JP2006024977A - Convergence apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem of a conventional three-tube projection television receiver that the power consumption of a current amplifier circuit for a sub deflection coil is increased because it is required to reduce a distance between the screen and the projection tubes for attaining a downsized and lower-profile configuration for the television receiver, resulting in increasing raster distortion of each color and needing a large convergence correction amount. <P>SOLUTION: A convergence apparatus disclosed herein in a CRT display apparatus is provided with: a correction signal generating section for generating a correction signal to correct distortion and color slippage of a screen of the display apparatus; a current amplifier section for supplying the correction signal to the sub deflection coil arranged to the CRT; and a voltage switching section that controls a power supply voltage so as to increase the power supply voltage applied to the current amplifier section when a convergence correction region covers positions corresponding to four corners of the screen and to decrease the power supply voltage for the other regions. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a convergence device such as a display device having a cathode ray tube (CRT), such as a television receiver or a projection type television receiver.

  Conventionally, a projection television receiver (hereinafter referred to as a three-tube projection television receiver) or a television receiver having three CRTs (projection tubes) corresponding to R (red), G (green), and B (blue). In the machine, convergence adjustment is necessary, and a digital convergence apparatus is generally known.

  For example, a digital convergence device disclosed in Japanese Patent Application Laid-Open No. 7-212779 discloses a digital memory in which M × N adjustment points are arranged on a display screen, and convergence correction data corresponding to each adjustment point is stored. And interpolation calculation means for creating interpolation data for filling between the adjustment points using the data of a plurality of adjustment points read from the memory with low-pass filter characteristics, and output from the interpolation calculation means An auxiliary deflection amplifier that performs analog conversion of data and performs current amplification is provided, and a convergence correction signal is supplied from the amplifier to a sub deflection yoke (convergence yoke) attached to the projection tube neck. Thereby, the convergence can be adjusted satisfactorily.

  FIG. 7 is a configuration diagram simply illustrating the convergence device. The digital convergence device 101 is supplied with a horizontal synchronization signal, a vertical synchronization signal, and a control signal from a microcomputer (not shown), and outputs a convergence correction signal. The convergence correction signal is supplied to the plus terminal of the current amplifier circuit 102. A current having the same signal waveform as that of the convergence correction signal is extracted from the current amplifier circuit 102 and supplied to one end of the sub deflection yoke 103. The other end of the sub deflection yoke 103 is grounded via a current detection resistor 104.

  A voltage proportional to the current flowing through the sub deflection yoke 103 is taken out at a node between the sub deflection yoke 103 and the current detection resistor 104, and this voltage is supplied to the negative terminal of the current amplifier circuit 102. The current amplifier circuit 102 controls the output current so that the voltage at the plus terminal is the same as the voltage at the minus terminal. By such control, the same correction current as the convergence correction signal output from the digital convergence circuit 101 can be supplied to the sub deflection yoke 103.

  The current amplifying circuit 102 is devised to reduce power consumption by being configured with a class B push-pull circuit or the like, but it is still necessary to provide a large radiator to promote heat dissipation and protect the internal elements from thermal damage. . Further, when the three-tube projection television receiver is to be thin and small, it is necessary to shorten the distance between the screen and the projection tube, and the distortion of the raster of each color becomes large. As a result, the load on the current amplification circuit 102 in the convergence device increases, and the size of the heatsink must be increased. On the other hand, an increase in the size of the radiator is an obstacle to making the receiver thinner and smaller.

In a display device using a CRT, in order to reduce power consumption in the current correction unit for convergence correction, a high power supply voltage is applied to the current amplification unit when the convergence correction waveform changes abruptly as in Patent Document 2. In other cases, a low power supply voltage is applied to improve the response of convergence.
Japanese Patent Laid-Open No. 7-212779 Japanese Patent Laid-Open No. 10-322713

   When trying to make a three-tube projection television receiver thin and small, it is necessary to shorten the distance between the screen and the projection tube, and the distortion of the raster of each color increases. As a result, the load on the current amplification circuit in the convergence device increases, and the size of the heatsink must be increased. On the other hand, increasing the size of the radiator is an obstacle to reduction in thickness and size. The present invention provides a convergence device that suppresses power consumption by paying attention to the fact that raster distortion increases at the four corners of a display image.

