JP2005316133A - Display device and its driving circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device with which the variations of impedances arising between individual current routes can be suppressed in driving the display device with fewer switching elements and desired images can be obtained by making display characteristics uniform. <P>SOLUTION: The display device comprises a front substrate 1f and back substrate 1b constituting a panel 2, a plurality of X electrodes 3 extended in a longitudinal direction (horizontal side direction) of the front substrate 1f, a plurality of Y electrodes 4 arranged alternately with the X electrodes 3, and at least one switching element 6x connected to the plurality of the X electrodes 3 to supply an electric current to the X electrodes 3, and at least one switching element 6y connected to the plurality of the Y electrodes 4 to supply the electric current to the Y electrodes 4. The position of the switching element 6x in the direction (vertical side direction) of the front substrate 1f is different from the position of the switching element 6y in the short side direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a display device and a drive circuit therefor, and particularly to a display device driven by fewer switching elements and a drive circuit therefor.

  In recent years, plasma display panel devices (hereinafter also referred to as PDPs) as large-sized thin displays have been widely used not only for business purposes but also for consumer use. Further development is necessary to make PDP more popular. One of the major targets of the development is circuit cost reduction and capacity reduction.

  The PDP has a structure in which two glass substrates are bonded to each other and a discharge gas is sealed between them. The glass substrate in which the discharge gas is sealed is called a panel. A drive circuit including a power element is mounted on the back surface of the panel. A current is passed through the panel by the power element, so that the panel is turned on and a desired image is displayed.

  In addition to the panel, the PDP has a large proportion of drive circuits that can apply a high voltage of 300 V or more at a maximum and flow a current of 200 A instantaneously. Further, this drive circuit occupies a specific gravity equivalent to that of the panel in terms of actual cost.

  The drive circuit mounted on the PDP is composed of many circuit parts, but the part that requires the most current capacity is the part called the sustain circuit. In addition, a portion called a recovery circuit also requires a large current capacity.

  The PDP panel is provided with an X electrode and a Y electrode in parallel, and when a current is applied to these electrodes from the sustain circuit, a discharge is generated between the electrodes. In the surface discharge AC type PDP, since the electrode is covered with a dielectric, a capacitive load is formed between the X electrode and the Y electrode. Therefore, the sustain circuit is connected to the switching element of the upper arm for raising the voltage necessary for driving and the switching element of the lower arm for reducing the potential to zero, and a total of two pairs of left and right half bridges are configured. become. In an actual PDP, various switching elements and circuits are further mounted so that a plurality of voltages and complex waveforms can be applied for display operation.

  When driving the PDP, charging / discharging of the capacitive load occurs, and at this time, a very large current flows, which greatly increases the loss of the switching element of the sustain circuit. In order to avoid this and to effectively use the charge stored in the capacitive load, a recovery circuit is provided. The recovery circuit temporarily transfers the charge stored in the capacitive load to the capacitor in the recovery circuit, effectively using power, reducing the current flowing through the switching element of the sustain circuit, and greatly reducing loss. Has been reduced.

  The maintenance circuit and the recovery circuit are provided with a plurality of switching elements. For these switching elements, field effect transistors (hereinafter also referred to as FETs) are usually used. This is because the PDP is driven at a frequency of 100 kHz or more and with a voltage rise speed of about 100 ns, etc., so that an FET capable of high-speed switching has to be employed as a switching element. However, since a large current is required to drive the PDP, the current capacity of one FET is insufficient to drive the entire PDP. In order to suppress the loss of the FET to a realistic value, a plurality of FETs are usually provided in parallel.

  As a switching element used for driving a PDP, an FET has a very advantageous feature in terms of high-speed switching. However, since a very large current is required for driving the PDP as described above, a sufficient current capacity and ON resistance cannot be obtained with the FET, and a plurality of FETs must be arranged in parallel in the PDP drive circuit. was there. The need for multiple FETs is disadvantageous in terms of circuit implementation. For example, the cost of the FET itself and the cost of mounting work may increase, and the area of the circuit board may increase. Therefore, attempts have been made to drive the PDP with a smaller number of switching elements using switching elements other than FETs.

  For example, Patent Document 1 proposes to use an insulated gate bipolar transistor (hereinafter also referred to as IGBT) as a PDP drive circuit. The IGBT has advantageous features such as a large current capacity, a low ON voltage (ON resistance), and a small change in the ON voltage even when the element temperature is high, as compared with the FET. However, it has not been adopted in the PDP drive circuit due to the disadvantage of slow switching speed.

  Specifically, a conventional IGBT is usually used at a frequency of not more than kHz from a commercial frequency, and is used for a PDP drive circuit that performs switching of 100 kHz or more and requires a sharp voltage rise. It was unsuitable. However, with the recent development of IGBTs, IGBTs capable of high-speed switching have been obtained. Thus, if an IGBT capable of high-speed switching can be employed in a PDP drive circuit, a switching portion in which a large number of FETs are used in parallel can be substituted with one IGBT. If the PDP can be driven by one IGBT, the number of switching elements can be greatly reduced, the area of the circuit board can be reduced, the mounting work can be facilitated, and the cost can be reduced. Note that the X electrode and the Y electrode require switching elements for the sustain circuit and the recovery circuit, respectively, and if one IGBT is used for each upper and lower arm switching element, the PDP as a whole requires eight IGBTs. Become.

JP 2000-330514 A

  A plurality of X electrodes and Y electrodes are formed in parallel on the panel. The X electrode and the Y electrode occupy almost one side of the panel, have a very long distance, and a plurality of X electrodes and Y electrodes are formed, so the width is narrow. For this reason, the inductances of the X electrode and the Y electrode are increased. However, since the return current flows through the metal back plate provided to fix the panel, the total inductance of the panel is reduced. Therefore, the inductance in each current path provided in the PDP is determined by the inductance of the wiring from the switching element of the drive circuit to the X electrode or the Y electrode.

  Further, the X electrode and the Y electrode provided in the PDP have almost the same shape, and the inductance does not differ depending on the individual current paths. However, in each current path, the length of the wiring from the switching element of the drive circuit to the X electrode or the Y electrode varies depending on the position of the switching element, so that the inductance varies depending on the individual wiring.

  When FETs are used as switching elements in the drive circuit and many are connected in parallel, the number of X or Y electrodes connected to one FET is reduced, and only the adjacent X or Y electrodes provided with the FET are connected. Therefore, there was not much difference in individual wiring distance from the FET to the X electrode or the Y electrode.

  However, when a plurality of switching elements are replaced with one IGBT as shown in Patent Document 1, all the X electrodes or Y electrodes of the panel and the IGBT must be connected. The length varies greatly between the wiring leading to the Y electrode and the wiring leading to the X electrode or Y electrode at the most distant position. When the length of the wiring is different in each current path, the inductance of the current path varies.

  For example, when the IGBT is provided at the center of one side of the panel, the current path passing through the center of the panel has a small inductance, but the inductance of the current path passing through the upper end (or the lower end) is very large. As a result, when the panel is turned on, the discharge characteristics greatly change between the upper end or lower end of the panel and the central portion of the panel, and the luminance differs between the upper end or lower end and the central portion. In addition, if the discharge characteristics are greatly different between the upper end or lower end of the panel and the center of the panel, there may be an influence such as failure to obtain a voltage condition for stably lighting the entire panel.

  Such variation in the inductance of the current path is greater when one IGBT is used as the switching element than when a plurality of FETs are used as the switching element. This is because, when a plurality of FETs are used for the switching element, the FETs can be distributed and arranged so as to suppress variations in wiring from the FET to the X electrode or the Y electrode. This is because all X electrodes or Y electrodes are concentrated on one IGBT.

  Therefore, the present invention provides a display device capable of obtaining a desired image by suppressing variation in impedance generated between individual current paths and uniformizing display characteristics when the display device is driven with fewer switching elements. The purpose is that.

