JP2007072288A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce dispersion and change with time of characteristics of an emission current to a drive voltage for each electron source, in a display device in which a plurality of electron sources utilizing field emission or the like is arranged in a matrix form and the electrons from the electron sources are made to radiate against a fluorescent material to emit light. <P>SOLUTION: In a first period of two periods obtained by dividing one horizontal period, a cathode electrode is driven for a predetermined period via a voltage driving circuit which outputs a voltage corresponding to a display gray scale data, and then in the latter period, the cathode electrode is driven via a constant current driving circuit which outputs a current corresponding to the display gray scale data. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a display device in which a plurality of electron sources using field emission or the like are arranged in a matrix, and the electrons from the electron sources are projected onto a phosphor to emit light, and in particular, the driving voltage thereof. The present invention relates to a display device in which variations in emission current characteristics among electron sources and changes with time are reduced.

  As a first prior art, as a prior art for automatically adjusting a change in characteristics due to a change with time of an electron-emitting device constituting a display panel, dummy pixels are provided in a row or a column of a display pixel matrix, and the characteristics are set. There is a technique that corrects a change in light emission characteristics by finely adjusting a driving voltage of a display pixel or a pulse width of pulse width modulation by measuring (see, for example, Patent Document 1). In this prior art, dummy pixels are installed, and the change in the characteristics of the entire display panel is observed by looking at the change in the characteristics. It is effective to measure the characteristics of the dummy pixels and fine-tune the display pixel drive when it is assumed that variations in display characteristics within the display panel and changes over time are almost uniform. It is. However, for example, in a field emission display device (hereinafter referred to as CNT-FED) using carbon nanotubes as an electron source, the characteristics of the driving voltage of the electron source versus the emission current are within the surface of the display panel. Greatly varies, and even if it is between adjacent pixels. Therefore, this conventional technique cannot cope with variations in individual pixel characteristics and changes with time in the CNT-FED display panel.

  As a second prior art, the anode current of a field emission display device (hereinafter referred to as FED) is measured in real time and corrected for gradation driving (combination of voltage amplitude modulation and voltage pulse width modulation). Some of them correspond to unevenness and changes with time (for example, see Patent Document 2). In this prior art, the change in the characteristics of the display panel is measured by the change in the anode current. Since the anode current is the sum of the emission currents emitted from the respective pixels, it can be corrected for a change in brightness of the entire display panel. However, the measurement of the anode current cannot measure the change or variation in the characteristics of individual pixels, and thus has no effect on display unevenness and its change over time.

  As a third conventional technique, in an FED in which each pixel is configured by a cathode electrode, a gate electrode, and an insulating layer existing between the cathode electrode, the gate electrode, and the insulating layer thickness in the initial period of the pixel selection period. There is a driving method in which a corresponding potential (a potential necessary to display the minimum luminance) is set, and charge injection corresponding to the display luminance is performed on the pixel in the subsequent period (see, for example, Patent Document 3). In this prior art, first, voltage driving is performed so that the minimum luminance is displayed, and then driving is performed with a current corresponding to the display luminance. However, in this method, in the case of a large-sized display panel using a CNT-FED and having a large cathode electrode capacity load, the voltage range from the minimum luminance to the maximum luminance is 50V. In particular, even if an emission current of 10 μA that emits light at the maximum luminance is applied, it takes 1 ms, and driving is not completed within one horizontal period.

  As a third prior art, there is a time-division subfield driving method which is a general gradation driving method in a plasma display panel. In this driving method, there is a problem that a pseudo contour is generated in a part of an image when displaying a moving image. This is because when there are pixels that display different gradations within one field, the light emission start time and the light emission stop time are different, and in addition, when the subject moves, the image changes every moment. This is a phenomenon that appears as noise on the display because interference occurs between the timing shift and the light emission timing by the time-division subfield drive.

JP-A-2001-195026 JP-A-2001-350442 Japanese Patent Laid-Open No. 2002-055652

  An object of the present invention is to provide a display device that eliminates the above-described problems and mainly reduces variations in driving voltage versus emission current characteristics among electron sources and changes with time.

  The above and other objects and novel features of the present invention will become apparent from the description of this specification and attached drawings.

