JPH0863117A - Crt display device with rotating raster - Google Patents

Abstract

PURPOSE: To provide a CRT display device capable of controlling raster rotation without affecting color purity or a convergence. CONSTITUTION: The CRT display device includes CRT providing a screen 210 and a neck 350. An electric beam is directed from the neck 350 to the screen 210 along the axis (S) of CRT including the center of the screen 210. A deflecting means 320 provided in the neck 350 deflects the beam from the axis at the deflective center (X) of CRT and scans over the screen 210 in a raster pattern shape. Raster rotating means 300 and 310 rotates a raster pattern around the center of the screen 210. The raster rotating means 300 and 310 include first and second coils. The first coil 300 is arranged at the deflective center (X) or in the periphery of the neck 350 in the neighborhood of it so as to generate a first magnetic field in the pass of the electronic beam. The second coil 310 is arranged in parallel with the first coil in the periphery of the neck at a leaving side from the screen 210 at the time of viewing from the deflective center (X) so as to generate the second magnetic field in the pass of the electronic beam, which is provided with a polarity being opposite to the first magnetic field.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CRT display device for producing a rotatable raster scan image with respect to a CRT (cathode ray tube) display screen.

[0002]

BACKGROUND OF THE INVENTION Conventional color CRT display devices include a color CRT supported in a bezel and electrically connected to a display drive circuit. The CRT includes a screen on which the phosphor material is applied, a neck and a bell-shaped portion between the screen and the neck. The neck houses red, green and blue electron guns. The display driving circuit includes a line scanning circuit, a frame scanning circuit, an ultra high voltage (EHT: ex)
Includes a tra high tension generator and a video amplifier connected to the electron gun. A line deflection coil and a frame deflection coil are placed around the neck of the CRT. The deflection coil is connected to the line scanning circuit and the frame scanning circuit. In operation, the EHT generator creates an electric field in the CRT that accelerates electron beams corresponding to the red, green and blue primaries, respectively, toward the red, green and blue phosphor dots on the CRT screen. A conductive shadow mask overlaying the phosphor screen in the CRT directs the electron beam towards the corresponding phosphor dot. The line scanning circuit and the frame scanning circuit respectively generate a line scanning current and a frame scanning current flowing in the deflection coil. The line scan current and frame scan current take the form of a ramp signal to produce a time-varying magnetic field that scans the electron beam across the CRT screen in a raster pattern. The line scan signal and the frame scan signal are supplied to the broadcast television receiver or the personal television by the line scan circuit and the frame scan circuit, respectively.
It is synchronized with an input line sync signal H and an input frame sync signal V from a video source such as a computer. The video amplifier modulates the red, green and blue electron beams and produces an output display on the CRT as a function of the corresponding input video signals R, G and B produced by the video source.

[0003]

[Problems to be Solved by the Invention]
ter) is a CRT in which the overlaid red, green and blue images are traced by red, green and blue electron beams, respectively.
Formed in the output display above. Ideally, these images are spatially coincident. However, images generally do not match exactly at every point on the screen. Normally, a 0.3 mm mis-convergence is detected at the corner of the screen. This convergence error appears in the display output so that one side of the displayed character is bordered and colored.

In addition to convergence errors, the display output may show color purity errors. Color purity errors occur when an electron beam of one color is directed onto phosphor dots of different colors. This is caused by distortion or magnetization of the shadow mask.

The raster, and thus the rectangular image displayed on the CRT screen, is preferably aligned with the bezel. This provides a good appearance and maximizes the available screen area where the image can be displayed without data loss. However, the raster can be undesirably skewed with respect to the bezel. Such raster skew is a mechanical misalignment of the CRT with respect to the bezel.
ent), mechanical misalignment of the deflection coil on the CRT,
It is generated by mechanical misalignment of the electron gun in the CRT, an external magnetic field such as geomagnetism, or a combination thereof. It will be appreciated that the effect of geomagnetism on raster rotation can vary with geographic location and CRT orientation.