  The solving means according to the present invention includes a substrate constituting the panel, a plurality of first electrodes extending in the lateral direction of the substrate on the substrate, and extending in the lateral direction on the substrate. A plurality of second electrodes arranged alternately with one electrode, at least one first switching element connected to the plurality of first electrodes and supplying a current to the first electrode, and a plurality of second electrodes And at least one second switching element that supplies a current to the second electrode, and the position of the first switching element in the longitudinal direction of the substrate is the second switching element in the longitudinal direction. It is different from the position of the element.

  The display device according to the present invention includes a substrate constituting the panel, a plurality of first electrodes extending in the lateral direction of the substrate on the substrate, and extending in the lateral direction on the substrate. A plurality of second electrodes arranged alternately with the first electrode, at least one first switching element connected to the plurality of first electrodes and supplying a current to the first electrode, and a plurality of second electrodes At least one second switching element that is connected to the second electrode and supplies a current to the second electrode, and the position of the first switching element in the longitudinal direction of the substrate is the second position in the longitudinal direction. Since the position is different from the position of the switching element, there is an effect that it is possible to obtain a desired image by suppressing variation in impedance generated between individual current paths and uniformizing display characteristics.

(Embodiment 1)
FIG. 1 is a schematic diagram showing a display device according to the present embodiment. In this embodiment, the display device will be described below as an AC type PDP (hereinafter simply referred to as a PDP). The PDP shown in FIG. 1 forms a panel 2 by bonding two glass plates called a front substrate 1f and a back substrate 1b. An X electrode 3 and a Y electrode 4 called sustain electrodes are formed on the front substrate 1f. A plurality of X electrodes 3 are extended in the longitudinal direction (lateral side direction) of the panel 2, and the X electrodes 3 are arranged so as to be parallel to each other. A plurality of Y electrodes 4 are also extended in parallel with the longitudinal direction (lateral direction) of the panel 2 and are alternately arranged with the X electrodes 3.

  The PDP generates a discharge between the X electrode 3 and the Y electrode 4 by applying a predetermined voltage to the X electrode 3 and the Y electrode 4, and emits pixels to display an image. These X electrode 3 and Y electrode 4 are pulled out from the longitudinal direction of the panel 2 as shown in FIG. 1 and connected to a drive circuit. The X electrode 3 is drawn from the left side of FIG. 1, and the Y electrode 4 is drawn from the right side of FIG. In the PDP, a writing electrode or the like is formed on the back substrate 1b, but is omitted in FIG.

  FIG. 2 is a circuit diagram showing a drive circuit according to the present embodiment. The PDP covers the X electrode 3 and the Y electrode 4 by forming a dielectric. Therefore, there is a capacitive load between the X electrode 3 and the Y electrode 4. In FIG. 2, this capacitive load is schematically shown as a capacitor 5. In order to drive the panel 2, it is necessary to apply a necessary voltage to the X electrode 3 and the Y electrode 4 at both ends of the capacitor 5. In the circuit shown in FIG. 2, the left side represents the X electrode 3 side, and the right side represents the Y electrode 4 side.

  On the X electrode 3 side of the capacitor 5, an upper arm switching element 6 x for raising the voltage Vs necessary for driving and a lower arm switching element 7 x for reducing the potential to zero are connected to form a half bridge. doing. This portion is called a sustain circuit on the X electrode 3 side that constitutes a part of the drive circuit.

  On the Y electrode 4 side of the capacitor 5, a switching element 6y of the upper arm for raising the voltage Vs necessary for driving and a switching element 7y of the lower arm for reducing the potential to zero are connected to form a half bridge. doing. This portion is called a sustain circuit on the Y electrode 4 side that constitutes a part of the drive circuit.

  In FIG. 2, one of the switching elements 6 x and 6 y is connected to the potential Vs, and the other is connected to the capacitor 5. Further, one of the switching elements 7 x and 7 y is connected to the potential zero, and the other is connected to the capacitor 5. In the sustain circuit provided in the actual PDP, various switching elements and circuits are further mounted so that a plurality of voltages and complicated waveforms can be applied for the display operation.

  As described above, the panel 2 of the PDP is a capacitive load, and when this is driven by an inverter, a very large current flows when charging / discharging the capacitor 5 and the switching elements 6x, 6y of the sustain circuit are flown. , 7x, 7y loss becomes very large. Therefore, in order to effectively use the electric charge stored in the capacitor 5 of the panel 2, a circuit called a recovery circuit is provided. This recovery circuit is also provided on the X electrode 3 side and the Y electrode 4 side. The recovery circuit on the X electrode 3 side includes a resonant reactor 8x, an upper arm switching element 9x, a lower arm switching element 10x, and a capacitor 11x. The recovery circuit on the Y electrode 4 side includes a resonant reactor 8y, an upper arm switching element 9y, a lower arm switching element 10y, and a capacitor 11y.

  As shown in FIG. 2, one of switching elements 9x, 10x, 9y, and 10y is connected to each sustain circuit via resonant reactors 8x and 8y, and the other is connected to capacitors 11x and 11y, respectively. With these recovery circuits, the charge stored in the capacitor 5 of the panel 2 can be temporarily transferred to the capacitors 11x and 11y. As a result, the drive circuit can effectively use power, reduce the current flowing through the switching elements 6x, 6y, 7x, and 7y of the sustain circuit, and greatly reduce the loss.

  As shown in FIG. 2, the sustain circuit and the recovery circuit included in the drive circuit include four switching elements 6x, 7x, 9x, 10x on the X electrode 3 and four switching elements 6y, 7y, 9y, 10y (8 places in total) are required. These switching elements 6x, 7x, 9x, 10x, 6y, 7y, 9y, and 10y are portions that require the largest current capacity in the PDP drive circuit.

  In the present embodiment, the switching elements 6x, 7x, 9x, 10x, 6y, 7y, 9y, and 10y used in the maintenance circuit and the recovery circuit are IGBTs. As described in the background art, when an FET having a small current capacity is used, the current capacity necessary for driving cannot be satisfied unless, for example, four FETs are arranged in parallel with the switching element 6x of the X electrode 3. Similarly, for example, four FETs must be arranged in parallel with the switching elements 7x, 9x, 10x of the X electrode 3 and the switching elements 6y, 7y, 9y, 10y of the Y electrode 4, respectively. Therefore, when FETs are used for the switching elements 6x, 7x, 9x, 10x, 6y, 7y, 9y, and 10y, a total of 32 FETs are required. However, by using IGBTs for the switching elements 6x, 7x, 9x, 10x, 6y, 7y, 9y, and 10y as in the present embodiment, the number of necessary elements can be greatly reduced.

  Next, the positions where the switching elements included in the driving circuit of the PDP according to the present embodiment are provided will be described below. In the following description, the switching elements (the switching elements 6x and 6y shown in FIG. 2) of the upper arm of the sustain circuit included in the drive circuit will be described. In addition, the following description can be similarly applied to other switching elements (switching elements 7x, 7y, 9x, 9y, 10x, and 10y shown in FIG. 2).

  FIG. 3 shows a plan view of the PDP according to the present embodiment. In the PDP shown in FIG. 3, a switching element 6x connected by a plurality of X electrodes 3 and a plurality of wirings 12 is provided in the upper left part of the panel 2 shown in the drawing (hereinafter also simply referred to as the upper left part of the panel 2). ing. The switching element 6x is a switching element of the upper arm of the sustain circuit on the X electrode 3 side. In the PDP shown in FIG. 3, a switching element 6y connected to a plurality of Y electrodes 4 and a plurality of wirings 12 is provided at the lower right portion of the panel 2 shown in the drawing (hereinafter also simply referred to as the lower right portion of the panel 2). Is provided. The switching element 6y is a switching element of the upper arm of the sustain circuit on the Y electrode 4 side.

