JP2851842B2 - CRT display device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CRT display device which can reduce moire. [Prior Art] The present invention relates to a CRT display device that has been used to reduce moire. As a conventional example of a CRT display device, there is “NHK Color Television Textbook (above)” (p.231 to 239, p.166 to 167) (hereinafter referred to as a first conventional example). In addition, regarding the occurrence of moiré, refer to “I.E.E.E.E.
On-Consumer Electronics Vol. 28. No.1.2 Feb. 1982. Pages 44 to 54 (IEEE T
ransaction on Consumer Electronics, vol CE-28.No.
1. February. Pp. 44-55) ”(hereinafter referred to as a second conventional example). A conventional CRT display block diagram is shown in FIG. This conventional example has a deflection circuit 2 and a video amplifier 1. The video amplifier 1, a color video signal V _in is input, the display information. The deflection circuit 2 includes a horizontal delay circuit 3, a PLL 4, a horizontal drive and horizontal output circuit 5, a vertical delay circuit 6, a vertical oscillation circuit 7,
It comprises a vertical drive and vertical output circuit 8. This deflection circuit 2
, A horizontal synchronizing signal H _s and a vertical synchronizing signal V _s are applied from outside, and the signal H _s is taken into the horizontal delay circuit 3 and the signal V _s is taken into the vertical delay circuit 6. Signal H _s is performing horizontal deflection of the CRT electron beam through a horizontal delay circuit 3, PLL 4, a horizontal drive and horizontal output circuit 5. Signal V _s do vertical deflection of the CRT electron beam through a vertical delay circuit 6, the vertical oscillating circuit 7, the vertical drive and vertical output circuit 8. Electron beam at this time, an electron beam generated by receiving a video signal V _in from the video amplifier 1. The CRT is a shadow mask type, and the deflected electron beam collides with the phosphor screen through the shadow mask, and
To excite the fluorescent particles for display and display the required color. [Problems to be Solved by the Invention] In order to display a sharp image in a CRT display device, it is necessary that the beam spot diameter is small and the beam spot is sharp. However, in a color CRT display device, since a shadow mask is present in a cathode ray tube, as discussed in the second conventional example, when the beam diameter is reduced, light and dark fringes having a gentle period called moiré are generated. It is known that the contrast of light and dark of the moire depends on the beam spot diameter, and has a characteristic that when the spot diameter becomes smaller than a certain value with respect to the shadow mask pitch, it is sharply enhanced. For this reason, in order to display a high quality image that is sharp and free from moiré, a beam spot shape having a thickness that does not cause moire and a sharp shape (FIG. 9A)
Is preferred). On the other hand, in the conventional CRT display device, the beam shape is determined by the characteristics of the CRT as shown in the first conventional example, and the beam shape is controlled by adjusting the bias voltage of the focusing electrode of the CRT. That was going on. In this case, at the best focus point, the brightness distribution of this spot is shaped like a sharp bell as shown in FIG. 9 (b), but when the spot diameter is increased, the spot brightness distribution is shown in FIG. 9 (c). The hem spreads out,
The disadvantage of trying to eliminate moiré is that the sharpness deteriorates significantly. Further, recent CRT display devices have various resolutions, and more and more CRT display devices are used with variable resolutions. CRT display devices are shipped to the customer at the optimal resolution specified by the customer so that moire does not occur when delivered to the customer.However, when the customer changes to a different resolution, moire occurs. is there. An object of the present invention is to provide a CRT display device capable of suppressing the occurrence of moire corresponding to various resolutions. [Means for Solving the Problems] An object of the present invention is to provide a raster scan type CRT display device that irradiates an electron beam onto a phosphor screen through a shadow mask, in a state where the beam diameter of the electron beam is narrowed. When scanning in the direction, the electron beam is reciprocated in the horizontal direction periodically or aperiodically at the beam landing position of the electron beam, and the beam thickness is increased in appearance in the moving direction by the reciprocating movement. This is achieved by providing means and a moving amount variable means for adjusting the moving amount of the reciprocating movement and adjusting the apparent thickness of the electron beam. [Operation] Moire is caused by interference generated based on the difference between the pitch of the landing position of the electron beam and the pitch of the shadow mask. However, the appearance of the moire varies depending on the pitch of the shadow mask, and also varies depending on the thickness of the electron beam. Therefore, it is possible to make moiré invisible by reciprocating (vibrating) the electron beam to increase the beam diameter equivalently, but the resolution of the CRT display device is changed to another resolution. Then, Moire is seen again. Therefore, in the present invention,
