JP2002328645A - Image display device and its drive method and circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display a high-quality image having satisfactory gradation property in accordance with an image signal. SOLUTION: This drive circuit for image display device has a driving current detecting circuit 10 which detects driving currents to be supplied respectively to a plurality of electron emitting elements of a display panel having the plurality of electron emitting elements which are arranged in a matrix shape and generates voltages corresponding to the driving currents, a control voltage generating circuit 30 which generates control voltages in accordance with picture signals corresponding respectively to the plurality of the electron emitting elements, a voltage comparing circuit 40 which compares the control voltages to be outputted from the driving current detecting circuit 10 with the control voltages to be outputted from the control voltage generating circuit 30 and a driving current interrupting circuit 50 which controls the driving of the electron emitting elements in accordance with the comparison results by the voltage comparing circuit 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image display apparatus for displaying an image by driving a plurality of electron-emitting devices wired in a matrix, and a driving method and circuit thereof.

[0002]

2. Description of the Related Art Various types of display devices are known as image display devices. As an example, a display (hereinafter referred to as a SED) that uses a surface conduction electron-emitting device and displays an image by electrons emitted from the electron-emitting device. Will be briefly described.

FIG. 10 shows a surface conduction electron-emitting device (SED).
FIG. 3 is a schematic diagram of an image display panel using an electron-emitting device called a so-called electron-emitting device.

In FIG. 1, reference numeral 1001 denotes a high-voltage power supply;
02 is a constant current power supply, 1011 is a substrate on which electron-emitting devices are arranged, 1012 and 1013 are device electrodes, 1014 is a conductive thin film, 1015 is an electron-emitting portion, and 1016 is an anode electrode.

Here, when power is supplied from the constant current power supply 1002 to the device electrodes 1012 and 1013, electrons are emitted from the electron emission portion 1015 of the device. The electrons thus emitted correspond to the anode electrode 10 to which the high voltage is applied.
16 is captured. By applying a fluorescent material to the surface of the anode electrode 1016 on which electrons collide, a pixel can be displayed by emitting light at a brightness corresponding to the amount of electrons emitted from the electron emission portion 1015 of the element.

FIG. 11 is a schematic view of an SED image display panel in which the electron-emitting devices shown in FIG. 10 are arranged in a matrix.

In FIG. 1, reference numeral 2001 denotes a Y driver which applies a scanning voltage to a row wiring to select and drive a row wiring to be driven for display. An X driver 2002 applies a signal corresponding to an image signal to each column direction wiring. 200
Reference numeral 3 denotes a plurality of electron-emitting devices. Here, the Y driver 2001 selects any one row wiring (line) to be drawn from a plurality of row direction wirings, and applies a constant voltage to the selected row wiring. Also, X driver 200
2 corresponds to the constant current power supply 1002 shown in FIG.
The driver 2001 supplies a constant current to each element connected to the row direction wiring to which a voltage is applied.

Here, the anode electrode corresponding to each element on the line to which the Y driver 2001 applies a voltage is:
Electrons emitted from the electron emission portion of each element are captured. The X driver 2002 is driven by a signal having a pulse width corresponding to the image signal, and flows a constant current for a time length corresponding to the brightness of each pixel on a line to be driven for drawing. As described above, each line is sequentially selected by the Y driver 2001, and the X line is selected for an arbitrary time during the selection period.
An image is displayed by the driver 2002 driving each element at a constant current.

[0009]

In the case of the constant current driving method of the SED described above, the driving current of each element is as shown in FIG.
As shown in FIG. 2, the rising portion has a blunt waveform. The point x in FIG. 12 indicates the timing when the driving current to the adjacent pixel is stopped, and the output driving current changes at this time.

[0010] Due to the rounding of the waveform at the rising portion and the influence of the driving current of the adjacent pixel, there arises a problem that the gradation of the pixel to be displayed becomes non-linear, and a current loss in the constant current source circuit occurs. There is also the problem of becoming larger.

The present invention has been made in view of the above conventional example, and controls a current value flowing through each electron-emitting device in accordance with an image signal, thereby providing a high-quality image with high reproducibility of gradation. It is an object of the present invention to provide an image display device capable of displaying an image, a driving method thereof, and a circuit.

