in Fig. 2;
Figs. PA through Go are timing charts for explaining the~liyhting circuit shown in Fig. 2;
Figs. PA through ED are exemplary diagrams thus-treating the lighting order of the lighting circuit shown it jig. 2;
- 10~ fix Fig. 6 is a circuit diagram of a lighting circuit for an image display apparatus according to the second embodiment of this invention;
Figs. PA through ED are timing charts illustrating lighting timings in the lighting circuit shown in Fig. 6 at a time white is lit;
Fig. 8 is a circuit diagram of a lighting circuit for an image display apparatus according to the third embodiment of this invention;
Figs. PA through 9C illustrate arbitrary lighting timings in the lighting circuit shown in Fig. 8, and are a timing chart for a power control transistor, a timing chart for a lighting control transistor and a timing chart for a fighting dot corresponding to a lamp, respectively;
Fig. 10 is a circuit diagram of a lighting circuit for an image display apparatus according to the fourth embodiment of this invention;
jig. 11 is a circuit diagram of a lighting circuit for an image display apparatus according to the fifth embodiment of this invention;
Fig. 12 is a circuit diagram of a lighting circuit for an image display apparatus according to the sixth embodiment of this invention; and Figs. AYE through 13C illustrate lighting timings in the lighting circuit shown in Fig. 12 at a time white is lit, and are a timing chart for a power control transistor, a timing chart for a lighting control tray-sister and a timing chart for a lighting dot correspond-in to a lamp, respectively.
Preferred embodiments of this invention will now be described referring to the accompanying draw-ins.
Fig. 1 schematically illustrates an image display apparatus according to the first embodiment of this invention. A signal generator 12 for generating a video signal Thor NTSC) and a digital signal (for a computer) is coupled with an image processor 14 for converting these electric signals into optical signals. This image processor 14 has a color decoder 16 for separating a video signal into three color signals, R (red), G
(green) and B (blue), an A/D converter 18 for performing A/D conversion of the separated R, G and B signals, and an approximation processor 20 for executing a process for thinning scanning lines, a process for adding scanning lines, etc., for example. The image processor 2G 14 further includes a memory 22 for storing character data or the like by a digital signal from the signal generator 12, a mixer 24 for mixing the output of the memory 22 with the output of the approximation processor 20, a CPU (Central Processing Unit) 26 for controlling the memory 22 upon reception of the output of the mixer 24, and an optical link 28 for converting an mixed electric signal from the mixer 24 into an optical signal.
The image processor 14 outputs the optical signal converted by the optical link 28 to a display section 32 through an optical cable 30. In the display section 32, the optical signal sent over the optical cable 30 is converted into an electric signal by an optical link 34.
This electric signal is sent via a receiver 36 and a transmitter 38 to a plurality of display controllers 40.
Each display controller 40, whose detailed description will be given later, executes time divisional lighting control of individual display elements of a display panel 42 comprising many discharge tubes (display elements). Through this control, the desired image having gradation or the like controlled is displayed.
Fig. 2 illustrates the display controller 40 serving as a controller of the image display apparatus and the display panel 42 serving as a lighting circuit.
Each signal based on the video signal sent from the transmitter 38 is stored into a dynamic memory 44.
Stored in this memory 44 is image data of R, G and B, i.e., data of display luminance of each discharge path on the display face (although G here is the luminance resulting from combining two discharge paths Go and Go, if there is a single discharge path, it is a single luminance). The memory 44 sequentially outputs display luminan e data corresponding to each discharge tube in accordance with the output signal of a counter 46.
The counter 46 receives at its input OK a periodic signal from an oscillator 48 and outputs a signal through an inventor 50 to a flip-flop 52 from its carry (CA) output. Thy Q output of the flip-flop 52 is sent to the counter 45, and the Q output is sent together with the output of the oscillator 48 to an OR circuit 54. The counter 46, inventor 50 and flip-flop 52 constitute a reset circuit.
The counter 46 sends its output representing the lighting order of a discharge path (which will be described later) to a data selector 56 constituting a time-divisional memory 54. The data selector 56 has output terminals corresponding in number to the disk charge paths. For instance, provided that there are four discharge tubes as will be described later, the data selector 56 has 16 output terminals. The outputs from these output terminals 1 to 16 are input to RAND
circuits 581, 582, 583 and 584. More specifically, the NOD circuit 581 receives the outputs "1," "4," "14" and "15" of the data selector 56, the RAND circuit 582 the outputs "2," "7," "12" and "13," the RAND circuit 583 the outputs "3," "6," "9" and "16," and the RAND circuit 584 the outputs "5," "8," "10" and "11." The outputs of these RAND circuits are supplied to input terminals 1 to 4 of a data selector 60.
A counter 62 receives a vertical sync signal (60 Ho ED/ and a quadruple vertical sync signal - 14 ~7 ( 240 HO ) 4VD/ having a frequency four times that of the former sync signal. The vertical sync signal 4VD/
is supplied through output terminals QUA and QB Of the counter 62 to input terminals A and B of the data selector 60. Both vertical sync signals ED/ and 4VD/
are input through an AND circuit 64 to a PRY terminal of the flip-flop 52.
A data selector 66 receives a signal from the data selector 50 as well as data I bits) from the alone-mentioned memory 44 at its terminal A and reference data I bits) at its terminal B. 8-bit gradation data of the data selector 65 is input to a PAM (Pulse Width Modulation) controller 68 which performs PAM control to determine the lighting duty ratio. The PAM controller 68 also receives the output of the aforementioned OR
gate 54 as a data strobe signal DSTB/. This controller 68 generates a switch ON signal having a pulse width corresponding to the data from the data selector 66 and sends it to those switching elements which render the currents of the associated discharge paths, such as SW
to Swahili Reference numeral 70 is a tricolor single tube type discharge tube having a common electrode, as disclosed in, for example, Unexamined Published Japanese Patent Application No. 63-198023. General, there are 100 to 250 discharge tubes vertically and 150 to 400 discharge tube horizontally arranged on the display face of the ~2~7 display panel 42 of the image display apparatus, though only four discharge tubes are illustrated here. The four discharge tubes 70 have four types of discharge paths, B (701, 703, 75, 77~ Go (702~ 74~ 706~ 78)~
Go (709, 7011, 713~ 715) and R (7010~ 712~ 714 716)~ inside, as shown in Figs. AUDI referred to later. Those of 16 discharge paths which are of the same color are coupled together through respective switching elements Sicily, and are coupled to one ends lo of inductances (choke coils) 72 (B), 74 (Go), 76 tG2) and 78 (R) as corresponding ballasts. The ballasts 72, 74, 76 and 78 each have their other end coupled to a high frequency generator (not shown).