Of the inventions disclosed in this document, the outline of typical ones will be briefly described as follows.
(1) A vacuum envelope provided with a translucent part at least in part, a plurality of cathode electrodes extending in a first direction, and extending in a second direction intersecting the first direction, A plurality of gate electrodes spaced apart from the plurality of cathode electrodes and arranged to face the plurality of cathode electrodes, each having an opening at each of the intersections with the plurality of cathode electrodes; and each of the openings A plurality of electron sources disposed on the plurality of cathode electrodes so as to face each other; and an anode electrode including a phosphor irradiated with electrons from the plurality of electron sources; and the plurality of gate electrodes. Is supplied with a gate drive signal for sequentially selecting the plurality of gate electrodes, and each of the plurality of cathode electrodes is subjected to display gradation data in correspondence with the plurality of gate electrodes being sequentially selected. Driven by signals corresponding to In the display device, the voltage drive circuit that outputs the voltage corresponding to the display gradation data to the plurality of cathode electrodes in the first period of two periods obtained by dividing one horizontal period. After driving for a predetermined period of time, in the latter period of the two periods, the plurality of cathode electrodes are connected via a constant current driving circuit that outputs a current corresponding to the display gradation data. A display device that is driven.
(2) In the display device according to (1), each of the plurality of cathode electrodes is provided with a pair of the voltage driving circuit and the constant current driving circuit. A display device, wherein an output of any one of the constant current drive circuits is selected by a changeover switch and output to the plurality of cathode electrodes.
(3) A vacuum envelope provided with a translucent part at least in part, a plurality of cathode electrodes extending in a first direction, and extending in a second direction intersecting the first direction, A plurality of gate electrodes spaced apart from the plurality of cathode electrodes and arranged to face the plurality of cathode electrodes, each having an opening at each of the intersections with the plurality of cathode electrodes; and each of the openings A plurality of electron sources disposed on the plurality of cathode electrodes so as to face each other; and an anode electrode including a phosphor irradiated with electrons from the plurality of electron sources; and the plurality of gate electrodes. Is supplied with a gate drive signal for sequentially selecting the plurality of gate electrodes, and each of the plurality of cathode electrodes is subjected to display gradation data in correspondence with the plurality of gate electrodes being sequentially selected. Driven by signals corresponding to In the display device, the emission current from the corresponding electron source among the plurality of electron sources reaches a predetermined value in the first of the two periods obtained by dividing one horizontal period. Until the plurality of cathode electrodes are driven through a voltage driving circuit that outputs a voltage corresponding to display grayscale data, and in the latter period of the two periods, the plurality of cathode electrodes Is driven through a constant current driving circuit that outputs a current corresponding to display gradation data.
(4) In the display device according to (3), each of the plurality of cathode electrodes is provided with a pair of the voltage driving circuit and the constant current driving circuit. A display device, wherein an output of any one of the constant current drive circuits is selected by a changeover switch and output to the plurality of cathode electrodes.
(5) A vacuum envelope provided with at least a light transmitting part, a plurality of cathode electrodes extending in a first direction, and extending in a second direction intersecting the first direction, A plurality of gate electrodes spaced apart from the plurality of cathode electrodes and arranged to face the plurality of cathode electrodes, each having an opening at each of the intersections with the plurality of cathode electrodes; and each of the openings A plurality of electron sources disposed on the plurality of cathode electrodes so as to face each other; and an anode electrode including a phosphor irradiated with electrons from the plurality of electron sources; and the plurality of gate electrodes. Is supplied with a gate drive signal for sequentially selecting the plurality of gate electrodes, and each of the plurality of cathode electrodes is subjected to display gradation data in correspondence with the plurality of gate electrodes being sequentially selected. Driven by signals corresponding to In the display device, at the start of one horizontal period, a voltage driving circuit that outputs a voltage corresponding to display gradation data to the plurality of cathode electrodes, and a constant current driving circuit that outputs a current corresponding to the display gradation data The display device is characterized in that the plurality of cathode electrodes are driven only by the constant current drive circuit within the one horizontal period and after a predetermined period has elapsed.
(6) In the display device according to (5), each of the plurality of cathode electrodes is provided with a pair of the voltage driving circuit and the constant current driving circuit. A display device, wherein an output of a drive circuit can be disconnected from the plurality of cathode electrodes.
(7) A vacuum envelope provided with a translucent part at least in part, a plurality of cathode electrodes extending in a first direction, and extending in a second direction intersecting the first direction, A plurality of gate electrodes spaced apart from the plurality of cathode electrodes and arranged to face the plurality of cathode electrodes, each having an opening at each of the intersections with the plurality of cathode electrodes; and each of the openings A plurality of electron sources disposed on the plurality of cathode electrodes so as to face each other; and an anode electrode including a phosphor irradiated with electrons from the plurality of electron sources; and the plurality of gate electrodes. Is supplied with a gate drive signal for sequentially selecting the plurality of gate electrodes, and each of the plurality of cathode electrodes is subjected to display gradation data in correspondence with the plurality of gate electrodes being sequentially selected. Driven by signals corresponding to In the display device, at the start of one horizontal period, a voltage driving circuit that outputs a voltage corresponding to display gradation data to the plurality of cathode electrodes, and a current driving circuit that outputs a constant current corresponding to the display gradation data After the emission current from the corresponding electron source in the plurality of electron sources reaches a predetermined value within the one horizontal period, the plurality of cathode electrodes are connected to the fixed electrode. A display device that is driven only by a current driving circuit.
(8) In the display device according to (7), each of the plurality of cathode electrodes is provided with a pair of the voltage driving circuit and the constant current driving circuit. A display device, wherein an output of a drive circuit can be disconnected from the plurality of cathode electrodes.
(9) A vacuum envelope provided with a translucent part at least in part, a plurality of cathode electrodes extending in a first direction, and extending in a second direction intersecting the first direction, A plurality of gate electrodes spaced apart from the plurality of cathode electrodes and arranged to face the plurality of cathode electrodes, each having an opening at each of the intersections with the plurality of cathode electrodes; and each of the openings A plurality of electron sources disposed on the plurality of cathode electrodes so as to face each other; and an anode electrode including a phosphor irradiated with electrons from the plurality of electron sources; and the plurality of gate electrodes. Is supplied with a gate drive signal for sequentially selecting the plurality of gate electrodes, and each of the plurality of cathode electrodes is subjected to display gradation data in correspondence with the plurality of gate electrodes being sequentially selected. Driven by signals corresponding to In the display device, in the first period of two periods obtained by dividing one horizontal period, the plurality of cathode electrodes are driven for a predetermined period via a voltage driving circuit that outputs a voltage. Thereafter, in the latter period of the two periods, the plurality of cathode electrodes are driven via a constant current driving circuit that outputs a current corresponding to display gradation data, and the cathode electrodes are driven. The display scale used in the voltage drive circuit is such that the emission current of the electron source when driven by the voltage drive circuit approaches the emission current of the electron source when the cathode electrode is driven by the constant current drive circuit. A display device, comprising: a conversion table for converting tone data in advance on the basis of an average characteristic of the driving voltage versus emission current of the electron source.
(10) A vacuum envelope provided with a translucent part at least in part, a plurality of cathode electrodes extending in a first direction, and extending in a second direction intersecting the first direction, A plurality of gate electrodes spaced apart from the plurality of cathode electrodes and arranged to face the plurality of cathode electrodes, each having an opening at each of the intersections with the plurality of cathode electrodes; and each of the openings A plurality of electron sources disposed on the plurality of cathode electrodes so as to face each other; and an anode electrode including a phosphor irradiated with electrons from the plurality of electron sources; and the plurality of gate electrodes. Is supplied with a gate drive signal for sequentially selecting the plurality of gate electrodes, and each of the plurality of cathode electrodes is subjected to display gradation data in correspondence with the plurality of gate electrodes being sequentially selected. Drive with signals compatible with In a moving display device, in the first period of two periods obtained by dividing one horizontal period, the emission current from the corresponding electron source among the plurality of electron sources becomes a predetermined value. The plurality of cathode electrodes are driven through a voltage driving circuit that outputs a voltage corresponding to display grayscale data until reaching a predetermined period, and then the plurality of cathode electrodes are used in a later period of the two periods. The emission current of the electron source when the electrode is driven through a constant current drive circuit that outputs a current corresponding to display grayscale data and the cathode electrode is driven by the voltage drive circuit causes the cathode electrode to The display gradation data used in the voltage drive circuit is set so as to approach the emission current of the electron source when driven by the constant current drive circuit. Based on the average characteristics of the flow, the display device characterized by comprising a conversion table for converting in advance.
(11) A vacuum envelope provided with a translucent part at least in part, a plurality of cathode electrodes extending in a first direction, and extending in a second direction intersecting the first direction, A plurality of gate electrodes spaced apart from the plurality of cathode electrodes and arranged to face the plurality of cathode electrodes, each having an opening at each of the intersections with the plurality of cathode electrodes; and each of the openings A plurality of electron sources disposed on the plurality of cathode electrodes so as to face each other; and an anode electrode including a phosphor irradiated with electrons from the plurality of electron sources; and the plurality of gate electrodes. Is supplied with a gate drive signal for sequentially selecting the plurality of gate electrodes, and each of the plurality of cathode electrodes is subjected to display gradation data in correspondence with the plurality of gate electrodes being sequentially selected. Drive with signals compatible with In a moving display device, at the start of one horizontal period, a voltage drive circuit that outputs a voltage corresponding to display gradation data and a constant current drive that outputs a current corresponding to the display gradation data at the plurality of cathode electrodes Both the circuits are driven, and within the one horizontal period and after a predetermined period, the plurality of cathode electrodes are driven only by the constant current driving circuit, and the cathode electrodes are driven by the voltage driving circuit. Display gradation data used in the voltage drive circuit is such that the emission current of the electron source when driven approaches the emission current of the electron source when the cathode electrode is driven by the constant current drive circuit. A display device comprising a conversion table for converting in advance based on an average characteristic of driving voltage versus emission current of an electron source.
(12) A vacuum envelope provided with at least a part of a light transmitting part, a plurality of cathode electrodes extending in a first direction, and extending in a second direction intersecting the first direction, A plurality of gate electrodes spaced apart from the plurality of cathode electrodes and arranged to face the plurality of cathode electrodes, each having an opening at each of the intersections with the plurality of cathode electrodes; and each of the openings A plurality of electron sources disposed on the plurality of cathode electrodes so as to face each other; and an anode electrode including a phosphor irradiated with electrons from the plurality of electron sources; and the plurality of gate electrodes. Is supplied with a gate drive signal for sequentially selecting the plurality of gate electrodes, and each of the plurality of cathode electrodes is subjected to display gradation data in correspondence with the plurality of gate electrodes being sequentially selected. Drive with signals compatible with In a moving display device, at the start of one horizontal period, a voltage driving circuit that outputs a voltage according to display gradation data and a current drive that outputs a constant current according to the display gradation data at the plurality of cathode electrodes Driven by both of the circuits, and after the emission current from the corresponding electron source in the plurality of electron sources reaches a predetermined value within the one horizontal period, the plurality of cathode electrodes are The emission current of the electron source when driven by only the constant current drive circuit and the cathode electrode is driven by the voltage drive circuit is the emission current of the electron source when the cathode electrode is driven by the constant current drive circuit Display gradation data used in the voltage driving circuit is converted in advance based on an average characteristic of the driving voltage versus emission current of the electron source so as to approach the current. Display apparatus comprising the conversion table.
(13) In the display device according to (1), in the first period of the two periods, the gate drive signal for selecting a corresponding gate electrode of the plurality of gate electrodes is: A display device, which starts after a predetermined period with respect to a driving voltage for driving the plurality of cathode electrodes.
(14) In the display device according to (3), in the first period of the two periods, the gate drive signal for selecting a corresponding gate electrode of the plurality of gate electrodes is: A display device, which starts after a predetermined period with respect to a driving voltage for driving the plurality of cathode electrodes.
(15) In the display device according to (5), in the first period of the two periods, the gate drive signal for selecting a corresponding gate electrode of the plurality of gate electrodes is: A display device, which starts after a predetermined period with respect to a driving voltage for driving the plurality of cathode electrodes.
(16) In the display device according to (7), in the first period of the two periods, the gate drive signal for selecting a corresponding gate electrode of the plurality of gate electrodes is: A display device, which starts after a predetermined period with respect to a driving voltage for driving the plurality of cathode electrodes.
(17) A vacuum envelope provided with a translucent part at least in part, a plurality of cathode electrodes extending in a first direction, and extending in a second direction intersecting the first direction, A plurality of gate electrodes spaced apart from the plurality of cathode electrodes and arranged to face the plurality of cathode electrodes, each having an opening at each of the intersections with the plurality of cathode electrodes; and each of the openings A plurality of electron sources disposed on the plurality of cathode electrodes so as to face each other; and an anode electrode including a phosphor irradiated with electrons from the plurality of electron sources; and the plurality of gate electrodes. Is supplied with a gate drive signal for sequentially selecting the plurality of gate electrodes, and each of the plurality of cathode electrodes is subjected to display gradation data in correspondence with the plurality of gate electrodes being sequentially selected. Drive with signals compatible with In a moving display device, a voltage driving circuit that outputs a voltage corresponding to display gradation data to the plurality of cathode electrodes in the first period of two periods obtained by dividing one horizontal period After driving for a predetermined period of time, in a later period of the two periods, the plurality of cathode electrodes are connected via a constant current driving circuit that outputs current corresponding to the display gradation data. Display gradation data when the plurality of cathode electrodes are driven through the voltage driving circuit in the first period of the two periods, and the latter of the two periods. In the period, the sample values obtained by measuring the voltages of the plurality of cathode electrodes when the plurality of cathode electrodes are driven through the constant current driving circuit according to the display gradation data are displayed gradation data. Converted value And a correction memory for storing the difference calculated as a data correction value, and in the next frame, the first period of two periods obtained by dividing one horizontal period corresponding to the one horizontal period In the display device, the plurality of cathode electrodes are driven via the voltage driving circuit using the display gradation data supplied with the data correction value corrected as display gradation data. .
(18) In the display device according to (17), the data correction value is calculated for each of the plurality of electron sources, and the correction memory has a number of addresses corresponding to the number of the plurality of electron sources. A display device comprising:
(19) In the display device according to (17), the data correction value is calculated for at least a part of gradation levels represented by the display gradation data of each of the plurality of electron sources, A display device stored in the correction memory.
(20) The display device according to any one of (1), (3), (5), (7), (9), (10), (11), (12) and (17) The display device is characterized in that the voltage driving circuit and the constant current driving circuit are arranged in the vicinity of one end of each of the plurality of cathode electrodes.
(21) The display device according to any one of (1), (3), (5), (7), (9), (10), (11), (12) and (17) The voltage driving circuit is disposed in the vicinity of one end of each of the plurality of cathode electrodes, and the constant current circuit is disposed in the vicinity of the other end of each of the plurality of cathode electrodes. A display device characterized by that.
(22) The display device according to any one of (1), (3), (5), (7), (9), (10), (11), (12) and (17) The display device according to claim 1, wherein the plurality of electron sources are composed of carbon nanotubes.
(23) The display device according to any one of (1), (3), (5), (7), (9), (10), (11), (12) and (17) The display device according to claim 1, wherein the plurality of electron sources comprises a cone-shaped Spindt field emission cathode.

  According to the configuration of the present invention, it is possible to reduce the variation of the drive voltage versus emission current characteristic for each electron source and the change with time.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings for explaining the embodiments, parts having the same function are given the same reference numerals, and repeated explanation thereof is omitted.

  The present invention can be applied to a display device in which a plurality of electron sources using field emission or the like are arranged in a matrix, and the phosphors emit light by projecting electrons from the electron sources onto the phosphors. That is, for example, as disclosed in JP-A-11-162383, JP-A-2002-55652 and the like, a display device whose electron source is composed of carbon nanotubes (hereinafter referred to as CNT-FED), or Similarly, it can be applied to display devices disclosed in JP-A-11-162383, JP-A-2002-55652, etc., in which the electron source is composed of a cone-shaped Spindt field emission cathode. . Accordingly, in the following description, examples will be described by taking CNT-FED as an example, but the present invention is an electron source using field emission or the like other than a display device using CNT-FED and Spindt-type cathode. Needless to say, the present invention can be applied to a display device in which the phosphors are emitted by projecting the electrons from the electron source onto the phosphor.

