JP4269700B2 - Display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a display device (system display) in which a central display region and peripheral circuit portions are integrally formed on a common insulating substrate. More specifically, the present invention relates to a technique for mounting a DC / DC converter included as a block of a peripheral circuit unit.
[0002]
[Prior art]
An active matrix liquid crystal panel using TFT as a switching element has an advantage that a so-called system display can be constructed because a peripheral circuit portion can be integrated and formed in addition to a display region. The system display is used as a display component of an electronic device and operates according to display data and a power supply voltage supplied from the main body side of the electronic device. The circuit section of the system display includes a DC / DC converter that converts a primary power supply voltage supplied from the electronic device main body side (set side) into a secondary power supply voltage according to the specifications of the display panel. In general, the DC / DC converter is divided into a built-in circuit mounted on an insulating substrate constituting the display panel and an external component such as a flying capacitor connected to the built-in circuit via a connection terminal. A DC / DC converter for system display is described in Patent Document 1, for example.
[0003]
[Patent Document 1]
JP 2000-305504 A
[0004]
[Problems to be solved by the invention]
In the DC / DC converter described in Patent Document 1, the conversion efficiency of the DC / DC converter mounted on the system display has been greatly improved by improving the drive system. However, the improvement of the mounting technology is not progressing compared with the improvement of the drive system, which is a problem to be solved.
[0005]
First, in the conventional DC / DC converter, the layout arrangement on the panel is not optimized, and this is a factor that hinders further improvement in conversion efficiency.
[0006]
Second, in a display device equipped with a plurality of DC / DC converters according to the panel specifications, some parts such as flying capacitors and bypass capacitors included in the DC / DC converter have a very large element area. In some cases, it is mounted on a flat cable connecting the panel side constituting the display device and the device main body side (set side). In this case, since a plurality of external parts are mounted on the flat cable, the wiring has to be crossed, and the wiring structure is multilayered. Conventionally, the optimal DC / DC converter terminal arrangement for realizing single-layer wiring has not been devised, and it has been necessary to use multi-layer wiring, so the cost of flat cables has increased and problems to be solved It has become.
[0007]
Thirdly, when a DC / DC converter is mounted on a panel, it needs to have sufficient capacity to supply all the current required by the peripheral circuit section, and it is difficult to incorporate a flying capacitor. there were. If the flying capacitor is laid out outside the panel as an external component, it causes an increase in the number of components and an increase in cost.
[0008]
[Means for Solving the Problems]
  In view of the above-described problems of the prior art, the present invention improves the mounting structure of a DC / DC converter in a system display that incorporates a peripheral circuit portion in addition to a display area, thereby further improving the efficiency of the DC / DC converter. The purpose is to reduce the cost and cost. The following measures were taken in order to achieve this purpose. The first surface is used as a display component of an electronic device, operates in accordance with display data and a power supply voltage supplied from the main body side of the electronic device, and includes a display area, a peripheral circuit unit that drives the display region, and the electronic device. A display device comprising a panel integrally formed on an insulating substrate with a terminal portion connected to the main body side of the device, wherein the insulating substrate has the display area arranged in the center, and the circuit portion on four sides surrounding the display region. And the terminal portion is arranged at one end of the four sides, and the circuit portion converts the primary power supply voltage supplied from the electronic device main body to the secondary power supply voltage according to the specifications of the panel. The DC / DC converter includes a built-in circuit mounted on the insulating substrate, and an external component connected to the built-in circuit via the terminal unit. The built-in circuit is provided with the terminal portion. Disposed between the terminal portion and the display area on one side which, turn into shortening the wiring length for connecting the inner built circuit and external attached components through the terminal portionThe in frontThe DC / DC converter includes a flying capacitor pumped to a primary power supply voltage with a pumping pulse, and the pumped capacitor.Primary power supply voltageA clamping circuit for extracting a secondary power supply voltage and a bypass capacitor for removing noise contained in the secondary power supply voltage, wherein the clamping circuit is included in the built-in circuit, while the flying capacitor The bypass capacitor is incorporated as an external component.