The operation of thus constituted image display apparatus will now be described referring to the timing charts of Figs. PA through ED and PA through 4G and the exemplary diagrams of the lighting order of the disk charge paths shown in Figs. PA through ED.
A vertical sync signal ED/ of a period of 16.7 my as shown in Fig. PA and a quadruple vertical sync signal 4VD/ (Fig. 3B) whose peril (4 my) is about 1~4 of the period of the wormer sync signal ED/ are input to the counter 62 and AN circuit 64. Upon reception of these signals ED/ and 4VD/, the data shown in jig. 3C (the data being indicated by the oblique lines) is written in the succeeding PAM circuit by the data strobe signal DSTB/ shown in Fig. I The data added to the signal 2~267 DSTB/ is determined in accordance with the number of discharge paths (i.e., display elements). In the case of this embodiment, data corresponding to 16 discharge paths is used, due to the use of discharge paths 701-7016. The time between the rising and walling of the signal DSTBJ is a time in which PAM driving is done.
Data divided into 16 segments by the counter 46 and data selector 56 are output to the data selector 66 through the data selector 60 from the RAND circuits 581, 582, 583 and 584 according to the lighting order of the discharge tube 70. The data selector 66 selects data on the terminal A side when input data is "L." When the counter 46 counts up to "15" from "0," the reset circuit having this counter 46 outputs CA to reset the counter to "0." When the input data is "H," however, data on the terminal B side is selected (data on the terminal B
side being "L" to be data off).
In this manner, the PAM controller 68 switches the switching elements Sol to SUE to fight the individual discharge paths 71-716 in accordance with the lighting order of the discharge tubes 70.
Referring to Figs. PA through 4G and PA through ED, assume that the vertical sync signal ED/ has fallen as shown in Fig. YE. Then, the individual discharge : paths 71-716 shown in Figs. AYE are sequentially rendered in lighting enable state, by writing the data in the PAM circuit on the basis of the data strobe - 17 - Go 7 signal DSTB/ (Figs. OF and 4G), as mentioned above.
In this case, Fig. PA illustrates the discharge tubes 701r 703, 705 and 707 of B, Fig. 4B the discharge tubes 702, 74, 76 and 78 of Go, jig. 4C the discharge tubes 709, 7011, 713 and 715 of Go, and Fig. ED the discharge tubes owe, 712~ 714 and 716 Of R, At time if, the PAM controller 68 sets only the switching elements Sol, SUE, SUE and SUE on and the other off so as to turn on the discharge tubes core-sponging to the input of the RAND circuit 581, i.e., the discharge tubes 701, 704, 714 and 715~ as shown in ivy PA. In this case, it is assumed that shaded portions in Figs. PA through ED are light. Then, at time to, only the switching elements SUE, SUE, SUE
and SUE are likewise set on in association with the input of the RAND circuit 582, and the discharge tubes 72, 77, 712 and 713 are lit as shown in Fig. 5B.
similarly, at time to, only the switching elements SUE, SUE, Swig and Swahili are likewise set on in association with the input of the RAND circuit 583, and the disk charge tubes 703, 70ç, 709 and 716 are lit as shown in Fig. 5C. At time to, only the switching elements SUE, Swig, Sue and Swahili are likewise set on in association with the input of the RAND circuit 584, and the disk charge tubes 705, 708, owe and 7011 are lit as shown in Fig. ED.
Referring to Figs. PA through 4G, times if and to, , .
I so to and to, to and to, and to and to are timings (time of the maximum illumination) at of ems width which provides the time divisional fighting enable state of each discharge path at an "H" level. The PAM controller 68 controls the "H" level width with the illustrated state as the maximum width, thereby controlling the display luminance of each discharge path. The time division should not necessarily be done at equal intervals.
Further, although the foregoing description of this embodiment has been given with the switching elements for time divisional lighting also serving as the switching elements for the PAM control, this embodiment is not restricted to this particular type.
For instance, the switching elements may be provided separately.
Although a medium size image display apparatus employing a tricolor single tube type discharge tube has been explained in the foregoing description, the image display apparatus is not restricted to this particular type. For instance, this invention can also apply to a large image display apparatus using a single discharge lamp for each color as well as an image display Papa-Wright employing two color lamps or four or more color lamps.
As described above, according to this invention, since one ballast is shared by a plurality of discharge paths, the number of required ballasts which are rota-lively large components can be reduced, thus permitting electric circuits to be more compact. In addition, since the same ballast is shared by those discharge paths which display the same color and the discharge paths are lit at equal intervals in time divisional manner, the discharge paths coupled to that ballast can be lit at the same luminance. This can eliminate the need for lighting time control or relative luminance adjustment between the discharge paths. Further, con-dueling the time divisional lighting at equal intervals requires a less number of components such as a flip-flop circuit.
Furthermore, the luminance for each color or the lamp current for each color can be easily set by setting the specifications of a ballast or setting the induct-ante if it is an L ballast. Color balance such as white balance can be adjusted by setting the ballast specific cations. In other words, color ballast can be provided without the lighting control or controlling the transmittivity of a color filter.
The second 2mbsdiment of this invention will be described below referring to Figs. 6 and PA through ED.
Referring to Fig. 6, VB, VGl, OR and VG2 are power supplies for supplying power to single tube multicolor lamps LPl to LP4 of display discharge paths, which are constituted by B, Go, R and Go. The lamps LPl to LP4 each have an anode B for forming a discharge path for displaying blue, anodes Go and Go for green display and an anode R for red display as well as common cathodes El to En. Aft to AYE are starting auxiliary electrodes, V2 is an excess heating power supply for the cathodes El to En, and F is a high-frequency power supply used for ionization electrodes (i.e., third electrodes) Tub is a switching transistor for supplying a current to the anode B, and TrGl, Try and Trig are likewise switching transistors for supplying a current to the anodes Go, R and Go, respectively. These transistors each have their base supplied with a pulse lighting control signal from a controller 80, and their activation is controlled based on this control signal.
Controlling the activation of the transistors supplies a current to the discharge paths of the individual colors to turn on or off the associated discharge tubes.
Us RGl, RR and RG2 are ballast resistances which have the same value.
The operation of the second embodiment will be described below referring is Figs. PA through ED, which 111ustrate the timing at which the lamp LPl in Fig. 6 is lit white.