  FIG. 1 is a diagram showing the configuration of the first embodiment of the present invention. Reference numeral 1 is a controller for processing control signals and display data of the display panel, 2 is a horizontal drive circuit, 3 is a vertical drive circuit, 4 is a cathode electrode, 5 is a gate electrode, and 6 is an electron source. Display data output from the controller 1 is sequentially taken into the horizontal drive circuit 2, and a signal corresponding to the display data is output from the cathode electrode 4 in accordance with the timing of the line selection signal output from the vertical drive circuit 3 to the gate electrode 5. Is output. As a result, electrons are emitted from the electron source 6 associated with the selected gate electrode 5 in accordance with the signal output to the cathode electrode 4.

  The controller 1 uses as input signals a horizontal synchronizing signal 14, a vertical synchronizing signal 15, a dot clock 16, and display data 17 output from a display signal source (not shown) such as a signal processing circuit of a computer or a television. The display data 17 includes color display data such as RGB signals and composite signals. From these input signals, the controller 1 outputs a horizontal start signal 18, a horizontal clock 19, horizontal display data 20, a line latch clock 21, and a switching signal 22 to the horizontal drive circuit 2, while the vertical drive circuit 3 has a vertical signal. A start signal 23 and a vertical clock 24 are output.

  The horizontal drive circuit 2 includes a shift register circuit 7, a data latch circuit 8, a line latch circuit 9, and a cathode drive circuit 10. Here, the cathode drive circuit 10 includes a voltage drive circuit 11 that outputs a voltage according to display data, a current drive circuit 12 that outputs a current according to display data, and a voltage and current output from the voltage drive circuit 11. The switch 13 switches the current output from the drive circuit 12 by the switching signal 22, and the signal output line 25 outputs the voltage signal or current signal selected by the switch 13 to the cathode electrode 4.

  The vertical drive circuit 3 includes a gate signal line 26 that outputs a signal for driving the gate electrode 5 from the vertical start signal 23 and the vertical clock 24 input from the controller 1, and sequentially scans the gate electrode 5. Line sequential driving is realized.

  Although FIG. 1 shows five cathode electrodes 4 and four gate electrodes, this is an example for explanation, and if applied to a computer display, XGA (1024 (RGB) × 768). ), SXGA (1280 (RGB) × 1024), UXGA (1600 (RGB) × 1200) and the like cathode electrodes and gate electrodes are arranged. For application to television, a number of cathode electrodes and gate electrodes such as 1280 (RGB) × 720 are arranged. Further, in FIG. 1, each pixel is arranged in a matrix, but each pixel may be in a so-called delta arrangement.

  Next, a cross-sectional structure of a pixel disposed on the intersection of the cathode electrode 4 and the gate electrode 5 will be described with reference to FIG. The cathode electrode 4, the gate electrode 5, and the electron source 6 are formed on the substrate 65. On the other hand, an anode electrode 67 and a phosphor 66 are formed on a substrate 68 facing the substrate 65. The space between the substrates 65 and 68 is set to a high vacuum state (ultra-low pressure state), and a voltage of several kilovolts to several tens of kilovolts is applied between the gate electrode 5 and the anode electrode 67 by the high voltage power source 69, whereby the electron source 6 Electrons are emitted from the anode toward the anode electrode 67, and an emission current flows. The emitted electrons reach the phosphor 66, and this energy causes the phosphor 66 to emit light, and light is emitted through the anode electrode 67 and the substrate 68. Each pixel emits light in this manner, thereby forming a display as a whole.

  FIG. 21 shows the emission current characteristics of the electron source 6 shown in FIG. If the potential difference between the voltage applied to the cathode electrode 4 and the voltage applied to the gate electrode 5 is defined as a drive voltage, the emission current increases as the drive voltage increases as shown in FIG. Therefore, the emission current can be increased or decreased by controlling this drive voltage. Further, since the amount of light emission of the phosphor 66 increases as the emission current increases, the light emission luminance can be controlled by controlling the drive voltage. However, large variations occur in the characteristics of the drive voltage and emission current. For example, if the drive voltage for displaying the minimum luminance at which the emission current starts flowing is defined as the threshold voltage Vth, the threshold voltage Vth varies greatly from pixel to pixel. Also, the emission current varies when the same drive voltage is applied. Further, the slope of the characteristic curve of drive voltage vs. emission current and the shape of the curve also vary from pixel to pixel.

  The first embodiment of the present invention provides a display in which an emission current is stably supplied to an electron source having such characteristics, thereby reducing variations in luminance. The configuration and operation will be described below in detail with reference to FIGS.

  FIG. 2 shows a detailed configuration of the cathode drive circuit 10 built in the horizontal drive circuit 2. The same parts as those in FIG. 1 are given the same reference numerals. The cathode drive circuit 10 includes a DA converter 27, a buffer amplifier 28 for voltage drive, a buffer amplifier 29 for current drive, a transistor 30, and a resistor 31. A circuit for current driving is composed of a buffer amplifier 29, a transistor 30, and a resistor 31. With this configuration, the voltage input from the DA converter 27 to the positive polarity input terminal of the buffer amplifier 29 is converted into a current by the transistor 30 and the resistor 31 and appears at the collector terminal of the transistor 30. The cathode drive circuit 10 is arranged in the horizontal drive circuit 2 corresponding to the number of cathode electrodes 4 as shown in FIG.

  Next, the operation of the horizontal drive circuit 2 will be described. The horizontal drive circuit 2 receives the horizontal start signal 18 from the controller 1 and drives the shift register circuit 7 by the horizontal clock 19, and the shift register circuit 7 sequentially outputs a selection signal to the data latch circuit 8. The data latch circuit 8 takes in the horizontal display data 20 output from the controller 1 in response to a selection signal from the shift register circuit 7 and temporarily holds the data and outputs it to the line latch circuit 9. When the data latch circuit 8 is sequentially selected by the shift register circuit 7, the horizontal display data 20 is sequentially taken into the data latch circuit 8. After all the display data for one horizontal is taken into the data latch circuit 8, the controller 1 outputs the line latch clock 21 to drive the line latch circuit 9 and simultaneously to the cathode drive circuit 10, the line latch circuit 9. The display data held in is output.

  Further, the operation of the cathode drive circuit 10 will be described with reference to FIG. The cathode drive circuit 10 converts the display data output from the line latch circuit 9 into an analog voltage according to the display data by the DA converter 27. This analog voltage is guided to the terminal a of the switch 13 as a voltage via the buffer amplifier 28. On the other hand, the analog voltage output from the DA converter 27 is also input to the other buffer amplifier 29. When the buffer amplifier 29 drives the base of the transistor 30, a current I corresponding to the value R of the resistor 31 connected to the emitter of the transistor 30 is guided from the collector of the transistor 30 to the terminal b of the switch 13. Between the current I at this time, the voltage V output from the DA converter 27, and the resistor R, there is a relationship of I = V / R. Therefore, the configuration including the buffer amplifier 29, the transistor 30, and the resistor 31 operates as a voltage-current converter that converts the analog voltage output from the DA converter 27 into a corresponding current.

  Next, the relationship between the cathode drive waveform output to the cathode electrode 4 using the cathode drive circuit 10 and the gate drive waveform for driving the gate electrode 5 will be described with reference to FIG. FIG. 3 shows drive waveforms when one of the plurality of gate electrodes 5 is selected and the gate electrode is driven. A period for selecting and driving one gate electrode is defined as one horizontal period. In this embodiment, the one horizontal driving period is divided into two periods, that is, step A and step B, respectively, and the cathode electrode 4 and the gate electrode 5 are driven.

  First, in Step A, the cathode drive circuit 10 outputs the analog voltage output from the buffer amplifier 28 to the signal output line 25 to drive the cathode electrode 4 with voltage. That is, in order to select the gate electrode 5 in step A, the gate electrode 5 is changed from a voltage level of 0 V, which has been a non-selection level, to a voltage level of 50 V, which is a selection level. At the same time, the switch 13 is connected to the terminal a, and the analog voltage output from the buffer amplifier 28 is output to the signal output line 25 and applied to the cathode electrode 4. At this time, since the cathode driving circuit 10 operates as a voltage driving circuit, the cathode driving circuit 10 is in a low output impedance state, and the cathode electrode is driven by the analog voltage output from the DA converter 27, so the cathode electrode is rapidly changed from the black level + 50V to the white level. Driven toward 0V.

  Next, in step B, the signal output line 25 is connected to the collector of the transistor 30 by connecting the switch 13 from the terminal a to the terminal b while maintaining the gate drive waveform at the selection level of 50V. Since the current corresponding to the analog voltage output from the DA converter 27 appears at the collector of the transistor 30 as described above, a constant current flows through the signal output line 25, and the cathode electrode 4 has a constant current. Driven.

  As described above, the gate electrode is driven by dividing one horizontal period into two periods. However, when the next gate electrode is driven, if the gate electrode in the above description is the Nth gate electrode, N + 1 rows This is a period for driving the gate electrode of the eye. The one horizontal period for driving the gate electrode of the (N + 1) th row is also divided into two periods of Step A and Step B as described above and driven in the same manner. In order to change the gate electrode of the Nth row from the selection level to the non-selection level, a step A period in one horizontal period of the (N + 1) th row is used. That is, the gate electrode 5 in the Nth row is changed from 50 V, which has been the selected level, to 0 V, which is the non-selected level, and the switch 13 of each cathode driving circuit 10 is connected to the terminal a, and the buffer amplifier 28 The cathode drive voltage is set to a drive voltage necessary for the display of the next N + 1th row. In FIG. 3, two values of black level + 50V and white level 0V are shown. In the case of gradation display, a voltage between 0V and 50V is output from the buffer amplifier 28. The gate electrode 5 is selected and the cathode electrode 4 is driven by the series of operations of Step A and Step B described above.

  The state in which electrons emitted from the electron source 6 on the matrix of the selected gate electrode 5 and cathode electrode 4 by the above driving flow into the anode electrode, that is, the emission current will be described below.

  In step A, the gate drive waveform is a process of transition from the non-selection level to the selection level, while the cathode drive waveform is also a process of voltage transition from the black level to the white level by voltage drive. Therefore, the emission current gradually starts to flow due to the voltage difference between the cathode drive voltage and the gate drive voltage. Next, in Step B, since the gate drive voltage is at a selection level and the cathode drive voltage is also a voltage sufficient to flow an emission current, when the constant current drive is performed, the constant current flows as an emission current, That is, electrons are emitted to the anode electrode 67. Thereby, the phosphor 66 emits light. Since this current is a constant current, the amount of electrons required for light emission is constant, and stable light emission, that is, light emission that reduces display unevenness is possible.