  The present invention relates to a convergence device in a CRT type display device, wherein a correction signal generating unit that generates a correction signal for correcting distortion and color misalignment of the screen of the display device, and a sub-deflection in which the correction signal is arranged in the CRT. When the current amplifier for supplying to the coil and the convergence correction area are at positions corresponding to the four corners of the screen, the power supply voltage of the current amplifier is increased, and the power supply voltage is decreased in other areas. And a voltage switching unit for controlling the above.

  According to the convergence apparatus of the present invention, when the convergence correction area is at a position corresponding to the four corners of the screen, the power supply voltage of the current amplification unit is controlled to be high, and otherwise the power supply voltage is low. Therefore, it is possible to reduce the power consumption in the current amplifying unit, to suppress the heat generation in the current amplifying unit to the necessary minimum, and to realize the downsizing of the radiator.

  Hereinafter, a convergence device according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing the overall configuration of the convergence apparatus of the present invention. The video signal S is input to the input terminal 11. This video signal may be given from the outside of the receiver, or may be received by a built-in tuner (not shown). The video signal S is supplied to the selection circuit 12, and an adjustment pattern signal from the adjustment pattern signal generation circuit 13 that generates a convergence adjustment pattern is also input to the selection circuit 12.

  The selection circuit 12 selects either the video signal S or the adjustment pattern signal according to a command from the microprocessor 15 controlled in response to a command from the input device 14 such as a remote controller. The video signal S selected by the circuit 12 is supplied to the video signal processing circuit 16. The video signal processing circuit 16 converts the signals into RGB signals based on the supplied video signal S, amplifies the signals by the amplification circuits 171, 172, and 173, respectively, and outputs projections corresponding to the three primary colors of RGB. Supplied to the tubes 181, 182, and 183, and appropriately projected onto the back surface of the screen 19 through an optical system (not shown). As a result, projection images from the projection tubes 181 to 183 are projected and superimposed on the screen 19 to display a color image. This color image is visually recognized by the viewer.

  Further, the video signal S selected by the selection circuit 12 is further supplied to the synchronization separation circuit 20, where the synchronization signal is separated and extracted. This synchronization signal is supplied to the main deflection signal generation circuit 21. The horizontal (H) and vertical (V) main deflection signals generated by the main deflection signal generation circuit 21 are supplied to the input terminals of the main deflection coils attached to the necks of the projection tubes 181 to 183 corresponding to RGB. Is done. Further, the main deflection signal generation circuit 21 generates horizontal and vertical timing signals synchronized with the respective main deflection timings, and supplies them to the digital convergence unit 22.

  Here, a reflecting mirror is appropriately disposed between the three projection tubes 181 to 183 and the screen 19, and the image light projected from each of the projection tubes 181 to 183 is folded by this reflecting mirror and guided to the screen 19. This makes it possible to reduce the thickness of the device. Further, the positional relationship between the three projection tubes 181 to 183 and the screen 19 is different. For this reason, even if they are in the same projection tube, the positional relationship is different between the central portion and the peripheral portion of the screen, and the projected RGB color images do not overlap correctly, and distortion also occurs.

  The digital convergence unit 22 performs convergence adjustment to cope with such a problem, and a command from the microprocessor 15 and a synchronization signal from the main deflection signal generation circuit 21 are input to the convergence unit. Then, horizontal and vertical auxiliary deflection signals (six types) corresponding to the projection tubes 181 to 183 are generated, and these six types of auxiliary signals are supplied to the plus side terminals of the amplifier circuits 231 to 236.

  The outputs of the amplifiers 231 to 236 are supplied to horizontal and vertical auxiliary deflection coils 241 to 246 provided at the necks of the projection tubes 181 to 183, respectively. Each of the auxiliary deflection coils 241 to 246 is grounded via a current detection resistor 251 to 256, respectively. At both ends of these resistors 251 to 256, a voltage proportional to the current flowing through the auxiliary change coils 241 to 246 appears and is supplied to the negative terminals of the respective amplifier circuits 231 to 236. With the above configuration, a current proportional to the voltage waveform supplied to the plus side terminals of the amplifier circuits 231 to 236 flows through the auxiliary deflection coils 241 to 245.