The power supplies VB, VGl, or and vG2 supplies predetermined power through ballast resistances RUB, RGl, RR and RG2 to the switching transistors Tub, TrGl, Try and Trig. The controller 80 outputs a control signal to the bases of these transistors Tub, TrGl, Try and Trig at a predetermined timing according to which the transistors are turned on or off. In accordance with the ON/OFF timing of the transistors Tug, Trig, Try and Trig, power is supplied to the individual discharge paths of the lamps LP1-LP4. For instance, at the lighting timings as given in Figs. 7~-7D, B becomes lighting enable state first, than Go, R and Go become lighting enable state in the named order. In the above, the lighting enable state of lamp LPl was described, 'Duty the time during which B of lamps LP2, LP3 and LP4 is kept in the lighting enable state is different from the time during which B of lamp LPl is kept in the lighting enable state. This is also true in the case of Go, R, Go-According to the second embodiment, power is supplied from a common power supply to the discharge paths associated with the same lamp current, ire., the discharge paths for each color. Accordingly, control-lying the voltages of these power supplies can adjust the luminance for each color. Since the source voltages can be controlled for each color, a single type of ballast resistances may be used. This can eliminate the need for various types of ballasts or ballast transformers.
Nor is it necessary to adjust the pulse width for luminance control.
The third embodiment of this invention will be described below referring to Figs. 8 and PA through 9C.
The same reference numerals as used for the components shown in Fig. 6 are also used to denote the identical or corresponding elements in the second embodiment, thus omitting their description.
Referring to Fig. 8, the power supplies VB, vG1, OR and VG2 are connected with power source control transistors TrlB, TrlGl, Troweler and Truly as illustrated.
These transistors have their bases coupled to a con-troller 82, so that their activation is controlled byte controller 82. ballast resistances Al and R2 are coupled at one end to the transistors TrlB, Try Troweler and TrlG2 through reverse-current preventing diodes DUB, DGl~ DRY and DG2. The other ends of the ballast resistances Al and R2 are coupled through lighting control switching transistors Tribe, Tr2Gl, Truer and Trig to single tube multicolor lamps LPl and LP2 of display discharge paths, respectively. The transistors Tribe, Tr2Gl, Truer and Trig serve to control power supply to the individual discharge paths of the lamps LPl and LP2 to lit dots corresponding to the individual discharge paths for the desired period of time. Al-though the case of using two lamps has been described above, this embodiment is not restricted to this type;
for example, the same arrangement can also apply to a case involving four lamps in use.
The operation of the third embodiment will be described below referring to Figs. PA through 9C, which illustrate the lighting timings for those dots which correspond to the power supply control transistors TrlB, TrlGl, Troweler and TrlG2, the lighting control switching transistors Tribe, Trig, Truer and Trig, and the lamp LPl.
As shown in Fig. PA, the transistors TrlB, TrlGl, Troweler and TrlG2 repeatedly switched on in sequential manner with a pulse width common to the individual discharge paths. In order to turn on the individual dots at gradation based on an instruction from the controller 82, the switching transistors Tribe, Tr2Gl, Truer and Trig are tllrned on at a pulse width according to the gradation (see Fig. 9B). When the transistors Tribe, Tr2Gl, Truer and Trig are turned on for lighting the dots, those dots which are associated with the individual discharge paths are lit in accordance with the ON activation of the transistors TrlB, TrlGl, Troweler and TrlG2, as shown in Fig. 9C. Therefore, the time for the lighting enable state of the dots of the discharge paths can be determined.
Fig. 10 illustrates the fourth embodiment of this invention. In the fourth embodiment, AC power supplies VFB, VFGl, VFR and VFG2 ox different frequencies are inserted in the power supplies VB, VGl~ OR and VG2 of the circuit of the third embodiment shown in jig. 8. As the other portions are the same as those of the third 2~7 embodiment, a description of the structural elements of those portions and the operation will be omitted.
Referring to Fig. 10, the selection of arbitrary frequencies for the power supplies VFg, v~G1, VFR and VFG~ determines the levels of the currents of the lamps LPl and LP2. Therefore, altering the frequencies of the power supplies can facilitate luminance adjustment for each color.
According to the second to fourth embodiments, a triodes type having a activating auxiliary electrode is used as a lamp. The fifth and sixth embodiments, which will be described below, are modifications of the second and third embodiments in which the lamp is replaced with a fine discharge type. The same reference numerals as used to denote components of the above-described embodiments will also be used to specify the identical or corresponding elements in the fifth and sixth embodiments, thus omitting their otherwise redundant description.
Fig. 11 illustrates the fifth embodiment of this invention, which corresponds to the second embodiment shown in Fig. 6. Although the diagram illustrates two lamps connected in the fifth embodiment, four or more lamps may be connected as in the circuit shown in Fig. 6. Referring to Fig. 11, Visa is a power supply for fine discharging, and Rot and Row are fine discharge limiting resistances. Dot and Do are reverse-current preventing diodes.
With the above arrangement, this invention can apply to a lamp which has only two electrodes (anode and cathode but no activating auxiliary electrode.
Fig. 12 illustrates the sixth embodiment of this invention, which corresponds to the circuit of the third embodiment shown in Fig. 8. Although the diagram illustrates two lamps connected in the sixth embodiment, this embodiment is not restricted to this type. Refer-10 ring to this diagram, RB1, Rg2, Rg3, RB4~ are main discharge limiting resistances, which become RBl = RB2 =
RB3 = RB4 by varying the source voltages. If the currents for Go and Go are equal to each other, the power supply VG2 can be omitted.
The operational timing of the lighting circuit for thus constituted image display apparatus will now be described referring to Figs. AYE through 13C. Fig. AYE
illustrates the timing chart for the power supply control transistors TrlB, TrlGl, Troweler and TrlG2,;
according to this timing chart, transistors are anti-voted in the order from TrlB to TrlG1 to Troweler to TrlG2.
In response to the activation of the transistors, the transistors Trig, Tr2Gl, Truer and Trig for lighting the lamp LPl are sequentially turned on as shown in Fig. 13B. The transistors Tribe, Tr2Gl, Truer and Trig for lighting the lamp LP2 are likewise turned on sequentially. In other words, those dots corresponding to the individual discharge paths of each lamp are lit in accordance with the ON activation of the transistors TrlB, TrlGl, Troweler and TrlG2. Accordingly the time for the lighting enable state for the dots of the discharge paths is determined.