Another object of the present invention is to provide an image display device capable of displaying a high-quality image with good gradation and displaying an image in accordance with image quality adjustment of a displayed image, and a driving method and circuit thereof. It is in.

[0013]

In order to achieve the above object, an image display device according to the present invention has the following arrangement.
That is, a display panel having a plurality of electron-emitting devices arranged in a matrix, and a drive current detecting means for detecting a drive current supplied to each of the plurality of electron-emitting devices and generating a voltage corresponding to the drive current An integration unit that generates a voltage obtained by integrating a voltage output from the drive current detection unit; a voltage generation unit that generates a control voltage corresponding to an image signal corresponding to each of the plurality of electron-emitting devices; Comparing means for comparing the voltage generated by the integrating means with the control voltage output from the voltage generating means,
The comparing means includes a driving current control means for controlling the driving of the electron-emitting device in accordance with the comparison result.

In order to achieve the above object, a driving circuit of an image display device according to the present invention has the following configuration. That is,
A driving circuit of an image display device for displaying an image by driving a display panel having a plurality of electron-emitting devices arranged in a matrix in accordance with an image signal, wherein the driving panel supplies a drive signal to each of the plurality of electron-emitting devices. Drive current detection means for detecting a current to generate a voltage corresponding to the drive current; voltage generation means for generating a control voltage corresponding to an image signal corresponding to each of the plurality of electron-emitting devices; A comparing means for comparing the voltage generated by the detecting means with a control voltage output from the voltage generating means, a driving current control means for controlling the driving of the electron-emitting device according to the comparison result by the comparing means, It is characterized by having.

In order to achieve the above object, a method for driving an image display device according to the present invention includes the following steps. That is,
What is claimed is: 1. A method of driving an image display device, which drives a display panel having a plurality of electron-emitting devices arranged in a matrix in accordance with an image signal to display an image, wherein the driving is performed to supply each of the plurality of electron-emitting devices. A drive current detection step of detecting a current to generate a voltage corresponding to the drive current; a voltage generation step of generating a control voltage corresponding to an image signal corresponding to each of the plurality of electron-emitting devices; A comparison step of comparing the voltage generated in the detection step with the control voltage output in the voltage generation step, and a drive current control step of controlling the driving of the electron-emitting device according to the comparison result in the comparison step; It is characterized by having.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

[First Embodiment] FIG. 1 is a block diagram showing a configuration of a driving circuit per one element in an element driving circuit according to a first embodiment of the present invention. For example, in the case of a display panel as shown in FIG. 11 described above, this drive circuit is an X driver 200 that controls a drive current applied to each column direction wiring.
2 is provided.

In FIG. 1, reference numeral 6 denotes an X driver output terminal connected to the element electrode 1012 (FIG. 10) of the current emitting element, and 7 denotes a trigger input terminal for inputting a drive start trigger signal. For example, FIG.
From the control unit 1306. A drive current detection circuit 10 detects a value of a current flowing from the X driver output terminal 6 to the element electrode 1012. Reference numeral 20 denotes an integration circuit for integrating the output of the drive current detection circuit 10. Reference numeral 30 denotes a control voltage generation circuit. Reference numeral 40 denotes a voltage comparison circuit,
And the output voltage of the control voltage generating circuit 30 are compared. 50 is connected to the power supply VCC, and whether or not to supply the voltage from the power supply VCC to the drive current detection circuit 10 in accordance with the output signal level of the voltage comparison circuit 40, that is, to drive the corresponding electron-emitting device Is a drive current cutoff circuit that switches whether or not to supply the current.

It should be noted that the integration circuit 20 need not be provided as long as the output voltage of the drive current detection circuit 10 is stable.

In FIG. 1, before starting display driving, the drive current cutoff circuit 50 is in an OFF (open) state.
When the output terminal 6 is open, no current is supplied to the corresponding element. In this state, when a trigger signal instructing the start of display is input to the trigger input terminal 7, the output voltage of the integration circuit 20 decreases, the output of the voltage comparison circuit 40 becomes low level, and the drive current cutoff circuit 50 is turned on ( Short circuit). As a result, a drive current flows from the drive current detection circuit 10 to the element electrode 1012 of the current emission element through the output terminal 6, and the display drive of the electron emission element selected at that time is started.