  More specifically, the position of the switching element 6x in the short direction (longitudinal direction) of the panel 2 is different from the position of the switching element 6y in the short direction (longitudinal direction) of the panel 2. In the PDP shown in FIG. 3, the distance from one lateral side (upper side) of the panel 2 to the switching element 6x and the other lateral side (lower side) opposite to the one lateral side of the panel 2 to the switching element 6y. The position is adjusted to be equal to the distance. In the PDP shown in FIG. 3, the distance from the switching element 6x to the left side is also equal to the distance from the switching element 6y to the right side.

  Next, FIG. 4 shows a plan view of a general PDP with respect to the PDP according to the present embodiment shown in FIG. In the PDP shown in FIG. 4, the switching element 6x connected to the X electrode 3 is provided at the left center portion of the panel 2 shown in the drawing, and the switching element 6y connected to the Y electrode 4 is connected to the panel 2 shown in the drawing. It is provided in the right center. That is, in a general PDP, the position of the switching element 6x in the short direction of the panel 2 is equal to the position of the switching element 6y in the short direction of the panel 2.

  Next, the impedance of each current path is compared between the PDP shown in FIG. 3 and the PDP shown in FIG. Before that, first, the current path of the PDP will be described. FIG. 5 shows a cross-sectional view of the PDP. In the PDP shown in FIG. 5, a panel 2 composed of a front substrate 1 f and a back substrate 1 b is fixedly supported on a back plate 13. The back plate 13 is provided with a drive circuit 14 connected to the X electrode 3 on the left side in the figure and a drive circuit 15 connected to the Y electrode 4 on the right side in the figure. Here, the drive circuit 14 includes a circuit board 16, a switching element 6x, and a capacitor 11x, and the drive circuit 15 includes a circuit board 16 and a switching element 6y. Note that the capacitor 11 y may be provided in the drive circuit 15.

  In the PDP shown in FIG. 5, the switching element 6 x is connected to the X electrode 3, and the switching element 6 y is connected to the Y electrode 4 via the wiring 12. The circuit board 16 is also connected to the back plate 13. In FIG. 5, the description of switching elements other than the switching elements 6x and 6y is omitted. With the configuration described above, the current path of the PDP is such that the drive circuit 14 (switching element 6x) -X electrode 3-capacitance 5-Y electrode 4-drive circuit 15 (switching element 6y)- This is a path of the back plate 13 and the drive circuit 14.

  As described in the background art, the total inductance of the portion of the X electrode 3 -capacitance 5-Y electrode 4 inside the panel 2 and the portion of the back plate 13 in the current path of the PDP is small. Since the inductances of the path portions are substantially uniform, these path portions do not affect the difference in inductance between the current paths. On the other hand, the portion of the wiring 12 connecting the drive circuit 14 (switching element 6x) -X electrode 3 and the drive circuit 15 (switching element 6y) -Y electrode 4 is connected to the switching elements 6x, 6y and the X electrodes 3, Y electrodes 4. The length of each wiring 12 differs depending on the positional relationship. For this reason, the portion of the wiring 12 affects the difference in inductance between the current paths.

  First, looking at the current path of the general PDP shown in FIG. 4, the switching elements 6 x and 6 y are arranged on the left and right of the center portion of the panel 2. Therefore, the wiring 12 from the switching elements 6x and 6y to the X electrode 3 and the Y electrode 4 at the center of the panel 2 is shortened. Therefore, the current path located at the center of the panel 2 has a small inductance (arrow a in FIG. 4).

  On the other hand, the current path located at the upper part of the panel 2 has a larger inductance because the wiring 12 from the switching elements 6x and 6y to the X electrode 3 and the Y electrode 4 at the upper part of the panel 2 becomes longer (arrow b in FIG. 4). Similarly, the inductance of the current path located at the lower part of the panel 2 also increases. That is, in the general PDP shown in FIG. 4, since the switching elements 6 are arranged on the left and right of the center portion of the panel 2, the inductance of the current path increases from the center portion of the panel 2 to the upper portion or the lower portion. As a result, the impedances of the individual current paths vary greatly within the panel 2. If the impedance of the current path varies, the discharge characteristics of the PDP will not be uniform in the plane, resulting in uneven brightness and reduced display quality.

  Therefore, in the PDP according to the present embodiment, the variation in the impedance of the current path is suppressed by changing the positions of the switching elements 6x and 6y. The PDP shown in FIG. 3 is different from the PDP shown in FIG. 4 in the positions of the switching elements 6x and 6y. Specifically, in the PDP shown in FIG. 3, the switching element 6 x is provided in the upper left part of the panel 2, and the switching element 6 y is provided in the lower right part of the panel 2.

  By providing the switching elements 6x and 6y at positions as shown in FIG. 3, the length of the wiring 12 from the switching element 6x to the X electrode 3 is about half of the left side in the current path passing through the center in the figure. The length of the wiring 12 from the switching element 6y to the Y electrode 4 is also about half of the right side (arrow c shown in FIG. 3). On the other hand, in the current path passing through the upper side in the figure, the length of the wiring 12 from the switching element 6x to the X electrode 3 is the shortest, but the length of the wiring 12 from the switching element 6y to the Y electrode 4 is the right side. The lengths are almost the same (arrow d shown in FIG. 3).

  Therefore, in the PDP shown in FIG. 3, the wiring 12 from the switching element 6 x to the X electrode 3 and the wiring 12 from the switching element 6 y to the Y electrode 4 in the current path passing through the center part and the current path passing through the upper side part. The total length is approximately the same as the length of one side of the left side or the right side. The other current paths have the same length. Therefore, the impedance difference between the individual current paths is reduced, and the variation in the impedance of the current paths is reduced. When the variation in the impedance of the current path is reduced, the discharge characteristics of the PDP become uniform in the plane, and an image with high display quality that does not cause luminance unevenness can be obtained.

  In the PDP shown in FIG. 4, the lengths of the left wiring 12 and the right wiring 12 are always the same. However, in the PDP shown in FIG. 3, when the left wiring 12 becomes longer, the right wiring 12 becomes shorter, and conversely, when the left wiring 12 becomes shorter, the right wiring 12 becomes longer. For this reason, the PDP shown in FIG. 3 is configured such that the sum of the left wiring 12 and the right wiring 12 is uniform in each current path, thereby reducing variations in impedance of the current paths.

  In order to minimize the variation in the impedance of the current path, it is necessary to make the distance from the upper side to the switching element 6x and the distance from the lower side to the switching element 6y in FIG. become. That is, by arranging the switching element 6x and the switching element 6y on the diagonal of the panel 2 as in the PDP shown in FIG. 3, the variation in impedance can be minimized.

  The switching elements 6x and 6y are IGBT semiconductor elements. Even though it is a semiconductor element, it has a finite size, and there are problems such as the arrangement of the circuit board 16, the wiring around the semiconductor element, the mounting form, and the structure of the PDP casing. Since it cannot arrange | position so that a lower side may be touched, it is desirable to arrange | position in the realistic position near the panel 2 upper end or lower end.

  As described above, although it is the distance from the upper side or the lower side of the panel 2 to the switching elements 6x and 6y, it is desirable to arrange them as close as possible, but there is a possibility that problems other than the above may occur. As one of them, for example, the switching element 6x connected to the X electrode 3 has a small distance to the upper side of the panel 2, but conversely, a distance to the lower side of the panel 2 is increased. In the vicinity of the lower side of the panel 2, the wiring 12 needs to be connected to the X electrode 3 at a steep angle, and it may be necessary to consider the influence of the inductance of this connection portion.

  Therefore, it is conceivable to perform a numerical evaluation of inductance by electromagnetic field analysis to confirm the distribution of inductance of the PDP. As a specific example, the switching elements 6x and 6y such as the PDP shown in FIG. 4 are arranged at the center of the left and right sides, and the switching elements 6x and 6y like the PDP shown in FIG. In the case of arranging them at the diagonals, an electromagnetic field analysis is performed to calculate how the inductance distribution will be. FIG. 6A shows the case of the PDP shown in FIG. 4, and FIG. 6B shows the case of the PDP shown in FIG. A load capacitance (capacitance 5) formed between one X electrode 3 and one Y electrode 4 is 10 nF.