  As described above, in the first embodiment of the present invention, it is possible to emit light at a constant current particularly in a display panel having an electron source such as a CNT-FED panel having a large screen and a high definition, thereby emitting phosphors. Thus, it is possible to reduce the variation in characteristics such as the applied voltage of the electron source versus the emission current, so that the display unevenness can be greatly reduced.

  Next, a second embodiment will be described with reference to FIGS. FIG. 4 shows a modification of the cathode drive circuit 10 for realizing the second embodiment of the present invention. The same reference numerals are given to the same parts as those in the first embodiment. Reference numeral 32 denotes a buffer amplifier that outputs the analog voltage output from the DA converter 27 and controls the power consumption of the buffer amplifier 32 by the switching signal 22, that is, the voltage drive state and the low power consumption standby state. It is a circuit that can. The output of the buffer amplifier 32 is connected to the switch 33, and the switching signal 22 controls whether the output of the buffer amplifier 32 is connected to the signal output line 25 or disconnected. On the other hand, the buffer amplifier 29, the transistor 30, and the resistor 31 forming the constant current drive circuit have the same configuration as in the first embodiment, except that the collector output of the transistor 30 is connected to the signal output line 25 as it is. .

  FIG. 5 is a drive waveform diagram showing the operation of the second embodiment. FIG. 5 shows drive waveforms when one of a plurality of gate electrodes 5 is selected and the gate electrode is driven as in the case of the first embodiment. A period for selecting and driving one gate electrode is defined as one horizontal period. Similarly to the first embodiment, the cathode electrode 4 and the gate electrode 5 are driven by dividing one horizontal drive period into two periods, that is, step A and step B, respectively.

  The operation of the second embodiment having such a configuration will be described with reference to FIGS. The digital display data output from the line latch circuit 9 is input to the DA converter 27 in the cathode drive circuit 10, converted into an analog voltage corresponding to the digital display data, and output to the buffer amplifier 32 and the buffer amplifier 29. Is done. In step A, the buffer amplifier 32 transmits the analog voltage output from the DA converter 27 to the switch 33. During the period of step A, the switching signal 22 is controlled by the controller 1 so that the switch 33 is turned on, so that the output voltage of the buffer amplifier 32 is output as it is to the signal output line 25 and is transmitted to the cathode electrode 4. At the same time, during the period of step A, the voltage-current conversion circuit including the buffer amplifier 29, the transistor 30, and the resistor 31 also operates. That is, the analog voltage corresponding to the display data output from the DA converter 27 is input to the buffer amplifier 29, and the constant current converted to the collector terminal of the transistor 30 by the voltage-current conversion circuit is output to the signal output line 25. . In general, since the output impedance of the voltage drive circuit is lower than the output impedance of the current drive circuit, the voltage drive signal is dominant in the cathode drive waveform of the cathode electrode 4, and the waveform is the cathode drive waveform of FIG. Further, during the period of step A, the gate drive waveform is changed from the non-selection level to the selection level to select the gate electrode 5.

  Next, in step B, the switch 33 is turned off by the switching signal 22 while keeping the constant current output operation of the constant current drive circuit composed of the buffer amplifier 29, the transistor 30, and the resistor 31 as it is. As a result, the voltage output of the buffer amplifier 32 is electrically disconnected from the signal output line 25, and during the period of step B, the signal output line 25 is driven by constant current driving, and a constant current flows through the cathode electrode 4. On the other hand, the switching signal 22 controls the power consumption of the buffer amplifier 32. That is, during the period of step B, the output of the buffer amplifier 32 is electrically disconnected from the signal output line 25 by the switch 33, so that the operation of the buffer amplifier 32 is unnecessary. Therefore, when the switching signal 22 is at a signal level that turns off the switch 33, the operation of the buffer amplifier 32 is stopped to reduce the power consumption of the entire cathode drive circuit 10.

  As a result of the above driving, electrons are emitted from the electron source 6 on the matrix of the selected gate electrode 5 and cathode electrode 4 to the anode electrode, that is, current emission has a non-gate driving waveform in step A. This is a process of transition from the selection level to the selection level, while the cathode drive waveform is also a process of voltage transition from the black level to the white level by voltage driving and constant current driving. Therefore, the emission current gradually starts to flow due to the voltage difference between the cathode drive voltage and the gate drive voltage. Next, in Step B, the gate drive voltage is at the selected level, and the cathode drive voltage is also sufficient to allow the emission current to flow. Therefore, even if the voltage drive buffer amplifier is electrically disconnected, constant current drive is performed. A constant current flows as an emission current, that is, electrons are emitted to the anode electrode. Thereby, the phosphor 66 emits light. Since this current is a constant current, the amount of electrons required for light emission is constant, and stable light emission, that is, light emission that reduces display unevenness is possible.

  As described above, the second embodiment of the present invention has an electron source such as a CNT-FED panel having a particularly large screen and a high definition, and can thereby emit constant current in a display panel that emits phosphors. Thus, it is possible to reduce the variation in characteristics such as the applied voltage of the electron source versus the emission current, so that the display unevenness can be greatly reduced. Furthermore, since the low-voltage driven buffer amplifier can be stopped during the period of step B during constant current driving, the power consumption of the entire cathode driving circuit 10 can be reduced. It is to be noted that such an operation of the buffer amplifier can be stopped in the first embodiment as well, and the effect thereof can similarly reduce the power consumption of the cathode drive circuit 10 as a whole. . Since the operation of the low voltage buffer amplifier itself is the same, its description is omitted.

  Next, a third embodiment of the present invention will be described with reference to FIG. 6, FIG. 7, and FIG. FIG. 6 shows a modified example of the controller 1 and the horizontal drive circuit 2 that realize the third embodiment of the present invention. The same reference numerals are given to the same parts as those in the first embodiment and the second embodiment. is there.

  In FIG. 6, the controller 1 is provided with a data conversion table 37 for correcting and converting display data used for voltage driving in advance. In the horizontal drive circuit 2, the same display data as in the first embodiment and the second embodiment is latched as it is, and the data conversion circuit 37 converts the display data temporarily and holds the display data temporarily. The data latch circuit 8a latches the displayed display data and temporarily holds the display data. The line latch circuit 9 is a latch circuit that collectively holds the outputs of the data latch circuit 8a and the data latch circuit 8b for one line. The line latch circuit 9 outputs display data to the DA converter 34a and the DA converter 34b, respectively. The display data held in the data latch circuit 8b is output to the DA converter 34b via the line latch circuit 9, converted by the data conversion table 37, and then held in the data latch circuit 8a. The displayed data is output to the DA converter 34a via the line latch circuit 9.

  Here, the purpose of the data conversion table 37 will be described. The data conversion table 37 is for correcting and converting the input display data into display data suitable for voltage driving. That is, as shown in FIG. 21, in general, the drive voltage versus emission current characteristics of the electron source of the CNT-FED are not linear but a curve. Further, in the CNT-FED, since the phosphor emits light depending on the current, in the first and second embodiments of the present invention, an attempt is made to reduce unevenness in light emission by flowing a constant current through the cathode electrode 4. It was something to do. Therefore, the average characteristic of the drive voltage versus the emission current shown in FIG. 21 is incorporated in the data conversion table 37 in advance, and the display data is corrected and converted in advance in the table 37, and the corrected and converted display data is displayed. By performing voltage driving using the voltage, it is possible to obtain a voltage that can pass a current close to a desired current for light emission during voltage driving, and improve the accuracy during constant current driving. Thus, a panel with reduced display unevenness can be realized.

  Next, the operation of the third embodiment will be described. The controller 1 outputs the input display data to the horizontal drive circuit 2 as it is, and outputs to the horizontal drive circuit 2 data converted from the input display data using the data conversion table 37. In the horizontal drive circuit 2, the display data is latched in the data latch circuit 8b and the data latch circuit 8a, respectively. As for the correspondence relationship between the display data, the display data converted by the data conversion table 37 is latched in the data latch circuit 8a. As in the first and second embodiments, after all the display data for one horizontal is taken into the data latch circuits 8a and 8b, the controller 1 outputs the line latch clock 21 and drives the line latch circuit 9. The display data held in the line latch circuit 9 is output to the cathode drive circuit 10 all at once.

  Next, the cathode drive circuit 10 uses the display data output from the data latch circuit 8a via the line latch circuit 9 as the display data input of the DA converter 34a, and outputs it from the data latch circuit 8b via the line latch circuit 9. The displayed data is used as display data input for the DA converter 34b. The DA converter 34 a converts the input display data into an analog voltage and outputs the analog voltage to the buffer amplifier 35. Similarly, the DA converter 34 b converts the input display data into an analog voltage and outputs it to the buffer amplifier 29. The operations of the transistors 30, the resistor 31, the switch 36, and the like after the buffer amplifiers 29 and 35 are the same as those in the second embodiment, and thus the description thereof is omitted.

  The drive waveform of the third embodiment operating as described above will be described with reference to FIG. The characteristic of the drive waveform of the third embodiment is a voltage that allows a predetermined emission current to flow during voltage drive during the step A of the cathode drive waveform as compared with the drive waveforms in the first and second embodiments. It is in the point which the accuracy of convergence to reach improves. The load capacity of the cathode electrode 4 is about 200 pF, and the voltage change per unit time when this is driven at a constant current with an emission current of 10 μA for emitting light at the maximum luminance is 50 mV / 1 μs.

  When considering application to a high-definition television with a large screen, the number of pixels is, for example, 1280 × 720 pixels, and the time taken for one horizontal period of steps A and B is maximum when the frame frequency is 60 Hz. 23 μs. Although depending on the period assigned to each of steps A and B, when the voltage is driven in step A, the accuracy of reaching a predetermined voltage in the drive voltage vs. emission current characteristics is poor (corresponding to the case where ΔV in FIG. 7 is large). ), The step B period may end without reaching the predetermined emission current in the step B period. That is, a predetermined light emission luminance cannot be obtained. However, in the third embodiment, when the voltage is driven, the display data is corrected and converted in advance by the data conversion table 37 so as to correspond to the drive voltage vs. emission current characteristics, so that the predetermined voltage in step A is reached. Therefore, it is possible to reach a predetermined emission current during the period of step B, and it is possible to realize a display panel with higher accuracy and less display unevenness.

