JP2006184461A - Display device and driving method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the luminance lifetime of a display panel, by correcting the luminance of the display panel falling off, dependent on the accumulated total of the operation time, based on the accumulated total of the operation time or the fall off of the luminance in an image display device. <P>SOLUTION: A video processing circuit 4 to supply a video signal to the display panel 11 of the image display device is characterized in that the amount of correction set at the drive voltage ought to be outputted at the initial period, in a state in which the characteristics in the initial period are corrected by a correction circuit 40 is instructed to the signal driver, based on the driving voltage capable of providing the luminance to be increased, when the luminance of the video signal falls off. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image display device and a method for manufacturing the same, and more specifically, an electron source and a phosphor screen for displaying an image by irradiation of an electron beam emitted from the electron source are provided in a vacuum vessel. The present invention relates to an image display device and a driving method thereof (image display method).

  As an image display device that replaces a cathode ray tube (CRT), electron-emitting devices (electron sources) are arranged in a planar and matrix form, and electrons are selectively applied to a planar fluorescent screen (front substrate) facing each other at a predetermined interval. 2. Description of the Related Art Image display devices that display an image by emitting light of an arbitrary color from a phosphor screen by irradiating a line have been developed. This type of image display apparatus is called a field emission display (hereinafter referred to as FED). In addition, among FEDs, a display device using a surface conduction type emitter as an electron source is sometimes classified as a surface conduction type electron emission display (hereinafter referred to as SED). As a generic term, the term FED is used.

  The FED can set the gap between the electron source side substrate and the phosphor screen side substrate to several mm or less, and can be made thinner than a known CRT. The thickness can be equal to or less than that of such an image display device. Therefore, it is expected in terms of weight reduction.

  In addition, since it is a self-luminous type similar to a CRT or plasma display, the brightness of the display image is also easy to obtain.

  On the phosphor screen provided on the inner surface of the front substrate, red (R), blue (B), and green (G) phosphors are arranged in a predetermined size and in a predetermined order. An anode electrode for applying a predetermined sweep voltage to each phosphor is connected to each phosphor on the phosphor screen.

  The substrate on the electron source side has a matrix of scanning lines and signal lines for emitting a predetermined amount of electrons from a previously specified emitter for emitting a phosphor screen facing an emitter at an arbitrary position. It is connected to the.

The above-described FED generally includes a display panel and a drive unit that drives the display panel. The display panel has a plurality of scanning lines extending in the horizontal (horizontal) direction, a plurality of signal lines extending in the vertical (vertical) direction intersecting with the individual scanning lines, and at the intersections of the respective scanning lines and signal lines. It includes a plurality of display pixels arranged (see, for example, Patent Document 1).
JP 2002-221933 A

  By the way, the element characteristics of the display pixels of the phosphor screen, that is, the display panel, specifically, the luminance characteristics of the phosphors used in the phosphor screen depend on the accumulated display time (operation time), and are deteriorated or overcurrent or discharged. There is a problem of gradually decreasing due to phosphor damage caused by the phenomenon.

  If the decrease in luminance is considered as the lifetime of the phosphor (luminance lifetime), the luminance lifetime is generally considered to be a point in time when the initial luminance decreases to approximately ½, for example. In addition, it is known that the luminance life is a time when the light emitting ability of the phosphor is reduced due to overload.

  An object of the present invention is to increase the luminance life of a phosphor screen of a display substrate in an image display device including a display substrate having a phosphor screen and an electron source substrate that emits electrons toward the phosphor screen of the display substrate.

  The present invention holds a first substrate holding an electron beam source, and a phosphor layer that outputs light of a predetermined color when irradiated with an electron beam output from the electron beam source. In a method for driving a display panel, comprising: a second substrate opposed to each other at a predetermined interval; and a sidewall having a closed structure of the first substrate and the second substrate. Between the phosphor layer and the electron beam source The driving voltage that regulates the luminance of the light emitted from the phosphor layer has a second luminance generated by the cumulative operating time with respect to the first luminance at the initial time, compared to the second luminance. The driving method of the image display device is characterized in that the driving voltage is set to be capable of providing a high third luminance.

  According to another aspect of the present invention, a plurality of scanning lines, a plurality of signal lines intersecting with the plurality of scanning lines, a plurality of scanning lines and a plurality of signal lines are disposed at intersections of the plurality of scanning lines and the plurality of signal lines, respectively. A plurality of display pixels driven corresponding to pixel voltages between the signal lines, a scanning line driver that sequentially drives the plurality of scanning lines, and a period during which each of the plurality of scanning lines is driven by the scanning line driver The signal line driver for driving the plurality of signal lines and the drive voltage that can provide the brightness that should be increased when the brightness of the video signal is reduced are output in the initial state with the initial characteristics corrected. And a compensation circuit for instructing the signal line driver of a correction amount set to a driving voltage to be provided.