  Next, the power supply of the amplifier circuits 231 to 236 will be described. For the power source, + A and + B are prepared on the plus side, and -A and -B (condition: A> B) are prepared on the minus side. The positive side power source is supplied to the switching circuit 261 and the negative side power source is supplied to the switching circuit 262, and the voltage is appropriately switched under the control of the switching timing signal generating circuit 27. The switching timing signal generating circuit 27 is supplied with a timing signal output from the main deflection signal generating circuit 21 and synchronized with the horizontal scanning and the vertical scanning. Then, the selection operation is performed so that + A and -A are selected only when the convergence correction region is at a position corresponding to the four corners of the screen, and + B and -B are selected in the other portions.

  FIG. 3 shows a detailed configuration of the digital convergence unit 22. The nonvolatile memory 30 stores data indicating the correction amount of the convergence adjustment point. FIG. 2 shows a screen at the time of the convergence adjustment. There are adjustment points at the intersections of the vertical and horizontal lines, and the convergence correction amount data at each adjustment point is stored in the nonvolatile memory 30. Data stored in the nonvolatile memory is transferred to the memory 32 by the operation of the microprocessor 15. The timing signal generation unit 34 is based on the vertical and horizontal scanning timings supplied from the main deflection signal generation unit, controls signals related to addresses and reading of the memories 31 and 32, and is necessary for the interpolation calculation unit 35. Generate a control signal. Convergence data is read from the memory 32 at a predetermined timing synchronized with scanning.

  The data read from the memory 32 is supplied to the interpolation calculation unit 35. The interpolation calculation unit 35 calculates the correction amount of the entire screen from the adjustment data of the adjustment point that is input, and outputs the convergence correction amount calculated in accordance with the scanning timing to the D / A converters 361 to 366. The convergence correction amount is an analog signal by the D / A converters 361 to 366, but is still a stepped waveform including a harmonic component. Therefore, the harmonic components are removed by the LPFs 371 to 376 and then output from the digital convergence unit 22.

Next, the convergence adjustment operation will be described. When the microprocessor 15 receives an instruction to start convergence adjustment via the input device 14, the microprocessor 15 controls the selection circuit 12 to select the output of the adjustment pattern signal generation circuit 13. Then, an adjustment image as shown in FIG. 2 is displayed on the screen. The adjuster instructs the adjustment position of convergence to the microprocessor 15 via the input device 14. The microprocessor 15 controls the adjustment pattern generation signal generation circuit 13 so that a certain marker (in the drawing, a square) is displayed in the vicinity of the adjustment point designated by the adjuster.

   The viewer adjusts the convergence of the marker position while looking at the screen. When the microprocessor 15 receives an instruction to perform adjustment by the viewer, the microprocessor 15 immediately increases or decreases the data in the memory 32 in the digital convergence. As a result, the convergence is adjusted as the viewer intends. When the viewer gives an instruction to complete the adjustment to the microprocessor 15, the microprocessor 15 stores the data in the memory 32 in the nonvolatile memory 30. Then, the selection circuit 12 is controlled so that the selection circuit 12 displays the video signal supplied to the input terminal 11. This completes a series of adjustment operations.

On the other hand, in the present invention, only when the convergence correction area is at a position corresponding to the four corners of the screen, the power supply voltage of the current amplifying circuits 231 to 236 is controlled to be high, and the correction area is located at a position other than the four corners. If the power supply voltage is low, the power loss of the current amplifier circuits 231 to 236 is reduced by lowering the power supply voltage. The basic principle of the present invention will be described in detail.

Assume that the white grid pattern shown in FIG. 4A is displayed on the screen. If the convergence is good, a similar image is displayed on the screen. FIG. 4B shows a diagram when the convergence correction is stopped. For each color of RGB, a lattice shape is found, and as a result, a color shift occurs. 5A to 5C individually show display patterns of RGB colors. In any of the figures, the distortion at the four corners of the screen is large. On the left and right sides of the screen, the distortion correlation is cut off. When attention is paid to the current waveform for correcting this distortion, the current change in the horizontal blanking period becomes large. Further, this current change becomes larger toward the upper end or lower end of the screen. Since the change amount (dI / dt) of the current flowing through the sub deflection yokes 241 to 246 is proportional to the output voltage of the current amplifier circuit, the required voltage is increased at the four corners of the screen.