[0006]

According to the present invention, a CRT having a screen and a neck, a means for directing an electron beam from the neck toward the screen along the axis of the CRT including the center of the screen, and the neck Deflection means provided above and for deflecting the beam from the axis at the deflection center of the CRT and scanning the beam in a raster pattern over the screen, and a raster rotation for rotating the raster pattern around the center of the screen. And a CRT display device including the means. In particular, a raster rotation means is arranged around the neck at or near the deflection center and produces a first magnetic field in the path of the electron beam.
And a second magnetic field which is arranged parallel to the first coil around the neck away from the screen when viewed from the deflection center and which generates a second magnetic field having a polarity opposite to the first magnetic field in the path of the electron beam. And a coil.

The magnetic field from the first coil provides the raster rotation. At the same time, the second coil produces a magnetic field in the neck that corrects for convergence and purity errors that result from the rotation of the raster under the magnetic field of the first coil. The present invention thereby allows control of raster rotation without affecting color purity or convergence.

When the first and second coils are connected in series, the first coil preferably has a much higher number of turns than the second coil. On the other hand, when the first and second coils are connected in parallel, the second coil is the first
It is preferable to have a much higher number of turns than the coil of. In both cases, the device preferably comprises a DC voltage source for supplying a DC voltage across the coil.

In a preferred embodiment of the present invention, there is provided control means which is connected to a voltage source and which varies the DC voltage supplied across the coil by the voltage source to vary the current flowing through the coil. This control means preferably includes means for reversing the direction of the current flowing through the coil.

In a particular preferred embodiment of the invention, a manual input means is provided which is connected to the control means and which regulates the current flowing in the coil in response to the manual input. Preferably, sufficient current is provided to allow rotation of the raster within about 2 ° in both directions.

Looking at the present invention from another aspect, a CRT having a screen and a neck, a means for directing an electron beam from the neck toward the screen along an axis of the CRT including the center of the screen, and on the neck. And a deflection means for deflecting the beam from the axis at the deflection center of the CRT and scanning the beam in a raster pattern across the screen.
A method is provided for rotating a raster pattern about the center of the screen in a T-display. Particularly, this method includes a step of generating a first magnetic field in the path of the electron beam by a first coil arranged around the neck of the deflection center or in the vicinity thereof, and a neck away from the screen when viewed from the deflection center. A second coil disposed in the periphery in parallel with the first coil
Generating a second magnetic field having a polarity opposite to that of the first magnetic field in the path of the electron beam by the coil.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, the CRT display device of the present invention includes a color CRT display screen 210 connected to a display drive circuit 200. The display drive circuit 200 has an ultra high voltage (E
HT) generator 230 and a video amplifier 250 connected to the display screen 210. A line deflection coil 290 and a frame deflection coil 280 are placed on the yoke 320 around the neck of the CRT. Deflection coils 290 and 2
80 is connected to the line scanning circuit 220 and the frame scanning circuit 240, respectively. Line scan circuit 220 and EHT generator 230 each take the form of a flyback circuit, the operation of which is well known to those skilled in the art. Further, the EHT generator 230 and the line scanning circuit 220 are
It can also be integrated in a single flyback circuit.
Power supply (not shown) via power rail (not shown)
It is connected to the EHT generator 230, the video amplifier 250, the line scanning circuit 220, and the frame scanning circuit 240.
Power is supplied along the power rail from line and neutral connections (not shown) to the domestic electrified mains source (domestic elect).
power to the ricity mains supply). The power supply can take the form of a switch mode power supply, the operation of which is known to those skilled in the art.

EHT generator 230, video amplifier 25
0, line scanning circuit 220 and frame scanning circuit 240
Are each connected to a display processor 270. Display processor 270 includes a microprocessor. The user control panel 260 is provided on the front surface of the display device 130. The control panel 260 includes a plurality of manually operated switches. The user control panel is connected to the keypad interrupt line of processor 270.