The thickness of the apparent electron beam is adjusted by the moving amount variable means so that moiré is not visible at any resolution. [Embodiment] FIG. 1 shows an embodiment of a color display device of the present invention. The display device includes an image amplifier 1, a deflection circuit 2, a deflection control circuit 50, and a color CRT4. Video up width unit 1 performs incorporation predetermined increase width of the video signal V _in. Deflection circuit 2 performs horizontal and vertical scanning of capture electron beam horizontal sync signal H _s, a vertical synchronizing signal V _s. The internal configuration of the deflection circuit 2 is substantially the same as in FIG. The CRT 4 displays the video signal Vin synchronized with this scanning _in color. CRT4 is a shadow mask type. In the shadow mask type, a shadow mask that allows an RGB electron beam to pass is provided in front of the fluorescent screen of the CRT, and the RGB electron beam is passed through this shadow mask.
This is a CRT that collides with R, G, and B fluorescent particles to generate fluorescent light. The above is a normal CRT operation. The feature of this embodiment is that a deflection control circuit 3 is provided. The deflection control circuit 3 has a CR
It functions to periodically reciprocate the beam landing position (display pattern position) on the display surface of T4 as shown by the solid line and the dotted line. To this end, the deflection control circuit 50
Creates a deflection control signal and inputs it to the deflection circuit 2 to achieve the above function. In the following description, in order to simplify the expression of the position of the beam landing, that is, the position of the display pattern, the position is simply referred to as a display image or an image. The deflection circuit 2 scans under the control of the deflection control circuit 50 to generate a fluctuation state of an image. As a result, two states of a solid line and a dotted line appear as in the image 4A, and visually appear as in the image 4B. Thus, moiré was removed. FIG. 2 shows a specific embodiment of the present invention. The configuration of the deflection circuit 2 is the same as that of FIG. 8, and FIG. 2 shows only the features of this embodiment. The horizontal drive and horizontal output circuit 5 can be divided into a horizontal drive circuit 5A and a horizontal output circuit 5B, and the vertical drive and vertical output circuit 8 can be divided into a vertical drive circuit 8A and a vertical output circuit 8B. The horizontal output circuit 5B includes a transistor 9, a diode 10,
It comprises a capacitor 11, a flyback transformer 13, a horizontal deflection coil 14, and a capacitor 15. The base of the transistor 9, joined by a horizontal synchronizing signal H _s, the horizontal deflection coil 14, flows the horizontal deflection current, performs horizontal scanning of the electron beam. The vertical output circuit 8B includes an amplifier 20, a vertical deflection coil 21, and a capacitor 22. The amplifier 20, joined by a vertical synchronizing signal V _s, the flow vertical deflection current to the vertical deflection coil 21, performing the vertical scanning of the electron beam. The deflection control circuit 50 has a JK flip-flop (FF:
Electron beam moving means) 25, transistor 26, diode
27, 28, and variable resistors (moving amount variable means) 29, 30.
One ends of the variable resistors 29 and 30 are connected to output terminals of the horizontal deflection coil 14 and the vertical deflection coil 21, and only the DC components I ₀ and I ₁ are taken into the deflection control circuit 50. FF25 is, the input clock a vertical synchronization signal V _s. Accordance connexion, pulse synchronization (one vertical period, i.e. synchronized to one field) of the vertical synchronizing signal V _s to the ON
Repeat with OFF. _Tr 26 turns on in response to Q output 25a of FF25
Perform switching with OFF. Due to ON and OFF of the _Tr 26, the inflow currents of the DC components I ₀ and I ₁ are intermittent. As a result, the DC current flowing through the horizontal deflection coil 14 and the vertical deflection coil 21 is interrupted, and the raster center is moved horizontally and vertically. That is, the raster is alternately moved for each field. This amount of movement depends on the variable resistor 2
Adjustable in size of 9,30. In FIG. 1, the solid line in the screen indicates the state when _Tr 26 is OFF. At this time, no DC current flows through the horizontal deflection coil 14 and the vertical deflection coil 21. This is because they are cut off by the capacitors 15 and 22, respectively.