Although the description of the second to sixth embodiments has been given with reference to the case where a single tube multicolor discharge lamp is turned on, these embodiments are not restricted to this part-cuter type, but can apply to a single tube monochromatic lamp. Further, this invention can apply to a display element having tricolor (RUB) dot structure which does not require separation of G (green) into two components, or a display element constituted by a combination of two or more colors.
additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, and representative apparatuses shown and described. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
;
To adjust the brightness of each dot, convent tonally, the section to supply a current to a dot for luminance adjustment is controlled or the ballast resistance is changed for each dot to alter the value of the current through pulse width control. For instance, if one discharge path (lamp) is to initiate in white lighting, when lighting power is supplied from a power source, dots for the individual colors are switched on in the order of, for example, from B
to Go to R to Go. By repeating the lighting of the individual dots at such a timing in time divisional manner, the discharge path us lit white. on view of - 5 - my the aforementioned low/high relation of luminance, the pulse width of the lighting control signal for B is set long and that for G is set short. As R generally falls within the intermediate range, its pulse width is - 5 shorter than that of B and longer than that of G.
According to the type which controls the lighting time of each dot by altering each pulse width under the pulse width control, it is always necessary to perform this control dot by dot when white lighting is into-axed, thus complicating the control system. Part-ocularly, in executing gradation control, the pulse width of the lighting control signal is segmented into, for example, 64 sections, and a pulse having the same pulse width as the width of the desired one of the 64 US segments is given as a control signal, thus ensuring expression of 64 different gradations. Since the pulse width at the time of providing white lighting differs color by color, the segmented pulse widths also vary for each color. The control system therefore becomes further complicated. Provided that the pulse width for given dots consisting Go and Go are a half that for blue, making such a narrow pulse width even narrower to be 1/256 (8 bits causes the pulse width for one gradation to be too narrow to activate or turn on the lamp.
Further, there is a system in which a ballast resistance is provided for each dot or each color so that luminance can be controlled by altering the value of the ballast resistance and thus changing the value of a current flowing through each dot. This system however requires different ballast resistances with different values for the individual dots, which increases the cost. In a particular case where a transformer, not a resistance, is used as a ballast, many different types of transformers are necessary, which also increases the cost.
Accordingly, it is a primary object of this invent lion to provide an image display apparatus which permits one ballast to be shared by a plurality of discharge paths for time divisional lighting of the individual discharge lamps to reduce the number of required ballasts and can adjust color balance such as white balance without adjusting the lighting time and filter transmittivity.
It is another object of this invention to provide an image display apparatus which adjusts the brightness for each display element not by pulse width control and eliminates the need to provide a ballast for each element.
According to one aspect of the present invention, there is provided an image display apparatus comprising:
so B at generating means for generating an electric signal corresponding to an image to be displayed image processing means for converting the electric signal generated by the signal generating means into a prude-termined color image signal; display control means for executing pulse width modulation control to display the color image signal processed by the image processing means; and display means for displaying the color image signal controlled by the display control means, the display means having a plurality of discharge paths two-dimensionally arranged each for displaying one of a plurality of predetermined colors, the display means having ballast means connected to the discharge paths, wherein the display control means permits a plurality of discharge paths of the same color of the display means to be coupled to the same ballast means to thereby time-divide a lighting time of the plurality of discharge paths for lighting control.
According to another aspect of the present invent lion, there is provided an image display apparatus comprising: signal generating means for generating an electric signal corresponding to an image to be disk played; image processing means for converting the electric signal generated by the signal generating means : into a predetermined color image signal; display control means for executing pulse width modulation control to display the color image signal processed by the image processing means; and display means for displaying the color image signal controlled by the display control means, the display means having a plurality of discharge paths two-dimensionally arranged each for displaying one of a plurality of predetermined colors, the display means having power supply means connected to the disk charge paths, wherein the display control means permits a plurality of discharge paths of the swamp color of the display means to be coupled to the same power supply means to thereby time-divide a lighting time of the plurality of discharge paths for lighting control.
According to still another aspect of the present lo invention, there is provided a light circuit for an image display apparatus, comprising: control means for executing pulse width modulation control of an image signal corresponding to an image to be displayed; a plurality of discharging means for displaying the image signal controlled by the control means and each disk playing one of a plurality of predetermined colors; and a plurality of ballast means for supplying power to those of the plurality of discharging means which supply current with the same current value, wherein the control means permits a plurality of discharge elect troves of the same color of the discharging means to be coupled to same ballast means to thereby time-divide a lighting lime of the plurality of discharge electrodes of the same color for lighting control.
: Additional objects and advantages of the invention ;: will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
The accompanying drawings, which are incorporated in and constitute a part of the specification, thus-trades presently preferred embodiments of the invention and, together with the general description given above and the detailed description of the preferred embody-mints given below, serve to explain the principles of the invention.
This invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which:
Fig. 1 is a block diagram schematically thus-treating an image display apparatus according to the first embodiment of this invention;
Fig. 2 is a circuit diagram illustrating a controller and a lighting circuit of the image display apparatus shown in Fig. 1;
Figs. PA through ED are timing charts for explain-in the controller shown in Fig. 2;
Figs. PA through Go are timing charts for explaining the~liyhting circuit shown in Fig. 2;
Figs. PA through ED are exemplary diagrams thus-treating the lighting order of the lighting circuit shown it jig. 2;
- 10~ fix Fig. 6 is a circuit diagram of a lighting circuit for an image display apparatus according to the second embodiment of this invention;
Figs. PA through ED are timing charts illustrating lighting timings in the lighting circuit shown in Fig. 6 at a time white is lit;
Fig. 8 is a circuit diagram of a lighting circuit for an image display apparatus according to the third embodiment of this invention;
Figs. PA through 9C illustrate arbitrary lighting timings in the lighting circuit shown in Fig. 8, and are a timing chart for a power control transistor, a timing chart for a lighting control transistor and a timing chart for a fighting dot corresponding to a lamp, respectively;
Fig. 10 is a circuit diagram of a lighting circuit for an image display apparatus according to the fourth embodiment of this invention;
jig. 11 is a circuit diagram of a lighting circuit for an image display apparatus according to the fifth embodiment of this invention;
Fig. 12 is a circuit diagram of a lighting circuit for an image display apparatus according to the sixth embodiment of this invention; and Figs. AYE through 13C illustrate lighting timings in the lighting circuit shown in Fig. 12 at a time white is lit, and are a timing chart for a power control transistor, a timing chart for a lighting control tray-sister and a timing chart for a lighting dot correspond-in to a lamp, respectively.
Preferred embodiments of this invention will now be described referring to the accompanying draw-ins.