  As described above, in the third embodiment of the present invention, the data conversion table 37 for converting data in advance is provided before inputting display data to the cathode drive circuit 10 in correspondence with the drive voltage vs. emission current characteristics. Thus, it is possible to realize a display panel in which display unevenness is greatly reduced.

  Next, a fourth embodiment will be described with reference to FIG. The fourth embodiment is a modification of the first or second embodiment, and the circuit configuration is the same as that of each embodiment. Here, description will be made with reference to FIGS. 1 and 2 showing the first embodiment.

  The feature of the fourth embodiment is the gate drive waveform in FIG. That is, step A is further subdivided into two periods, step A1 and step A2. As described in the description of the operation of the first embodiment, the period of step A is a process in which the gate drive waveform transitions from the non-selected level to the selected level, while the cathode drive waveform is also blackened by voltage drive. This is the process of voltage transition from level to white level. Therefore, the emission current gradually starts to flow due to the voltage difference between the cathode drive voltage and the gate drive voltage. This means that the emission current starts to flow gradually from the period of step A in the first embodiment, and light emission is gradually started accordingly. Since this slight light emission is not light emission by a predetermined emission current, an error may occur in display luminance when averaged in one frame depending on the amount. For this reason, the fourth embodiment provides a display panel that can reduce display luminance errors by reducing the gradual emission of light during the period of step A.

  Details of driving will be described with reference to FIGS. 1 and 2 together with FIG. As shown in FIG. 8, one horizontal period is divided into two periods, step A and step B. Further, the step A period is subdivided into a step A1 period and a step A2 period. In the period of step A, the signal output line 25 is connected to the terminal a, so that the output of the buffer amplifier 28 is given to the cathode electrode 4. Therefore, since the output of the buffer amplifier 28 is given to the cathode electrode 4 during the period of step A1, the drive voltage changes from the black level toward the white level. On the other hand, during the period of step A1, the gate drive waveform is held at the non-selected level. For this reason, unlike the case of the first embodiment, the emission current does not gradually start to flow during the period of step A, and therefore slight light emission during this period hardly occurs. Next, in order to make the gate drive voltage transition from the non-selected state to the selected level in the period of step A2, light emission is started from this period. Since the operation after Step B is the same as that in the first embodiment, the description thereof is omitted.

  As described above, in the fourth embodiment, since the slight light emission in the step A period can be reduced, an error in display luminance when averaged over one frame period can be reduced, and a display panel with high image quality can be obtained. realizable. Needless to say, this embodiment is applicable not only to the first embodiment but also to the second and third embodiments. Further, the present invention can be similarly applied to the embodiments described below.

  Next, a fifth embodiment will be described with reference to FIGS. 9, 10, 11, 12, and 13. FIG. In each drawing of the fifth embodiment, the same reference numerals are given to the same portions as those in the first embodiment. The main feature of the fifth embodiment is that a voltage measurement circuit 38 for measuring the voltage of the signal output line 25, which is the output of the horizontal drive circuit 2, is built in the display panel as shown in FIG. Further, the data correction circuit 52 as shown in FIG.

  In FIG. 9, a voltage measurement circuit 38 includes a sample hold circuit 39 that samples and temporarily holds the voltage of the signal output line 25, and an AD converter 40 that sequentially converts the voltage held by the sample hold circuit 39 into digital data. And built-in. Further, the voltage measuring circuit 38 samples the voltage of the signal output line 25 and reads a sample hold control signal 41 for instructing the sample hold circuit 39 to hold the sampled voltage and the analog voltage held in order. It is controlled by a clock 42, a read start signal 44 for instructing the start of reading of the analog voltage held in the sample hold circuit 39, and a next stage start signal 45 for transmitting the read start signal 44 to the next sample hold circuit 39. The The digital signal converted by the AD converter 40 is transferred to the controller 1 by the digital sampling data 43. These signals are output from the controller 1 or input to the controller 1.

  Next, a detailed configuration of the sample hold circuit 39 will be described with reference to FIG. The sample and hold circuit 39 includes a buffer amplifier 46 for taking in and buffering the voltage of the signal output line 25, a switch 47 for opening and closing the output of the buffer amplifier 46 by the sample and hold control signal 41, and a buffer amplifier when the switch 47 is on. 46, the capacitor 48 that holds the voltage in the off state, the buffer amplifier 49 that buffers and outputs the voltage held in the capacitor 48, and the output of the buffer amplifier 49 is output to the AD converter 40. The switch 51 is connected to an analog input, and a flip-flop 50 that controls on / off of the switch 51 by inputting a read clock 42 and a start signal 44.

  Next, a detailed configuration of the data correction circuit 52 will be described with reference to FIG. The data correction circuit 52 stores a correction value in advance for display data to be written at the time of voltage driving in the next frame based on digital data corresponding to the analog voltage of the signal output line 25 converted by the AD converter 40. In addition, data correction is performed on display data for voltage driving using the correction value so that an emission current for obtaining a brightness close to a desired one is discharged in advance during voltage driving. .

  In FIG. 11, a data correction circuit 52 calculates a correction value in advance from a line memory 53 for temporarily storing display data input to the controller 1, digital sampling data 43, and display data stored in the line memory 53. The correction value calculation circuit 54 for storing the correction value, the voltage correction memory 57 having an address corresponding to at least the number of pixels of the display panel, and the correction data output from the correction value calculation circuit 54 are written in the voltage correction memory 57. A memory write circuit 55 that performs control, a vertical address generation circuit 56 that generates a memory address corresponding to the address of the gate electrode 5 of the display panel, and a memory read circuit 58 that reads correction data stored in the voltage correction memory 57. Read the input display data and memory It is composed of an arithmetic unit 59 for calculating processing with the correction data read out from the circuit 58.

  Next, the operation of the fifth embodiment will be described with reference to FIGS. In FIG. 12, the cathode drive waveform, the gate drive waveform, and the selection signal are the same as in the first embodiment. That is, as already described, one horizontal period is divided into two periods of step A and step B, and voltage driving and constant current driving are performed in each period. In the present embodiment, one of the features is that the operation of measuring the voltage is performed in the constant current driving period of Step B while the voltage of the cathode electrode 4 is sufficiently stable. In response to the sample hold control signal 41, the voltage of the cathode electrode 4 is turned on by the buffer amplifier 46 and the switch 47, and the voltage of the cathode electrode 4 is sampled in the capacitor 48. Next, the switch 47 is turned off and the voltage of the cathode electrode 4 is held in the capacitor 48. The voltage held in the capacitor 48 is buffered by the buffer amplifier 49 and guided to the switch 51.

  On the other hand, when the flip-flop 50 is activated by the input of one clock of the read clock 42 and the input of the start signal 44, the switch 51 is turned on. The output of the buffer amplifier 49 becomes an analog input of the AD converter 40 and is input to the controller 1 as the digital sampling data 43 by the AD converter 40.

  The output of the flip-flop 50 is output as a start signal for the sample hold circuit 39 in the next stage while the switch 51 is turned on. When the read clock 42 is next input, the switch 51 of the sample-and-hold circuit 39 at the current stage is turned off, and the switch 51 is turned on when the flip-flop 50 at the next stage is activated. By sequentially inputting the read clock 42 in this way, the voltage of the cathode electrode 4 held by each sample and hold circuit 39 becomes the analog input of the AD converter 40 in addition to the analog input of the AD converter 40 in addition. The input is output as digital sampling data 43 to the controller 1.

  Also, the data correction circuit 52 built in the controller 1 shown in FIG. 11 uses the sampling data 43 as an input to the correction value calculation circuit 54. The correction value calculation circuit 54 calculates a difference, that is, a data correction value, between the input sampling data 43 and the display data at the time of voltage driving stored in the line memory 53. The display data at the time of voltage driving stored in the line memory 53 is voltage driven (step A) immediately before the sampling data 43 corresponding to the cathode voltage currently driven at constant current (step B). Display data is stored. Therefore, by calculating the difference between the sampling data 43 and the display data at the time of voltage driving stored in the line memory 53, the arithmetic unit 59 described later is used to calculate the display data at the time of voltage driving in the next frame. By calculating the difference between the levers, it is possible to obtain a desired emission current during voltage driving.

  The data correction value calculated by the correction value calculation circuit 54 is written to a predetermined address in the voltage correction memory 57 by the memory writing circuit 55 and the vertical address generation circuit 56. This voltage correction memory 57 corresponds to the number of horizontal pixels and the number of vertical pixels of the display panel. This is because the applied voltage vs. emission current characteristics of the electron source of each pixel vary, and it is necessary to have a data correction value corresponding to each. Therefore, for example, when the number of horizontal and vertical pixels of the display panel is 1280 pixels and 720 pixels, respectively, the corresponding address bits are provided, and the voltage correction memory 57 has a memory area corresponding to each display pixel. I have. Furthermore, when the display panel is in color display, each pixel of RGB is, for example, a vertical stripe because each pixel emits three primary colors of red (R), green (G), and blue (B). The number of cathode electrodes 4 corresponding to this is provided. In other words, if the number of horizontal pixels is 1280 pixels, the cathode electrode 4 is provided with 3840 times that number, and accordingly, the memory capacity of the voltage correction memory 57 is also required to be 3 times the above capacity.

  Next, the data correction value stored in the voltage correction memory 57 is read by the memory reading circuit 58 and the vertical address generation circuit 56 and the data correction value stored at a predetermined address is read and output to the computing unit 59. The computing unit 59 performs a correction operation on the display data at the time of voltage driving using the data correction value read from the voltage correction memory 57 with respect to the input display data. Then, by using the display data that has been subjected to the correction calculation, it is possible to apply a driving voltage to the cathode electrode 4 so that an emission current close to a desired value can be obtained during voltage driving.

  This will be described with reference to FIG. FIG. 13 is different from FIG. 12 described above in the drive waveform applied to the cathode electrode 4 before and after correction in the voltage drive period, that is, the period of step A by calculating and correcting the display data. FIG. As shown in the figure, by measuring the driving voltage of the cathode electrode at the time of constant current driving with the driving waveform of the cathode electrode 4 before correction, the voltage of the cathode electrode 4 is driven in the next frame, that is, at step A. Since the voltage is driven by the display data that has already been corrected and calculated during the period, it is possible to obtain a driving voltage that can release a substantially predetermined emission current at this stage.

