JP2006235169A - Image display device, control method thereof, and television device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the reliability of an image display device by controlling driving of an indicating element in an unstable state at the time of turning the power on and off without adding an external circuit, and by preventing applying an abnormal voltage to the indicating element. <P>SOLUTION: The image display device has a plurality of scan wires 2 and a plurality of modulation wires 3, and controls the brightness by applying a voltage to an electron emission element by the wires. A logic voltage detector 7 for monitoring a source voltage, a selection voltage detector 8, and a non-selection voltage detector 9 are disposed to a scan drive control unit 5 for driving the scan wires 2. At the time of turning the power on and off, the driving by a scan wiring drive output 11 is stopped when the voltage of at least one of the voltage detectors falls outside the scope of the specified voltage. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image display apparatus, a control method therefor, and a television apparatus, and is particularly suitable for application to display on / off control in an image display apparatus.

  Conventionally, as a method for controlling image display, techniques described in Patent Literature 1 and Patent Literature 2 are known.

  Patent Document 1 describes a control method including a step of outputting a signal instructing the start of a display on sequence from an MPU to a display body driving unit. That is, in the prior art described in Patent Document 1, the output of the display body driving means is controlled by an MPU provided separately.

Patent Document 2 describes a display-off control method in which the display element driving unit sets the applied potential to the display element to a specific state based on a signal from the display control unit, and the display is blanked. . That is, in the prior art described in Patent Document 2, the potential applied to the display element is set to a specific state by the display element driving means based on the signal from the display control means, and the display is blanked.
Japanese Patent No. 3139495 (paragraph number [0026] and FIG. 1) Japanese Patent No. 3269502 (paragraph number [0025] and FIG. 1)

  However, according to the knowledge of the present inventor, the on / off control method in the image display device described in Patent Document 1 or Patent Document 2 requires power supply sequence processing.

  That is, as shown in FIG. 9, in the conventional technique, an MPU 4 ′ as a control unit and a power supply 14 for supplying power are provided, and a scan output control signal 12 is supplied from the MPU 4 ′ to the scan drive control unit 5. While the scanning wiring is driven, power is supplied from the power supply 14 to the respective scanning drive control units 5 through the power supply wiring 15. And control of this power supply 14 was also performed by MPU4 '. This complicates the configuration of the MPU4 ′ circuit, which is a power supply circuit and a control circuit, and has been a factor in increasing costs. In addition, when the power is suddenly turned off, such as when the user intentionally unplugs the power outlet, a large-capacitance capacitor is required to maintain the power supply voltage of the MPU 4 ′ until the MPU 4 ′ completes the power-off sequence. there were.

  Therefore, an object of the present invention is to provide an image display apparatus and a control method thereof that can reduce the cost by eliminating the need for power supply sequence processing and avoiding the complexity of the configuration of the power supply circuit and the control circuit MPU circuit. It is to provide. Another object of the present invention is to provide a television device having such an image display device.

In order to achieve the above object, the first invention of the present invention provides:
A display element;
A drive circuit for applying a drive voltage to the display element;
A power supply for applying a power supply voltage and a logic voltage to the drive circuit;
Voltage detection means for detecting whether the power supply voltage and the logic voltage are within a predetermined voltage value range is provided in the drive circuit,
An image display device configured to apply a drive voltage to a drive circuit when the power supply voltage and the logic voltage are within a predetermined voltage value range by the voltage detection means.

The second invention of this invention is:
A plurality of scanning wires;
Multiple modulation wires;
A plurality of display elements located in the vicinity of the intersection of the scanning wiring and the modulation wiring and arranged in a matrix;
A plurality of scanning drive circuits for applying a voltage to the scanning wiring;
A power source for applying a voltage to at least the display element and the scanning drive circuit,
Each of the plurality of scan driving circuits is provided with voltage detection means configured to be able to detect a voltage supplied from a power source,
The image display device is configured so that no voltage is applied to the scanning drive circuit when a voltage deviating from a predetermined range is detected by the voltage detecting means.

