JPH0715613A - Monitor device - Google Patents

Abstract

PURPOSE:To effectively evade the shifts of images which are produced in both forward and reverse scans by forming a magnetic field in order to increase and reduce the beam scanning speed of a CRT in response to the image shift correcting current. CONSTITUTION:A linearity correcting coil 12 of the same configuration as a speed modulating coil 10 is placed on a G4 electrode put adjacent to the coil 10 in a monitor device 1. Then the coil 12 is driven by an error correcting circuit 13. Under such conditions, when a magnetic field is formed by the coil 12 so that the magnetic flux pierces vertically through the neck of a CRT 2, the beam scanning speed is variable by the change of the magnetic flux. Then it is possible to effectively evade the shifts of images produced in both forward and reverse scans by controlling the current of the coil 12.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. Fields of Industrial Application Conventional Technology (FIGS. 18 to 20) Problems to be Solved by the Invention (FIGS. 18 to 23) Means for Solving the Problems (FIGS. 1 to 3, FIG. 5, FIG. 7)
8, FIG. 12, FIG. 13, and FIG. 15 to FIG. 17) Operation (FIGS. 1 to 3, FIG. 5, FIG. 7, FIG. 8, FIG. 12, and FIG. 13)
15 to 17) Example (1) First Example (FIGS. 1 to 3) (2) Second Example (FIGS. 4 to 7) (3) Third Example (FIG. 8) To FIG. 12) (4) Fourth embodiment (FIGS. 13 to 16) (5) Fifth embodiment (FIG. 17) (6) Other embodiments Effect of the invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monitor device, and particularly to a monitor device to which a horizontal deflection circuit for bidirectional deflection is applied.

[0003]

2. Description of the Related Art Conventionally, in this type of monitor device,
As shown in comparison with the deflection method by raster scanning in FIGS. 18 and 19, a drive signal whose signal level changes symmetrically before and after a predetermined time point, such as a sine wave signal, is used. A deflection method for driving a horizontal deflection coil (hereinafter referred to as bidirectional deflection) has been proposed (US Pat. No. 4,672,449).

That is, as shown in FIG. 20, in this bidirectional deflection, the horizontal deflection coil is driven so that the deflection current _IL changes in signal level symmetrically before and after a predetermined time point t0. As a result, according to the deflection method, scanning from left to right of the screen (hereinafter referred to as forward scanning)
And conversely, scanning from the right to the left of the screen (hereinafter referred to as reverse scanning) can form a display image together and reduce the deflection frequency to 1/2. Further, since it is possible to prevent a sharp change in the deflection current such as a saw-tooth wave signal, it is possible to reduce unnecessary radiation and the like, and it is possible to reduce the load on the deflection circuit element.

[0005]

However, the bidirectional deflection system is characterized in that if the symmetry of the deflection current is slightly disturbed in the forward scanning and the backward scanning, the image quality of the display image is significantly deteriorated. That is, as shown in FIG.
In raster scanning, it is assumed that an image in which straight lines extending in the vertical direction are arranged at equal intervals in the horizontal direction is displayed.

As shown in FIG. 22, when the display image is displayed by applying the bidirectional deflection method, the display image is formed by the forward scanning and the backward scanning, respectively. When the deflection currents are formed symmetrically with respect to the directional scanning, the images formed by the forward scanning and the backward scanning are displayed in correct agreement.

On the other hand, as shown in FIG. 23, if the symmetry of the deflection current is slightly disturbed between the forward scanning and the backward scanning, the images formed by the forward scanning and the backward scanning are displaced and displayed. In this case, when the disturbance is small, the straight line is displayed thick and the focus characteristic of the display image is deteriorated. Further, when this disturbance becomes large, the straight line itself is displayed double, and in this case, the displayed image becomes extremely unsightly.

The present invention has been made in consideration of the above points, and provides a monitor device to which a bidirectional deflection system is applied, which can effectively avoid a shift of an image formed by forward scanning and backward scanning. It is a proposal.

