JPH06284309A - Monitor device - Google Patents

Abstract

PURPOSE:To obtain a monitor device having simple constitution in which picture quality can be improved by switching the polarity of a modulation magnetic field according to a back-and-forth path to modulate a speed according to bidirectional deflection. CONSTITUTION:This device is equipped with a modulating coil 10 which forms the modulation magnetic field for accelerating and decelerating the scanning speed of the beam of a cathode ray tube 2, and speed modulating means 11, 12, and 21-26 which obtain a differentiated signal S1 by differentiating a video signal SV1, generate a driving signal by using the differentiated signal S1 as a reference, and drive the modulating coil 10 by impressing the driving signal to the modulating coil 10. Then, the polarity of the driving signal to be impressed to the modulating coil 10 is switched by the speed modulating means 11, 12, and 21-26 according to the scanning of the back-and-forth path. Thus, the polarity of the driving signal to be impressed to the modulating coil 10 is switched according to the scanning of the back-and-forth path, so that even when the scanning direction is switched on the back-and-forth path, the scanning speed of the beam of the cathode ray tube 2 can be accelerated and decelerated corresponding to the switching of the scanning direction.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. Industrial Application Conventional Technology (FIGS. 6 and 7) Problem to be Solved by the Invention (FIGS. 8 to 10) Means for Solving the Problem (FIGS. 1 and 2) Action (FIGS. 1 and 2) ) Example (1) Configuration of Example (FIGS. 1 to 5) (2) Effect of Example (3) Other Example Effect of 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, there has been a monitor device adapted to improve a focus characteristic of a cathode ray tube by applying a velocity modulation method. That is, as shown in FIG. 6, for example, when the brightness level of the video signal SV changes rapidly during one horizontal scanning period, if the brightness level of the display screen changes rapidly following the change of the brightness level, the sharp Such a display image can be obtained (FIG. 6 (A)). By the way, if the video signal in one horizontal scanning period is continuous in the horizontal scanning period, a display image as shown in FIG. 6B is formed.

However, the cathode ray tube has a feature that it is difficult to reduce the beam diameter to a predetermined value or less, and further, even if the cathode voltage is rapidly changed, the beam current does not follow the rapid change and the beam current is not rapidly changed. Therefore, this video signal SV is shown in FIG.
As shown in an enlarged view of a portion in which the signal level of (1) is rapidly changed (FIG. 7A), even if the signal level of the video signal SV is rapidly changed by simply performing the raster scan of the beam, The display screen has a characteristic that the brightness changes only gradually (FIG. 7B).

Therefore, the monitor device to which the velocity modulation method is applied differentiates the video signal SV to obtain the differential signal S1 whose signal level changes at the rising and falling of the signal level of the video signal SV (see FIG. 7). (C)), the scanning speed of the raster scanning beam is varied with reference to the differential signal S1 (FIG. 7D). That is, when the signal level of the video signal SV rises abruptly, this type of monitor device increases the scanning speed immediately before the rising edge and decreases the scanning speed immediately after the rising signal level.

On the contrary, when the signal level of the video signal SV suddenly falls, the scanning speed is slowed down just before this trailing edge, and the scanning speed is increased immediately after the trailing signal level. By doing so, it is possible to form the same state as when the beam current changes abruptly before and after the rise and fall of the signal level, and thereby the brightness of the display screen can be rapidly raised and lowered. The focus characteristic of the display screen can be apparently improved.

Therefore, this type of monitor device forms a predetermined drive signal with reference to the differential signal generated from the video signal, and drives the velocity modulation coil with this drive signal. This velocity modulation coil is arranged in the neck portion of the cathode ray tube, and modulates the red, blue, and green beams so that they cross each other once and are emitted toward the tube surface so as to vertically penetrate the neck. Create a magnetic field.

As a result, the monitor device adjusts the modulation coil based on the differential signal so as to accelerate or decelerate the scanning speed V1 for raster scanning of the beam in accordance with the change in the signal level of the video signal. It is driven so that, as shown by a broken line in FIG.
The brightness of the display screen can be rapidly raised and lowered.