At the same time, the control voltage generation circuit 30
Generates a predetermined control voltage corresponding to the luminance to be displayed based on the input display image data, and supplies the control voltage to the voltage comparison circuit 40.

At this time, the drive current flowing through the driven element is detected by the drive current detection circuit 10, and the detected drive current is converted into a voltage. The voltage signal thus converted is supplied to the integration circuit 20, integrated, and supplied to the voltage comparison circuit 40.

The voltage comparison circuit 40 compares the voltage indicating the result of the integration in the integration circuit 20 with the control voltage from the control voltage generation circuit 30, and when both reach the same level, opens the drive current cutoff circuit 50. Turn off.

As described above, the control voltage generation circuit 30
, The integrated value of the drive current to the electrode 1012 of the electron-emitting device, that is, the charge amount can be controlled.

FIG. 2 is a circuit diagram showing a first embodiment according to the present invention.
1 is a block diagram showing a detailed circuit configuration of FIG. FIG. 3 is a timing chart showing the waveform of each part of this circuit.

First, the configuration of the drive current detection circuit 10 will be described.

Reference numeral 11 denotes a drive current detection resistor, and reference numeral 12 denotes an OP amplifier. The peripheral resistors 121 to 124 constitute a voltage amplifier circuit. Here, when the power supply voltage is supplied from the drive current cutoff circuit 50, a current flows toward the element electrode 1012. This current causes a potential difference between both ends of the drive current detection resistor 11, and this potential difference is amplified by the OP amplifier 12 and output to the integration circuit 20.

Next, the integration circuit 20 will be described.

21 is an OP amplifier, 22 is an integrating resistor, 23
Is an integrating capacitor, which forms an integrating circuit 20 together with the peripheral resistor 211. The integration circuit 20 integrates the voltage input from the drive current detection circuit 10 according to the integrated value of the resistor 22 and the capacitor 23 and outputs the integrated voltage.

An NPN transistor 71 is connected to the output of the integrating circuit 20 via a discharge resistor 72. When a driving start trigger signal is input at a high level via a terminal 7, the transistor 72 is activated. It turns on, and one input (non-inverting input) of the voltage comparison circuit 40 is forcibly set to the low level, and the output of the voltage comparison circuit 40 is set to the low level. As a result, the drive current cutoff circuit 50 is turned on, that is, short-circuited.

Next, the control voltage generation circuit 30 will be described.

Reference numeral 31 denotes a D / A converter, which latches digital video data "Video Data" in response to a drive start trigger signal input via a terminal 7, and D / A converts the data to generate a control voltage.

Reference numeral 41 denotes a comparator having a hysteresis characteristic which constitutes the voltage comparison circuit 40.

Reference numerals 51 and 52 denote a PNP transistor and a base current supply pull-up resistor which constitute the drive current cutoff circuit 50, respectively.

FIG. 3 is a waveform chart for explaining the waveform of each part in FIG.

In FIG. 3, reference numeral 300 denotes a trigger signal input from the terminal 7. 301 is a control voltage generation circuit 30
3 shows the control voltage output from the control circuit. Reference numeral 302 denotes a drive current output from the output terminal 6. 303
Is the drive current detection circuit 1 that detects the drive current 302
An output voltage of 0 is shown. Reference numeral 304 denotes an output voltage of the integration circuit 20 corresponding to the output voltage 302. 305
Indicates an output signal of the voltage comparison circuit 40 in this case.

The details will be described below.

When a trigger signal as shown at 300 in FIG. 3 is input at the timing “t1” in FIG. 3, the transistor 71 is turned on, and the charge remaining in the integration capacitor 23 is discharged through the discharge resistor 72. Discharge. Thus, the potential of the non-inverting input terminal of the comparator 41 becomes 0V. At the same time, as indicated by reference numeral 301 in FIG.
When the control voltage is generated from 1, "Vref1" is input to the inverting input terminal of the comparator 41. This allows
Since the potential of the inverting input terminal of the comparator 41 is higher than the potential of the non-inverting input terminal, the output of the comparator 41 becomes low level as indicated by 305 in FIG.