  In FIG. 6A, the current path in the center portion has the minimum inductance, and its value is 40 nH. In FIG. 6A, the inductance of the current path on one side is shown on the left side, and the inductance of the entire current path is shown on the center. In FIG. 6A, the upper (or lower) current path has the maximum inductance, and its value is 160 nH. In FIG. 6A, the difference between the minimum inductance and the maximum inductance is as large as 120 nH.

  On the other hand, also in FIG. 6B, the current path in the center portion has the minimum inductance, and the value is 130 nH. 6B also shows the inductance of the current path on one side on the left side and the inductance of the entire current path on the center. Also in FIG. 6B, the upper (or lower) current path has the maximum inductance, and its value is 190 nH. In FIG. 6B, the difference between the minimum inductance and the maximum inductance is 60 nH, which is about half that of FIG. Therefore, when the switching elements 6x and 6y are arranged at the diagonal of the panel 2, the variation in inductance becomes small, the discharge characteristics in the panel 2 become uniform, and the luminance unevenness can be minimized.

  In the above description, it has been described that the variation in inductance affects the display quality of the PDP. First, the extent to which the inductance affects the operation of the PDP will be examined below.

  The inductance of the current path varies depending on the size of the panel 2 and the wiring shape at the electrode portion. Therefore, the inductance of the current path is normalized by the capacitance of the panel 2. Thereby, the normalized inductance of the current path can eliminate the influence of the size of the panel 2 and the wiring shape at the electrode portion.

  Specifically, the capacitance between the X electrode and the Y electrode is proportional to the electrode area or the number of electrodes. Therefore, the capacitance of the panel 2 is proportional to the size of the panel 2 in the short direction. On the other hand, the inductance of the current path is simply inversely proportional to the width of the wiring. Therefore, the integrated value of the inductance of the current path and the capacitance of the panel 2 is constant regardless of the width of the wiring. Therefore, the integrated value or a value obtained by dividing the integrated value by the capacitance between the electrodes is used as a standardized index of the inductance of the current path.

  FIG. 7 shows the result of circuit simulation of how much the voltage drop during discharge occurs when the capacitance of the panel 2 is 100 nF and the inductance of the current path is changed. Calculation is performed for the case where the entire PDP is lit (when the display area of 100% is lit) and the case where the PDP is partially lit (when the display area of 10% is lit). The lower side of the horizontal axis in FIG. 7 represents the inductance value of the current path with respect to the capacitance of 100 nF of the panel 2, which is a normalized inductance value, and the unit is [nH × 100 nF]. On the other hand, the upper side of the horizontal axis represents the inductance value of the current path converted to a capacitance of 1 nF, and the unit is [μH × 1 nF]. Note that the inductance value of the current path with respect to the capacitance of 1 nF is generally a value converted into a capacitance corresponding to five electrodes. Moreover, the vertical axis | shaft of FIG. 7 represents the voltage drop value at the time of discharge, and a unit is [V].

  Referring to FIG. 7, the voltage drop at the time of discharge from when the inductance of the current path exceeds 2 nH × 100 nF = 2 μH × 1 nF, even when the entire surface is lit (black circle display) or partially lit (white circle display). Begins to grow rapidly. If it is 5 μH × 1 nF or more, a voltage drop of 20 V or more occurs even if it is partially lit. If a voltage drop of 20 V or more occurs at the time of discharge, it is considered that a problem occurs on the display of the PDP. From the above, it is considered that the inductance of the current path is desirably 5 μH × 1 nF or less.

  Generalizing the above conditions, when the capacitance of panel 2 (when not discharged) is Cp [nF], the inductance [μH] of each current path is set to (5 μH × 1 nF) / Cp [nF] or less. By doing so, it is possible to prevent a problem in display of the PDP due to a voltage drop during discharge.

  Next, a study will be made as to how much inductance difference is generated between the current paths, causing non-uniform discharge characteristics in the panel 2 and luminance unevenness to the extent that the display quality is lowered.

  In the PDP shown in FIG. 3, the inductance of the current path is empirically considered to be about 1 μH × 1 nF to 3 μH × 1 nF. In this case, if an inductance variation of about 1 μH × 1 nF occurs between the individual current paths, the voltage drop during discharge greatly changes in the individual current paths as can be seen from FIG. Therefore, it is considered that the discharge characteristics are non-uniform between the individual current paths. From the above, it can be seen that the difference in inductance between the individual current paths is preferably 1 μH × 1 nF or less.

  Generalizing the above conditions, when the capacitance of panel 2 (when not discharged) is Cp [nF], the difference in inductance [μH] between current paths is (1 μH × 1 nF) / Cp [nF] or less. By doing so, the discharge characteristics in the panel 2 can be made uniform, and luminance unevenness can be minimized.

  Incidentally, in the PDP shown in FIG. 6A, the capacitance of the panel 2 is 10 nF, the inductance of the minimum current path is 40 nH, and the inductance of the maximum current path is 160 nH. Therefore, the difference between these inductances is 160 nH × 10 nF (1.6 μH × 1 nF) −40 nH × 10 nF (0.4 μH × 1 nF) = 120 nH × 10 nF (1.2 μH × 1 nF). That is, in the case of the PDP shown in FIG. 6A, the difference in inductance between the current paths is larger than 1 μH × 1 nF, the discharge characteristics in the panel 2 become non-uniform, and the brightness unevenness to the extent that the display quality is degraded may occur You can see that there is sex.

  On the other hand, in the PDP shown in FIG. 6B, the capacitance of the panel 2 is 10 nF, the inductance of the minimum current path is 130 nH, and the inductance of the maximum current path is 190 nH. Therefore, the difference between these inductances is 190 nH × 10 nF (1.9 μH × 1 nF) −130 nH × 10 nF (1.3 μH × 1 nF) = 60 nH × 10 nF (0.6 μH × 1 nF). That is, in the case of the PDP shown in FIG. 6B, since the difference in inductance between the current paths is 1 μH × 1 nF or less, the discharge characteristics in the panel 2 can be made uniform, and luminance unevenness can be minimized. Note that the PDP shown in FIG. 6B has a maximum current path inductance of 1.9 μH × 1 nF, which is 5 μH × 1 nF or less, so that there is no problem in display of the PDP due to a voltage drop during discharge.

  In the above description, the discussion has been limited only to reducing the inductance of the current path. However, considering the display performance of the entire PDP, lowering the inductance may not necessarily improve the display performance. For example, since the light emission efficiency of the PDP depends on the peak value of the current, the light emission efficiency may be higher in a PDP having a certain amount of current path inductance. However, even in this case, it is necessary to increase the inductance of the current path uniformly over the entire screen in order not to cause uneven brightness. Therefore, the method for equalizing the inductance between the current paths described in the present invention is also effective in the above case. In other words, the inductance of the current path is reduced by using the method of the present invention, variation is reduced, and an appropriate inductance is newly added to the current path.

  In this embodiment, an IGBT is used as an element having a large current capacity. However, the present invention is not limited to this. The current capacity is large (or the ON voltage (ON resistance) is small), and a display device such as a PDP is used. Any element that is suitable for driving can be used. For example, an FET module in which a plurality of chips are modularized in parallel to allow a large current to flow can be handled in the same manner. Even if each switching element is composed of a plurality of elements (IGBT or the like), the same effect can be obtained if the individual elements satisfy the requirements described above.