[0009]

In order to solve such a problem, in the first invention, the forward and backward scanning is alternately repeated with reference to a predetermined video signal SV, and the video signal SV is sent to the cathode ray tube 2. Device 1 for forming a display image of
In, the image shift correction means 12 and 13 are provided, and the image shift correction means 12 and 13 are attached to the cathode ray tube 2 and an image forming a magnetic field so as to accelerate and decelerate the scanning speed of the beam of the cathode ray tube 2. A shift correction coil 12 and a coil drive circuit 13 that drives the image shift correction coil in correspondence with the forward and reverse scans so as to correct the shifts of the images formed in the forward and reverse scans, respectively. Be prepared.

Further, in the second invention, the coil drive circuit 13 corrects the image shift in which the shift amount changes in the vertical period by modulating the drive current I1 of the image shift correction coil in the vertical period of the video signal SV. To do.

Further, in the third invention, the video signal SV
The velocity modulation means 41, 42, 43, 44 for driving the velocity modulation coil 10 to form a modulation magnetic field so as to accelerate and decelerate the beam scanning velocity on the basis of the signal level of (1) to enhance the contour of the display image. , 45, 46, 47, 48, and the image shift correction means 10, 48, 49 share the velocity modulation coil 10 with the image shift correction coil.

Further, in the fourth invention, the velocity modulating means 41, 42, 43, 44, 45, 46, 47, 48 are:
A predetermined modulation coil drive signal S based on the video signal SV
D is generated and the velocity modulation coil 10 is driven based on the modulation coil drive signal SD, and the coil drive circuit 49 performs modulation so as to correct the deviation of the images formed by the forward scan and the reverse scan. The coil drive signal SD is corrected.

Further, in the fifth invention, the coil drive circuit 23 amplitude-modulates the drive current I1 of the image shift correction coil in the vertical period of the video signal SV to thereby shift the image shift in which the shift amount changes in the vertical period. to correct.

Further, in the sixth invention, the coil drive circuit 33 drives the image shift correction coil drive current I1 so that the current value rises in a triangular wave shape during a predetermined period of the horizontal cycle.
Is generated and the rising of the current value and the peak value are changed in the vertical cycle, thereby correcting the deviation of the image in which the deviation amount changes in the vertical cycle.

[0015]

The image shift correction coil 12 that forms a magnetic field so as to accelerate and decelerate the beam scanning speed is attached to the cathode ray tube 2 so as to correct the shift of the images formed by the forward and reverse scanning. Further, if the image shift correction coil 12 is driven in correspondence with the forward and backward scans, the image shift can be effectively avoided even when the symmetry of the deflection current is disturbed in the forward and reverse scans. You can

At this time, the drive current I of the image shift correction coil
1 is amplitude-modulated, or for the drive current I1 of the image shift correction coil in which the current value rises in a triangular wave shape during a predetermined period of the horizontal cycle, the rising of this current value and the peak value are changed in the vertical cycle, It is possible to correct the deviation of the image in which the deviation amount changes in a cycle.

At this time, the velocity modulation coil 10 can be shared with the image shift correction coil to simplify the overall configuration, and the modulation coil drive signal SD is corrected to correct the image shift, thereby further simplifying the overall configuration. Can be transformed.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

(1) First Embodiment In FIG. 1, reference numeral 1 denotes a monitor device as a whole, which drives a cathode ray tube 2 by applying a bidirectional deflection method, thereby forming a desired display image. That is, the monitor device 1
Drives the horizontal deflection coil 4 with the bidirectional deflection circuit 3 and drives the vertical deflection coil 6 with the vertical deflection circuit 5, whereby a bidirectional deflection method is applied to form a display screen.

Further, in order to cope with this bidirectional deflection, the monitor device 1 separates the horizontal synchronizing signal and the vertical synchronizing signal from the sequentially input video signal SV and outputs them to the bidirectional deflecting circuit 3 and the vertical deflecting circuit 5. Further, the video signal SV is input to the time axis inversion circuit 7, and the time axis of the video signal SV is inverted every horizontal scanning period. As a result, the monitor device 1 converts the time axis of the video signal by the time axis inverting circuit 7 so as to correspond to the forward scanning and the backward scanning to generate the video signal SV1, and the drive circuit based on the video signal SV1. The cathode ray tube 2 is driven at 8.