Fig. 1 schematically illustrates an image display apparatus according to the first embodiment of this invention. A signal generator 12 for generating a video signal Thor NTSC) and a digital signal (for a computer) is coupled with an image processor 14 for converting these electric signals into optical signals. This image processor 14 has a color decoder 16 for separating a video signal into three color signals, R (red), G
(green) and B (blue), an A/D converter 18 for performing A/D conversion of the separated R, G and B signals, and an approximation processor 20 for executing a process for thinning scanning lines, a process for adding scanning lines, etc., for example. The image processor 2G 14 further includes a memory 22 for storing character data or the like by a digital signal from the signal generator 12, a mixer 24 for mixing the output of the memory 22 with the output of the approximation processor 20, a CPU (Central Processing Unit) 26 for controlling the memory 22 upon reception of the output of the mixer 24, and an optical link 28 for converting an mixed electric signal from the mixer 24 into an optical signal.
The image processor 14 outputs the optical signal converted by the optical link 28 to a display section 32 through an optical cable 30. In the display section 32, the optical signal sent over the optical cable 30 is converted into an electric signal by an optical link 34.
This electric signal is sent via a receiver 36 and a transmitter 38 to a plurality of display controllers 40.
Each display controller 40, whose detailed description will be given later, executes time divisional lighting control of individual display elements of a display panel 42 comprising many discharge tubes (display elements). Through this control, the desired image having gradation or the like controlled is displayed.
Fig. 2 illustrates the display controller 40 serving as a controller of the image display apparatus and the display panel 42 serving as a lighting circuit.
Each signal based on the video signal sent from the transmitter 38 is stored into a dynamic memory 44.
Stored in this memory 44 is image data of R, G and B, i.e., data of display luminance of each discharge path on the display face (although G here is the luminance resulting from combining two discharge paths Go and Go, if there is a single discharge path, it is a single luminance). The memory 44 sequentially outputs display luminan e data corresponding to each discharge tube in accordance with the output signal of a counter 46.
The counter 46 receives at its input OK a periodic signal from an oscillator 48 and outputs a signal through an inventor 50 to a flip-flop 52 from its carry (CA) output. Thy Q output of the flip-flop 52 is sent to the counter 45, and the Q output is sent together with the output of the oscillator 48 to an OR circuit 54. The counter 46, inventor 50 and flip-flop 52 constitute a reset circuit.
The counter 46 sends its output representing the lighting order of a discharge path (which will be described later) to a data selector 56 constituting a time-divisional memory 54. The data selector 56 has output terminals corresponding in number to the disk charge paths. For instance, provided that there are four discharge tubes as will be described later, the data selector 56 has 16 output terminals. The outputs from these output terminals 1 to 16 are input to RAND
circuits 581, 582, 583 and 584. More specifically, the NOD circuit 581 receives the outputs "1," "4," "14" and "15" of the data selector 56, the RAND circuit 582 the outputs "2," "7," "12" and "13," the RAND circuit 583 the outputs "3," "6," "9" and "16," and the RAND circuit 584 the outputs "5," "8," "10" and "11." The outputs of these RAND circuits are supplied to input terminals 1 to 4 of a data selector 60.
A counter 62 receives a vertical sync signal (60 Ho ED/ and a quadruple vertical sync signal - 14 ~7 ( 240 HO ) 4VD/ having a frequency four times that of the former sync signal. The vertical sync signal 4VD/
is supplied through output terminals QUA and QB Of the counter 62 to input terminals A and B of the data selector 60. Both vertical sync signals ED/ and 4VD/
are input through an AND circuit 64 to a PRY terminal of the flip-flop 52.
A data selector 66 receives a signal from the data selector 50 as well as data I bits) from the alone-mentioned memory 44 at its terminal A and reference data I bits) at its terminal B. 8-bit gradation data of the data selector 65 is input to a PAM (Pulse Width Modulation) controller 68 which performs PAM control to determine the lighting duty ratio. The PAM controller 68 also receives the output of the aforementioned OR
gate 54 as a data strobe signal DSTB/. This controller 68 generates a switch ON signal having a pulse width corresponding to the data from the data selector 66 and sends it to those switching elements which render the currents of the associated discharge paths, such as SW
to Swahili Reference numeral 70 is a tricolor single tube type discharge tube having a common electrode, as disclosed in, for example, Unexamined Published Japanese Patent Application No. 63-198023. General, there are 100 to 250 discharge tubes vertically and 150 to 400 discharge tube horizontally arranged on the display face of the ~2~7 display panel 42 of the image display apparatus, though only four discharge tubes are illustrated here. The four discharge tubes 70 have four types of discharge paths, B (701, 703, 75, 77~ Go (702~ 74~ 706~ 78)~
Go (709, 7011, 713~ 715) and R (7010~ 712~ 714 716)~ inside, as shown in Figs. AUDI referred to later. Those of 16 discharge paths which are of the same color are coupled together through respective switching elements Sicily, and are coupled to one ends lo of inductances (choke coils) 72 (B), 74 (Go), 76 tG2) and 78 (R) as corresponding ballasts. The ballasts 72, 74, 76 and 78 each have their other end coupled to a high frequency generator (not shown).
The operation of thus constituted image display apparatus will now be described referring to the timing charts of Figs. PA through ED and PA through 4G and the exemplary diagrams of the lighting order of the disk charge paths shown in Figs. PA through ED.
A vertical sync signal ED/ of a period of 16.7 my as shown in Fig. PA and a quadruple vertical sync signal 4VD/ (Fig. 3B) whose peril (4 my) is about 1~4 of the period of the wormer sync signal ED/ are input to the counter 62 and AN circuit 64. Upon reception of these signals ED/ and 4VD/, the data shown in jig. 3C (the data being indicated by the oblique lines) is written in the succeeding PAM circuit by the data strobe signal DSTB/ shown in Fig. I The data added to the signal 2~267 DSTB/ is determined in accordance with the number of discharge paths (i.e., display elements). In the case of this embodiment, data corresponding to 16 discharge paths is used, due to the use of discharge paths 701-7016. The time between the rising and walling of the signal DSTBJ is a time in which PAM driving is done.
Data divided into 16 segments by the counter 46 and data selector 56 are output to the data selector 66 through the data selector 60 from the RAND circuits 581, 582, 583 and 584 according to the lighting order of the discharge tube 70. The data selector 66 selects data on the terminal A side when input data is "L." When the counter 46 counts up to "15" from "0," the reset circuit having this counter 46 outputs CA to reset the counter to "0." When the input data is "H," however, data on the terminal B side is selected (data on the terminal B
side being "L" to be data off).
In this manner, the PAM controller 68 switches the switching elements Sol to SUE to fight the individual discharge paths 71-716 in accordance with the lighting order of the discharge tubes 70.