The third invention of the present invention is:
A display element;
A drive circuit for outputting a drive voltage to the display element;
A power supply that outputs power supply voltage and logic voltage to the drive circuit;
A control method for an image display device having a control unit that controls a drive circuit and a power supply in cooperation with each other,
A step of supplying an image signal to the drive circuit by the control unit;
Applying a power supply voltage and a logic voltage to the drive circuit by a power supply based on a signal from the control unit;
And a step of applying a driving voltage to the display element in synchronization with rising or falling of the power supply voltage and the logic voltage by the driving circuit.

The fourth invention of the present invention is:
An image display device including the first invention or the second invention;
It is a television device characterized by comprising receiving means for receiving a television signal.

  According to the present invention, since the function as the power supply monitoring means is provided in the drive circuit of the display body drive means, the power supply sequence processing by the external circuit is not required. In addition, since the control circuit is provided in the scan drive unit, the wiring between the control circuit and the display body drive circuit is shortened without causing an increase in cost, so there is no problem of malfunction due to unconnected wiring. In addition, no harness is required, and space can be saved.

  As described above, according to the present invention, the power supply monitoring function is provided in the drive circuit, so that the display element in an unstable state when the power is turned on and when the power is turned off without adding an external circuit. Since the drive can be controlled, the reliability of the entire image display apparatus can be improved without applying an abnormal voltage to the display element, and the output sequence control of the power supply circuit is not required. The design can be simplified.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings of the following embodiments, the same or corresponding parts are denoted by the same reference numerals. First, an image display apparatus according to an embodiment of the present invention will be described. FIG. 1 shows the overall configuration of an image display apparatus according to this embodiment.

  As shown in FIG. 1, the image display apparatus according to this embodiment includes a matrix panel 1, a scanning wiring 2, a modulation wiring 3, a control unit 4, a scanning drive control unit 5 including a scanning driving IC, and a modulation driving IC. A modulation drive control unit 6 is provided.

  The matrix panel 1 is configured such that a plurality of field emission elements 3a are connected in a matrix by a plurality of scanning wirings 2 and a plurality of modulation wirings 3 on the rear panel 1a, and wiring for the rear panel 1a is provided. A face plate 3b provided with a phosphor 3c is provided opposite to the surface. The electrons emitted from the field emission device 3a reach the face plate 3b to which a high voltage of several kV to several tens kV is applied. The electrons collide with the phosphors 3c arranged on the face plate 3b to emit light, and display images and images on the matrix panel 1.

  In FIG. 1, the matrix panel 1 includes a rear panel 1a and a face plate 3b. The rear panel 1 a has a field emission element 3 a disposed at the intersection of the scanning wiring 2 and the modulation wiring 3. In the matrix panel 1, the scanning drive control unit 5 and the modulation drive control unit 6 are controlled using the control unit 4. Then, by applying a voltage of, for example, several tens of volts between the scanning wiring 2 and the modulation wiring 3, electrons are emitted from the field emission element 3a.

  In the normal scanning mode, the scanning drive control unit 5 applies a selection potential to one scanning wiring 2 of the plurality of scanning wirings 2 and applies a non-selection potential (for example, grounding) to the other scanning wirings 2 that are not selected. This is a drive circuit for sequentially switching the selected scanning wiring 2 by applying a potential.

  The modulation drive control unit 6 is a drive circuit that controls outputs from a plurality of constant voltage power sources in accordance with an input image signal and applies the modulated signals to the plurality of modulation wirings 3 in parallel. The control unit 4 is a control circuit for supplying image data to the scanning drive control unit 5 and the modulation drive control unit 6 and displaying an image on the matrix panel 1. Here, in the scanning drive control unit 5, for example, eight circuits are arranged in parallel. The scanning drive control unit 5 applies a predetermined voltage to the scanning wiring 2 and displays an image on the matrix panel 1.

  In another scanning mode, the scanning drive control unit 5 simultaneously selects a plurality of scanning wirings 2 among the scanning wirings 2 and applies a selection potential to sequentially shift the scanning wirings 2 to be selected one by one. It can also be switched.

(Scanning drive control unit)
Next, the scanning drive control unit 5 for applying the selection voltage to the scanning wiring 2 and switching sequentially will be described in detail. FIG. 2 shows the configuration of the scan drive control unit 5 according to this embodiment.