Further, in the case of this embodiment, the monitor device 1
Is a region of the cathode of the cathode ray tube 2 where three beams are crossed and emitted to the tube surface (that is, on the G ₄ electrode),
A velocity modulation coil 10 formed of a pair of upper and lower coils is arranged, and the magnetic flux formed by the velocity modulation coil 10 penetrates the neck of the cathode ray tube in the vertical direction.
As a result, the monitor device 1 is provided with the velocity modulation coil 10
Are driven by the speed modulation circuit 11 to form a modulation magnetic field, and by this modulation, the scanning speed of the beam can be modulated to perform speed modulation, so that the resolution of the display image can be improved. Has been done. In this velocity modulation, the polarity of the modulation magnetic field is switched in the forward scanning and the backward scanning corresponding to the bidirectional deflection.
As a result, even if the scanning direction is switched, the contour can be correctly emphasized.

Further, in this embodiment, the monitor device 1
Arranges a linearity correction coil 12 having the same structure as the velocity modulation coil 10 on the G ₄ electrode adjacent to the velocity modulation coil 10.
2 is driven by the error correction circuit 13 so that the deviation of the images formed by the forward scanning and the backward scanning can be effectively avoided.

That is, if a magnetic field is formed by the linearity correction coil 12 so that the magnetic flux penetrates through the neck of the cathode ray tube in the vertical direction, the scanning speed of the beam can be varied by changing the magnetic flux, and the linearity correction coil is accordingly increased. 1
The current of 2 can be adjusted to effectively avoid the shift of the images formed in the forward scanning and the backward scanning.

For this reason, in this embodiment, the error correction circuit 13 shown in FIG. 2 drives the linearity correction coil 12 to prevent image shift. That is, the error correction circuit 13 forms an emitter grounding circuit with the transistor 15, and connects the collector of the transistor 15 to the power supply 17 via the parallel circuit of the linearity correction coil 12 and the damping resistor 16.

As a result, as shown in FIG. 3 based on the deflection current I _L of the horizontal deflection coil 4 (FIG. 3A), the error correction circuit 13 raises the signal level at a predetermined timing of forward scanning. By applying the horizontal drive pulse SH to the base of the transistor 15 and controlling the transistor 15 to be turned on and off by the horizontal drive pulse SH, the current value of the linearity correction coil 12 is triangular while the signal level of the horizontal drive pulse SH rises. It is designed to rise in a wavy manner.

As a result, the period during which the horizontal drive pulse SH rises is selected as the period for correcting the image shift, and the voltage of the power supply 17 is set according to the image shift correction amount, so that the image formed during the forward scan is displayed. This can be corrected, and thus, the shift of the image formed by the forward scan and the backward scan in the horizontal direction can be effectively avoided.

According to the above construction, the linearity correction coil 12 is arranged in the neck of the cathode ray tube so that the magnetic flux penetrates the neck of the cathode ray tube in the vertical direction, and the linearity correction coil 12 is arranged at a predetermined timing of forward scanning. By driving the beam to change the scanning speed of the beam, the image formed during forward scanning can be corrected, thereby effectively avoiding the deviation of the image formed during forward scanning and backward scanning in the horizontal direction. can do.

(2) Second Embodiment Incidentally, in this kind of image shift, as shown in FIG. 4, the shift amount may change in the vertical cycle. Incidentally, FIG. 4 corresponds to the case where the deflection current in the forward scan changes in the parabola shape in the vertical cycle with respect to the reverse scan.

In this case, the error correction circuit shown in FIG. 2 cannot completely correct the image shift. Therefore, in this embodiment, as shown in FIG. 5, the terminal voltage of the linearity correction coil 12 is modulated by the vertical modulation signal VM to correct the image shift that changes in the vertical cycle.

That is, in the error correction circuit 23, a totem pole circuit is formed by the transistors 24 and 25 and the diode 26, and this totem pole circuit is used as the power supply 17
And the linearity correction coil 12 between them. Furthermore, the error correction circuit 23, as shown in FIG.
This totem pole circuit is driven by the vertical modulation signal VM whose signal level changes in a parabola shape in a cycle), thereby changing the terminal voltage of the linearity correction coil 12 so as to follow the signal level of the vertical modulation signal VM.