  According to the present invention, a plurality of scanning lines, a plurality of signal lines intersecting with the plurality of scanning lines, and a plurality of scanning lines and the plurality of signal lines are respectively arranged at intersection positions, and each of the pair of scanning lines. An image display device driving method comprising: a plurality of display pixels driven corresponding to a pixel voltage between a line and a signal line, wherein the plurality of signal lines are increased when the luminance is reduced (luminance halved). An image display characterized by being supplied with a voltage value in which a driving voltage defined with an initial characteristic corrected based on a driving voltage capable of providing a desired luminance is set to the original initial driving voltage It is a drive method of an apparatus.

  According to the present invention, in an image display device including a display substrate having a phosphor screen and an electron source substrate that emits electrons toward the phosphor screen of the display substrate, the luminance life of the display substrate is improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows an example of a circuit configuration of a flat image display device to which the present invention is applied.

  The image display device shown in FIG. 1 is a field emission display (FED) device in which, for example, horizontal 1280 × vertical 768 display pixels are formed. The image display device includes a display panel 1, an X driver (signal line driving circuit) 2, a Y driver (scanning line driving circuit) 3, and a video signal processing circuit 4.

  The display panel 1 includes 768 scanning lines Y (m = 768, Y1 to Ym) provided substantially parallel to each other in the horizontal (horizontal or Y) direction, and a vertical (vertical or X) orthogonal to the scanning lines Y1 to Ym. ) × 1280 signal lines X (n = 1280, X1 to Xn) provided in the direction.

  At the intersections of the scanning lines Y1 to Ym and the signal lines X1 to Xn, m × n (= about 2.76 million) display pixels PX are provided. Each display pixel PX includes three display pixels PX (R, G, B) that are adjacent to each other in the horizontal direction (not shown).

  Each of the individual display pixels PX (R, G, and B) of the display panel 1 is red (R) that emits light by the surface conduction electron-emitting device 11 and the electron beam emitted from the individual electron-emitting device 11. The phosphor 12 of green (G) and blue (B) (an example of a cross section is shown in FIG. 5) is included.

  Each scanning line Y1 to Ym is connected to the electron-emitting device 11 of the display pixel PX in the corresponding horizontal line (row) and used as a scanning electrode. Each signal line X1 to Xn is connected to the electron-emitting device 11 of the display pixel PX in the corresponding column (vertical direction) and used as a signal electrode.

  The signal line driving circuit 2, the scanning line driving circuit 3, and the video signal processing circuit 4 are arranged around the display panel 1 as a display driving unit. For example, a control signal and a control signal are transmitted from a timing controller (not shown) provided outside. The image is displayed on the display panel 1 by supplying the image signal.

  The video signal processing circuit 4 is supplied from an external signal source and processes a video signal including R, G, and B signals in a digital format. The scanning line driving circuit 3 sequentially drives the scanning lines Y1 to Ym using the scanning signal, and the signal line driving circuit 2 displays video while each of the scanning lines Y1 to Ym is driven by the scanning line driving circuit 3. In response to the video signal from the signal processing circuit 4, the signal lines X1 to Xn are driven.

  The video processing circuit 4 changes (increases) the drive voltage Vf to be applied to the phosphor on the phosphor screen, which gradually decreases according to the cumulative operation time (display time), that is, is applied to the emitter 11. A correction circuit 40 for correcting the driving voltage Vf is included.

  The X driver (signal line drive circuit) 2 samples and holds a video signal for one horizontal line supplied from the video processing circuit 4 in synchronization with the horizontal synchronization signal HD, and the line memory 20 Drive signal generation unit 21 for generating n drive signals respectively corresponding to video signals for one horizontal line output in parallel from.

  The drive signal generator 21 generates n pulse width modulation circuits 22 that generate pulse signals having a pulse width proportional to the gradation level of the video signal of each corresponding pixel, and pulse signals from the corresponding pulse width modulation circuits 22. In this case, n output buffers (AMP) 23 for outputting the reference voltage Vref from the drive reference voltage terminal to the signal lines X1 to Xn at a predetermined timing for a period equal to the pulse width of.

  The pulse width modulation circuit 22 and the output buffer 23 function as a drive signal output unit for one signal line X. That is, as the pulse signal generated from the pulse width modulation circuit 22, for example, the reference voltage Vref is output and supplied to the n pulse width modulation circuits 22.