  FIG. 6A shows a portion with a large current change, that is, a region where a high voltage is required, by a dotted line. In the regions 281 and 283, a high voltage is required in the horizontal blanking period and before and after. Therefore, as shown in FIG. 6B, in this region, the positive side waveform of the power supply voltage is controlled as indicated by 292, and the negative side waveform is controlled as indicated by 294. Further, in the region 282 other than the four corners of the screen, a high voltage is not required, and therefore, the power supply voltage is controlled as in the plus side waveform 295 and the minus side is controlled as in the waveform 296. A waveform 291 is a horizontal synchronization signal, and a waveform 293 is an auxiliary line indicating zero volts.

The maximum output voltage of the current amplification units 231 to 236 depends on the power supply voltage. On the other hand, the current outputs of these current amplifying units 231 to 236 do not depend on the power supply voltage but depend on the input signal. Generally, these current amplifying units 231 to 236 are configured by a class B push-pull circuit, and if the output current is constant, the higher the power supply voltage, the larger the power consumption inside the current amplifying unit. The calorific value increases. In the application of convergence correction, if the power supply voltage is increased only at the four corners of the screen where the current change is large, the heat generation of the current amplification unit can be suppressed to the minimum necessary, and the radiator can be downsized.

As described above, according to the convergence apparatus of the present invention, it is possible to satisfactorily prepare the convergence and suppress power consumption inside the current amplifying unit.

In the above description, the three-tube projection television receiver has been described, but it goes without saying that it can be used for a general television receiver.

The block diagram which shows the projection television receiver using this invention convergence apparatus. Explanatory drawing of the convergence adjustment screen in this invention. The block diagram which shows the digital convergence part in this invention. Explanatory drawing explaining a convergence correction amount. The figure explaining the convergence correction amount for every color of RGB. Explanatory drawing which shows the convergence correction | amendment and power supply waveform by this invention. The block diagram which illustrates a general convergence apparatus simply.

Explanation of symbols

11 ... Input terminal 12 ... Selection circuit
13 ... Pattern signal generating circuit for adjustment
14 ... Input device
DESCRIPTION OF SYMBOLS 15 ... Microprocessor 16 ... Video signal processing circuit 171,172,173 ... Amplifier circuit 181,182,183 ... Projection tube 19 ... Screen 20 ... Synchronous separation circuit 21 ... Main deflection signal generation circuit 22 ... Digital convergence section 231-236 ... Amplification circuit 241-246 ... Auxiliary deflection coil 261,262 ... Power supply voltage switching circuit 27 ... Switch timing generation circuit

Claims (5)

A convergence device in a CRT type display device,
A correction signal generator for generating a correction signal for correcting distortion and color misalignment of the screen of the display device;
A current amplifying unit for supplying the correction signal to a sub deflection coil disposed in the CRT;
A voltage switching unit that controls the power supply voltage of the current amplification unit to be high when the correction area of convergence is at a position corresponding to the four corners of the screen and the power supply voltage to be low in other regions; Convergence device characterized by   The current amplifying unit has a positive power source terminal and a negative power source terminal, and the voltage switching unit has a positive power terminal and a negative power source terminal when the convergence correction region is at a position corresponding to the four corners of the screen. 2. The convergence apparatus according to claim 1, wherein control is performed so that the voltage value is increased and the voltage values of the positive and negative power supply terminals are decreased in other regions. A convergence device in a projection display device having three projection tubes corresponding to R (red), G (green), and B (blue),
Sub-deflection coils respectively provided in the projection tube;
A correction signal generator for generating a correction signal for correcting distortion and color misalignment of the screen of the display device;
A current amplifying unit for supplying the correction signal to a sub deflection coil disposed in the projection tube;
A voltage switching unit that controls the power supply voltage of the current amplification unit to be high when the correction area of convergence is at a position corresponding to the four corners of the screen and the power supply voltage to be low in other regions; Convergence device characterized by   The current amplifying unit has a positive power source terminal and a negative power source terminal, and the voltage switching unit has a positive power terminal and a negative power source terminal when the convergence correction region is at a position corresponding to the four corners of the screen. 4. The convergence apparatus according to claim 3, wherein control is performed so that the voltage value is increased and the voltage values of the positive and negative power supply terminals are decreased in other regions. The voltage switching unit sets the power supply voltage of the current amplification unit at timings corresponding to the upper left, upper right, lower left, and lower right of the screen based on a horizontal / vertical synchronization signal that is a reference for deflection scanning of the projection tube. 4. The convergence apparatus according to claim 3, wherein the convergence apparatus is made high.

Images