On the other hand, the dotted line portion in the screen of FIG. 1 indicates the ON state of _Tr 26. At this time, DC components I ₀ and I ₁ flow through the horizontal deflection coil 14 and the vertical deflection coil 21, respectively. The above operation waveforms in FIG. 2 are shown in FIG. For each field of the vertical synchronizing signal V _s, the DC component I _0, I ₁ it can be seen that the flow intermittently. In FIG. 1, the display is performed for each field in a solid line and a dotted line as in the screen 4A, but in a human field of view, the display screen 4B is synthesized due to the persistence of the human eye, and only the movement is apparent. It will be seen as one fat image. This has the same effect as making the beam spot wider by the movement equivalently, and the shape of the beam does not spread, so that the sharpness of the image is maintained. FIG.
FIG. 10 is a diagram in comparison with FIG. 9, and according to the present embodiment, the state is as shown in FIG. 4 (d). As described above, according to the present invention, the apparent beam spot diameter can be increased while the focus of the CRT is squeezed, so that the moire can be reduced without deteriorating the sharpness of the image. Also, since the adjustment of the beam spot diameter is performed by the deflection circuit system, the CRT only needs to focus on the optimum design of the focus pursuing only the sharpness, thereby facilitating the design of the electron gun. In other words, a color that has reduced moiré and optimized focus
A CRT display device can be easily realized. Also, compared to the conventional method of adjusting the focusing voltage,
According to this method, since the beam spot diameter can be adjusted independently in the horizontal and vertical directions, there is an effect that the optimum adjustment can be performed independently in the horizontal and vertical directions. FIG. 5 shows another embodiment of the present invention. In this embodiment,
It is characterized in that the screen is moved by adjusting the delay time of the horizontal delay circuit 3. In this embodiment, the horizontal delay circuit 3 is externally provided with a capacitor 4 for delay time adjustment.
0, a variable resistor 41 is provided, and a variable resistor 42 for connection to the FF 25 of the deflection control circuit 50 is provided at the connection point f. FF25 is Yotsute ON, and OFF of the presence of the vertical synchronizing signal V _s, Yotsute thereto,
The FF output side end of the variable resistor 42 is intermittent. Thus, as the resistance component, a parallel circuit of a resistor 41 and 42, and the single resistor of the resistor 41 only repeated in synchronism with the synchronizing signals V _s. As a result, the delay time can be adjusted. For example, if the delay time is determined by (capacity C of capacitor 40) × (resistance R),
The resistance R is a parallel resistance of the resistance 41 and the resistance 42 in a certain field, and is a resistance of only the resistance 41 in the next field, and the delay time changes alternately for each field. FIG. 6 shows the PLL 4 and the horizontal drive circuit 5A in the embodiment of FIG.
FIG. 3 shows an embodiment diagram centered on the horizontal output circuit 5B. The operation waveform diagram is shown in FIG. Horizontal delay circuit 3 generates a horizontal delay signal 3a delays the phase of the horizontal synchronizing signal H _s. The horizontal delay signal 3a has a different delay time for each field of the deflection control circuit 50 as described with reference to FIG. The horizontal drive circuit 5A includes a resistor 32, a transistor 33, a transformer 34, a resistor 36, a capacitor 35, resistors 37, 39, and a diode 3.
Consists of eight. The horizontal output circuit 5B is the horizontal output circuit 5B shown in FIG.
Is the same as The flyback transformer 13 has been disclosed in detail.
In the figure, this point is omitted. The horizontal delay signal 3a is guided to the horizontal output circuit 5B via the PLL 4 and the horizontal drive circuit 5A, and the deflection current flows to the horizontal deflection coil 14. As a result, the raster is displayed on the screen during the trace period, and the flyback transformer 13
A flyback pulse 13a is generated in the next winding 13A. The PLL 4 applies a flyback pulse 13 to the horizontal delay signal 3a.