When the output of the comparator 41 goes low in this way, the transistor 5 of the drive current cutoff circuit 50
1 is turned on when the base potential becomes low level,
From the X driver output terminal 6 to the electrode 1012 of the current emitting element
The drive current starts flowing. Due to this drive current, a potential difference occurs between both ends of the drive current detection resistor 11. This potential difference is obtained by the OP amplifier 12 multiplying the amplification factor α determined by the values of the peripheral resistors 121 to 124 (V = −α · i ×
r: i = drive current, r = resistance value of the detection resistor 11). This voltage is integrated by the OP amplifier 21 of the integration circuit 20, and an output as indicated by 304 in FIG. 3 can be obtained.

Here, at the time when the drive current to the electrode 1012 starts flowing, the current waveform is rounded as indicated by 302 in FIG. 3, but at the time "t2", the current value becomes almost stable, and Continue.

"T3" is the timing at which the supply of the driving current to the current emitting element of the adjacent pixel is stopped.
The output current of the driver circuit changes subtly.

At time "t4", when the output voltage of the OP amplifier 21 of the integration circuit 20 reaches the level "Vref1" of the control voltage output from the D / A converter 31, the output of the comparator 41 goes high. Turn (3 in Fig. 3)
05). Since the comparator 41 has a hysteresis characteristic, once the output of the comparator 41 changes to the high level, the output is maintained at the high level even if the input voltage of the comparator 41 slightly changes due to the influence of noise or the like.

When the output of the comparator 41 turns to the high level in this way, the transistor 51 of the drive current cutoff circuit 50 turns off, and the supply of the drive current to the current emission element is cut off. In this way, the drive current is supplied to the electron-emitting device until a constant charge is supplied to the current-emitting device regardless of the drive current value.

By a series of these operations, the display processing for one horizontal line is completed, and the display processing for the next line is started from the timing of "t1 '". This time, according to the next control voltage "Vref2", , The drive current is supplied to the current emitting element until the time point of “t4 ′” to perform the display processing (30 in FIG. 3).
5).

As described above, according to the first embodiment, the control voltage is controlled according to the image data corresponding to the electron-emitting device, and the charge amount supplied to the electron-emitting device according to the control voltage. , The linearity of the gradation display according to the image data can be remarkably improved.

[Second Embodiment] Next, a second embodiment of the present invention will be described. In the first embodiment described above, the detection of the drive current of the electron-emitting device is performed based on the current value supplied from the X driver that discharges the drive current.
Considering the principle of the SED, there is also a method of drawing current into the X driver. Therefore, a case will be described as a second embodiment in which an X driver that draws in current is used.

FIG. 4 is a block diagram showing a second embodiment of the present invention.
FIG. 5 is a timing chart showing waveforms at various points in this circuit. In FIGS. 4 and 5, the same parts as those in FIGS. 2 and 3 are denoted by the same reference numerals.

The difference between the second embodiment and the first embodiment is that the connection polarity of the operational amplifier 12 and the comparator 41 and the polarity of the transistor 51 forming the drive current cutoff circuit 50 are different. On the point.

The operation of the circuit of FIG. 4 is basically the same as the operation of the circuit of FIG. 2 of the first embodiment, and therefore will be briefly described. In the circuit of FIG. 4, a current flows from the element electrode. Therefore, the direction of the potential difference generated in the resistor 11 is opposite to that in FIG. Accordingly, the connection between the input terminal of the OP amplifier 12a for detecting the potential difference generated in the resistor 11 and the resistor 11 is opposite to that in the case of FIG. That is, the element electrode side of the resistor 11 is connected to the inverting input terminal of the OP amplifier 12a, and the other end of the resistor 11 is connected to the non-inverting input terminal. When the output of the comparator 41 is at a high level, a drive current is supplied to the electron-emitting device,
When the output of the comparator 41 becomes low level, the power supply to the electron-emitting device is stopped.
Therefore, the connection of the input terminal of the comparator 41 is reversed from that in FIG. 2, and the transistor 51a of the drive current cutoff circuit 50 is an NPN transistor. Supply is possible.

FIG. 5 is a waveform diagram for explaining the operation of the circuit of FIG. In FIG. 5, 300 to 304
Are common to the waveform diagram of FIG. 3 described above, and therefore description thereof is omitted.