In FIG. 2, the scan drive control unit 5 includes a shift register 11A including a flip-flop 11D for selecting a scan line, a scan line drive output unit 11 for driving the scan line, and a logic voltage detection unit for monitoring the power supply voltage. 7, a Vsel voltage detection unit 8, a Vusel voltage detection unit 9, and an AND circuit 10 that performs an AND operation on signals from the respective voltage detection units. Although not shown, the power source is provided outside the scan drive control unit 5.

  First, the shift register 11A includes a plurality of flip-flops 11D, and shifts the shift data 11B from the control unit 4 sequentially from the top at the rising timing of the shift clock 11C from the control unit 4. Each flip-flop 11D supplies an output control signal 29 to the scanning wiring drive output unit 11 at the timing when the shift data is shifted.

  When a predetermined potential within a range of −10 to −15 V is defined as a selection voltage to be applied to the selected one or a predetermined number of scanning wirings 2, the selection voltage detector 8 detects the actual selection voltage. Is a circuit for detecting whether or not the voltage is within a range of ± 5% with respect to the specified voltage, that is, whether or not the voltage can be regarded as the specified voltage. In the selection voltage detection unit 8, when the selection voltage falls within a range of, for example, ± 5% of the specified voltage, “1 (high)” is output.

  In addition, the non-selection voltage detection unit 9 defines a predetermined potential within a range of 0 to 5 V, for example, as a non-selection voltage to be applied to the scanning line 2 that is not selected among the plurality of scanning lines 2. This is a circuit for detecting whether or not the actually applied non-selection voltage is within a range of, for example, ± 5% of the specified voltage, that is, whether or not the non-selected voltage has become the specified voltage. When the non-select voltage detected by the non-select voltage detector 9 falls within a range of, for example, ± 5% of the specified voltage, “1 (high)” is output.

  The logic voltage detector 7 is for detecting a logic voltage applied by the logic power supply. In this case, the logic voltage is about 3.3V or 5V, for example, as the specified voltage. When the logic voltage detected by the logic voltage detector 7 falls within a range of, for example, ± 5% of the specified voltage, “1 (high)” is output.

  The AND circuit 10 outputs “1 (high)” when the outputs from the logic voltage detection unit 7, the selection voltage detection unit 8, and the non-selection voltage detection unit 9 are all “1 (high)”. Is output.

  Next, a power-on sequence and a power-down sequence will be described. FIG. 3 shows on / off control in the scanning drive control unit 5 according to this embodiment, that is, a sequence for raising and lowering the power supply voltage applied to the modulation wiring 3 and the scanning wiring 2.

(Start-up sequence)
First, the startup sequence will be described. As shown in FIG. 3, in the power on / off control, first, the logic power supply is turned on in order to apply the logic voltage to the modulation wiring 3 by the modulation drive control unit 6. Next, the power supply for supplying the enable signal is turned on, and then the modulation wiring drive power supply is turned on.

  After the power-on control for the modulation wiring 3, that is, the X driver control is completed, the power-on control for voltage application to the scanning wiring 2, that is, the Y driver control is executed.

  First, a power supply (selection voltage power supply VEE) for applying a selection voltage to the scanning wiring 2 is turned on. As a result, “high” is output from the selection voltage detector 8 shown in FIG. On the other hand, since the other power supplies (the power supply for applying the logic power supply (VDD) and the scanning wiring non-selection voltage Vus (scanning wiring non-selection power supply)) are not turned on, the logic voltage detection unit 7 and the non-selection voltage detection unit 9 outputs “0 (low)”.

  Thereafter, as shown in FIG. 3, when the scanning wiring non-selection power source Vus is started and turned on, “1 (high)” is output from the non-selection voltage detector 9. Further, when the logic power supply VDD is started and turned on, “1 (high)” is output from the logic voltage detection unit 7. Accordingly, all the inputs to the AND circuit 10 shown in FIG. 2 become “1 (high)”, so that “1 (high)” is supplied to the scanning wiring drive output unit 11 and voltage can be applied. The drive output is turned on.