As a result, in the error correction circuit 23,
As shown in FIG. 7, the current I1 of the linearity correction coil 12 can be amplitude-modulated by the vertical modulation signal VM, whereby image shift can be effectively avoided even when the shift amount changes in the vertical cycle.

According to the configuration shown in FIG. 5, by amplitude-modulating the current of the linearity correction coil in the vertical cycle,
Even when the shift amount changes in the vertical cycle, it is possible to effectively avoid the shift of the images formed by the forward scanning and the backward scanning.

(3) Third Embodiment By the way, in the case where the current of the linearity correction coil is changed in the vertical cycle as described above, the same state can be formed even if the period in which the transistor 15 is turned on is changed. it can. Further, when the shift amount changes in the vertical cycle as described above, the range in which the shift is corrected by changing the shift amount may change in the vertical cycle. Therefore, in this embodiment, the image shift can be corrected even when the shift amount and the shift range change in the vertical cycle.

That is, as shown in FIG. 8, in this embodiment, the error correction circuit 33 inputs the horizontal drive signal SH1 and the vertical drive signal SV to the comparison circuit (COM) 34, and the output signal of this comparison circuit 34 causes the transistor Drive 15 Here, as shown in FIG. 9, the horizontal drive signal SH1 is
It is formed so that the signal level rises in a triangular wave shape in the horizontal cycle (H cycle), and as shown in FIG. 10, the vertical drive signal SV is configured such that the signal level changes in a parabolic shape in the vertical cycle.

As a result, the error correction circuit 33 phase-modulates the drive signal of the transistor 15 as shown in FIG. 11, thereby varying the period in which the transistor 15 is turned on in the vertical cycle. Has been done. Therefore, the current I1 of the linearity correction coil 12
In FIG. 12, as shown in FIG. 12, both the timing at which the current value rises in a triangular waveform and the peak value can be corrected in the vertical cycle, and even if the shift amount and the shift range change in the vertical cycle, the image shift Can be effectively avoided.

According to the configuration shown in FIG. 8, the transistor 1
By phase-modulating the drive signal of No. 5, the image shift can be effectively avoided even when the shift amount and the shift range change in the vertical cycle.

(4) Fourth Embodiment As shown in FIG. 13, in this embodiment, the monitor device 40 utilizes the velocity modulation coil 10 to correct the image shift. That is, as shown in FIG. 14, for example, during one horizontal scanning period, the brightness level of the video signal SV is held at the white level and the black level for a predetermined period, and during the period when the white level and the black level are held. When the signal level changes momentarily (FIG. 14 (A)), if the video signal of one horizontal scanning period continues in the horizontal scanning period, a display image as shown in FIG. 14 (B) is formed.

As shown in FIG. 15, the monitor device 40 supplies the video signal SV thus continuous (FIG. 15A) to the time axis inversion circuit 7, where the time axis is inverted every horizontal scanning period. Then, the video signal SV1 (FIG. 15B) applied to the bidirectional deflection is generated. Further, the monitor device 1 applies the video signal SV1 to the inverting amplifier 41 and the non-inverting amplifier 42, where the video signal SV1 is amplified and output with gains of 1 and -1, respectively.

The phase correction circuits 43 and 44 receive the output signals of the inverting amplifier 41 and the non-inverting amplifier 42, respectively,
Here, after phase correction of this output signal, the capacitor 45
The direct current component is cut and output via the output terminals 46 and 46. The selection circuit 47 inputs the output signals of the capacitors 45 and 46, and switches the contacts in forward and reverse scanning to alternately select and output the output signals of the inverting amplifier 41 and the non-inverting amplifier 42.

As a result, the monitor device 40 generates the video signal SV2 having the same polarity as that of the video signal SV input to the monitor device 40 in the forward scan (FIG. 15C), while In the directional scanning, the video signal SV2 whose polarity and time axis are inverted with respect to the video signal SV
To generate.