[0009]
  The second surface is used as a display component of an electronic device, operates in accordance with display data and a power supply voltage supplied from the main body side of the electronic device, and displays a display region and a peripheral circuit unit that drives the display region on an insulating substrate. And a flat cable in which a plurality of wirings connecting the panel to the main body side of the electronic device are arranged in a plane, and the circuit unit is supplied from the electronic device main body. Including a plurality of DC / DC converters that convert the primary power supply voltage to a secondary power supply voltage of a plurality of levels according to the specifications of the panel, and each DC / DC converter is mounted on the insulating substrate Including a built-in circuit and an external component mounted on the flat cable and connected to the built-in circuit via wiring, and a plurality of external components belonging to a plurality of DC / DC converters are connected to the flat cable. Properly laid such that the wiring does not cross over table, to characterized in that the single layer wiring of the flat cable Te TsuThe eachThe DC / DC converter includes a flying capacitor pumped to a primary power supply voltage by a pumping pulse, and the pumped capacitor.Primary power supply voltageA clamping circuit for extracting a secondary power supply voltage and a bypass capacitor for removing noise contained in the secondary power supply voltage, wherein the clamping circuit is included in the built-in circuit, while the flying capacitor And bypass condenserSaMounted on a flat cable as an external component.
[0011]
  According to the first aspect of the present invention, the built-in circuit portion of the DC / DC converter is laid out between the connection terminal and the display area on one side on the insulating substrate on which the connection terminal is arranged. As a result, the wiring length connecting the internal circuit portion of the DC / DC converter and the external component such as the flying capacitor via the connection terminal can be shortened to the limit. By shortening the wiring length, it is possible to suppress harmful output voltage drop, and at the same time, the conversion efficiency is improved.
  According to the second aspect of the present invention, the DC / DC converter includes a built-in circuit mounted on an insulating substrate constituting the panel, and an external component mounted on the flat cable and connected to the built-in circuit via wiring. It is divided into and. The external components belonging to a plurality of DC / DC converters have been properly laid out so that the wiring does not cross on the flat cable, and the flat cable has been successfully made into a single layer wiring. This can reduce the overall system cost.The
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of a display device according to the present invention. As shown in the figure, the display device 0 is integrated on an insulating substrate 1 made of glass or the like. A display region 2 is formed at the center of the insulating substrate 1, and peripheral circuit portions are also integrally formed so as to surround it. A connection terminal is formed on the upper side of the rectangular insulating substrate 1 and is connected to the electronic device main body side (set side) via a flexible printed cable (FPC) 11. The FPC 11 is a flat cable having a single layer structure in which a plurality of wirings are arranged in a plane.
[0013]
The display region 2 has a matrix configuration in which row-like gate lines G1 to Gm and column-like signal lines S1 to Sn are arranged to cross each other. Pixels are formed at the intersections of the gate lines G and the signal lines S. In this embodiment, each pixel includes a liquid crystal element LC, an auxiliary capacitor CS, and a thin film transistor TFT. The liquid crystal element LC includes a pixel electrode, a common electrode (COM) facing the pixel electrode, and a liquid crystal (electro-optical material) held between the pixel electrode and the common electrode (COM). The gate electrode of the TFT is connected to the gate line G, the source electrode is connected to the signal line S, and the drain electrode is connected to the pixel electrode of the liquid crystal element LC. The auxiliary capacitor CS is connected between the drain electrode of the TFT and the auxiliary capacitor line. The TFT is turned on by the selection pulse supplied from the gate line G, and the signal voltage supplied from the signal line S is written to the pixel electrode of the corresponding liquid crystal element LC. The auxiliary capacitor CS holds the signal voltage for one frame or one field.
[0014]
The liquid crystal element LC is generally AC driven. That is, the polarity of the signal voltage written to the liquid crystal element LC via the signal line S is periodically reversed. In accordance with this, it is necessary to periodically reverse the polarity of the common voltage VCOM applied to the common electrode COM of the liquid crystal element LC. Here, the liquid crystal element LC and the TFT that performs switching driving thereof have asymmetry with respect to polarity. For this reason, if the center level is matched between the pixel electrode side and the common electrode side, asymmetry with respect to the polarity appears, and image quality deterioration such as image sticking occurs. As a countermeasure, the common voltage is offset by a predetermined voltage with respect to the signal voltage to cancel the asymmetry related to the polarity. The auxiliary capacitor CS also needs to be AC-operated in accordance with the AC driving of the liquid crystal element LC. For this reason, it is necessary to apply a voltage whose polarity is inverted in the same predetermined cycle to the auxiliary capacitor line commonly connected to each auxiliary capacitor CS.