  In other words, the scanning drive control unit 5 is provided with a detection unit that monitors the power source to which the respective scanning wiring selection voltage VEE, scanning wiring non-selection voltage Vus, and logic voltage VDD are applied, and these voltage values are predetermined. For example, the drive output supplied to the scanning wiring drive output unit 11 is turned on when it reaches ± 5% of the voltage (specified voltage).

(Falling sequence)
Next, in the fall sequence, processing is executed in approximately the reverse order of the above-described launch sequence.

First, the logic voltage VDDy is turned off. Along with this, “0 (low)” is output from the logic voltage detector 7 shown in FIG. The output of the AND circuit 10
Since “0 (low)” is output from the voltage, no voltage is applied to the scanning wiring drive output unit 11, and the drive output is turned off.

  In other words, the scanning drive control unit 5 is configured to be able to monitor the power supply of the voltage applied to the scanning wiring 2, and the voltage from one of these power supplies is, for example, ± 5% with respect to the specified voltage. The drive output supplied to the scanning wiring drive output unit 11 is turned off when it is out of the range.

  After the drive output to the scanning wiring drive output unit 11 is turned off, the scanning wiring non-selection power supply Vus and the scanning wiring selection power supply VEE are sequentially turned off as shown in FIG. Subsequently, the power supply of the voltage applied to the modulation wiring 3, that is, the modulation wiring drive power supply Vn, the power supply for the enable signal, and the logic power supply VDDx are sequentially turned off, and the power supply shutdown sequence ends.

(Voltage detector)
Next, a power supply monitoring circuit used as a voltage detection unit will be described. FIG. 4 shows an example of the logic voltage detection unit 7.

  As shown in FIG. 4, in the power supply monitoring circuit according to this embodiment, the base of the transistor 19 a is connected to the current source 16. Therefore, a constant current is attempted to flow regardless of the voltage of the power source 21. As a result, the base of the transistor 19a is pulled, and the potential V7 of the node of the transistor 19a increases as the power supply voltage increases. The transistor 19a is balanced when the collector current of the transistor 19a becomes equal to the current I1 from the current source 16.

  On the other hand, a voltage due to resistance division by the voltage dividing resistor 20 is applied to the base of the transistor 19b. As a result, no current flows through the node V5 of the transistor 19b, so that the voltage becomes 0V. When the voltage of the power supply 21 rises, the voltages of the transistors 19a and 19b become balanced. When this voltage further increases, the relationship between the base potentials of the transistors 19a and 19b is reversed, the potential V7 of the node of the transistor 19a decreases, and the potential V5 of the node of the transistor 19b increases.

  The potential V7 of the node of the transistor 19a and the potential V5 of the node of the transistor 19b are compared by the comparator 24, and the comparison result is output as the potential V9. The output of V9 is supplied to the AND circuit 10 shown in FIG.

  FIG. 5 shows changes in the potentials V5, V7, and V9 in the above power supply monitoring circuit. As shown in FIG. 5, the node potential V7 of the transistor 19a and the node potential V5 of the transistor 19b are monitored, and the inversion position of these potentials is detected by the comparator 24, whereby the voltage of the power source 21 and the specified voltage are Comparison can be performed, and it is possible to detect whether or not the applied voltage has become a specified voltage by the power source.

  6 shows a circuit diagram of the scanning wiring drive output unit 11 of FIG. 2 according to one embodiment of the present invention. FIG. 7 shows an output control signal 29 (see FIG. 7A) and an output unit mask signal in this circuit diagram. 30 (see FIG. 7B) and a drive output signal 35 (see FIG. 7C) based on these signals.

  In FIG. 6, an output control signal 29 is an output of the flip-flop 11D constituting the shift register 11A shown in FIG. 2, and controls the rise and fall of the drive output signal 35 applied to the selected scanning wiring. . Then, the output of the logic operation circuits 31 and 32 that receive the output control signal 29 and the output portion mask signal 30 supplied through the AND circuit 10 as an input turns on the drive output signal output to the selected scanning wiring. Control off (selected, unselected). The NOR circuit 32 is connected to the gate of the pMOS transistor 33 connected to the non-select voltage power source (Vusel) via the level shifter 38. For example, when the output of the NOR circuit 32 is Lo (0 V), the gate of the pMOS transistor 33 is shifted to the potential of Vusel-3.3 V by the level shifter 38, and the drive output signal 35 is changed to the Vusel potential (non-selection potential). Fixed to.