Reference numeral 306 denotes an output signal of the comparator 41. In FIG. 4, since the connection of the input terminal of the comparator 41 is opposite to that in FIG. Are respectively VCC and V
EE.

As described above, according to the second embodiment, the control voltage is controlled in accordance with the image data corresponding to the electron-emitting device, and the charge amount supplied to the electron-emitting device in accordance with the control voltage. , The linearity of the gradation display according to the image data can be remarkably improved.

[Third Embodiment] FIG. 6 is a diagram for explaining another embodiment of the drive current detection circuit 10 according to the second embodiment described above. Here, the drive current detection circuit 10 and the integration circuit 2 are shown.
0 is shown.

In the figure, a transistor 13, a transistor 14, a resistor 131 and a resistor 141 constitute a current mirror circuit. That is, a current equivalent to the drive current of the electron-emitting device flowing through the transistor 13 is applied to the transistor 1.
Flow to 4. The voltage generated in the resistor 141 by this current is directly input to the integration circuit 20 and integrated.

The remaining circuit configuration is the same as that of the above-described second embodiment, and a description thereof will be omitted. Also, the configuration according to the third embodiment can be applied to a current-sinking type X driver as in the first embodiment.

[Fourth Embodiment] Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, a case will be described in which the control voltage generation circuit 30 in the first and second embodiments has an image quality adjustment function.

FIG. 7 shows a fourth embodiment of the present invention corresponding to the X driver of the current discharge type according to the first embodiment of the present invention.
FIG. 3 is a block diagram for explaining a configuration of a control voltage generation circuit 30a according to the first embodiment.

In the figure, reference numerals 7, 31, and 41 denote trigger input terminals for inputting a drive start trigger signal and digital video data "Video", respectively, as in the first embodiment.
D / A converter that generates control voltage based on “Data”
This is a comparator included in the voltage comparison circuit 40. 33
Is a D / A converter for generating an image quality adjustment voltage, and 32 and 34 are resistors.

As in the first embodiment, the D / A converter 31 sets “Video Data” at the start of display processing.
"Image voltage" is generated based on On the other hand, when adjusting the image quality, the D / A converter 33 receives “Cont Data (control data)” corresponding to the adjustment amount of “brightness” and generates a “brightness adjustment voltage” corresponding thereto. The resistance 32 and the resistance 34
The “image voltage” and the “brightness adjustment voltage” are added in an analog manner based on the resistance ratio, and a control voltage to be applied to the comparator 41 is obtained. Note that the control data for adjusting the brightness is input, for example, by an instruction from a luminance volume, a remote controller, or the like.

In this case, the brightness of the displayed image can be increased in proportion to the “brightness adjustment voltage” corresponding to the adjustment value instructed by the remote controller or the like. As a result, the image having the increased “brightness” can be obtained. Will be obtained.

[Fifth Embodiment] Next, a fifth embodiment of the present invention will be described. Here, Embodiment 1 and Embodiment 1 described above are used.
An example will be described in which the control voltage generation circuit in FIG. 2 further has an image quality adjustment function.

FIG. 8 shows a fifth embodiment of the present invention corresponding to a current-sinking type X driver according to the first embodiment of the present invention.
FIG. 3 is a block diagram showing a configuration of a control voltage generation circuit 30b according to the first embodiment.

Reference numerals 7 and 31 and 41 denote a trigger input terminal for inputting a drive start trigger signal and a D / A converter for generating a control voltage based on digital video data "Video Data", as in the first embodiment. , The voltage comparator 40. 36 is a reference voltage generator, and 35 and 37 are variable resistors. here,
By changing the resistance values of the variable resistors 35 and 37, the contrast of the displayed image can be changed.

As in the first embodiment, the D / A converter 31 generates an "image voltage" based on "Video Data" at the start of the display processing. Variable resistance 35 and variable resistance 3
7 analogly adds the "image voltage" and the "reference voltage" based on the resistance ratio to obtain a control voltage.

In this case, the smaller the resistance value of the variable resistor 35, the higher the contrast of the displayed image, and the smaller the resistance value of the variable resistor 37, the higher the brightness of the displayed image and the “brightness”. The obtained image is obtained.