The drive circuit 48 extracts the contour of the video signal SV by differentiating the video signal SV2 to generate a differentiated signal SD (FIG. 15 (D)). By differentiating the video signal SV2 which is inverted, the polarity of the differential signal SD is inverted between the forward scanning and the backward scanning with respect to the change in the signal level of the video signal SV1. As a result, the drive circuit 48
Is the velocity modulation coil 10 based on the differential signal SD.
Is driven, and in the monitor device 40,
As a result, a modulation magnetic field can be formed with a polarity corresponding to bidirectional deflection to perform velocity modulation.

At this time, the monitor device 40 has the modulation current correction signal S1 (FIG. 15) generated by the correction signal generation circuit 49.
The current of the velocity modulation coil 10 is corrected based on (E)), and thus the image shift can be corrected using the velocity modulation coil 10.

That is, as shown in FIG. 16, the drive circuit 48
, The differential signal SD and the modulation current correction signal S1 are supplied to the drive unit 52 via the buffer circuits 50 and 51, respectively.
Output to. Here, the buffer circuits 50 and 51 form an emitter follower circuit with the transistors 53 and 54 and the resistors 55 and 56, respectively, and output the emitter output to the drive unit 52 via the capacitors 57 and 58.

The driving section 52 includes transistors 59 and 60.
Formed by a low output impedance drive circuit formed by the above, and after adding the emitter outputs of the buffer circuits 50 and 51, they are input to the bases of the transistors 59 and 60 via capacitors 61 and 62, respectively. As a result, the drive unit 52 adds the differential signal SD and the modulation current correction signal S1 and sets the signal level of the differential signal SD to the modulation current correction signal S.
It is designed to be corrected by 1.

In the drive unit 52, the resistors 63 to 67, the capacitors 68 to 70, and the zener diodes 71 and 72 form a bias circuit for the transistors 59 and 60. Further, the capacitors 74 and 75 and the resistors 76 to 79 form the transistor 59 and 60. It is adapted to form an emitter circuit of 60 and is operated by a power supply 80. As a result, the drive unit 52 drives the speed modulation coil 10 via the collector load of the capacitor 81 and the resistor 82. At this time, the signal level of the differential signal SD is corrected by the modulation current correction signal S1. An image shift is also corrected by the velocity modulation coil 10.

According to the configuration shown in FIG. 16, the differential signal SD
By correcting the signal level of 1 with the modulation current correction signal S1, it is possible to also correct the image shift by the velocity modulation coil 10, and thus the linearity correction coil can be omitted and the image shift can be performed with a simple configuration as a whole. It can be effectively avoided.

(5) Fifth Embodiment As shown in FIG. 17, in this embodiment, the differential signal S
Instead of correcting the signal level of D, the current of the velocity modulation coil 10 is directly corrected, and thereby the image shift is corrected. That is, the drive circuit 90 connects the collector of the transistor 15 to the speed modulation coil 10 via the coil 91, and further reverses the polarity of the horizontal drive pulse SH via the inversion circuit 92 to drive the transistor 15.

As described above, even if the current of the velocity modulation coil 10 is directly corrected, the image shift can be corrected, and thus the image shift can be effectively avoided with a simple structure.

(6) Other Embodiments In the above-described embodiments, the case where the image shift is corrected by changing the beam scanning speed during the forward scanning has been described, but the present invention is not limited to this. When scanning in the reverse direction, you may correct the image shift by changing the scanning speed of the beam,
Further, the image shift may be corrected by changing the beam scanning speed in both the forward scanning and the backward scanning.

Further, in the above-described embodiment, the image shift in which the shift amount changes in the vertical cycle is corrected by performing the amplitude modulation and further changing both the timing at which the current value rises in a triangular wave shape and the peak value thereof. However, the present invention is not limited to this, and only the timing may be changed to correct the image shift.

[0051]

As described above, according to the present invention, by forming the magnetic field so as to accelerate and decelerate the scanning speed of the beam of the cathode ray tube according to the image shift correction current, the forward scanning and the backward scanning are performed. It is possible to obtain a monitor device to which a bidirectional deflection method is applied, which can effectively avoid the deviation of the image formed in 1.