As the level shifter 38, for example, a Zener diode is used. The AND circuit 31 is connected to the gate of the nMOS transistor 34 connected to the selection voltage power supply (Vsel) via the level shifter 38. For example, when the AND circuit 31 is Hi (3.3 V), the gate of the nMOS transistor 34 is connected. The signal shifted to the potential of Vusel + 3.3V by the level shifter 38 is input to fix the drive output signal 35 to the selection potential (Vsel).

  Then, as shown in FIG. 7, the output control signal 29 is masked by the output portion mask signal 30, so that the scanning wiring drive output signal 35 actually supplied to the scanning wiring 2 is shown in FIG. 7C. Even during the selection voltage output period, the non-selection voltage is output at the rising timing of the output portion mask signal 30. In this way, the scanning wiring drive output signal 35 supplied to the scanning wiring 2 is controlled, and a voltage outside the specified voltage range, that is, an abnormal voltage is applied to the electron-emitting device 3a and the scanning wiring drive output unit 11. Can be prevented.

  A driving voltage is applied to the electron-emitting device 3a shown in FIG. 1 based on the scanning wiring output signal and the modulation wiring output signal thus controlled.

(Television device)
Next, a television apparatus using the layer display apparatus according to this embodiment will be described. FIG. 8 shows a television apparatus using the image display apparatus according to this embodiment.

  As shown in FIG. 8, the television device includes a receiving circuit 120, an image processing unit 121, a display device 125 including a control unit 122, a drive circuit 123, and a display panel 124.

  The receiving circuit 120 includes a tuner and a decoder. The receiving circuit 120 is configured to receive a television signal such as a satellite broadcast or a terrestrial wave, a data broadcast via a network, and the like, and output decoded video data to the image processing unit 121. The image processing unit 121 includes a γ correction circuit, a resolution conversion circuit, an interface (I / F) circuit, and the like. The image processing unit 121 is configured to be able to output image data to the display device 125 by converting the image data that has undergone image processing into a display format of the display device.

  The display device 125 includes the display panel 124, the drive circuit 123 including the scan drive control unit 5 and the modulation drive control unit 6 according to the above-described embodiment, and the control unit 122. The control unit 122 performs signal processing such as correction processing suitable for the display panel on the input image data, and can supply the image data and various control signals to the drive circuit 123. The driving circuit 123 supplies a driving signal to the display panel 124 based on the input image data, and displays a television image.

  Note that the reception circuit 120 and the image processing unit 121 may be housed in a separate housing from the display device 125 as a set-top box (STB) 126 as illustrated in FIG. Other than these cases, various combinations can be adopted.

  The embodiment of the present invention has been specifically described above, but the present invention is not limited to the above-described embodiment, and various modifications based on the technical idea of the present invention are possible.

  For example, in the above-described embodiment, the case where the scanning drive control unit 5 is provided with the power supply voltage or logic voltage detection unit has been described, but the modulation drive control unit 6 may be provided with the power supply voltage detection unit. . In this case, the on / off control described above can also be adopted for the on / off control in the modulation drive control unit 6.

  For example, in the above-described embodiment, the predetermined voltage range serving as the detection reference in each of the detection units 7, 8, and 9 is ± 5% of the specified voltage, but is not necessarily limited to ± 5%. However, other ranges are possible, and it is possible to set an arbitrary range including this specified voltage as necessary.