  As described above, the display device described in the present embodiment extends in the longitudinal direction (lateral direction) of the front substrate 1f on the front substrate 1f and the rear substrate 1b constituting the panel 2 and the front substrate 1f. A plurality of X electrodes 3, a plurality of Y electrodes 4 extending in the longitudinal direction (lateral direction) on the front substrate 1 f, and arranged alternately with the X electrodes 3, and connected to the plurality of X electrodes 3. The front substrate 1f is provided with at least one switching element 6x that supplies current to the X electrode 3 and at least one switching element 6y that is connected to the plurality of Y electrodes 4 and supplies current to the Y electrode 4. The position of the switching element 6x in the hand direction (longitudinal direction) is different from the position of the switching element 6y in the short direction (vertical direction), and the distance from the upper side (one horizontal side) to the switching element 6x. , Is equal from the lower side (the other horizontal side) and the distance to the switching element 6y, it can be driven so that the display characteristics become uniform, it is possible to obtain a high desired image display quality.

  Further, in the display device according to the present embodiment, since the display device is an AC plasma display, the discharge characteristics in the panel 2 can be made uniform, and luminance unevenness can be minimized.

  Furthermore, in the display device according to the present embodiment, since the switching elements 6x and 6y are IGBTs, a sufficient current capacity can be secured and the number of necessary switching elements can be reduced.

(Embodiment 2)
In the first embodiment, the switching elements 6x and 6y included in the drive circuits 14 and 15 have been described. However, the drive circuits 14 and 15 include other switching elements 7x, 7y, 9x, and 9y as described with reference to FIG. , 10x, 10y. Other switching elements 7x, 7y, 9x, 9y, 10x, and 10y are also arranged so as to satisfy the conditions described in the first embodiment. However, since it cannot be physically provided at the same position as the switching elements 6x and 6y, other switching elements 7x, 7y, 9x, 9y, 10x, and 10y are provided in the vicinity of the switching elements 6x and 6y. Therefore, in the present embodiment, the positional relationship between the switching elements 6x and 6y and the switching elements 7x, 7y, 9x, 9y, 10x, and 10y will be described.

  In the PDP shown in FIG. 3, the positions of the switching elements 6x and 6y are shown. The switching elements 6x and 6y are switching elements of the upper arm of the sustain circuit. Therefore, the switching element of the lower arm of the sustain circuit is provided in the vicinity of the switching elements 6x and 6y. FIG. 8 shows a plan view of the PDP according to the present embodiment. In the PDP shown in FIG. 8, a switching element 6 x and a switching element 7 x are provided side by side in the short direction of the panel 2 at the upper left of the panel 2. Further, a switching element 6 y and a switching element 7 y are provided in the lower right side of the panel 2 side by side in the short direction of the panel 2. In the PDP shown in FIG. 8, the switching element 7x is provided closer to the upper side in the figure than the switching element 6x, and the switching element 7y is provided closer to the lower side in the figure than the switching element 6y.

  The switching elements 6x and 6y, which are the conditions described in the first embodiment, are different from the positions of the switching elements 6y in the short direction of the panel 2 in the short direction. The position has been adjusted. However, the positions of the switching elements 6x and 6y are adjusted so that the distance from the upper side of the panel 2 to the switching element 6x is the same as the distance from the lower side of the panel 2 to the switching element 6y.

  Similarly, the positions of the switching elements 7x and 7y are adjusted so that the position of the switching element 7x in the short direction of the panel 2 is different from the position of the switching element 7y in the short direction of the panel 2. However, the positions of the switching elements 7x and 7y are also adjusted so that the distance from the upper side of the panel 2 to the switching element 7x is the same as the distance from the lower side of the panel 2 to the switching element 7y.

  The distance between the switching element 6x and the switching element 7x must be separated to some extent depending on the mounting conditions, but it is desirable that the distance be as close as possible. The same applies to the distance between the switching element 6y and the switching element 7y.

  As described above, the switching elements 6 x and 7 x and the switching elements 6 y and 7 y of the PDP shown in FIG. 8 are provided at rotationally symmetric positions with respect to the center of the panel 2. As a result, the difference between the inductance of the current path located at the center of the panel 2 and the inductance of the current path located at the top or bottom is reduced, and the difference in inductance generated between the current paths is kept small throughout the panel 2. be able to.

  In FIG. 8, the switching element 6x and the switching element 7x are arranged along the short direction of the panel 2, but the arrangement of the switching elements is not limited to this. For example, as shown in FIG. 9, the switching element 6x and the switching element 7x are arranged in the longitudinal direction of the panel 2 on the upper left of the panel 2, and the switching element 6y and the switching element 7y are arranged on the lower right of the panel 2 in the panel 2. They may be provided side by side in the longitudinal direction.

  In the PDP shown in FIG. 9, the switching element 7x is provided closer to the left side in the figure than the switching element 6x, and the switching element 7y is provided closer to the right side in the figure than the switching element 6y. The distance between the switching element 6x and the switching element 7x and the distance between the switching element 6y and the switching element 7y are preferably as close as possible.

  As shown in FIG. 9, even if the switching elements 6x, 7x, 6y, 7y are arranged, the switching elements 6x, 7x and the switching elements 6y, 7y are provided at rotationally symmetric positions with respect to the center of the panel 2. Thus, the same effect as the PDP shown in FIG. 8 can be obtained.

  Next, as shown in FIG. 2, the driving circuit of the PDP includes not only a maintenance circuit but also a recovery circuit. Conventionally, a plurality of FETs are provided in parallel for the switching elements 9x, 9y, 10x, and 10y of the recovery circuit. Similarly to the maintenance circuit, for example, if the required performance of the recovery circuit can be satisfied by using a switching element having a large current capacity such as an IGBT, a switching element having a large current capacity such as an IGBT may be used for the recovery circuit. it can. By using one switching element having a large current capacity such as IGBT instead of the plurality of FETs, the number of switching elements mounted on the recovery circuit can be greatly reduced.

  Since the sustain circuit is a circuit for supplying a current necessary for display to the sustain electrode of the panel 2, variation in inductance from the sustain circuit to the panel 2 affects display characteristics. Similarly to the sustain circuit, the recovery circuit is a circuit that allows a current necessary for display to flow to the sustain electrode of the panel 2, and thus the display characteristics are affected by variations in inductance.

  As shown in FIG. 2, the recovery circuit includes a reactor 8, switching elements 9 x, 9 y, 10 x, 10 y and a capacitor 11. If there is a variation in inductance between the individual current paths from the panel 2 to the switching elements 9x, 9y, 10x, 10y and the capacitor 11, the resonance reactor 8 provided to reduce the power loss is included. Variations also occur in the inductance of the current path. Variation in the inductance of the current path fluctuates the recovery efficiency of the recovery circuit. Therefore, it is necessary to adjust the arrangement of the switching elements 9x, 9y, 10x, and 10y of the recovery circuit based on the same conditions as those of the maintenance circuit described above.

  In the PDP shown in FIG. 10, switching elements 6x and 7x of the sustain circuit and switching elements 9x and 10x of the recovery circuit are provided on the upper left of the panel 2. The switching element 6 x and the switching element 7 x and the switching element 9 x and the switching element 10 x are provided side by side in the short direction of the panel 2. The switching element 7x and the switching element 10x are arranged at a position closer to the upper side in the drawing than the switching element 6x and the switching element 9x. The switching element 9x and the switching element 10x are arranged in the longitudinal direction of the panel 2 and 6x, respectively.

  On the other hand, switching elements 6y and 7y of the sustain circuit and switching elements 9y and 10y of the recovery circuit are provided in the lower right of the panel 2. The switching element 6 y and the switching element 7 y and the switching element 9 y and the switching element 10 y are provided side by side in the short direction of the panel 2. In addition, the switching element 7y and the switching element 10y are arrange | positioned in the position near the upper side in a figure compared with the switching element 6y and the switching element 9y. The switching element 9y and the switching element 10y are arranged in the longitudinal direction of the panel 2 and 6y, respectively.