Referring to Figs. PA through 4G and PA through ED, assume that the vertical sync signal ED/ has fallen as shown in Fig. YE. Then, the individual discharge : paths 71-716 shown in Figs. AYE are sequentially rendered in lighting enable state, by writing the data in the PAM circuit on the basis of the data strobe - 17 - Go 7 signal DSTB/ (Figs. OF and 4G), as mentioned above.
In this case, Fig. PA illustrates the discharge tubes 701r 703, 705 and 707 of B, Fig. 4B the discharge tubes 702, 74, 76 and 78 of Go, jig. 4C the discharge tubes 709, 7011, 713 and 715 of Go, and Fig. ED the discharge tubes owe, 712~ 714 and 716 Of R, At time if, the PAM controller 68 sets only the switching elements Sol, SUE, SUE and SUE on and the other off so as to turn on the discharge tubes core-sponging to the input of the RAND circuit 581, i.e., the discharge tubes 701, 704, 714 and 715~ as shown in ivy PA. In this case, it is assumed that shaded portions in Figs. PA through ED are light. Then, at time to, only the switching elements SUE, SUE, SUE
and SUE are likewise set on in association with the input of the RAND circuit 582, and the discharge tubes 72, 77, 712 and 713 are lit as shown in Fig. 5B.
similarly, at time to, only the switching elements SUE, SUE, Swig and Swahili are likewise set on in association with the input of the RAND circuit 583, and the disk charge tubes 703, 70ç, 709 and 716 are lit as shown in Fig. 5C. At time to, only the switching elements SUE, Swig, Sue and Swahili are likewise set on in association with the input of the RAND circuit 584, and the disk charge tubes 705, 708, owe and 7011 are lit as shown in Fig. ED.
Referring to Figs. PA through 4G, times if and to, , .
I so to and to, to and to, and to and to are timings (time of the maximum illumination) at of ems width which provides the time divisional fighting enable state of each discharge path at an "H" level. The PAM controller 68 controls the "H" level width with the illustrated state as the maximum width, thereby controlling the display luminance of each discharge path. The time division should not necessarily be done at equal intervals.
Further, although the foregoing description of this embodiment has been given with the switching elements for time divisional lighting also serving as the switching elements for the PAM control, this embodiment is not restricted to this particular type.
For instance, the switching elements may be provided separately.
Although a medium size image display apparatus employing a tricolor single tube type discharge tube has been explained in the foregoing description, the image display apparatus is not restricted to this particular type. For instance, this invention can also apply to a large image display apparatus using a single discharge lamp for each color as well as an image display Papa-Wright employing two color lamps or four or more color lamps.
As described above, according to this invention, since one ballast is shared by a plurality of discharge paths, the number of required ballasts which are rota-lively large components can be reduced, thus permitting electric circuits to be more compact. In addition, since the same ballast is shared by those discharge paths which display the same color and the discharge paths are lit at equal intervals in time divisional manner, the discharge paths coupled to that ballast can be lit at the same luminance. This can eliminate the need for lighting time control or relative luminance adjustment between the discharge paths. Further, con-dueling the time divisional lighting at equal intervals requires a less number of components such as a flip-flop circuit.
Furthermore, the luminance for each color or the lamp current for each color can be easily set by setting the specifications of a ballast or setting the induct-ante if it is an L ballast. Color balance such as white balance can be adjusted by setting the ballast specific cations. In other words, color ballast can be provided without the lighting control or controlling the transmittivity of a color filter.
The second 2mbsdiment of this invention will be described below referring to Figs. 6 and PA through ED.
Referring to Fig. 6, VB, VGl, OR and VG2 are power supplies for supplying power to single tube multicolor lamps LPl to LP4 of display discharge paths, which are constituted by B, Go, R and Go. The lamps LPl to LP4 each have an anode B for forming a discharge path for displaying blue, anodes Go and Go for green display and an anode R for red display as well as common cathodes El to En. Aft to AYE are starting auxiliary electrodes, V2 is an excess heating power supply for the cathodes El to En, and F is a high-frequency power supply used for ionization electrodes (i.e., third electrodes) Tub is a switching transistor for supplying a current to the anode B, and TrGl, Try and Trig are likewise switching transistors for supplying a current to the anodes Go, R and Go, respectively. These transistors each have their base supplied with a pulse lighting control signal from a controller 80, and their activation is controlled based on this control signal.
Controlling the activation of the transistors supplies a current to the discharge paths of the individual colors to turn on or off the associated discharge tubes.
Us RGl, RR and RG2 are ballast resistances which have the same value.
The operation of the second embodiment will be described below referring is Figs. PA through ED, which 111ustrate the timing at which the lamp LPl in Fig. 6 is lit white.
The power supplies VB, VGl, or and vG2 supplies predetermined power through ballast resistances RUB, RGl, RR and RG2 to the switching transistors Tub, TrGl, Try and Trig. The controller 80 outputs a control signal to the bases of these transistors Tub, TrGl, Try and Trig at a predetermined timing according to which the transistors are turned on or off. In accordance with the ON/OFF timing of the transistors Tug, Trig, Try and Trig, power is supplied to the individual discharge paths of the lamps LP1-LP4. For instance, at the lighting timings as given in Figs. 7~-7D, B becomes lighting enable state first, than Go, R and Go become lighting enable state in the named order. In the above, the lighting enable state of lamp LPl was described, 'Duty the time during which B of lamps LP2, LP3 and LP4 is kept in the lighting enable state is different from the time during which B of lamp LPl is kept in the lighting enable state. This is also true in the case of Go, R, Go-According to the second embodiment, power is supplied from a common power supply to the discharge paths associated with the same lamp current, ire., the discharge paths for each color. Accordingly, control-lying the voltages of these power supplies can adjust the luminance for each color. Since the source voltages can be controlled for each color, a single type of ballast resistances may be used. This can eliminate the need for various types of ballasts or ballast transformers.
Nor is it necessary to adjust the pulse width for luminance control.
The third embodiment of this invention will be described below referring to Figs. 8 and PA through 9C.
The same reference numerals as used for the components shown in Fig. 6 are also used to denote the identical or corresponding elements in the second embodiment, thus omitting their description.
Referring to Fig. 8, the power supplies VB, vG1, OR and VG2 are connected with power source control transistors TrlB, TrlGl, Troweler and Truly as illustrated.
These transistors have their bases coupled to a con-troller 82, so that their activation is controlled byte controller 82. ballast resistances Al and R2 are coupled at one end to the transistors TrlB, Try Troweler and TrlG2 through reverse-current preventing diodes DUB, DGl~ DRY and DG2. The other ends of the ballast resistances Al and R2 are coupled through lighting control switching transistors Tribe, Tr2Gl, Truer and Trig to single tube multicolor lamps LPl and LP2 of display discharge paths, respectively. The transistors Tribe, Tr2Gl, Truer and Trig serve to control power supply to the individual discharge paths of the lamps LPl and LP2 to lit dots corresponding to the individual discharge paths for the desired period of time. Al-though the case of using two lamps has been described above, this embodiment is not restricted to this type;
for example, the same arrangement can also apply to a case involving four lamps in use.