[0015]
Peripheral circuit portions are integrated and formed on the four sides of the upper, lower, left and right sides surrounding the display area 2 described above. In the case of the present embodiment, the peripheral circuit section includes an interface 8 including a vertical driver 3, a horizontal driver 4, a COM driver 5, a CS driver 6, a DC / DC converter 7, a DC / DC converter 7a, and a level shifter (L / S). , A timing generator 9, an analog voltage generator 10, and the like. However, the present invention is not limited to this configuration, and necessary circuits are appropriately added according to the specifications of the display device (system display) 0, while unnecessary circuits are deleted. For example, in some cases, a driver for generating a signal voltage level used for complete white display or complete black display separately from the signal voltage may be incorporated.
[0016]
The vertical driver 3 is connected to each of the gate lines G1 to Gm, and supplies a selection pulse line by line. The horizontal driver 4 is formed in a pair of upper and lower sides, is connected to both ends of each signal line S1 to Sn, and supplies a predetermined signal voltage from both sides simultaneously. This signal voltage corresponds to display data (image information) sent from the set side via the FPC 11.
[0017]
The common driver (COM driver) 5 applies a common voltage VCOM whose polarity is periodically inverted to a common electrode common to each liquid crystal element LC. The COM driver 5 is attached with an offset circuit and a start circuit (COM starter). The offset circuit adjusts the offset level of the common voltage generated by the common driver 5. The start circuit (COM starter) charges the offset circuit when the panel is started, and quickly starts application of the common voltage VCOM. The CS driver 6 applies a voltage whose polarity is periodically inverted to the auxiliary capacitor line common to the auxiliary capacitors CS.
[0018]
The DC / DC converter 7 converts the primary power supply voltage supplied from the electronic device main body via the FPC 11 into a secondary power supply voltage according to the specifications of the panel (display device 0). In particular, the DC / DC converter 7 is used for conversion of the positive power supply voltage VDD. On the other hand, the DC / DC converter 7a is used for conversion of the negative power supply voltage VSS.
[0019]
The interface 8 including L / S accepts control signals such as a clock signal, a synchronization signal, and an image signal supplied from the set side via the FPC 11. The level shifter L / S shifts the level of the control signal (external control signal) sent from the set side, and generates a control signal (internal control signal) that conforms to the circuit operation specifications inside the display device. In this specification, when it is necessary to distinguish between the external control signal and the internal control signal, the number (3) is added in the case of the external control signal after the symbol indicating the type of each control signal. The number (5) may be attached. The timing generator 9 processes a clock signal and a synchronization signal sent from the interface 8 including the L / S, and generates a clock signal necessary for timing control of each part of the circuit. The analog voltage generator 10 supplies a plurality of levels of analog voltages corresponding to gradations to the horizontal driver 4 in advance. The horizontal driver 4 writes in the liquid crystal element LC an analog signal voltage that is grayscaled according to image information sent from the main body side of the electronic device.
[0020]
FIG. 2 is a timing chart showing a control sequence on the set side with respect to the display device side, where (A) represents an on sequence and (B) represents an off sequence. However, it represents a normal case where there is no sequence control related to the standby mode (standby mode). A master clock MCK, a horizontal synchronization signal HSYNC, a vertical synchronization signal VSYNC, display data DATA, a reset signal RST, a display permission signal PCI, and a power supply voltage VDD are input according to a predetermined sequence from the set side to the display side. In the on sequence (A) in which the display side is raised from the set side, VDD first rises and then MCK, HSYNC, and VSYNC become active. After the time ton1 has elapsed, the reset signal RST switches from low to high, and the display circuit section is initialized. Thereafter, after the time ton2 has elapsed, DATA is switched from low to active, and the display permission signal PCI is switched from low to high. As a result, an image is displayed on the display area of the display.
[0021]
In the off sequence (B) in which the display is lowered from the set side, first, DATA is switched from active to low, and the display permission signal PCI is switched from high to low. After the time toff1 has elapsed, the reset signal RST switches from high to low to reset the internal state of the display circuit. After the time toff2 has elapsed, the supply of MCK, HSYNC, and VSYNC is cut off, and finally VDD is lowered. As a result, VDD becomes a ground potential or a floating potential.