The phase of the output 4a is adjusted so that the phase of a coincides, and the timing of the horizontal output unit is controlled. Therefore, the timing of the raster can be synchronized with the horizontal delay signal. In addition, since the video signal V _in is input in synchronization with the horizontal synchronizing signal H _s, the horizontal synchronizing signal H _s, a horizontal delay signal 3a
It is changing the phase, and varying the phase of the raster timing for the video signal V _in. At this time, on the screen, the raster corresponds to the background of the screen and is stationary.
The image is observed to move in the horizontal direction. Therefore,
By changing the phase of the signal 3a against H _s, it is possible to change the position of the image on the tube surface. The phase difference between H _s and the signal 3a is adjusted by changing the time constant of the external elements 40, 41. According to this embodiment, the image could be moved in the horizontal direction. Further, since only the phase is controlled as compared with the embodiment of FIG. 2, there is an effect that the power consumption can be reduced.
In addition, movement only in the vertical direction is also possible. The setting of each of the variable resistors 29, 30, 41, and 42 in FIGS. 2 and 5 can be performed by manual operation. in this case,
It may be variable in conjunction with the brightness adjustment volume. That is, since the beam spot size of the CRT increases as the beam brightness increases, the amount of movement is increased at low brightness and the amount of movement is reduced at high brightness.
This has the effect of keeping the beam spot thickness constant regardless of the beam brightness. The above is an embodiment in which an image is periodically moved. However, in order to perform this aperiodically, the input signal of the FF25 is not replaced by a periodic signal (for example, a vertical synchronization signal). A periodic signal may be used. For this purpose, a signal output from an independent oscillator may be used. Furthermore, for example, a random number from 0 to 9 is generated in the cycle of the oscillator, a signal is output at 0 to 4 to output HIGH, and a signal at 5 to 9 is output at LOW level. The image can be moved periodically. In the above embodiments, the configurations of the horizontal drive circuit 5A, the horizontal output circuit 5B, and the vertical output circuit 8B are not limited to the circuit configurations of FIGS. [Effects of the Invention] According to the present invention, it is possible to make moiré invisible by making the beam thickness of the electron beam seemingly thick, and even if moire occurs due to a change in resolution, the apparent thickness of the electron beam becomes large. There is an effect that generation of moiré can be suppressed by adjusting the amount according to the amount.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing an embodiment of a color display device according to the present invention;
FIG. 2 is a detailed embodiment diagram including a horizontal output circuit, a vertical output circuit, and a deflection modulation circuit of the present invention, FIG. 3 is a waveform diagram of each part in FIG. 2, and FIG. FIG. 5 shows another embodiment of the present invention in which the horizontal delay time is changed, FIG. 6 shows an embodiment of the horizontal deflection circuit 2A of the present invention, and FIG. FIG. 8 is a diagram of a conventional deflection circuit,
FIG. 9 is an explanatory view of a conventional beam spot diameter. 1. Video amplifier, 2. Deflection circuit, 50. Deflection control circuit.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Kunihiko Onuma               5-2-1 Omikacho, Hitachi City Stock Association               Omika Plant of Hitachi, Ltd. (72) Inventor Toshiyuki Ide               5-2-1 Omikacho, Hitachi City Stock Association               Omika Plant of Hitachi, Ltd. (72) Inventor Akira Hoshikawa               5-2-1 Omikacho, Hitachi City Stock Association               Omika Plant of Hitachi, Ltd.                (56) References JP-A-55-936 (JP, A)                 JP-A-56-168473 (JP, A)

Claims (1)

(57) [Claims] In a raster scan type CRT display device that irradiates a fluorescent screen with an electron beam through a shadow mask, when the electron beam is scanned in a horizontal direction while the beam diameter of the electron beam is narrowed, the electron beam is scanned at a beam landing position. An electron beam moving means for periodically or non-periodically reciprocating the electron beam in the horizontal direction and making the beam thickness apparently thicker by the reciprocating movement in the moving direction; and A CRT display device comprising: a moving amount variable means for adjusting an apparent thickness of an electron beam.