Here, the variable resistor 35 and the variable resistor 37
The same effect can be obtained by using an element whose resistance value is changed by an external control signal, for example, an FET instead of a so-called "volume".

[Sixth Embodiment] Next, a sixth embodiment of the present invention will be described. Here, Embodiment 1 and Embodiment 1 described above are used.
The case where the control voltage generation circuit in 2 is further provided with an image quality adjustment function will be described.

FIG. 9 shows a fifth embodiment of the present invention corresponding to a current source type X driver according to the first embodiment of the present invention.
FIG. 3 is a block diagram showing a configuration of a control voltage generation circuit 30c according to the first embodiment.

Reference numerals 7, 31, and 41 denote a trigger input terminal for inputting a drive start trigger signal and a D / A converter for generating a control voltage based on digital video data "Video Data", as in the first embodiment. , The voltage comparator 40. Reference numeral 38 denotes a first reference voltage source for determining the top level "VTOP" of the D / A converter 31, and reference numeral 39 denotes a second reference voltage source for determining the bottom level "VBOTTOM" of the output D converter 31. Both of the first and second reference voltage sources 38 and 39 output their output voltage “VTO” by an external control signal (not shown).
P ”and“ VBOTTOM ”can be changed to arbitrary values, so that the D / A converter 31 outputs“ VTOP ”,
Digital video data “Video” at the potential between “VBOTTOM”
A control voltage is generated based on “Data.” For example, when the digital video data “Video Data” is 8 bits, the digital video data “Vido Data” is “00h” (h is 16 bits).
(Base number), "VBOTTOM" is the control voltage, and "VFFh" is the control voltage, "VTOP".

In order to increase the contrast of the displayed image, the potential difference between “VTOP” and “VBOTTOM” is increased, and to increase “brightness”, “VTOP” and “VBOTTOM” are used.
M ”may be raised while the potential difference between them is maintained.

In any of the above-described fourth to sixth embodiments, the present invention can be applied to the X driver of the current sink type as in the above-described second embodiment by taking measures such as reversing the input terminal of the comparator 41. Needless to say, this is possible.

In the first and second embodiments, the image quality can be adjusted by performing digital arithmetic processing on the digital video data “Video Data”.

Further, in any of the above embodiments, a C-MOS switch such as an FET may be used for the drive current cutoff circuit 50, or a circuit using a transistor or the like instead of the OP amplifier may be employed. Is also good.

FIG. 13 is a block diagram showing the configuration of the image display device according to the embodiment of the present invention. Note that FIG.
The image forming apparatus shown in FIG. 3 is applicable to any of the first to sixth embodiments.

In FIG. 13, reference numeral 1300 denotes a display panel in which, for example, a plurality of electron-emitting devices (here, surface conduction electron-emitting devices) are wired in a matrix. 1301
Is a Y driver that selects a row-direction wiring of the display panel 1300 in synchronization with a horizontal synchronization signal of an image supplied from the decoder 1309, and applies a predetermined voltage to the selected row-direction wiring. Reference numeral 1302 denotes an X driver, which supplies a current to each column wiring of the display panel 1300 according to an image signal to drive an electron-emitting device connected to the row wiring selected by the Y driver 1301. Reference numeral 1302 denotes a drive control circuit which is a characteristic part of the present embodiment, and corresponds to the above-described FIG.
It has a circuit as shown in FIG. 4 and further has a control voltage generating circuit as shown in FIGS. 7 to 9, and can adjust the contrast and brightness of an image. Although FIG. 13 shows the X driver 1302 and the drive control circuit 1303 separately, the present invention is not limited to this. For example, the X driver has the two functions integrated. There may be.

Reference numeral 1304 denotes a line memory, and the display panel 1
The display data for one line to be displayed in 300 is stored. A serial / parallel conversion circuit 1305 receives and holds a serial image signal decoded and input by a decoder 1309, converts the serial image signal into a parallel signal, and outputs the parallel signal to a line memory 1305. The decoder 1309 receives an analog image signal, converts it into a digital signal, and outputs it as a serial image signal. Also, various timing signals are generated based on the synchronization signal of the input analog image signal. A control unit 1306 controls the operation of the entire image display apparatus, inputs adjustment data such as image quality and contrast input from the adjustment unit 1307, and outputs control data to the drive control circuit 1303 accordingly. ing. This makes it possible to perform display control for each element as described above. Reference numeral 1308 denotes a timing control circuit which is a shift clock to the serial / parallel conversion circuit 1305, a latch clock of one-line data to the line memory 1304, and a Y driver 130 based on a synchronization signal of an image signal sent from the decoder 1309.
1 and the like.