[0022]
FIG. 3 is a timing chart showing an on sequence and an off sequence employing a standby mode (standby mode). For easy understanding, the same reference numerals are used for the portions corresponding to the normal on sequence and off sequence shown in FIG. The set side can be switched between a normal power consumption state and a low power consumption state. In accordance with this, it is necessary to switch the display side between the operation mode and the standby mode (standby mode), and for this reason, the set side inputs a standby signal STB to the display side.
[0023]
In the on sequence (A), first, the standby signal STB rises from low to high, and the display returns from the standby mode to the operation mode. MCK, HSYNC, and VSYNC become active at the rising edge of STB. However, VDD is always supplied regardless of STB. After the time ton1 has elapsed, RST changes from low to high, and the circuit state of the display is initialized. After time ton2 elapses, DATA becomes active and PCI switches to high, and an image is displayed in the display area.
[0024]
In the off sequence (B), first, DATA and PCI are inactive. After elapse of toff1, RST changes from high to low, and the internal circuit of the display is reset. After toff2, STB changes from high to low, and MCK, HSYNC, and VSYNC become inactive. When STB changes from high to low, the display side shifts from the operation mode to the standby mode. On the other hand, VDD is always maintained at the power supply voltage despite the transition to the standby mode.
[0025]
In the system adopting the standby mode as described above, the drive circuit system on the display side is made inactive according to the STB while VDD remains active. The signal STB used for standby mode control may be a control signal input independently from the set side as shown in the figure, but other external signals supplied from the set side are internally logically processed on the display side. Can also be generated. In the off sequence, the internal circuit of the display is logically reset by RST, and then STB falls.
[0026]
FIG. 4 is a circuit diagram showing a specific configuration example of the DC / DC converter 7 adapted to the standby mode. However, the present invention is not limited to this, and a DC / DC converter that does not support the standby mode can be used. As shown, the DC / DC converter 7 includes an AND element (AND) 701, a delay element (DELAY) 702, a multistage buffer 703, an external flying capacitor 704, clamping transistors 705 to 707, an output transistor 708, The circuit includes an internal capacitor 709, a level shifter (L / S) 710, an AND element 711, a buffer 712, an external bypass capacitor 720, a termination resistor 721, and the like. The DC / DC converter 7 includes a built-in circuit mounted on an insulating substrate and an external component connected to the built-in circuit via a connection terminal. In the illustrated example, the flying capacitor 704 and the bypass capacitor 720 are external components, and all the remaining circuit elements are built on the insulating substrate. The built-in circuit portion is composed of a TFT formed by the same process as the switching thin film transistor TFT formed in the display region.
[0027]
The DC / DC converter 7 converts the primary power supply voltage VDD1 supplied from the set side into a secondary power supply voltage VDD2 according to the specifications of the panel. Therefore, a clock signal for pumping (pumping pulse) is supplied to the multistage buffer 703 via the AND element 701 and the delay element 702 for phase adjustment. The primary side of the flying capacitor 704 is pumped to VDD1 by the pumping pulse through the multistage buffer 703. A clamping circuit composed of TFTs 705, 706, and 707 is connected to the secondary side of the flying capacitor 704, and clamps the output voltage of the flying capacitor 704 to VDD2. In this embodiment, clamping is performed up to VDD2 = 2 × VDD1. The output transistor 708 takes out the crest portion of the rectangular wave clamped to VDD2 and outputs a DC secondary power supply voltage VDD2. At that time, the external bypass capacitor (decoupling capacitor) 720 is smoothed by removing ripple noise contained in the secondary power supply voltage VDD2. The clock signal that has passed through the delay element 702 is applied to the drains of the clamping transistors 705 and 706 via the internal capacitor 709 and to the gate of the output transistor 708. The clock signal that has passed through the AND element 701 is shaped into a clamping pulse CLP by the level shifter 710, the AND element 711, and the buffer 712, and then applied to the gates of the transistors 705 and 706. If necessary, a control signal is input via an AND element 711 to reset the DC / DC converter 7. In this manner, the DC / DC converter 7 includes a flying capacitor 704 that is pumped to the primary power supply voltage VDD1 by a pumping pulse, and a clamp circuit that clamps the pumped flying capacitor 704 to extract the secondary power supply voltage VDD2. 705-708) and a bypass capacitor 720 for removing noise included in the secondary power supply voltage VDD.