  The Y driver (scanning line driving circuit) 3 supplies a scanning signal to each of the corresponding scanning lines Y1 to Ym via m output buffers (AMP) 32 connected to the shift register 31. That is, a scanning signal is supplied to every scanning line Y1, Y2, Y3,..., Ym-1, Ym in order for each line.

  Accordingly, an image signal having a predetermined magnitude (voltage or control pulse) corrected by the correction circuit 40 through an arbitrary AMP (buffer) 23 of the X driver 2 in a state where a scanning signal is supplied to an arbitrary scanning line. By supplying the (luminance signal) Vf, the electron-emitting devices (electron sources or emitters) 11 of the display pixels PX at the positions where the respective lines intersect are selectively turned on, and a predetermined color is output from the corresponding pixels PX. Light is output.

  By the way, as indicated by a curve a in FIG. 2, the intensity of light emitted from the display pixel PX (the luminance of the image light) gradually decreases in proportion to the operation time (cumulative display time). The decrease in luminance indicated by the curve a is caused by a decrease in the light emission ability of the phosphor due to, for example, overload. That is, as shown in FIG. 3, the luminance of the image light output from any pixel PX is the operating time even though the magnitude of the drive voltage Vf supplied to each emitter 11 is kept constant. Decreases according to the cumulative total (cumulative display time). If the state where the luminance has decreased to a predetermined level is defined as the luminance life, for example, the time when the initial luminance decreases to approximately ½ is generally considered as (luminance life).

  In other words, the luminance life can be extended by increasing the drive voltage Vf supplied to the emitter 11 in accordance with the decrease in the light emission capability of the phosphor. For example, as shown by a curve b in FIG. 2, the luminance life is increased by increasing the drive voltage Vf supplied to the emitter 11 to a predetermined level at the time point th when the initial luminance is reduced to a predetermined luminance. it can.

  Note that the time point th at which the drive voltage Vf is increased is, for example, the time point when the initial luminance is reduced to approximately half (when the luminance is halved). Further, as a method of detecting a change in luminance, that is, a half luminance, for example, it is possible to detect a change in the drive current If that is uniquely determined with respect to the drive voltage Vf. May be counted (integrated).

  By the way, when the magnitude of the drive voltage Vf supplied to the emitter (electron source) 11 is increased at the time th shown in FIG. 2 and FIG. 3, the luminance of the entire display area (screen) becomes uneven (brightness variation). For this reason, at the time th shown in FIG. 2, the luminance curve for obtaining the luminance of the curve b is replaced with the luminance (curve c) corresponding to the initial time (factory shipment) with almost no cumulative operation time. Thus, the drive voltage Vth that can provide the brightness may be defined, and at the initial stage, the voltage may be the drive voltage Vo that can provide the brightness of the curve a shown in FIG.

In FIG. 2, the drive voltage Vf is increased from Vo to Vth in order to increase the luminance indicated by the curve a at time th to the luminance indicated by the curve b in FIG. Here, when the luminance increment at time th (curve b-curve a in FIG. 2) is, for example, 25%, it is confirmed that the life (ratio of A and B in FIG. 2) is approximately 1.5 times. Has been. Further, when the luminance increment (curve b-curve a in FIG. 2) is 50%, for example, it has been confirmed that the lifetime is approximately 1.8 times.

  On the other hand, if the lifetime is approximately doubled, the luminance increment (curve b-curve a in FIG. 2) may be approximately 100%, but the magnitude of the initial driving voltage Vo increases unnecessarily. This is an increase in the load on the phosphor, and the luminance increment is determined in consideration of the initial driving voltage and the luminance lifetime.

  In this way, the magnitude of the drive voltage (luminance characteristic) is set so as to be able to provide a predetermined light emission characteristic in association with the time point th when the cumulative operating time reaches a predetermined time, and the cumulative operating time reaches a predetermined level of luminance. By increasing the drive voltage Vf at the time point when the decrease time th is reached, the luminance can be increased to a predetermined level even when the luminance is decreased due to the cumulative operation time. This can substantially prevent the luminance from being lowered due to the light emission ability of the phosphor due to overload or the like. Accordingly, the luminance life can be increased. In this case, since the predetermined drive voltage Vf is supplied to the emitter 11 using the curve B set on the assumption that the cumulative operation time reaches the predetermined time, the drive voltage Vf is set to the predetermined time. Even when it is increased by th, luminance unevenness (brightness variation) does not occur.

  4 and 5 show an example of the structure of the display panel incorporated in the image display device shown in FIG.