The control unit 1306 includes a CPU 1400 such as a microcomputer, a memory 1401 for storing a control program for the CPU 1400 and various data. When the drive control circuit 1303 has the control voltage generation circuit 30 as shown in FIG.
Reference numeral 06 denotes an output of the control voltage generation circuit 30 of the drive control circuit 1303 which converts adjustment values such as contrast, brightness, and color adjustment input from the adjustment unit 1307 into digital data.
/ A converter 33. When the adjustment unit 1307 includes a variable resistor such as a volume, the control voltage generation circuit 30 of the drive control circuit 1303 is directly controlled according to the adjustment amount of the volume (for example, in FIG. 8,
When the resistance values of the variable resistors 35 and 37 are directly changed).

Even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), a device including one device (for example, a copying machine, a facsimile machine, etc.) ) May be applied.

Further, an object of the present invention is to supply a storage medium (or a recording medium) in which a program code of software for realizing the functions of the above-described embodiments is recorded to a system or an apparatus, and a computer (a computer) of the system or the apparatus. Alternatively, the present invention is also achieved when a CPU or an MPU reads and executes a program code stored in a storage medium. In this case, the program code itself read from the storage medium implements the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention. When the computer executes the readout program codes, not only the functions of the above-described embodiments are realized, but also an operating system (OS) running on the computer based on the instructions of the program codes. This also includes a case where some or all of the actual processing is performed and the functions of the above-described embodiments are realized by the processing.

Further, after the program code read from the storage medium is written in a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer, the program code is read based on the instruction of the program code. , The CPU provided in the function expansion card or the function expansion unit performs part or all of the actual processing,
The case where the function of the above-described embodiment is realized by the processing is also included.

As described above, according to the present embodiment, by using a drive circuit for controlling the amount of charge (integral value of current) to a predetermined value for each electron-emitting device, the drive current of each device can be reduced. It is possible to eliminate the deterioration of the reproducibility of the gradation due to the rounding of the waveform at the rising portion and the influence of the adjacent pixels.

Further, it is possible to suppress the loss of the drive circuit, and it is also possible to relatively easily perform a part of the image quality adjustment function.

[0083]

As described above, according to the present invention, a high-quality image with high tone reproducibility is displayed by controlling the value of the current flowing through each electron-emitting device according to the image signal. it can.

According to the present invention, it is possible to display a high-quality image with good gradation and to display an image in accordance with image quality adjustment of the displayed image.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a functional configuration of an X driver circuit according to an embodiment of the present invention.

FIG. 2 is a diagram showing a circuit configuration of an X driver according to the first embodiment of the present invention.

FIG. 3 is a waveform chart of each part of the circuit according to the first embodiment shown in FIG. 2;

FIG. 4 is a diagram showing a circuit configuration of an X driver according to a second embodiment of the present invention.

5 is a waveform chart of each part of the circuit according to the second embodiment shown in FIG.

FIG. 6 is a circuit diagram showing a part of an X driver according to a third embodiment of the present invention.

FIG. 7 is a circuit diagram showing a configuration of a control voltage generation circuit in an X driver according to a fourth embodiment of the present invention.

FIG. 8 is a circuit diagram showing a configuration of a control voltage generation circuit in an X driver according to a fifth embodiment of the present invention.

FIG. 9 is a circuit diagram showing a configuration of a control voltage generation circuit in an X driver according to Embodiment 6 of the present invention.

FIG. 10 is a schematic diagram illustrating electron emission in an image display panel using an SED.

FIG. 11 is a schematic diagram of an image display panel.

FIG. 12 is a diagram illustrating a conventional drive current waveform.

FIG. 13 is a block diagram illustrating a configuration of an image display device according to an embodiment of the present invention.