  The switching elements 6x, 7x, 9x, 10x, 6y, 7y, 9y, and 10y arranged as described above satisfy the conditions described in the first embodiment. Specifically, the positions of the switching elements 6x, 6y, 9x, 9y so that the positions of the switching elements 6x, 9x in the short direction of the panel 2 are different from the positions of the switching elements 6y, 9y in the short direction of the panel 2. The position has been adjusted. However, the positions of the switching elements 6x, 6y, 9x, 9y are adjusted so that the distance from the upper side of the panel 2 to the switching elements 6x, 9x is the same as the distance from the lower side of the panel 2 to the switching elements 6y, 9y. ing.

  Further, the positions of the switching elements 7x, 7y, 10x, 10y are adjusted so that the positions of the switching elements 7x, 10x in the short direction of the panel 2 are different from the positions of the switching elements 7y, 10y in the short direction of the panel 2. Has been. However, the positions of the switching elements 7x, 7y, 10x and 10y are also adjusted so that the distance from the upper side of the panel 2 to the switching elements 7x and 10x is the same as the distance from the lower side of the panel 2 to the switching elements 7y and 10y. ing.

  The distances between the switching elements 6x, 7x, 9x, and 10x must be separated to some extent depending on the mounting conditions, but it is desirable that the distances be as close as possible. The same applies to the distance between the switching elements 6y, 7y, 9y, 10y.

  As shown in FIG. 10, the switching elements 6 x, 7 x, 9 x, and 10 x and the switching elements 6 y, 7 y, 9 y, and 10 y are provided at rotationally symmetric positions with respect to the center of the panel 2. As a result, the difference between the inductance of the current path located at the center of the panel 2 and the inductance of the current path located at the top or bottom is reduced, and the difference in inductance generated between the current paths is suppressed in the entire panel 2. Can do.

  The arrangement of the switching elements 6x, 7x, 9x, 10x and the switching elements 6y, 7y, 9y, 10y is not limited to the case shown in FIG. 10, and the switching elements 6x, 7x, 9x, 10x and the switching element 6y are arranged. , 7y, 9y, 10y may be arranged in any order as long as they are provided at rotationally symmetric positions with respect to the center of the panel 2.

  As described above, in the display device according to the present embodiment, the switching elements 6x, 7x, 9x, 10x and the switching elements 6y, 7y, 9y, 10y are the center of the panel 2 in which the front substrate 1f and the rear substrate 1b are bonded together. Therefore, the impedance difference generated between the individual current paths can be suppressed.

(Modification)
Next, a modification of the PDP according to the present embodiment is shown. In the PDP drive circuit according to this modification, a plurality of switching elements such as IGBTs and driver ICs are combined and integrated in one module 17. In this module 17, an element called IPM (Intelligent Power Module) may be used. If this IPM is used for the drive circuit, the number of elements to be mounted can be reduced, the area of the circuit board of the drive circuit can be reduced, and the mounting cost can be reduced.

  FIG. 11 shows a plan view of a PDP using IPM modules 17x and 17y. In the PDP shown in FIG. 11, a module 17x is provided instead of the switching elements 6x, 7x, 9x, and 10x, and a module 17y is provided instead of the switching elements 6y, 7y, 9y, and 10y. Thus, by integrating the switching elements 6x, 7x, 9x, and 10x and the switching elements 6y, 7y, 9y, and 10y in the modules 17x and 17y, the distance between the switching elements can be greatly reduced. Furthermore, the effect of inductance can be minimized by reducing the distance between the switching elements, and the number of elements can be reduced, the circuit board area can be reduced, and the mounting cost can be reduced by modularizing the switching elements. Can be realized.

  In FIG. 11, four switching elements are formed as one module. However, the present invention is not limited to this, and other modularization methods may be used, such as two switching elements as one module.

  As described above, in the display device described in this modification, the plurality of switching elements 6x, 7x, 9x, and 10x and the plurality of switching elements 6y, 7y, 9y, and 10y are at least one module 17x and 17y, respectively. The effect of inductance can be minimized by greatly reducing the distance between the switching elements 6x, 7x, 9x and 10x and between the switching elements 6y, 7y, 9y and 10y, and the number of elements can be reduced. The area can be reduced and the mounting cost can be reduced.

(Embodiment 3)
FIG. 12A shows a cross-sectional view of a PDP using an FET as a switching element, and FIG. 12B shows a perspective view of a PDP using an FET as a switching element. In FIG. 12A, the panel 2 in which the front substrate 1 f and the rear substrate 1 b are bonded together is fixedly supported on the back plate 13. A drive circuit is disposed on the surface of the back plate 13 located on the opposite side of the surface that supports the panel 2.

  When the FET is used for the sustain circuit and the recovery circuit as described in the background art, a plurality of sustain circuits and recovery circuits are connected to the X electrode and the Y electrode, respectively. In FIG. 12B, four sustain circuits and recovery circuit circuits are provided for each of the X electrode and the Y electrode. One maintenance circuit and recovery circuit circuit are provided with a maintenance circuit FET 18 for the upper and lower arms and a recovery circuit FET 19 for the upper and lower arms. Each circuit FET 18 and recovery circuit FET 19 are mounted on the circuit board 16.

  In the PDP shown in FIG. 12 (b), 16 sustain circuit FETs 18 and 16 recovery circuit FETs 19 are required, 32 in total. In FIG. 12B, since the drive circuit is schematically shown, the ratio of the size of the drive circuit to the size of the panel 2 is different from the actual PDP. Further, it is arranged at a position different from the position of the drive circuit actually arranged.

  The back plate 13 of the PDP has a role of fixing the panel 2 and a role of providing a current return path and extremely reducing the inductance of the current path. Further, the back plate 13 of the PDP also serves as a heat radiating plate of the panel 2 that absorbs heat generated by the panel 2 and dissipates heat. Generally, more than half of the electric power input to drive the PDP is released as heat from the panel 2. Since most of the heat released from the panel 2 flows to the back plate 13, the back plate 13 is heated to about 60 ° C. to 70 ° C. when the PDP is driven.

  On the other hand, when the PDP is driven, the sustain circuit FET 18 and the recovery circuit FET 19 are also considered to be in a high temperature state due to their own heat generation. However, since the sustain circuit FET 18 and the recovery circuit FET 19 have a characteristic that the ON resistance (ON voltage) increases when the temperature becomes high, the sustain circuit FET 18 and the recovery circuit FET 19 are cooled to obtain a desired ON resistance (ON voltage). There is a need. Therefore, a heat dissipation mechanism is essential for the sustain circuit FET 18 and the recovery circuit FET 19 mounted on the PDP, and air-cooling heat dissipation fins 20 are attached to each element.

  The radiating fins 20 are required to have a certain size because the radiating fins 20 are required to have a sufficient radiating capability to cool the sustain circuit FET 18 and the recovery circuit FET 19. Therefore, the size of the circuit board 16 on which the sustain circuit FET 18, the recovery circuit FET 19 and the heat radiation fin 20 are mounted is naturally increased. In FIG. 12A, one radiating fin 20 is provided for one group including the upper-arm maintenance circuit FET 18 and the upper-arm recovery circuit FET 19.

  On the other hand, FIG. 13A shows a cross-sectional view of the PDP according to the present embodiment, and FIG. 13B shows a perspective view of the PDP according to the present embodiment. In the drive circuit shown in FIG. 13A, the four upper arm sustain circuit FETs 18 are replaced with one sustain circuit IGBT 21, and the four lower arm sustain circuit FETs 18 are replaced with one sustain circuit IGBT 21. Yes. Further, the four recovery circuit FETs 19 in the upper arm are replaced with one recovery circuit IGBT 22, and the four recovery circuit FETs 19 in the lower arm are replaced with one recovery circuit IGBT 22.

  Further, the two replaced maintenance circuit IGBTs 21 and the two recovery circuit IGBTs 22 constitute one module 23. In FIG. 13A, one sustain circuit IGBT 21 and one recovery circuit IGBT 22 are shown in the figure because of the cross-sectional view, but another sustain circuit IGBT 21 and recovery circuit are arranged in a direction perpendicular to the paper surface. One circuit IGBT 22 is provided for each circuit.