In operation, the EHT generator 23
0 creates an electric field in the CRT 210, and this electric field
Accelerate the electron beams corresponding to the red, green, and blue primary colors toward the screen. The line scanning circuit 220 and the frame scanning circuit 240 include deflection coils 290 and 28.
A line scanning current and a frame scanning current flowing to 0 are generated respectively. The line scan current and the frame scan current take the form of ramp signals to produce a time-varying magnetic field that scans the electron beam across the CRT screen in a raster pattern. The line scan signal and the frame scan signal are synchronized with an input line sync signal H and an input frame sync signal V generated by a video source such as a personal computer system unit by the line scan circuit and the frame scan circuit, respectively. . Video amplifier 25
0 modulates the red, green and blue electron beams and the corresponding red, green and blue respective input video signals R, G and B generated by the video source.
Produces an output display on the CRT as a function of.

The display processor 270 is an EHT generator 23.
0, video amplifier 250, line scan circuit 220 and frame scan circuit 240 outputs are configured to be controlled via control link 275 as a function of preprogrammed display mode data and input from user control panel 260. To be done. The display mode data is a general display mode different from each other, for example, 1024 × 768 pixels,
It includes a set of preset image parameter values corresponding to 640 × 480 pixels, 1280 × 1024 pixels, or the like. Each set of image display parameter values includes a height and center value that sets the output of the frame scan circuit 240, and a width and center value that controls the line scan circuit 220. In addition, the display mode data is preset with common preset image parameter values that control the gain and cutoff of the red, green and blue channels of the video amplifier 250 and the output of the EHT generator 230. Contains the control value that was set. The image parameter value is responsive to the mode information from the video source,
Selected by the display processor 270. Display processor 270 processes the selected image parameter values and produces analog control levels on control link 275.

The user can manually adjust the control level transmitted from the display processor 270 to the drive circuit 200 through the user control panel 260, and adjust the position of the display picture according to personal preference. The user control panel 260 allows the image height, center, width,
Includes a set of up / down control keys for each of brightness and contrast. Each key is a display processor 27
0 controls one or a combination of various control levels. These control targets include the video amplifier 250.
The levels of video gain and cutoff for red, green and blue at, or the width, height and center level of the image at line scan circuit 220 and frame scan circuit 240 are included.

The control keys are preferably in the form of push buttons connected to keypad interrupt inputs to the display processor 270. For example, when the width up key is pressed, the user control panel 260 issues a corresponding interrupt to the display processor 270. The issuer of the interrupt uses the display processor 27 through the interrupt polling routine.
It is judged by 0. In response to the interrupt from the width key,
The display processor 270 gradually advances the line scanning circuit 220.
To increase the corresponding analog control level sent to. This gradually increases the width of the image. When the desired width is reached, the user releases the key. The removal of the interrupt is detected by the display processor 270 and the digital value that sets the width control level is saved. The settings of height, center, brightness and contrast are similarly adjusted by the user. User control panel 260 preferably also includes a store key. When the user presses the store key, an interrupt is generated and the display processor 270 responsively stores the parameter value corresponding to the current setting of the digital output to the D / A converter in memory as the preferred display format. . The user can thus program the display image parameters specific to the display device 130 according to personal wishes.

Referring to FIG. 2, CRT 210 has a symmetric horizontal axis S, which corresponds to the path through which the undeflected electron beam travels from the electron gun to the center of the display screen. The deflection center X is located on the axis S. At the deflection center X, all deflected electron beams appear to deviate from the axis S. A permanent magnet assembly 340 for optimizing color purity and beam focusing is placed around the neck 350 of the CRT 210. According to the present invention, the display device includes first and second raster rotating coils 300 and 310. First coil 3
00 includes or is at least close to the deflection center X,
It is arranged in the plane around the yoke 320 perpendicular to the axis S. The second coil 310 is disposed around the neck of the CRT 210 on the side away from the yoke 320 as viewed from the purity / focusing assembly.