  The display panel 1 is opposed to an electron source side substrate (first substrate, hereinafter referred to as a rear panel) 100 having an electron emitting element (electron source or emitter) 11 at a predetermined interval, and is output from the emitter 11. And a phosphor screen side substrate (second substrate, hereinafter referred to as a face plate) 200 including a phosphor screen (R, G, B phosphor 12) that outputs fluorescence when irradiated with an electron beam.

  As shown in FIG. 5, each of the rear panel 100 and the face plate 200 includes a rectangular back surface (electron source side) glass substrate 101 and a front surface (phosphor screen side) 201 each having a predetermined area. A predetermined number of electron sources (electron-emitting devices) and phosphors (light-emitting devices) are provided in the main portions of the base materials 101 and 201, that is, the display region corresponding portions.

Both substrates 100 and 200 are opposed to each other with a gap (interval) of 1 to 2 mm, and are joined to each other by a side wall 301 provided at the peripheral edge of both substrates 100 and 200. That is, the display panel 1 becomes an envelope 401 having a sealed structure by the two substrates 100 and 200 and the side wall 301. The inside of the envelope 401 is maintained at a degree of vacuum of about 10 ⁻⁴ Pa, for example.

  Between the glass substrates of the rear panel 100 and the face plate 200, a large number of spacers 501 formed in a plate shape or a column shape are provided in order to resist the atmospheric pressure acting on each of them in the assembled state as the envelope 401. Has been placed.

  On one surface of the glass substrate 201 used for the face plate 200, that is, the surface facing inward when assembled as the envelope 401, the phosphors 12 of R, G, and B described above are arranged in a predetermined order. Arranged phosphor screens 211 are provided. The phosphor screen 211 is provided with a metal thin film (metal back layer) that functions as an anode electrode, as will be described in detail later. A sweep voltage of 10 to 15 kV, for example, is applied between the electron source and the anode electrode.

  As shown in FIG. 5, the phosphor screen 211 has three types of phosphors 12-1 (R) that emit light of R, G, and B when electrons emitted from individual emitters of the rear panel 100 collide with each other. ), 12-2 (G), 12-3 (B), and light shielding layers (black masks) 221 arranged in a matrix for partitioning the respective phosphors.

  Each phosphor 12-1, 12-2, 12-3 has a longitudinal direction of the face plate 200 (glass substrate 201) in the first direction (X direction) and a width direction orthogonal to the X direction (longitudinal direction). In the case of two directions (Y direction), for example, it is formed in a stripe shape extending in the Y direction. In addition, although each fluorescent substance 12-1 to -3 demonstrated previously, three are arranged as 1 unit.

The light shielding layer 221 is, for example, a mixture of carbon and a binder material, and its resistance value is set to, for example, 10 ³ to 10 ⁸ [Ω]. The content of the binder material is regulated to 80% at maximum.

  As can be easily understood from FIGS. 4 and 5, the light shielding layer (black mask) 221 is arranged in 1280 × 3 columns and 768 rows in the X direction (column direction) and the Y direction (row direction), respectively. Suppose that For example, if the size of one pixel is 0.6 mm square, with respect to the Y direction in which each phosphor layer extends in a band shape, the thickness of the region corresponding to the width (X direction) is the thickness of the horizontal line portion. Compared with narrow. As an example, the width of the vertical line portion is 20 to 100 μm, more preferably 40 to 50 μm, between one pixel composed of R, G and B, that is, between B (12-3) and R (12-1). Then, the remaining portion, that is, between R (12-1) and G (12-2) or between G (12-2) and B (12-3) is 20 to 100 μm, more preferably 20 to 30 μm. On the other hand, the width | variety of a horizontal line part is 150-450 micrometers, More preferably, it is 300 micrometers.

  The phosphor screen 211 is provided on the entire surface covering the phosphor regions 12-1, 12-2, and 12-3 partitioned by the light shielding layer 221, and the phosphor region having an uneven surface is described below. As described above, a thin metal layer, that is, a metal back layer 231 that functions as an anode electrode and is used to reflect light emitted from each phosphor region toward the glass substrate 201 is formed to a predetermined thickness. . Although the term metal back layer is used, this layer is not limited to metal (metal) as long as it can function as an anode, and various materials can be used. . In addition, before the metal back layer 231 is formed, a smoothing layer capable of mutually fixing phosphor particles such as a resin may be provided on the entire surface of the phosphor region.

  As described above, according to the present invention, in an image display device that includes a display substrate having a phosphor screen and an electron source substrate that emits electrons toward the phosphor screen of the display substrate, the total operating time is predetermined. The driving voltage is set so that a preset luminance characteristic can be provided in association with the time point reaching the time, and the driving voltage is increased when the total operation time reaches a predetermined time. Thereby, the brightness | luminance of the light output from the fluorescent screen of a display substrate is maintained more than fixed brightness over a long period of time. Accordingly, the luminance life is increased, and the life as an image display device is extended.