  As described above, according to the fifth embodiment of the present invention, the display panel includes the voltage measurement circuit 38 that measures the voltage of the signal output line 25 that is the output of the horizontal drive circuit 2, that is, the voltage applied to the cathode electrode 4. Furthermore, based on this, the controller 1 has a built-in data correction circuit 52 that corrects the display voltage at the time of voltage driving, so that a substantially predetermined emission current can already be released during voltage driving, that is, during the period of step A. Since a drive voltage that can be obtained can be obtained, even if the drive voltage vs. emission current characteristic of the electron source 6 is different for each pixel, the characteristic can be corrected, and a high-quality display panel without display unevenness can be realized. I can do it.

  Next, a sixth embodiment will be described with reference to FIGS. The sixth embodiment is an embodiment of the configuration of the controller 1 that can correct the display data with higher accuracy with respect to the data correction circuit 52 in the fifth embodiment. Note that the same reference numerals are given to the same parts as those in the fifth embodiment, and a description thereof will be omitted.

  A major feature of the sixth embodiment is that the accuracy of data correction of display data is further improved by increasing the capacity of the voltage correction memory corresponding to the desired number of gradations. In this embodiment, the following description will be made on the assumption that the display panel has a gradation bit number of 10 bits, that is, 1024 gradations. The number of gradation bits is not limited to this, and can be freely determined by comprehensively considering the purpose of use and cost of the display panel. It is assumed that the number of pixels of the display panel is 1280 × 720 pixels RGB color display as in the fifth embodiment.

  The problem to be solved by the present embodiment is that the drive voltage vs. emission current characteristics as shown in FIG. 21 vary from pixel to pixel, and the shape of the curve varies. In other words, when the driving voltage is associated with each gradation data, the emission current with respect to the gradation data has a characteristic of increasing in a curve rather than a constant increase. This means that when the display data is corrected and driven by the voltage correction memory described in the fifth embodiment, the correction amount is not always constant with respect to the display voltage before correction. In view of this point, in the sixth embodiment, the voltage correction memory is provided with correction data corresponding to each gradation data one by one, thereby aiming at further highly accurate gradation driving. It is.

  FIG. 14 is a logical configuration diagram of the voltage correction memory. The X-axis direction has 3840 addresses of 1280 pixels × 3 (RGB) corresponding to the number of cathode electrodes 4, and the Y-axis direction indicates the gate electrode 5. It has 720 addresses corresponding to the number. The Z-axis direction is a memory logic structure having 1024 addresses corresponding to the number of gradations of 10 bits. Thus, in this embodiment, the logical structure of the memory has a three-dimensional logical structure having addresses in the Z-axis direction corresponding to the gradation bits, as compared with the fifth embodiment.

  FIG. 15 is a configuration example corresponding to the present embodiment of the data correction circuit 52 incorporated in the controller 1. In FIG. 15, a gradation bit address generation circuit 60 is a circuit that generates a memory address corresponding to an address in the Z-axis direction of the voltage correction memory 61 corresponding to the number of bits of input display data. With such a configuration, the voltage correction memory 61 can have a data correction amount corresponding to each gradation of the input display data.

  The input display data is input to the gradation bit address generation circuit 60. The gradation bit address generation circuit 60 generates an address corresponding to the Z-axis direction of the voltage correction memory 61 corresponding to the input display data. The gradation bit address generation circuit 60 reads the correction data corresponding to the display data input from the voltage correction memory 61 together with the memory read circuit 58 and the vertical address generation circuit 56, and together with the read correction data. The input display data is corrected and calculated by the calculator 59. Then, voltage driving is performed during the period of step A based on the display data subjected to the correction calculation. At this time, in the present embodiment, since the voltage correction memory 61 has correction data corresponding to each gradation, it is possible to perform highly accurate gradation driving for each gradation.

  On the other hand, regarding the writing of the correction data to the voltage correction memory 61, the display data temporarily stored in the line memory 53 is sequentially read out and output to the correction value calculation circuit 54 to calculate the correction data and to the memory writing circuit 55. The display data is also output. The memory writing circuit 55 generates an address corresponding to the Z-axis direction in FIG. 14 based on this display data, and writes the correction data calculated from the correction value calculation circuit 54 to the corresponding address in the voltage correction memory 61. As a result, correction data for correcting the drive voltage versus emission current characteristics of each electron source on the intersection of the cathode electrode 4 and the gate electrode 5 can be stored in the voltage correction memory 61.

  As described above, according to the sixth embodiment of the present invention, the voltage correction memory 61 has correction data corresponding to each gradation data having different characteristics of each pixel. It becomes possible to perform gradation driving with higher accuracy, and display with high image quality can be obtained.

  Next, a seventh embodiment will be described with reference to FIGS. 16, 17, 18, and 19. FIG. This embodiment is for obtaining a high-quality display while reducing the storage capacity of the voltage correction memory 61 of the sixth embodiment. As shown in FIG. 16, the addresses in the X-axis direction and the Y-axis direction are left unchanged, and the Z-axis direction is reduced to 64 addresses with respect to the 1024 addresses in the sixth embodiment.

  FIG. 17 shows the voltage correction memory 63 extracted for each address in the Z-axis direction with respect to one X-axis direction address and one Y-axis direction address in the voltage correction memory 63. Further, the gradation bit address generation circuit 60 shown in FIG. 15 of the sixth embodiment includes an adjacent reference address bit generation circuit 62 that generates a read address of the voltage correction memory 63, and the number of addresses is 64. The voltage correction memory 63, and similarly the memory read circuit 58 of FIG. 15, includes a correction data interpolation circuit 64.

  The adjacent reference address bit generation circuit 62 is a circuit for generating an address for reading two correction data stored in the voltage correction memory 63 from the input display data. In this embodiment, since the number of addresses of correction data is only 64, for example, when displaying 1024 gradation display data as in the sixth embodiment, the correction data is insufficient. Therefore, two read addresses are generated for the voltage correction memory 63 for one of the 1024 gradations, and the correction data interpolation circuit 64 together with the input display data is input from the two read correction data. The correction value is interpolated and output to the calculator 59.

  As shown in FIG. 18, the operation of the adjacent reference address bit generation circuit 62 is performed by equally dividing the input gradation data into 16 stages, and from one gradation data, the Z-axis of the two voltage correction memories 63 is obtained. Generate a read address for the direction. The voltage correction memory 63 outputs two correction data 1 and 2 from these two read addresses.

  The correction data interpolation circuit 64 interpolates the amount of display data to be corrected during voltage driving from the read correction data 1 and 2 and the previously input display data, and outputs the result to the calculator 59. .

  Further, as the read address output from the adjacent reference address bit generation circuit 62, as shown in FIG. 19, the gradation data is divided at unequal intervals, and one gradation data is used for the Z-axis direction of the two voltage correction memories 63. A read address may be generated. This is because, as shown in FIG. 21, the drive voltage versus emission current of the electron source is not linear, and there are a region with a large characteristic gradient and a region with a small gradient, so that the gradation data is divided at unequal intervals accordingly. Thus, it is possible to alleviate calculation errors caused by differences in the slope of characteristics.

  As described above, according to the seventh embodiment of the present invention, the correction data corresponding to the gradation data having different characteristics of each pixel is provided in the voltage correction memory 63 having a small capacity, thereby further improving the correction. Therefore, it is possible to perform gradation driving with high accuracy, and it can be realized with a memory with a small capacity, so that high-quality display can be obtained at a low price.

  Next, an eighth embodiment of the present invention will be described with reference to FIG. The eighth embodiment is an example in which the display panel of each embodiment described in the present invention is applied to a television 71. The display panel 70 described in each embodiment includes a controller 1, a horizontal drive circuit 2, a vertical drive circuit 3, a cathode electrode 4, a gate electrode 5, and an electron source 6 as main components. As described in the embodiments, the controller 1 and the horizontal drive circuit 2 incorporate the characteristic circuit of the present invention.

  Since it is configured as a television 71, an antenna terminal 72 for receiving terrestrial and satellite radio waves, a tuner 73 for separating the received broadcast radio waves into luminance signals and color signals, and the luminance signals and color signals to the display panel 70. TVs that convert red (R), green (G), and blue (B) signals for input, circuits that convert interlace signals into progressive signals, and video signals that are directly input from the video terminal 75 for processing The signal processing circuit 74 is used to process a video signal necessary for John.

  With such a configuration, a television device can be realized using a display panel using an electron source.

  FIG. 23 shows an application example in which the voltage driving circuit 11 and the constant current driving circuit 12 incorporated in the horizontal driving circuit 2 are separately arranged above and below the display panel. Among the horizontal drive circuits 2 described in the above embodiments, the voltage drive circuit 11 is a horizontal drive circuit A and the constant current drive circuit 12 is separated into a horizontal drive circuit B. The same reference numerals are assigned to similar circuits, and a suffix applied to the circuit applied to the horizontal drive circuit A is a, and b applied to the circuit applied to the horizontal drive circuit B. As in each of the embodiments described so far, one horizontal period is divided into two periods, Step A and Step B. In Step A, voltage driving is performed, and in Step B, constant current driving is performed.

  In step A, an analog voltage output from the cathode drive circuit 10a is output to the signal output line 25a to drive the cathode electrode 4 with a voltage. That is, in order to select the gate electrode 5 in step A, the gate electrode 5 is changed from a voltage level of 0 V, which has been a non-selection level, to a voltage level of 50 V, which is a selection level. At the same time, the switch 13 a is turned on, and the analog voltage output from the cathode drive circuit 10 a is output to the signal output line 25 and applied to the canode electrode 4. At this time, the cathode driving circuit 10a operates as a voltage driving circuit, so that it is in a low output impedance state, and the cathode electrode 4 is driven by the analog voltage output from the DA converter. Driven from a bell + 50V toward a white level 0V.

  Next, in step B, the signal output line 25b is connected to the collector of the transistor 30 by turning on the switch 13b while maintaining the gate drive waveform at the selection level of 50V. Since the current corresponding to the analog voltage output from the DA converter appears at the collector of the transistor 30 as described above, a constant current flows through the signal output line 25, and the cathode electrode 4 is in a constant current drive state. It becomes.