It is a basic diagram which shows the image display apparatus by one Embodiment of this invention. It is a block diagram which shows the scanning wiring drive part which has a power supply monitoring function by one Embodiment of this invention. FIG. 5 is a timing chart showing a power on / off sequence for the scanning wiring and modulation wiring of the image display device according to the embodiment of the present invention. It is a circuit diagram which shows the structure of the voltage detection part in the image display apparatus by one Embodiment of this invention. It is a graph for demonstrating the voltage detection method of the voltage detection part in the image display apparatus by one Embodiment of this invention. It is a circuit diagram which shows the structure of the scanning wiring drive output part of the image display apparatus by one Embodiment of this invention. It is a graph which shows the drive control signal in the scanning wiring drive output part of the image display apparatus by one Embodiment of this invention, an output part mask signal, and the signal by which the output by this was masked. It is a block diagram which shows the set top box and television apparatus using the image display apparatus by one Embodiment of this invention. It is a block diagram which shows the structure of the power supply and scanning wiring drive part in the image display apparatus by a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Matrix panel 1a Rear panel 2 Scanning wiring 3 Modulation wiring 3a Field emission element 3b Faceplate 3c Phosphor 4 Control part 5 Scan drive control part 6 Modulation drive control part 7 Logic voltage detection part 8 Selection voltage detection part 9 Non-selection voltage detection part DESCRIPTION OF SYMBOLS 10 AND circuit 11 Scanning wiring drive output part 12 Scanning output control signal 14 Power supply 15 Power supply wiring 16 Current source 19, 19a, 19b Transistor 20 Voltage dividing resistor 21 Power supply 24 Comparator 31 AND circuit 32 NOR circuit 33 pMOS transistor 34 nMOS transistor 38 Level shifter 120 Receiving circuit 121 Image processing unit 122 Control unit 123 Drive circuit 124 Display panel 125 Display device 126 STB

Claims (7)

A display element;
A driving circuit for applying a driving voltage to the display element;
A power supply for supplying a power supply voltage and a logic voltage to the drive circuit;
Voltage detection means for detecting whether the power supply voltage and the logic voltage are within a predetermined voltage value range is provided in the drive circuit,
An image display device configured to supply the drive voltage to the drive circuit when the power supply voltage and the logic voltage are within a predetermined voltage value range by the voltage detection means. A plurality of scanning wires;
Multiple modulation wires;
A plurality of display elements connected to the scanning wiring and the modulation wiring and arranged in a matrix;
A plurality of scan drive circuits for outputting a drive output signal to the scan wiring;
A power supply for supplying a power supply voltage to the scan drive circuit,
Each of the plurality of scanning drive circuits is provided with voltage detection means configured to be able to detect a power supply voltage supplied from the power supply,
The image display device, wherein the scanning drive circuit is configured not to output the drive output signal when the voltage detection means detects a voltage outside a predetermined range.   When the voltage detection unit has a logic voltage detection unit capable of detecting at least whether the logic voltage is within a predetermined logic voltage range, and the logic voltage is out of the predetermined logic voltage range. 3. The image display device according to claim 1, wherein the image display device is configured to perform control so that the voltage is not applied to the scanning drive circuit.   The voltage detection means can detect whether the logic voltage is within a predetermined logic voltage range and can detect whether the selection voltage is within a predetermined selection voltage range. A selection voltage detection unit, and a non-selection voltage detection unit capable of detecting whether or not the non-selection voltage is within a predetermined non-selection voltage range, the logic voltage, the selection voltage, and the non-selection voltage 3. The image display according to claim 1, wherein when at least one of the voltage values is out of the range, control is performed so that no voltage is applied to the scanning drive circuit. 4. apparatus. A display element;
A drive circuit for outputting a drive voltage to the display element;
A power supply that outputs a power supply voltage and a logic voltage to the drive circuit;
A control method for an image display device having a control unit that controls the drive circuit and the power supply in cooperation with each other,
A step of supplying an image signal to the drive circuit by the control unit;
Applying a power supply voltage and a logic voltage to the drive circuit from the power supply based on a signal from the control unit;
And a step of applying the drive voltage to the display element in synchronization with a rise or fall of the power supply voltage and the logic voltage by the drive circuit. A display element;
A driving circuit for applying a driving voltage to the display element;
A power supply for supplying a power supply voltage and a logic voltage to the drive circuit;
A control method of an image display device having a control unit that controls the drive circuit and the power supply in cooperation with each other,
An image signal is supplied from the control unit to the drive circuit;
Applying a power supply voltage and a logic voltage to the drive circuit from the power supply based on a signal from the control unit;
Detecting whether the power supply voltage and the logic voltage are within a predetermined voltage value range;
And a step of supplying the drive voltage to the drive circuit when the power supply voltage and the logic voltage are within a predetermined voltage value range. An image display device according to any one of claims 1 to 4,
A television apparatus comprising: a receiving means for receiving a television signal.

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