  In other words, an image display device capable of displaying a stable image over a long period of time without reducing the luminance of the display image until the luminance lifetime is obtained regardless of the total operation time.

  In each of the above-described embodiments, the drive signal may be a voltage amplitude drive system or a pulse width modulation drive system. Moreover, it is applicable also when using both drive systems together.

  The present invention is not limited to the above-described embodiments, and various modifications or changes can be made without departing from the scope of the invention when it is implemented. Moreover, each embodiment may be implemented in combination as appropriate as possible, and in that case, the effect of the combination can be obtained.

Schematic which shows an example of the circuit structure of the image display apparatus with which this invention is applied. Schematic explaining the relationship between the operating time and the luminance of the image display device shown in FIG. Schematic explaining the relationship between the operating time and drive voltage of the image display apparatus shown in FIG. Schematic which shows an example of the structure of the display panel of the image display apparatus shown in FIG. Schematic which shows an example (cross section) of the structure of the display panel of the image display apparatus shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Display panel, 11 ... Surface conduction electron-emitting device, 12 ... Phosphor, 12-1 ... Phosphor (R), 12-2 ... Phosphor (G), 12-3 ... Phosphor (B), 2 Signal line drive circuit, 3 Scan line drive circuit, 4 Video signal processing circuit, 40 Correction circuit, 100 Rear panel (electron source side substrate, first substrate), 101 Base material of first substrate, 200 Face plate (phosphor surface side substrate, second substrate), 201 ... base material of second substrate, 211 ... phosphor surface, 221 ... light shielding layer (black mask), 231 ... metal back layer (metal thin film, sweep voltage application unit) , 241 ... getter (impurity adsorption) layer, 301 ... side wall, 401 ... sealed structure (envelope), 501 ... spacer.

Claims (7)

A first substrate holding an electron beam source and a phosphor layer that outputs light of a predetermined color by being irradiated with an electron beam output from the electron beam source are held on the first substrate at predetermined intervals. In a method for driving a display panel, comprising: an opposed second substrate; and a sidewall having the first substrate and the second substrate as a sealed structure.
The driving voltage that is supplied between the phosphor layer and the electron beam source and defines the luminance of the light emitted from the phosphor layer is generated by the cumulative operation time with respect to the initial first luminance. A driving method for an image display device, wherein the second luminance is set to a driving voltage capable of providing a third luminance higher than the second luminance. A plurality of scan lines;
A plurality of signal lines intersecting the plurality of scanning lines;
A plurality of display pixels disposed at intersections of the plurality of scanning lines and the plurality of signal lines and driven according to pixel voltages between the pair of scanning lines and the signal lines, respectively;
A scanning line driver for sequentially driving the plurality of scanning lines;
A signal line driver that drives the plurality of signal lines while each of the plurality of scanning lines is driven by the scanning line driver;
A correction amount set to the drive voltage to be output at the initial stage in a state where the characteristics at the initial stage are corrected based on the drive voltage capable of providing the brightness to be increased when the luminance of the video signal is reduced. A compensation circuit to instruct the driver;
An image display device comprising:   The image display apparatus according to claim 2, wherein the luminance compensation circuit instructs the correction amount to the signal line driver at a predetermined timing.   The brightness compensation circuit is capable of providing a drive voltage capable of providing a third brightness higher than the second brightness, the second brightness generated by the cumulative operation time with respect to the initial first brightness. 3. The image display device according to claim 2, wherein the voltage is instructed to the signal line driver. A plurality of scan lines;
A plurality of signal lines intersecting the plurality of scanning lines;
An image display device comprising: a plurality of display pixels which are respectively arranged at intersections of the plurality of scanning lines and the plurality of signal lines, and are driven corresponding to pixel voltages between the pair of scanning lines and the signal lines. A driving method comprising:
The plurality of signal lines have a driving voltage defined in a state in which initial characteristics are corrected based on a driving voltage capable of providing a luminance to be increased when luminance decreases (luminance halved). A driving method for an image display device, wherein a voltage value set as a driving voltage is supplied.   6. The image display device driving method according to claim 5, wherein the voltage values are instructed to the plurality of signal lines at a predetermined timing.   For the plurality of signal lines, the second luminance generated by the accumulated operation time with respect to the initial first luminance is corrected to a driving voltage that can provide a third luminance higher than the second luminance. 6. The driving method for an image display device according to claim 5, wherein a driving voltage estimated by using a driving voltage capable of providing the third luminance as an initial voltage is supplied.

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