[0028]
Since the DC / DC converter 7 corresponds to the standby mode, the AND element 701 is used as a standby control means and receives the STB signal. When the STB signal is switched from high to low to instruct the transition to the standby mode, the AND element 701 is closed and the input of the clock signal (pumping pulse) is cut off. The pumping pulse is stopped and charging / discharging to the flying capacitor 704 is stopped, thereby reducing power consumption. When the standby mode is entered, the output terminal of the DC / DC converter 7 is fixed to a predetermined potential such as VDD1 or GND by the termination resistor 721. As a result, the power supply line in the system display is prevented from floating. In the illustrated example, the termination resistor 721 is built-in, but may be an external component.
[0029]
FIG. 5 schematically shows a problem when the DC / DC converter is mounted on the display device. When the DC / DC converter 7 is integrally formed on the insulating substrate 1 constituting the display device, the flying capacitor 704 and the bypass capacitor 720 are very large in element area, and are often external components. At this time, if the distance from the DC / DC converter 7 to the flying capacitor 704 is long, the wiring resistors r1 and r2 in the display device cause a decrease in the time constant of charging and discharging to the flying capacitor 704, resulting in deterioration in conversion efficiency. Connected. Further, if the distance from the DC / DC converter 7 to the bypass capacitor 720 is long, a drop ΔV1 + ΔV2 in the output voltage of the DC / DC converter 7 is caused by the wiring resistances r3 and r4 in the display device, which also leads to a decrease in conversion efficiency. .
[0030]
FIG. 6 schematically shows a layout devised to solve the problem shown in FIG. The display device is used as a display component of an electronic device, operates in accordance with display data and a power supply voltage supplied from a main body side (not shown) of the electronic device, and a display area 2 and peripheral circuits for driving the display region 2 And a terminal portion 12 that connects this portion to the main body side of the electronic device. The insulating substrate 1 is provided with a display area 2 in the center and circuit portions on the four sides surrounding it. The terminal portion 12 is disposed at the end of one of the four sides (the lower side in this embodiment). The circuit portion surrounding the display area 2 includes a DC / DC converter 7 that converts a primary power supply voltage supplied from the electronic device main body to a secondary power supply voltage according to the specifications of the panel. The DC / DC converter 7 includes a built-in circuit mounted on the insulating substrate 1 and an external component connected to the built-in circuit via the terminal portion 12. In this embodiment, the DC / DC converter 7 includes a flying capacitor 704 that is pumped to a primary power supply voltage by a pumping pulse, a clamp circuit that clamps the pumped flying capacitor 704 and extracts a secondary power supply voltage, And a bypass capacitor 720 for removing noise included in the secondary power supply voltage. While the clamp circuit is included in the built-in circuit, the flying capacitor 704 and the bypass capacitor 720 are incorporated as external components. As a feature of the present embodiment, the built-in circuit portion of the DC / DC converter 7 is disposed between the terminal portion 12 and the display area 2 on the lower side where the terminal portion 12 is disposed, and the built-in circuit is interposed via the terminal portion 12. And the length of the wiring 13 connecting the external parts is shortened.
[0031]
By adopting the layout shown in FIG. 6, the distance from the input terminal to the DC / DC converter 7 can be minimized. Since the influence of the wiring allocated to other control signals of the display device is small, there is a merit that the wiring width for the external component can be increased. The electrical resistance of the wiring 13 connected to the electrodes on both sides of the flying capacitor 704 and the wiring resistance from the output terminal of the built-in DC / DC converter 7 to the bypass capacitor 720 can be minimized, and the conversion efficiency of the DC / DC converter 7 can be improved. Connected.
[0032]
FIG. 7 shows a structure when a flying capacitor 704 and a bypass capacitor 720 are mounted on the flexible cable 11. The input terminal 12 on the display device side is connected to the output terminal on the main body side via a flexible cable (flat cable) 11. The connection terminals 1 and 2 for the flying capacitor 704 are disposed adjacent to the GND terminal. Further, two bypass capacitor connection terminals 2 are arranged next to it. This is an input terminal and an output terminal for the bypass capacitor 720 when viewed from the DC / DC converter side. The other terminal of the bypass capacitor 720 is connected to the GND terminal on the flexible cable 11. With such a layout, wiring does not cross on the flexible cable 11 and a single layer can be realized. The flexible cable 11 can be manufactured by a simple process, and the cost of parts of the flexible cable 11 can be reduced.