Referring to FIG. 3, in one embodiment of the present invention, coil 300 and coil 310 include variable DC voltage source 33.
0 connected in series. In particular, the voltage source 330 is the coil 3
In addition to increasing or decreasing the voltage applied to 00 and 310, it can also be inverted. This allows a DC current to flow in the coil in either direction. D
As the C current flows through the coil 300, a constant magnetic field is generated at or near the deflection center in the CRT. This magnetic field rotates the raster according to Fleming's left-hand rule. The degree of rotation depends on the magnetic field strength, and the magnetic field strength depends on the current value flowing through the coil 300. The direction of rotation depends on the direction of the current flowing through the coil 300. The same current that flows in coil 300 also flows in coil 310.

In operation, when the magnetic field from coil 300 provides the desired raster rotation, coil 31
0 is a CRT 21 for the magnetic field that corrects for convergence and purity errors that occur when the raster is rotated through the coil 300.
Generate within the 0 neck. The present invention thereby allows control of the rotation of the raster without affecting color purity or convergence. Preferably, sufficient current is provided to allow rotation of the raster within about 2 ° in both directions. User control panel 260 includes a pair of keys for controlling the output of voltage source 330 via display processor 270. One key allows the user to rotate the raster clockwise within the range and the other key allows it to rotate counterclockwise within the range. In series configuration, the coil 300 has, for example, 330 turns,
The coil 310 has, for example, 21 turns.

Referring to FIG. 4, another embodiment of the present invention is shown in which coils 300 and 310 are voltage sources 33.
0 is connected in parallel.

The voltage source 330 is configured to increase or decrease the voltage across both coils 300 and 310 as well as to be reversible. Therefore, also in this case, it is possible to pass the DC current in the coil in either direction. The functions of the coils 300 and 310 in the parallel configuration are
Substantially the same functions as described above in connection with the serial configuration of FIG. However, it will be appreciated that in a parallel configuration, the current flowing through coil 300 is not necessarily the same as the current flowing through coil 310. The same key buttons in the user control panel 260 allow the effects provided by the side-by-side configuration to be manually adjusted. In the parallel configuration described above, the coil 300 has, for example, 140 turns and the coil 310 has, for example, 1000 turns.

Referring to FIG. 5, coils 300 and 31
The currents flowing through 0 are indicated by I and I ', respectively. FIG.
It will be appreciated that in the series configuration of I and I ′ are the same. The arrows indicate the direction of current flow through the coils 300 and 310 to produce a counterclockwise raster rotation. The coil ends A, B, C and D correspond to the nodes A, B, C and D in FIGS. 3 and 4, respectively.

In general, the number of turns in each coil 300 and 310 is adjusted so that the convergence error introduced by coil 300 is offset by the correction magnetic field introduced by coil 310 into the neck of CRT 210. As a result, it is possible to provide a raster rotation function with reduced purity error and convergence error.

In summary, the following matters will be disclosed regarding the configuration of the present invention.

(1) A CRT having a screen and a neck,
A means for directing an electron beam from the neck toward the screen along an axis (S) of the CRT including the center of the screen; and the beam provided on the neck for directing the beam to the CRT.
Deflecting means for deflecting the beam in a raster pattern over the screen at the deflection center (X), and raster rotating means for rotating the raster pattern around the center of the screen. And a raster rotation means disposed around the neck at or near the deflection center (X) to generate a first magnetic field in the path of the electron beam. A coil,
A second coil having a polarity opposite to that of the first magnetic field is disposed in the path of the electron beam around the neck on the side away from the screen as viewed from the deflection center (X) and in parallel with the first coil. A second coil that produces a magnetic field. (2) The device according to (1), wherein the first coil and the second coil are connected in series. (3) The device according to (2), wherein the first coil has more turns than the second coil. (4) The device according to (1), wherein the first coil and the second coil are connected in parallel. (5) The device according to (4), wherein the second coil has more turns than the first coil. (6) The device according to any one of (1) to (5), including a DC voltage source that applies a DC voltage to the coil. (7) The control unit is connected to the voltage source and includes a control unit that varies a DC voltage applied to the coil by the voltage source to vary a current flowing through the coil.
The described device. (8) The device according to (7), wherein the control means includes means for reversing the direction of the current flowing through the coil. (9) Connected to the control means, in response to a manual input,
The device according to (7) or (8) above, which includes a manual input means for adjusting a current flowing through the coil. (10) A CRT having a screen and a neck, a means for directing an electron beam from the neck toward the screen along the axis of the CRT including the center of the screen, and the means provided on the neck, The beam is deflected from the axis at the deflection center of the CRT and the beam is rastered across the screen.
Deflection means for scanning in a pattern, and raster rotation means for rotating the raster pattern around the center of the screen,
A method of rotating the raster pattern about the center of the screen, wherein the first coil disposed around the neck at or near the deflection center of the electron beam A step of generating a first magnetic field in the path, and a second coil arranged parallel to the first coil around the neck on the side away from the screen viewed from the deflection center, Generating a second magnetic field of opposite polarity to the first magnetic field in the path of.