[Brief description of drawings]

FIG. 1 is a block diagram showing a monitor device according to an embodiment of the present invention.

FIG. 2 is a connection diagram showing the error correction circuit.

FIG. 3 is a signal waveform diagram for explaining the operation.

FIG. 4 is a schematic diagram showing an image shift that changes in a vertical cycle.

FIG. 5 is a connection diagram showing an error correction circuit according to a second embodiment.

FIG. 6 is a signal waveform diagram showing the modulated signal.

FIG. 7 is a signal waveform diagram showing an amplitude-modulated coil current.

FIG. 8 is a connection diagram showing an error correction circuit according to a third embodiment.

FIG. 9 is a signal waveform diagram showing a horizontal drive signal.

FIG. 10 is a signal waveform diagram showing a vertical drive signal.

FIG. 11 is a signal waveform diagram showing a drive signal.

FIG. 12 is a signal waveform diagram showing a coil current in that case.

FIG. 13 is a block diagram showing a monitor device according to a fourth embodiment.

FIG. 14 is a signal waveform diagram showing a video signal.

FIG. 15 is a signal waveform diagram for explaining the overall operation.

FIG. 16 is a connection diagram showing a drive circuit.

FIG. 17 is a connection diagram showing a drive circuit according to a fifth embodiment.

FIG. 18 is a schematic diagram for explaining raster scanning.

FIG. 19 is a schematic diagram for explaining bidirectional deflection.

FIG. 20 is a signal waveform diagram showing the deflection current.

FIG. 21 is a schematic diagram showing an image of raster scanning.

FIG. 22 is a schematic diagram showing a case where an image is correctly displayed by bidirectional deflection.

FIG. 23 is a schematic diagram showing a case where an image is displaced by bidirectional deflection.

[Explanation of symbols]

1, 40 ... Monitor device, 2 ... Cathode ray tube, 3 ... Bidirectional deflection circuit, 8, 48 ... Drive circuit, 10 ... Velocity modulation coil, 11 ... Velocity modulation circuit, 12 ... Linearity correction Coil, 13, 23, 33 ... Error correction circuit, 4
9 ... Correction signal generation circuit.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Osamu Maekawa 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (6)

[Claims] 1. A monitor device which alternately repeats forward and backward scanning on the basis of a predetermined video signal to form a display image of the video signal on a cathode ray tube, comprising an image shift correcting means, The image shift correction means is attached to the cathode ray tube, and forms an image shift correction coil that forms a magnetic field so as to accelerate and decelerate the scanning speed of the beam of the cathode ray tube, and forms the image shift correction coil in the forward and reverse directions, respectively. And a coil drive circuit that drives the image shift correction coil in response to the forward and reverse scanning so as to correct the image shift. 2. The coil drive circuit corrects the image shift in which the shift amount changes in the vertical period by modulating the drive current of the image shift correction coil in the vertical period of the video signal. The monitor device according to claim 1. 3. A speed for enhancing a contour of the displayed image by driving a speed modulation coil so as to accelerate and decelerate the scanning speed of the beam with reference to the signal level of the video signal to form a modulation magnetic field. 3. The monitor device according to claim 1, further comprising a modulation unit, wherein the image shift correction unit shares the speed modulation coil with the image shift correction coil. 4. The speed modulation means generates a predetermined modulation coil drive signal with reference to the video signal, drives the speed modulation coil based on the modulation coil drive signal, and the coil drive circuit comprises: 4. The monitor device according to claim 3, wherein the modulation coil drive signal is corrected so as to correct the shift of images formed by the forward scan and the reverse scan. 5. The coil drive circuit corrects the image shift in which the shift amount changes in the vertical cycle by amplitude-modulating the drive current of the image shift correction coil in the vertical cycle of the video signal. Claims 2 and 3 characterized
Alternatively, the monitor device according to claim 4. 6. The coil drive circuit generates a drive current for the image shift correction coil so that the current value rises in a triangular wave shape during a predetermined period of a horizontal cycle, and the rising and peak values of the current value are set as above. The deviation of the image, the deviation amount of which changes in the vertical cycle, is corrected by changing the deviation in the vertical cycle.
The monitor device described in 1.