  In FIG. 13B, two drive circuits each having the module 23 mounted on the circuit board 16 are provided on the back plate 13 and connected to the X electrode and the Y electrode, respectively. In FIG. 13B, since the drive circuit is schematically shown, the ratio of the size of the drive circuit to the size of the panel 2 is different from that of an actual PDP.

  In the drive circuit according to the present embodiment, since the IGBT is used for the module 23 instead of the FET, the operating temperature of the module 23 can be extremely increased. This has the characteristic that the ON resistance (ON voltage) of the element increases as the temperature rises, whereas the IGBT does not change much the ON voltage (ON resistance) of the element even when the temperature increases. This is because it has characteristics. When the ON voltage (ON resistance) of the element increases, the display characteristics of the panel 2 are also affected. For this reason, if the IGBT is used in the drive circuit, the drive temperature can be increased to the PDP as long as the temperature does not destroy the element. Therefore, in the drive circuit according to the present embodiment, the design temperature of the module 23 can be raised to a considerably high temperature.

  Further, in the case of FET, the heat radiation fin 20 is necessary because of the necessity of cooling. However, in the case of IGBT, the display characteristics are hardly affected even when operated at a high temperature. There is no need to dissipate heat with fins. Therefore, in the drive circuit according to the present embodiment, the module 23 mounted on the circuit board 16 is brought into contact with the back plate 13 and heat is radiated by the back plate 13. The back plate 13 is a single metal plate.

  As described above, the back plate 13 of the PDP is at a temperature of about 60 ° C. to 70 ° C. during operation. Further, it is considered that the amount of heat radiated by the module 23 (IGBT) of the drive circuit is sufficiently small with respect to the amount of heat released by the panel 2 of the PDP. Therefore, it is considered that the temperature of the back plate 13 hardly changes even if the heat from the module 23 is radiated to the back plate 13. As a result, the module 23 is maintained at a constant temperature of about 70 ° C., and the IGBT portion in the module 23 is also maintained at around 100 ° C. Even if the IGBT is driven at around 100 ° C., the display characteristics of the PDP are not affected and the IGBT is not damaged.

  In FIG. 13A, the module 23 is in contact with and joined to the back plate 13 on the surface opposite to the surface mounted on the circuit board. Since this joined portion needs to improve heat transfer, it may be necessary to devise, for example, using heat transfer grease. In the drive circuit shown in FIG. 13A, the radiation fin 20 is not necessary. The module 23 and the back plate 13 do not necessarily have to be joined, and it is sufficient that heat conduction occurs from the module 23 to the back plate 13. In the present invention, the sustain circuit IGBT 21 and the recovery circuit IGBT 22 may be in contact with and joined to the individual back plate 13 without being integrated like the module 23.

  As described above, in the drive circuit according to the present embodiment, the sustain circuit IGBT 21 and the recovery circuit IGBT 22 that supply current to the panel 2, and the circuit board 16 on which the sustain circuit IGBT 21 and the recovery circuit IGBT 22 are mounted. Provided, the sustain circuit IGBT 21 and the recovery circuit IGBT 22 are in contact with the back plate 13 supporting the panel 2 on the surface opposite to the surface mounted on the circuit board 16, so that the radiation fins 20 are not required. The cost of components, the mounting cost, the area of the circuit board 16 and the like can be greatly reduced. Furthermore, in the drive circuit according to the present embodiment, since the heat dissipating fins 20 are not necessary, the height direction of the drive circuit can be significantly reduced, and a thin PDP that cannot be realized by a conventional drive circuit. The device becomes possible.

  Further, in the drive circuit according to the present embodiment, by integrating a plurality of IGBTs in one module 23, it is possible to greatly reduce the number of elements, and the cost of the elements, the mounting cost, the area of the circuit board 16, etc. Can be greatly reduced.

  In the drive circuit according to the present embodiment, an IGBT is used as a switching element. However, the present invention is not limited to this, and any element can be used as long as it can operate at a low loss even at a high temperature as compared with an FET. Is possible. For example, it is considered that a SiC device or the like can be used instead of the IGBT.

(Embodiment 4)
FIG. 14 is a perspective view of the PDP according to the present embodiment. FIG. 14 is a perspective view of the back surface (surface opposite to the display surface) of the PDP. In the PDP shown in FIG. 14, the panel 2 in which the front substrate 1 f and the rear substrate 1 b are bonded together, the back plate 13 that fixes and supports the back surface of the panel 2, and the drive circuits 14 and 15 disposed on the back plate 13. It is comprised by. The drive circuit 14 is connected to the X electrode, and the drive circuit 15 is connected to the Y electrode.

  In the drive circuits 14 and 15, a module 23 is mounted on a circuit board 16. The module 23 is in contact with and joined to the back plate 13 on the surface opposite to the surface mounted on the circuit board 16. The module 23 includes a plurality of sustain circuit IGBTs 21 and recovery circuit IGBTs 22 as described in the third embodiment.

  In the PDP according to the present embodiment, the drive circuits 14 and 15 are provided at both ends of the panel 2 in the longitudinal direction. The drive circuit 14 drives the X electrode, and the drive circuit 15 drives the Y electrode. The position of the module 23 mounted on the drive circuit 14 in the short direction of the panel 2 is different from the position of the module 23 mounted on the drive circuit 15 in the short direction of the panel 2. That is, in the PDP shown in FIG. 14, the module 23 portion mounted on the drive circuit 14 and the module 23 portion mounted on the drive circuit 15 are mounted so as to be located on the diagonal of the panel 2.

  The PDP according to the present embodiment has a relationship in which the configuration of the driving circuit described in the third embodiment is combined with the configuration of the PDP described in the first and second embodiments. In FIG. 14, only the panel 2, the back plate 13, the module 23, and the circuit board 16 are shown. However, in an actual PDP device, other elements and capacitors for driving circuits and other writing circuits are provided on the circuit board 16. Circuit boards for image signal processing, circuit boards for processing video signals, power supply circuits, and the like.

  As described above, the display device according to the present embodiment further includes the back plate 13 that supports the panel 2, and the module 23 including the sustain circuit IGBT 21 and the recovery circuit IGBT 22 is mounted on the circuit board 16. Since the surface opposite to the surface (one surface) is in contact with the back plate 13, it can be driven to make the display characteristics uniform, a desired image can be obtained, and the radiation fin 20 is not required. Therefore, a further thin display device can be provided.

  In the present invention, the sustain circuit IGBT 21 and the recovery circuit IGBT 22 may be in contact with and joined to the individual back plate 13 without being integrated like the module 23.

(Embodiment 5)
The light emission of PDP uses gas discharge, and the discharge characteristics depend on the gas temperature. Accordingly, the display characteristics of the PDP also depend on the temperature of the panel 2. When the module 23 is mounted as in the PDP shown in FIG. 14, the module 23 serving as a heat source exists at a diagonal position of the panel 2 through the back plate 13. For this reason, a non-uniform portion may occur in the temperature distribution of the back plate 13. If the temperature distribution of the back plate 13 becomes non-uniform, the temperature distribution of the panel 2 supported by the back plate 13 also becomes non-uniform, which is considered to have a considerable influence on the display characteristics of the PDP.

  Therefore, in order to avoid the above influence, it is necessary to design the structure of the back plate 13 so as to have a uniform temperature distribution, not simply from the aspect of supporting the panel 2 alone. That is, when there is an inflow of heat from a heat source (module 23) that exists locally as in the PDP shown in FIG. 14, an appropriate thermal structure design is performed to keep the temperature distribution of the panel 2 as uniform as possible. It is necessary to provide the back plate 13 with possible means. As a means for making the temperature distribution of the panel 2 uniform, specifically, the thermal conductivity between the back plate 13 of the part in contact with the module 23 and the panel 2 is worse than that of the other part. In this way, a means for providing a heat insulating material 24 or the like on the back plate 13 in a portion in contact with the module 23 is conceivable (FIG. 15A). Alternatively, in order to easily release the heat flowing in from the portion in contact with the module 23 to the surroundings, a means for providing a portion 25 in which the back plate 13 of the portion in contact with the module 23 is thickened can be considered (FIG. 15 ( b)). Alternatively, a means for intentionally inserting a slit 26 or the like in the back plate 13 in order to make the temperature distribution of the panel 2 uniform by controlling the heat transfer in the surface of the back plate 13 can be considered (FIG. 15C).