[0027]

According to the present invention, a raster rotation function with reduced purity error and convergence error is provided.

[Brief description of drawings]

FIG. 1 is a block diagram of a CRT display device.

FIG. 2 is a side view of a CRT of a CRT display device.

FIG. 3 is a circuit diagram of a raster rotating coil for display.

FIG. 4 is another circuit diagram of a raster rotating coil for display.

FIG. 5 is a side view of a raster rotating coil on a CRT.

[Explanation of reference numerals] 200 display driving circuit 210 color CRT display screen 220 line scanning circuit 230 ultra high voltage (EHT) generator 240 frame scanning circuit 250 video amplifier 260 user control panel 270 display processor 275 control link 280 frame deflection coil 290 line deflection Coil 300 First raster rotating coil 310 Second raster rotating coil 320 Yoke 330 Variable DC voltage source 340 Permanent magnet assembly 350 Neck

Claims (10)

[Claims] 1. A CRT having a screen and a neck, means for directing an electron beam from the neck toward the screen along an axis (S) of the CRT including the center of the screen, and provided on the neck. Deflection means for deflecting the beam from the axis at the deflection center (X) of the CRT and scanning the beam in a raster pattern over the screen; and rotating the raster pattern around the center of the screen. CRT display device including: a raster rotating unit that rotates to a first position, wherein the raster rotating unit is disposed around the neck near the deflection center (X) or in the vicinity of the deflection center (X); A first coil for generating a magnetic field; and a first coil, which is arranged in parallel with the first coil around the neck on the side away from the screen when viewed from the deflection center (X). A second coil in the path that produces a second magnetic field of opposite polarity to the first magnetic field; 2. The device of claim 1, wherein the first coil and the second coil are connected in series. 3. The apparatus of claim 2, wherein the first coil has more turns than the second coil. 4. The apparatus of claim 1, wherein the first coil and the second coil are connected in parallel. 5. The apparatus of claim 4, wherein the second coil has more turns than the first coil. 6. The device according to claim 1, further comprising a DC voltage source for applying a DC voltage to the coil. 7. The apparatus of claim 6 including control means connected to said voltage source for varying the DC voltage applied to said coil by said voltage source to vary the current flowing through said coil. 8. The apparatus of claim 7 wherein said control means includes means for reversing the direction of current flow through said coil. 9. The apparatus of claim 7 or 8 including manual input means connected to said control means and responsive to manual input for adjusting the current flowing through said coil. 10. A CRT having a screen and a neck, means for directing an electron beam from the neck toward the screen along an axis of the CRT including the center of the screen, and the CRT being provided on the neck, Deflection means for deflecting the beam from the axis at the deflection center of the CRT and scanning the beam in a raster pattern over the screen; and raster rotation means for rotating the raster pattern around the center of the screen. A method for rotating the raster pattern around the center of the screen, wherein the first coil disposed around the deflection center or in the vicinity of the neck of the electron beam Generating a first magnetic field in the path, the first coil being provided around the neck on the side away from the screen when viewed from the deflection center. The are arranged in rows 2
Generating a second magnetic field of opposite polarity to the first magnetic field in the path of the electron beam by the coil of.