[0033]
FIG. 8 shows a layout when a flying capacitor 704 and a bypass capacitor 720 corresponding to a plurality of DC / DC converters (three in the illustrated example) are mounted on the flexible cable 11. Corresponding to the first DC / DC converter, the GND terminal, the flying capacitor connection terminals 1 and 2 and the bypass capacitor connection terminals 2 and 2 are arranged in the order of a, b and c as shown in the figure. The GND terminal is common to all DC / DC converters. The layout of b and c is repeated for the second DC / DC converter. Further, the layout of b and c is repeated for the third DC / DC converter. If the third DC / DC converter incorporates a flying capacitor as shown in the figure, the layout of b is omitted. In this way, after the ab-c layout for the first DC / DC converter, the b-c arrangement is repeated for the second and subsequent DC / DC converters, so that the wiring on the flexible cable 11 can be arranged. A single layer can be realized without crossing.
[0034]
FIG. 9 is a circuit diagram showing a DC / DC converter according to another embodiment of the present invention. Basically, it is the same as the previous DC / DC converter 7 shown in FIG. 4, and corresponding parts are denoted by corresponding reference numerals for easy understanding. The difference is that the DC / DC converter shown in FIG. 4 has the flying capacitor 704 externally attached thereto, whereas the DC / DC converter shown in FIG. 9 has the flying capacitor 704 built-in. By incorporating the flying capacitor 704 in the display device, the number of parts outside the display device can be reduced. Usually, the flying capacitor 704 requires sufficient current capability for the DC / DC converter to drive the circuit portion in the display device, and the flying capacitor 704 is also required to have a large capacity. However, if the capacitance is large, the element area also increases, which hinders incorporation. The current capability of the DC / DC converter is determined by the CVf value. C is the capacitance of the flying capacitor, V is the peak value of the pumping pulse, and f is the frequency of the pumping pulse. By increasing the pumping frequency, the element area of the flying capacitor can be reduced correspondingly, and the incorporation of the flying capacitor can be realized. However, if the pumping frequency is too fast, current loss due to the transition of the inverter constituting the multi-stage buffer 703 included in the DC / DC converter increases, and conversely, conversion efficiency decreases.
[0035]
As a solution to this problem, the present invention employs the configuration shown in FIG. First, the minimum frequency that can incorporate a flying capacitor is calculated as a premise. The pumping pulse must be set higher than this minimum frequency. However, it must be lower than the maximum external signal frequency. Under such a premise, first, an external signal input (MCK, HCK, etc.) is supplied to the timing generator 9. The timing generator 9 divides the external signal to generate a pumping pulse having a desired frequency. The DC / DC converter 7 uses this pumping pulse to pump the flying capacitor 704 built in the display device. As described above, in this embodiment, the timing generator 9 is used to divide the frequency of the fast frequency clock so as to be suitable for improving the efficiency of the DC / DC converter.
[0036]
FIG. 11 is a timing chart for explaining the operation of the system shown in FIG. As shown in the figure, a high frequency signal input from an external main body is frequency-divided by a timing generator in the display device to lower the frequency and used as a pumping pulse. The duty ratio of the input pulse may be arbitrary, and this is divided by a timing generator in the display device to a desired frequency required for the DC / DC converter and converted into a pumping pulse having an appropriate frequency and duty ratio. By inputting this to the DC / DC converter, it is not necessary to input pumping pulses individually from the external set side. Therefore, the number of input terminals of the display device can be reduced, which contributes to downsizing of the system. Moreover, the number of parts can be reduced by incorporating the flying capacitor in the display device.
[0037]
【The invention's effect】
As described above, according to the first aspect of the present invention, further improvement in conversion efficiency can be achieved by improving the layout of the DC / DC converter on the insulating substrate that constitutes the display device. Low power consumption of the device can be realized. In addition, according to the second aspect of the present invention, by optimizing the input terminal arrangement, it is possible to eliminate the cross wiring of the flat cable, making it possible to make the flat cable by a simple process, and realizing a reduction in component costs. it can. According to the third aspect of the present invention, the pumping pulse input to the DC / DC converter is generated by the timing generator in the display device. As a result, the number of input terminals of the display device can be reduced, which leads to downsizing of the system. Further, by incorporating the flying capacitor in the display device, the number of parts can be reduced.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overall configuration of a display device according to the present invention.