[Explanation of symbols]

 6 X driver output terminal 7 Trigger input terminal 10 Drive current detection circuit 20 Integration circuit 30 Control voltage generation circuit 40 Voltage comparison circuit 50 Drive current cutoff circuit

Claims (14)

[Claims] A display panel having a plurality of electron-emitting devices arranged in a matrix; and a drive for detecting a drive current supplied to each of the plurality of electron-emitting devices and generating a voltage corresponding to the drive current. Current detection means, voltage generation means for generating a control voltage corresponding to an image signal corresponding to each of the plurality of electron-emitting devices, and a voltage generated by the drive current detection means and output from the voltage generation means An image display device comprising: a comparing unit that compares a control voltage; and a driving current control unit that controls driving of the electron-emitting device in accordance with the comparison result. 2. The control apparatus according to claim 1, further comprising an integrating means for integrating a voltage output from said driving current detecting means, wherein said comparing means includes a voltage signal integrated by said integrating means and a control voltage output from said voltage generating means. The image display device according to claim 1, wherein: 3. The method according to claim 2, wherein the drive current control unit stops supplying current to the electron-emitting device when the comparison result by the comparison unit indicates that they are substantially the same. Item 3. The image display device according to item 1 or 2. 4. The driving current detecting means has a mirror circuit, and detects the driving current based on a value of a current flowing through one of the switching elements constituting the mirror circuit. The image display device according to any one of the above. 5. An image processing apparatus, further comprising: an adjustment instruction unit for adjusting the image quality to be displayed; and an adjustment control voltage generation unit for controlling an output voltage of the voltage generation unit in accordance with an adjustment value by the adjustment instruction unit. The image display device according to claim 1. 6. A driving circuit of an image display device for displaying an image by driving a display panel having a plurality of electron-emitting devices arranged in a matrix according to an image signal, wherein Drive current detection means for detecting a drive current supplied to each of them to generate a voltage corresponding to the drive current, and voltage generation means for generating a control voltage corresponding to an image signal corresponding to each of the plurality of electron-emitting devices A comparing means for comparing a voltage generated by the driving current detecting means with a control voltage output from the voltage generating means; and a drive for controlling the driving of the electron-emitting device according to the comparison result by the comparing means. And a current control means. 7. An integrator for integrating a voltage output from the drive current detector, wherein the comparator includes a voltage signal integrated by the integrator and a control voltage output from the voltage generator. 7. The driving circuit according to claim 6, wherein 8. The method according to claim 1, wherein the drive current control unit stops supplying current to the electron-emitting device when the comparison result by the comparison unit indicates that they are substantially the same. Item 8. The driving circuit according to item 6 or 7. 9. The driving current detecting means includes a mirror circuit, and detects the driving current based on a value of a current flowing through one of the switching elements constituting the mirror circuit. The drive circuit according to any one of the above items. 10. An apparatus according to claim 6, further comprising an adjustment control voltage generation means for controlling an output voltage of said voltage generation means in accordance with an adjustment value by an adjustment instruction means for adjusting the displayed image quality. The drive circuit according to any one of the above items. 11. A method for driving an image display device that displays an image by driving a display panel having a plurality of electron-emitting devices arranged in a matrix according to an image signal, the method comprising: A drive current detection step of detecting a drive current supplied to each of the plurality of electron emission elements to generate a voltage corresponding to the drive current; and a voltage generation step of generating a control voltage corresponding to an image signal corresponding to each of the plurality of electron-emitting devices. A comparing step of comparing a voltage generated in the driving current detecting step with a control voltage output in the voltage generating step; and a drive controlling the driving of the electron-emitting device according to a comparison result in the comparing step. A current control step. 12. The method according to claim 12, further comprising an integrating step of integrating a voltage output in the driving current detecting step, wherein the comparing step includes a voltage signal integrated in the integrating step and a control voltage output in the voltage generating step. 12. The driving method according to claim 11, wherein: 13. The driving current control step, wherein the current supply to the electron-emitting device is stopped when the comparison results in the comparison step indicate that they are substantially the same. Item 13. The driving method according to item 11 or 12. 14. The apparatus according to claim 11, further comprising a step of controlling an output voltage output in said voltage generation step in accordance with an adjustment value for adjusting displayed image quality. The driving method described in the paragraph.