The operation of the third embodiment will be described below referring to Figs. PA through 9C, which illustrate the lighting timings for those dots which correspond to the power supply control transistors TrlB, TrlGl, Troweler and TrlG2, the lighting control switching transistors Tribe, Trig, Truer and Trig, and the lamp LPl.
As shown in Fig. PA, the transistors TrlB, TrlGl, Troweler and TrlG2 repeatedly switched on in sequential manner with a pulse width common to the individual discharge paths. In order to turn on the individual dots at gradation based on an instruction from the controller 82, the switching transistors Tribe, Tr2Gl, Truer and Trig are tllrned on at a pulse width according to the gradation (see Fig. 9B). When the transistors Tribe, Tr2Gl, Truer and Trig are turned on for lighting the dots, those dots which are associated with the individual discharge paths are lit in accordance with the ON activation of the transistors TrlB, TrlGl, Troweler and TrlG2, as shown in Fig. 9C. Therefore, the time for the lighting enable state of the dots of the discharge paths can be determined.
Fig. 10 illustrates the fourth embodiment of this invention. In the fourth embodiment, AC power supplies VFB, VFGl, VFR and VFG2 ox different frequencies are inserted in the power supplies VB, VGl~ OR and VG2 of the circuit of the third embodiment shown in jig. 8. As the other portions are the same as those of the third 2~7 embodiment, a description of the structural elements of those portions and the operation will be omitted.
Referring to Fig. 10, the selection of arbitrary frequencies for the power supplies VFg, v~G1, VFR and VFG~ determines the levels of the currents of the lamps LPl and LP2. Therefore, altering the frequencies of the power supplies can facilitate luminance adjustment for each color.
According to the second to fourth embodiments, a triodes type having a activating auxiliary electrode is used as a lamp. The fifth and sixth embodiments, which will be described below, are modifications of the second and third embodiments in which the lamp is replaced with a fine discharge type. The same reference numerals as used to denote components of the above-described embodiments will also be used to specify the identical or corresponding elements in the fifth and sixth embodiments, thus omitting their otherwise redundant description.
Fig. 11 illustrates the fifth embodiment of this invention, which corresponds to the second embodiment shown in Fig. 6. Although the diagram illustrates two lamps connected in the fifth embodiment, four or more lamps may be connected as in the circuit shown in Fig. 6. Referring to Fig. 11, Visa is a power supply for fine discharging, and Rot and Row are fine discharge limiting resistances. Dot and Do are reverse-current preventing diodes.
With the above arrangement, this invention can apply to a lamp which has only two electrodes (anode and cathode but no activating auxiliary electrode.
Fig. 12 illustrates the sixth embodiment of this invention, which corresponds to the circuit of the third embodiment shown in Fig. 8. Although the diagram illustrates two lamps connected in the sixth embodiment, this embodiment is not restricted to this type. Refer-10 ring to this diagram, RB1, Rg2, Rg3, RB4~ are main discharge limiting resistances, which become RBl = RB2 =
RB3 = RB4 by varying the source voltages. If the currents for Go and Go are equal to each other, the power supply VG2 can be omitted.
The operational timing of the lighting circuit for thus constituted image display apparatus will now be described referring to Figs. AYE through 13C. Fig. AYE
illustrates the timing chart for the power supply control transistors TrlB, TrlGl, Troweler and TrlG2,;
according to this timing chart, transistors are anti-voted in the order from TrlB to TrlG1 to Troweler to TrlG2.
In response to the activation of the transistors, the transistors Trig, Tr2Gl, Truer and Trig for lighting the lamp LPl are sequentially turned on as shown in Fig. 13B. The transistors Tribe, Tr2Gl, Truer and Trig for lighting the lamp LP2 are likewise turned on sequentially. In other words, those dots corresponding to the individual discharge paths of each lamp are lit in accordance with the ON activation of the transistors TrlB, TrlGl, Troweler and TrlG2. Accordingly the time for the lighting enable state for the dots of the discharge paths is determined.
Although the description of the second to sixth embodiments has been given with reference to the case where a single tube multicolor discharge lamp is turned on, these embodiments are not restricted to this part-cuter type, but can apply to a single tube monochromatic lamp. Further, this invention can apply to a display element having tricolor (RUB) dot structure which does not require separation of G (green) into two components, or a display element constituted by a combination of two or more colors.
additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, and representative apparatuses shown and described. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
;
Claims (19)
1. An image display apparatus comprising:
signal generating means for generating an electric signal corresponding to an image to he displayed;
image processing means for converting said electric signal generated by said signal generating means into a predetermined color image signal;
display control means for executing pulse width modulation control to display said color image signal processed by said image processing means; and display means for displaying said color image signal controlled by said display control means, said display means having a plurality of discharge paths two-dimensionally arranged each for displaying one of a plurality of predetermined colors, said display means having ballast means connected to the discharge paths, wherein said display control means permits a plurality of discharge paths of the same color of said display means to be coupled to the same ballast means to thereby time-divide a lighting time of said plurality of discharge paths for lighting control.
signal generating means for generating an electric signal corresponding to an image to he displayed;
image processing means for converting said electric signal generated by said signal generating means into a predetermined color image signal;
display control means for executing pulse width modulation control to display said color image signal processed by said image processing means; and display means for displaying said color image signal controlled by said display control means, said display means having a plurality of discharge paths two-dimensionally arranged each for displaying one of a plurality of predetermined colors, said display means having ballast means connected to the discharge paths, wherein said display control means permits a plurality of discharge paths of the same color of said display means to be coupled to the same ballast means to thereby time-divide a lighting time of said plurality of discharge paths for lighting control.
2. An apparatus according to claim 1, wherein said plurality of discharge paths constitute a discharge element having a plurality of discharge paths of dif-ferent colors, and said display control means performs such a control as to permit discharging of only one discharge path in said discharge element having said plurality of discharge paths within a specific time.
3. An apparatus according to claim 1, wherein said display control means includes switch means for switching an on/off state of desired discharge paths to be lit in accordance with a predetermined lighting enable state signal.
4. An apparatus according to claim 1, wherein said display control means includes power supplies for individual colors, and switch circuit means for con-trolling on/off switching of said discharge paths of different colors in accordance with values of voltages of said power supplies.