  As described above, in the display device according to the present embodiment, the back plate 13 includes means for keeping the temperature distribution of the panel 2 uniform, so that the display characteristics can be made uniform and display quality can be improved. High image quality can be obtained.

(Embodiment 6)
When the module 23 is mounted as in the PDP shown in FIG. 14, the temperature distribution of the panel 2 is non-uniform because the module 23 serving as a heat source exists at the diagonal position of the panel 2 through the back plate 13. Become. If the temperature distribution of the panel 2 becomes non-uniform, it is considered that the display characteristics of the PDP are considerably affected. Therefore, in the fifth embodiment, the back plate 13 is provided with means capable of designing an appropriate thermal structure and keeping the temperature distribution as uniform as possible.

  However, there may be a case where the temperature distribution of the panel 2 cannot be made uniform to the extent that no difference in display characteristics appears even if the above-described means is provided on the back plate 13. In this case, in the PDP according to the present embodiment, it is conceivable to drive or correct the video signal so that no difference appears in the display characteristics.

  Usually, the temperature distribution of the panel 2 is very constant during driving. For this reason, if the temperature distribution of the panel 2 and the luminance change of the PDP accompanying the temperature distribution of the panel 2 are known, it is possible to drive the portion where the luminance changes or to correct the video signal. Driving or video signal correction can be performed by providing a correction controller in the driving circuit. In this correction control unit, the influence on the display characteristics due to the temperature distribution of the panel 2 is canceled by software by correcting the drive or video signal before display based on the known temperature distribution, and the display quality is high. An image can be obtained.

  Since the temperature distribution of the panel 2 is considered to depend on the temperature of the panel 2 itself, it is also possible to perform optimum correction based on this temperature while monitoring the temperature of the panel 2 itself. For example, since the temperature of the panel 2 itself immediately after the start of driving is low, this temperature is taken into consideration and the driving or video signal is corrected to cancel the influence on the display characteristics due to the temperature distribution of the panel 2. By this correction, the display can be maintained optimally. In addition, if an image with high display quality can be obtained only by driving or correcting video signals described in the present embodiment, the temperature distribution of the panel 2 on the back plate 13 described in the fifth embodiment is displayed. There is no need to provide a uniform means.

  As described above, the display device according to the present embodiment further includes the correction control unit that corrects the current supplied to the sustaining circuit IGBT 21 and the recovery circuit IGBT 22 based on the temperature distribution of the panel 2. The influence of the distribution can be canceled and an image with high display quality can be obtained.

  In the description from the first embodiment to the sixth embodiment, the PDP is described as an example of the display device. However, the present invention is not limited to the PDP. In addition to the PDP, it is considered that the present invention can be applied to any device in which elements are distributed over a relatively large area (or volume) and it is necessary to drive them as uniformly as possible. In particular, when each element is driven with a relatively large pulse current and the element is a capacitive load, it is possible to use a circuit configuration as shown in FIG. 2 that combines a half-bridge circuit and a power recovery circuit as a drive circuit. The contents of the present invention can be applied. As such an apparatus, an inorganic EL panel or the like can be considered.

It is a top view of the display apparatus which concerns on Embodiment 1 of this invention. 1 is a circuit diagram of a display device according to Embodiment 1 of the present invention. It is a top view of the display apparatus which concerns on Embodiment 1 of this invention. It is a top view of a general display apparatus. It is sectional drawing of the display apparatus which concerns on Embodiment 1 of this invention. It is a top view of the display apparatus which concerns on Embodiment 1 of this invention. It is the figure which showed the relationship between the inductance of a current path, and the voltage drop at the time of discharge. It is a top view of the display apparatus which concerns on Embodiment 2 of this invention. It is a top view of the display apparatus which concerns on Embodiment 2 of this invention. It is a top view of the display apparatus which concerns on Embodiment 2 of this invention. It is a top view of the display apparatus which concerns on Embodiment 2 of this invention. It is sectional drawing and a perspective view of a general display apparatus. It is sectional drawing and the perspective view of the display apparatus which concern on Embodiment 3 of this invention. It is a perspective view of the display apparatus which concerns on Embodiment 4 of this invention. It is a partial cross section figure of the display apparatus which concerns on Embodiment 5 of this invention.

Explanation of symbols

1f Front substrate, 1b Rear substrate, 2 panel, 3 X electrode, 4 Y electrode, 5 capacitance, 6x, 6y, 7x, 7y, 9x, 9y, 10x, 10y switching element, 8x, 8y reactor, 11x, 11y capacitor, 12 Wiring, 13 Back plate, 14, 15 Drive circuit, 16 Circuit board, 17, 23 Module, 18 Maintenance circuit FET, 19 Recovery circuit FET, 20 Radiation fin, 21 Maintenance circuit IGBT, 22 Recovery circuit IGBT, 24 insulation, 25 thickened parts, 26 slits.

Claims (13)

A substrate constituting the panel;
On the substrate, a plurality of first electrodes extending in the lateral direction of the substrate;
A plurality of second electrodes extending in the lateral direction on the substrate and arranged alternately with the first electrodes;
At least one first switching element connected to a plurality of the first electrodes and supplying a current to the first electrodes;
Comprising at least one second switching element connected to a plurality of the second electrodes and supplying a current to the second electrodes;
The position of the said 1st switching element in the vertical side direction of the said board | substrate differs from the position of the said 2nd switching element in the said vertical side direction, The display apparatus characterized by the above-mentioned. The display device according to claim 1,
The distance from the first lateral side of the substrate to the first switching element is equal to the distance from the second lateral side of the substrate facing the first lateral side to the second switching element. A display device. The display device according to claim 1,
The display device, wherein the first switching element and the second switching element are disposed at rotationally symmetric positions with respect to a center of the substrate. A display device according to any one of claims 1 to 3,
A display device, wherein a plurality of the first switching elements and a plurality of the second switching elements are each integrated in at least one module. A display device according to any one of claims 1 to 4,
The display device is an AC type plasma display. A display device according to any one of claims 1 to 5,
The display device, wherein the first and second switching elements are IGBTs. The display device according to claim 5,
When the capacitance between the first electrode and the second electrode is Cp [nF],
In the current path passing through the first and second electrodes and the first and second switching elements, a difference in individual inductance is (1 μH × 1 nF) / Cp or less. The display device according to claim 5 or 7,
When the capacitance between the first electrode and the second electrode is Cp [nF],
A display device, wherein an individual inductance is equal to or less than (5 μH × 1 nF) / Cp in a current path passing through the first and second electrodes and the first and second switching elements. A display device according to any one of claims 1 to 8,
A back plate for supporting the panel;
One of the first and second switching elements is in contact with the back plate. The display device according to claim 9,
The display device according to claim 1, wherein the back plate includes means for keeping the temperature distribution of the substrate uniform. The display device according to claim 9 or 10, wherein
The display device further comprising a correction control unit that corrects a current supplied to the first or second electrode based on a temperature distribution of the substrate. A drive circuit for driving a panel of a display device,
At least one element for supplying current to the panel;
A circuit board on which the element is mounted,
The drive circuit according to claim 1, wherein a surface of the element opposite to a surface mounted on the circuit board is in contact with a back plate supporting the panel. The drive circuit according to claim 12, comprising:
A drive circuit comprising a plurality of the elements integrated in at least one module.

Images