  As described above, in the ninth embodiment of the present invention, the cathode electrode is driven to a voltage at which a predetermined emission current corresponding to the display gradation can be taken out by driving the voltage in the first period of one horizontal period. Then, it is possible to stably emit light by applying an emission current corresponding to gradation display by constant current driving. For this reason, it is possible to reduce variations in characteristics of the electron source, such as applied voltage versus emission current, so that there is an effect of greatly reducing display unevenness.

  Further, in this embodiment, the voltage driving circuit and the constant current driving circuit are separately arranged in the upper and lower directions, so that each circuit can be easily mounted. In the present invention, since the voltage driving circuit and the constant current driving circuit are connected to one cathode electrode, the circuit scale becomes relatively large. However, the effect of facilitating the mounting of the horizontal driving circuit by dividing each of them vertically is provided. is there.

It is a block diagram which shows schematic structure of the display apparatus by Example 1 of this invention. It is a block diagram of the cathode drive circuit built in the horizontal drive circuit of the display apparatus by Example 1 of this invention. It is a time chart which shows the relationship between the cathode drive waveform and gate drive waveform in Example 1 of this invention. It is a block diagram of the cathode drive circuit incorporated in the horizontal drive circuit of the display apparatus by Example 2 of this invention. It is a time chart which shows the relationship between the cathode drive waveform and gate drive waveform in Example 2 of this invention. It is a schematic block diagram of the controller and horizontal drive circuit of the display apparatus by Example 3 of this invention. It is a time chart which shows the relationship between the cathode drive waveform and gate drive waveform in Example 3 of this invention. It is a time chart which shows the relationship between the cathode drive waveform and gate drive waveform in Example 4 of this invention. It is a block diagram which shows schematic structure of the display apparatus by Example 5 of this invention. It is a block diagram of the sample hold circuit incorporated in the voltage measurement circuit in Example 5 of this invention. It is a block diagram of the data correction circuit incorporated in the controller in Example 5 of this invention. It is a time chart which shows the relationship of the cathode drive waveform in Example 5 of this invention, a gate drive waveform, and a cathode voltage sample hold waveform. It is a time chart explaining the effect of correction | amendment of the cathode drive waveform in Example 5 of this invention. It is a logical block diagram of the voltage correction memory in Example 6 of this invention. It is a structural example of the data correction circuit built in the controller in Example 6 of this invention. It is a block diagram of the voltage correction memory in Example 7 of this invention. It is a figure explaining the voltage correction memory corresponding to each address of a Z-axis direction with respect to a certain combination of an X-axis direction address and a Y-axis direction address of the voltage correction memory in Example 7 of this invention. It is a figure explaining operation | movement of an example of the adjacent reference address bit generation circuit in Example 7 of this invention. It is a figure explaining operation | movement of the other example of the adjacent reference address bit generation circuit in Example 7 of this invention. It is sectional drawing which shows schematic structure of the pixel in the display apparatus by Example 1 of this invention. It is a graph explaining an example of the drive voltage versus emission current characteristic of the electron source in the display apparatus by Example 1 of this invention. It is a figure explaining the outline of Example 8 of this invention which applied the display panel by each Example of this invention to the television. It is a block diagram which shows schematic structure of the display apparatus by Example 9 of this invention which incorporated the voltage drive circuit and the constant current drive circuit which were incorporated in the horizontal drive circuit by this invention separately on the upper and lower sides of the display panel.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Controller, 2 ... Horizontal drive circuit, 3 ... Vertical drive circuit, 4 ... Cathode electrode, 5 ... Gate electrode, 6 ... Electron source, 7 ... Shift register circuit 8, 8a, 8b ... data latch circuit, 9 ... line latch circuit, 10, 10a ... cathode drive circuit, 11 ... voltage drive circuit, 12 ... current drive circuit, 13, 13a , 13b ... switch, 14 ... horizontal sync signal, 15 ... vertical sync signal, 16 ... dot clock, 17 ... display data, 18 ... horizontal start signal, 19 ... horizontal Clock, 20 ... Horizontal display data, 21 ... Line latch clock, 22 ... Switching signal, 23 ... Vertical start signal, 24 ... Vertical clock, 25, 25a, 25b ... Signal output 26 ... Gate signal line, 27 ... DA converter, 28 ... Buffer amplifier, 29 ... Buffer amplifier, 30 ... Transistor, 31 ... Resistor 32, buffer amplifier, 33 ... switch, 34a, 34b ... DA converter, 35 ... buffer amplifier, 36 ... switch, 37 ... data conversion table, 38 ... Voltage measurement circuit 39 ... Sample hold circuit 40 ... AD converter 41 ... Sample hold control signal 42 ... Reading clock 43 ... Digital sampling data 44 ... Start Signal, 45 ... Next stage start signal, 46 ... Buffer amplifier, 47 ... Switch, 48 ... Capacitor, 49 ... Buffer amplifier, 50 ... Flip-flop, 51 ... Switch, 52 ... Data correction circuit, 53 ... Line memory, 54 ... Correction value calculation circuit, 55 ... Memory write circuit, 56 ... Vertical address generation circuit, 57 ... Voltage correction memory, 58 ... Memory readout circuit, 59 ... Calculator, 60 ... Gradation bit address generation circuit 61 ... Voltage correction memory, 62 ... Adjacent reference address bit generation circuit, 63 ... Voltage correction memory, 64 ... Correction data interpolation circuit, 65 ... Substrate, 66 ... Phosphor, 67 ... Anode electrode, 68 ... Substrate, 69 ... High voltage power supply, 70 ... Display panel, 71 ... Television, 72 ... Antenna terminal, 73 ... Tuner, 74 .. .Signal processing circuit, 75 ... Video terminal.

Claims (23)