5. An apparatus according to claim 1, wherein said display control means controls a lighting enable state of said discharge paths of different colors for a same period of time.
6. An image display apparatus comprising:
signal generating means for generating an electric signal corresponding to an image to be displayed;
image processing means for converting said electric signal generated by said signal generating means into a predetermined color image signal;
display control means for executing pulse width modulation control to display said color image signal processed by said image processing means; and display means for displaying said color image signal controlled by said display control means, said display means having a plurality of discharge paths two-dimensionally arranged each for displaying one of a plurality of predetermined colors, said display means having power supply means connected to the discharge paths, wherein said display control means permits a plurality of discharge paths of the same color of said display means to be coupled to the same power supply means to thereby time-divide a lighting time of said plurality of discharge paths for lighting control.
signal generating means for generating an electric signal corresponding to an image to be displayed;
image processing means for converting said electric signal generated by said signal generating means into a predetermined color image signal;
display control means for executing pulse width modulation control to display said color image signal processed by said image processing means; and display means for displaying said color image signal controlled by said display control means, said display means having a plurality of discharge paths two-dimensionally arranged each for displaying one of a plurality of predetermined colors, said display means having power supply means connected to the discharge paths, wherein said display control means permits a plurality of discharge paths of the same color of said display means to be coupled to the same power supply means to thereby time-divide a lighting time of said plurality of discharge paths for lighting control.
7. An apparatus according to claim 6, wherein said plurality of discharge paths constitute a discharge element having a plurality of discharge paths of dif-ferent colors, and said display control means performs such a control as to permit discharging of only one discharge path in said discharge element having said plurality of discharge paths within a specific time.
8. An apparatus according to claim 6, wherein said display control means includes power supply means fur individual colors, and switch circuit means for controlling on/off switching of said discharge paths of different colors in accordance with values of voltages of said power supply means.
9. An apparatus according to claim 6, wherein said display control means controls a lighting enable state of said discharge paths of different colors for a same period of time.
10. An apparatus according to claim 8, wherein frequencies of said power supply means for individual colors can be variably set.
11. An apparatus according to claim 6, wherein said display control means has a plurality of discharge lamps each for display one of a plurality of predeter-mined colors, said power supply means supply power to those of said plurality of discharge lamps which provide a current with the same value, and a plurality of discharge electrodes of the same color of said discharge lamps are connected to the same power supply means of said display control means to thereby control time divisional lighting of a lighting time of said plurality of discharge electrodes of the same color.
12. An apparatus according to claim 11, wherein said plurality of discharge lamps have a plurality of discharge electrodes of different colors, and said display control means performs such a control as to permit discharging of only one discharge electrode in said plurality of discharge electrodes within a specific time.
13. An apparatus according to claim 11, wherein said display control means includes power supply means for individual colors, switch circuit means for con-trolling on/off switching of said discharge lamps of different colors in accordance with values of voltages of said power supply means, and a controller for controlling on/off activation of said switch circuit means.
14. An apparatus according to claim 13, wherein said display control means controls a lighting enable state of said discharge lamps of different colors for a same period of time.
15. An apparatus according to claim 13, wherein frequencies of said power supply means for individual colors can be variably set.
16. A light circuit for an image display appa-ratus, comprising:
control means for executing pulse width modulation control of an image signal corresponding to an image to be displayed;
a plurality of discharging means for displaying said image signal controlled by said control means and each displaying one of a plurality of predetermined colors; and a plurality of ballast means for supplying power to those of said plurality of discharging means which supply a current with the same current value, wherein said control means permits a plurality of discharge electrodes of the same color of said dis-charging means to be coupled to same ballast means to thereby time-divide a lighting time of said plurality of discharge electrodes of the same color for lighting control.
control means for executing pulse width modulation control of an image signal corresponding to an image to be displayed;
a plurality of discharging means for displaying said image signal controlled by said control means and each displaying one of a plurality of predetermined colors; and a plurality of ballast means for supplying power to those of said plurality of discharging means which supply a current with the same current value, wherein said control means permits a plurality of discharge electrodes of the same color of said dis-charging means to be coupled to same ballast means to thereby time-divide a lighting time of said plurality of discharge electrodes of the same color for lighting control.
17. An apparatus according to claim 16, wherein said plurality of discharging means have a plurality of discharge electrodes of different colors, and said display control means performs such a control as to permit discharging of only one discharge electrode on said plurality of discharge electrodes within a specific time.
18. An apparatus according to claim 16, wherein said display control means includes power supply for individual colors, switch circuit means for controlling on/off switching of said discharging means of different colors in accordance with values of voltages of said power supply.
19. An apparatus according to claim 16, wherein said display control means controls a lighting enable state of said discharging means of different colors for a same period of time.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1034959A JPH02214893A (en) | 1989-02-16 | 1989-02-16 | Video display device |
| JP1-34959 | 1989-02-16 | ||
| JP1170583A JPH0335288A (en) | 1989-06-30 | 1989-06-30 | Display element dynamic lighting device |
| JP1-170583 | 1989-06-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2010267A1 true CA2010267A1 (en) | 1990-08-16 |
Family
ID=26373841
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002010267A Abandoned CA2010267A1 (en) | 1989-02-16 | 1990-02-16 | Image display apparatus for controlling lighting of a plurality of discharge paths in time divisional manner |
Country Status (3)
| Country | Link |
|---|---|
| KR (1) | KR930005368B1 (en) |
| CA (1) | CA2010267A1 (en) |
| GB (1) | GB2229847A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100217279B1 (en) * | 1997-06-20 | 1999-09-01 | 전주범 | A separating adaptive method for system process of pdp-tv |
| JP4163787B2 (en) * | 1997-06-20 | 2008-10-08 | 株式会社大宇エレクトロニクス | Apparatus and method for timing control of AC plasma display flat plate apparatus |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4513281A (en) * | 1982-04-05 | 1985-04-23 | At&T Bell Laboratories | AC plasma panel shift with intensity control |
| JPS6023947A (en) * | 1983-07-18 | 1985-02-06 | Matsushita Electric Works Ltd | Color discharge lamp and its control |
-
1990
- 1990-02-12 GB GB9003115A patent/GB2229847A/en not_active Withdrawn
- 1990-02-16 KR KR1019900001935A patent/KR930005368B1/en not_active IP Right Cessation
- 1990-02-16 CA CA002010267A patent/CA2010267A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| KR930005368B1 (en) | 1993-06-19 |
| GB9003115D0 (en) | 1990-04-11 |
| GB2229847A (en) | 1990-10-03 |
| KR900013446A (en) | 1990-09-05 |
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