FIG. 2 is a timing chart showing an on sequence and an off sequence of the display device.
FIG. 3 is a timing chart showing an on sequence and an off sequence of a display device adopting a standby mode.
4 is a circuit diagram showing an embodiment of a DC / DC converter incorporated in the display device shown in FIG. 1. FIG.
FIG. 5 is a schematic diagram showing a problem of a built-in DC / DC converter.
FIG. 6 is a schematic view showing a display device according to the first embodiment of the present invention.
FIG. 7 is a schematic diagram showing a layout of components of a DC / DC converter.
FIG. 8 is a schematic diagram showing a DC / DC converter as a main part of a display device according to a second embodiment of the present invention.
FIG. 9 is a circuit diagram showing a DC / DC converter incorporated in a display device according to a third embodiment of the present invention.
10 is a schematic diagram showing a generation process of pumping pulses supplied to the DC / DC converter shown in FIG.
11 is a timing chart showing a generation process of pumping pulses supplied to the DC / DC converter shown in FIG. 9;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 0 ... Display apparatus, 1 ... Insulating substrate, 2 ... Display area, 7 ... DC / DC converter, 9 ... Timing generator, 11 ... Flat cable, 12 ... Input terminal 704 ... Flying capacitor, 720 ... Bypass capacitor

Claims (2)

Used as a display component for electronic devices, operates in accordance with display data and power supply voltage supplied from the main body side of the electronic device, and connects the display area and peripheral circuit units that drive the display area to the main body side of the electronic device. Do a terminal portion from integrally-formed panel on an insulating substrate which Ri,
In the insulating substrate, the display area is arranged in the center, the circuit part is arranged on four sides surrounding the display area, and the terminal part is arranged on one end of the four sides,
The circuit unit includes a DC / DC converter that converts a primary power supply voltage supplied from the electronic device main body into a secondary power supply voltage according to the specifications of the panel.
The DC / DC converter includes a built-in circuit mounted on the insulating substrate, and an external component connected to the built-in circuit via the terminal unit,
The DC / DC converter includes a flying capacitor that is pumped to a primary power supply voltage by a pumping pulse, a clamp circuit that clamps the pumped primary power supply voltage and extracts a secondary power supply voltage, and the secondary power supply voltage Including a bypass capacitor to remove noise contained in the power supply voltage,
While the clamp circuit is included in the built-in circuit, the flying capacitor and the bypass capacitor are incorporated as external components,
The built-in circuit is disposed between the terminal portion and the display region on one side where the terminal portion is disposed, and the flying capacitor and the bypass capacitor which are the built-in circuit and the external component through the terminal portion Viewing apparatus that turn into shorter wire length connecting. Used as a display component of electronic equipment, operates according to display data and power supply voltage supplied from the main body side of the electronic equipment, and integrally forms a display area and a peripheral circuit section for driving the display area on an insulating substrate consists was a panel, a flat cable in which a plurality of wires arranged in a plane which connects it to the main body of the electronic device,
The circuit unit includes a plurality of DC / DC converters that convert a primary power supply voltage supplied from the electronic device main body into a plurality of levels of secondary power supply voltages according to the specifications of the panel.
Each DC / DC converter includes a built-in circuit mounted on the insulating substrate and an external component mounted on the flat cable and connected to the built-in circuit via a wiring.
Each DC / DC converter includes a flying capacitor that is pumped to a primary power supply voltage by a pumping pulse, a clamping circuit that clamps the pumped primary power supply voltage to extract a secondary power supply voltage, Including a bypass capacitor to remove noise contained in the power supply voltage,
While the clamp circuit is included in the built-in circuit, the flying capacitor and the bypass capacitor are mounted on a flat cable as external components,
A plurality of flying capacitor and the bypass capacitor belonging to a plurality of DC / DC converters laid out appropriately such that no cross wires on the flat cable, Tsu Viewing device flat cable that turn into single-layer wiring Te.

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