A vacuum envelope provided with a translucent part at least in part;
A plurality of cathode electrodes extending in a first direction;
Extending in a second direction intersecting with the first direction, spaced from the plurality of cathode electrodes and arranged to face the plurality of cathode electrodes, at each of the intersections with the plurality of cathode electrodes A plurality of gate electrodes with openings;
A plurality of electron sources disposed on the plurality of cathode electrodes so as to face each of the openings;
An anode electrode including a phosphor irradiated with electrons from the plurality of electron sources,
A gate drive signal for sequentially selecting the plurality of gate electrodes is supplied to the plurality of gate electrodes,
In a display device that drives each of the plurality of cathode electrodes with a signal corresponding to display gradation data in correspondence with the plurality of gate electrodes being sequentially selected,
In the first period of two periods obtained by dividing one horizontal period, the plurality of cathode electrodes are connected to a predetermined period via a voltage driving circuit that outputs a voltage corresponding to display gradation data. After driving, in the latter period of the two periods, the plurality of cathode electrodes are driven via a constant current driving circuit that outputs a current corresponding to the display gradation data. A display device.   Each of the plurality of cathode electrodes is provided with a pair of the voltage driving circuit and the constant current driving circuit, and the output of either the voltage driving circuit or the constant current driving circuit is switched. The display device according to claim 1, wherein the display device is selected by a switch and outputs to the plurality of cathode electrodes. A vacuum envelope provided with a translucent part at least in part;
A plurality of cathode electrodes extending in a first direction;
Extending in a second direction intersecting with the first direction, spaced from the plurality of cathode electrodes and arranged to face the plurality of cathode electrodes, at each of the intersections with the plurality of cathode electrodes A plurality of gate electrodes with openings;
A plurality of electron sources disposed on the plurality of cathode electrodes so as to face each of the openings;
An anode electrode including a phosphor irradiated with electrons from the plurality of electron sources,
A gate drive signal for sequentially selecting the plurality of gate electrodes is supplied to the plurality of gate electrodes,
In a display device that drives each of the plurality of cathode electrodes with a signal corresponding to display gradation data in correspondence with the plurality of gate electrodes being sequentially selected,
In the first of the two periods obtained by dividing one horizontal period, the plurality of the plurality of electron sources until the emission current from the corresponding electron source reaches a predetermined value. After driving the cathode electrode through a voltage driving circuit that outputs a voltage corresponding to display gradation data, the plurality of cathode electrodes are connected to the display gradation in the later period of the two periods. A display device that is driven through a constant current drive circuit that outputs a current according to data.   Each of the plurality of cathode electrodes is provided with a pair of the voltage driving circuit and the constant current driving circuit, and the output of either the voltage driving circuit or the constant current driving circuit is switched. 4. The display device according to claim 3, wherein the display device is selected by a switch and outputs to the plurality of cathode electrodes. A vacuum envelope provided with a translucent part at least in part;
A plurality of cathode electrodes extending in a first direction;
Extending in a second direction intersecting with the first direction, spaced from the plurality of cathode electrodes and arranged to face the plurality of cathode electrodes, at each of the intersections with the plurality of cathode electrodes A plurality of gate electrodes with openings;
A plurality of electron sources disposed on the plurality of cathode electrodes so as to face each of the openings;
An anode electrode including a phosphor irradiated with electrons from the plurality of electron sources,
A gate drive signal for sequentially selecting the plurality of gate electrodes is supplied to the plurality of gate electrodes,
In a display device that drives each of the plurality of cathode electrodes with a signal corresponding to display gradation data in correspondence with the plurality of gate electrodes being sequentially selected,
At the start of one horizontal period, the plurality of cathode electrodes are driven by both a voltage driving circuit that outputs a voltage corresponding to display gradation data and a constant current driving circuit that outputs a current corresponding to the display gradation data. In the display device, the plurality of cathode electrodes are driven only by the constant current driving circuit within the one horizontal period and after a predetermined period.   Each of the plurality of cathode electrodes is provided with a pair of the voltage driving circuit and the constant current driving circuit, and an output of the voltage driving circuit can be disconnected from the plurality of cathode electrodes by a changeover switch. The display device according to claim 5. A vacuum envelope provided with a translucent part at least in part;
A plurality of cathode electrodes extending in a first direction;
Extending in a second direction intersecting with the first direction, spaced from the plurality of cathode electrodes and arranged to face the plurality of cathode electrodes, at each of the intersections with the plurality of cathode electrodes A plurality of gate electrodes with openings;
A plurality of electron sources disposed on the plurality of cathode electrodes so as to face each of the openings;
An anode electrode including a phosphor irradiated with electrons from the plurality of electron sources,
A gate drive signal for sequentially selecting the plurality of gate electrodes is supplied to the plurality of gate electrodes,
In a display device that drives each of the plurality of cathode electrodes with a signal corresponding to display gradation data in correspondence with the plurality of gate electrodes being sequentially selected,
At the start of one horizontal period, the plurality of cathode electrodes are driven by both a voltage driving circuit that outputs a voltage corresponding to display gradation data and a current driving circuit that outputs a constant current corresponding to the display gradation data. After the emission current from the corresponding electron source in the plurality of electron sources reaches a predetermined value within the one horizontal period, the plurality of cathode electrodes are connected only by the constant current driving circuit. A display device that is driven.   Each of the plurality of cathode electrodes is provided with a pair of the voltage driving circuit and the constant current driving circuit, and an output of the voltage driving circuit can be disconnected from the plurality of cathode electrodes by a changeover switch. The display device according to claim 7. A vacuum envelope provided with a translucent part at least in part;
A plurality of cathode electrodes extending in a first direction;
Extending in a second direction intersecting with the first direction, spaced from the plurality of cathode electrodes and arranged to face the plurality of cathode electrodes, at each of the intersections with the plurality of cathode electrodes A plurality of gate electrodes with openings;
A plurality of electron sources disposed on the plurality of cathode electrodes so as to face each of the openings;
An anode electrode including a phosphor irradiated with electrons from the plurality of electron sources,
A gate drive signal for sequentially selecting the plurality of gate electrodes is supplied to the plurality of gate electrodes,
In a display device that drives each of the plurality of cathode electrodes with a signal corresponding to display gradation data in correspondence with the plurality of gate electrodes being sequentially selected,
In a first period of two periods obtained by dividing one horizontal period, the plurality of cathode electrodes are driven for a predetermined period via a voltage driving circuit that outputs a voltage, and then the two In a later period of the period, the plurality of cathode electrodes are driven through a constant current driving circuit that outputs a current corresponding to display gradation data, and the cathode electrodes are driven by the voltage driving circuit. Display gradation data used in the voltage drive circuit is such that the emission current of the electron source when driven approaches the emission current of the electron source when the cathode electrode is driven by the constant current drive circuit. A display device comprising a conversion table for converting in advance based on an average characteristic of driving voltage versus emission current of an electron source. A vacuum envelope provided with a translucent part at least in part;
A plurality of cathode electrodes extending in a first direction;
Extending in a second direction intersecting with the first direction, spaced from the plurality of cathode electrodes and arranged to face the plurality of cathode electrodes, at each of the intersections with the plurality of cathode electrodes A plurality of gate electrodes with openings;
A plurality of electron sources disposed on the plurality of cathode electrodes so as to face each of the openings;
An anode electrode including a phosphor irradiated with electrons from the plurality of electron sources,
A gate drive signal for sequentially selecting the plurality of gate electrodes is supplied to the plurality of gate electrodes,
In a display device that drives each of the plurality of cathode electrodes with a signal corresponding to display gradation data in correspondence with the plurality of gate electrodes being sequentially selected,
In the first of the two periods obtained by dividing one horizontal period, the plurality of the plurality of electron sources until the emission current from the corresponding electron source reaches a predetermined value. After driving the cathode electrode through a voltage driving circuit that outputs a voltage corresponding to display gradation data, the plurality of cathode electrodes are connected to the display gradation in the later period of the two periods. The emission current of the electron source when the cathode electrode is driven by the voltage drive circuit is driven by a constant current drive circuit that outputs a current according to data, and the cathode electrode is driven by the constant current drive circuit. Display gradation data used in the voltage driving circuit is based on an average characteristic of the driving voltage versus the emission current of the electron source so as to approach the emission current of the electron source when driven. And a conversion table for conversion in advance. A vacuum envelope provided with a translucent part at least in part;
A plurality of cathode electrodes extending in a first direction;
Extending in a second direction intersecting with the first direction, spaced from the plurality of cathode electrodes and arranged to face the plurality of cathode electrodes, at each of the intersections with the plurality of cathode electrodes A plurality of gate electrodes with openings;
A plurality of electron sources disposed on the plurality of cathode electrodes so as to face each of the openings;
An anode electrode including a phosphor irradiated with electrons from the plurality of electron sources,
A gate drive signal for sequentially selecting the plurality of gate electrodes is supplied to the plurality of gate electrodes,
In a display device that drives each of the plurality of cathode electrodes with a signal corresponding to display gradation data in correspondence with the plurality of gate electrodes being sequentially selected,
At the start of one horizontal period, the plurality of cathode electrodes are driven by both a voltage driving circuit that outputs a voltage corresponding to display gradation data and a constant current driving circuit that outputs a current corresponding to the display gradation data. The electrons when the plurality of cathode electrodes are driven only by the constant current driving circuit and the cathode electrodes are driven by the voltage driving circuit within the one horizontal period and after a predetermined period elapses. The display gradation data used in the voltage drive circuit is compared with the drive voltage of the electron source so that the emission current of the source approaches the emission current of the electron source when the cathode electrode is driven by the constant current drive circuit. A display device comprising a conversion table for converting in advance based on an average characteristic of emission current. A vacuum envelope provided with a translucent part at least in part;
A plurality of cathode electrodes extending in a first direction;
Extending in a second direction intersecting with the first direction, spaced from the plurality of cathode electrodes and arranged to face the plurality of cathode electrodes, at each of the intersections with the plurality of cathode electrodes A plurality of gate electrodes with openings;
A plurality of electron sources disposed on the plurality of cathode electrodes so as to face each of the openings;
An anode electrode including a phosphor irradiated with electrons from the plurality of electron sources,
A gate drive signal for sequentially selecting the plurality of gate electrodes is supplied to the plurality of gate electrodes,
In a display device that drives each of the plurality of cathode electrodes with a signal corresponding to display gradation data in correspondence with the plurality of gate electrodes being sequentially selected,
At the start of one horizontal period, the plurality of cathode electrodes are driven by both a voltage driving circuit that outputs a voltage corresponding to display gradation data and a current driving circuit that outputs a constant current corresponding to the display gradation data. After the emission current from the corresponding electron source in the plurality of electron sources reaches a predetermined value within the one horizontal period, the plurality of cathode electrodes are connected only by the constant current driving circuit. Driving and the emission current of the electron source when the cathode electrode is driven by the voltage driving circuit approaches the emission current of the electron source when the cathode electrode is driven by the constant current driving circuit, A conversion table for converting display gradation data used in the voltage driving circuit in advance based on an average characteristic of the driving voltage of the electron source versus the emission current is provided. A display device.   In the first period of the two periods, the gate driving signal for selecting a corresponding gate electrode of the plurality of gate electrodes is in response to a driving voltage for driving the plurality of cathode electrodes. The display device according to claim 1, wherein the display device starts after a predetermined period of time.   In the first period of the two periods, the gate driving signal for selecting a corresponding gate electrode of the plurality of gate electrodes is in response to a driving voltage for driving the plurality of cathode electrodes. The display device according to claim 3, wherein the display device starts after a predetermined period of time.   In the first period of the two periods, the gate driving signal for selecting a corresponding gate electrode of the plurality of gate electrodes is in response to a driving voltage for driving the plurality of cathode electrodes. The display device according to claim 5, wherein the display device starts after a predetermined period of time.   In the first period of the two periods, the gate driving signal for selecting a corresponding gate electrode of the plurality of gate electrodes is in response to a driving voltage for driving the plurality of cathode electrodes. The display device according to claim 7, wherein the display device starts after a predetermined period of time. A vacuum envelope provided with a translucent part at least in part;
A plurality of cathode electrodes extending in a first direction;
Extending in a second direction intersecting with the first direction, spaced from the plurality of cathode electrodes and arranged to face the plurality of cathode electrodes, at each of the intersections with the plurality of cathode electrodes A plurality of gate electrodes with openings;
A plurality of electron sources disposed on the plurality of cathode electrodes so as to face each of the openings;
An anode electrode including a phosphor irradiated with electrons from the plurality of electron sources,
A gate drive signal for sequentially selecting the plurality of gate electrodes is supplied to the plurality of gate electrodes,
In a display device that drives each of the plurality of cathode electrodes with a signal corresponding to display gradation data in correspondence with the plurality of gate electrodes being sequentially selected,
In the first period of two periods obtained by dividing one horizontal period, the plurality of cathode electrodes are connected to a predetermined period via a voltage driving circuit that outputs a voltage corresponding to display gradation data. After driving, in the latter period of the two periods, the plurality of cathode electrodes are driven via a constant current driving circuit that outputs a current corresponding to the display gradation data,
Display gradation data when the plurality of cathode electrodes are driven via the voltage driving circuit in the first period of the two periods, and the latter in the latter period. A value obtained by converting sample values obtained by measuring voltages of the plurality of cathode electrodes when the plurality of cathode electrodes are driven through the constant current driving circuit according to the display gradation data into display gradation data; A correction memory for storing the difference calculated as a data correction value,
In the next frame, in the first of the two periods obtained by dividing one horizontal period corresponding to the one horizontal period, the supplied display gradation data is corrected with the data correction value. A display device characterized in that the plurality of cathode electrodes are driven through the voltage drive circuit using a display gradation data.   18. The display device according to claim 17, wherein the data correction value is calculated for each of the plurality of electron sources, and the correction memory includes a number of addresses corresponding to the number of the plurality of electron sources. .   The data correction value is calculated for at least a part of the gradation level represented by the display gradation data of each of the plurality of electron sources, and stored in the correction memory. Item 18. A display device according to Item 17.   The voltage driving circuit and the constant current driving circuit are disposed in the vicinity of one end of each of the plurality of cathode electrodes. The display device according to any one of 11, 12, and 17.   The voltage driving circuit is disposed in the vicinity of one end of each of the plurality of cathode electrodes, and the constant current circuit is disposed in the vicinity of the other end of each of the plurality of cathode electrodes. The display device according to any one of claims 1, 3, 5, 7, 9, 10, 11, 12, and 17.   The display device according to any one of claims 1, 3, 5, 7, 9, 10, 11, 12, and 17, wherein the plurality of electron sources are composed of carbon nanotubes. .   18. The electron source according to any one of claims 1, 3, 5, 7, 9, 10, 11, 12, and 17, wherein the plurality of electron sources are constituted by cone-shaped Spindt-type field emission cathodes. The display device according to item.

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