[0009]

By the way, in this type of monitor device, as shown in comparison with the deflection system by raster scanning in FIGS. 8 and 9, for example, a sine wave signal is used as a reference at a predetermined time point. Then, a deflection circuit that drives the horizontal deflection coil using a drive signal whose signal level changes symmetrically before and after this point (hereinafter referred to as a bidirectional deflection deflection circuit).
Have been proposed (US Pat. No. 4,672,449).

According to this deflection circuit, scanning from left to right of the screen (hereinafter referred to as forward scanning) and conversely, scanning from right to left of the screen (hereinafter referred to as backward scanning) are performed. Together they can form a display image and reduce the deflection frequency by half. 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.

However, the monitor device to which the bidirectional deflection is applied has a problem that the conventional velocity modulation method applied to the raster scanning cannot be applied as it is. That is, as shown in FIG. 10 in which the time axis and the scanning direction are opposite, in the case of bidirectional deflection, the backward scan is performed by inverting the time axis of the video signal in the opposite direction to the case of the conventional raster scan. As a result, the magnetic field forming direction of the horizontal deflection coil is opposite to that in the forward path.

Thus, when the velocity modulation method is applied to the bidirectional deflection circuit, the modulation magnetic field formed so as to accelerate the scanning speed on the forward path acts in the direction of decelerating the scanning speed on the reverse path. Therefore, the differential modulation S1 (FIG. 10 (C)) is generated from the video signal SV (FIGS. 10 (A) and (B)) by directly applying the velocity modulation method of Lathra scanning.
When the modulation magnetic field is formed on the basis of the differential signal S1, the beam scanning speed becomes slow immediately before the signal level rises and becomes high immediately after the signal level rises (FIG. 10 (D)). As shown by the broken line, the luminance change of the display screen to be emphasized is suppressed and displayed (FIG. 10 (E)).

Incidentally, on the outward path, the scanning speed can be accelerated and decelerated by following the change in the signal level of the video signal as in the case of the raster scanning, so that the change in the brightness of the display screen is emphasized and displayed. Like In this case, the image quality is greatly different between the forward pass and the return pass, and as a whole, the image quality of the display screen deteriorates.

The present invention has been made in consideration of the above points, and is intended to propose a monitor device having a simple structure which can be applied to the case of bidirectional deflection to improve the image quality by speed modulation. Is.

[0015]

In order to solve such a problem, in the first invention, the forward and backward scans are repeated with reference to a predetermined video signal SV1, and a display screen of the video signal SV1 is displayed on the cathode ray tube 2. In the monitor device 1 to be formed, a modulation coil 10 which forms a modulation magnetic field for accelerating and decelerating the scanning speed of the beam of the cathode ray tube 2, and a video signal SV.
1 is differentiated to obtain a differential signal S1, a drive signal is generated with the differential signal S1 as a reference, and the drive signal is applied to the modulation coil 10 to drive the modulation coil 10.
2, 21, 22, 23, 24, 25, and 26, and velocity modulation means 11, 12, 21, 22, 23, 24, 2
Reference numerals 5 and 26 switch the polarity of the drive signal applied to the modulation coil 10 in the forward and backward scans.

Further, in the second invention, the velocity modulation means 11, 12, 21, 22, 23, 24, 25, 26 are:
The video signal S is applied to the inverting amplifier circuit 12 and the non-inverting amplifier circuit 11.
Upon receiving V1, the inverting amplifier circuit 12 and the non-inverting amplifier circuit 12
By selectively differentiating the output signal of 1 to generate the differentiated signal S1, the polarity of the drive signal applied to the modulation coil 10 is switched in the forward and backward scans.

Further, in the third invention, the video signal SV
Reference numeral 1 is a video signal whose time axis is reversed in the forward and backward scanning.

[0018]

By switching the polarity of the drive signal applied to the modulation coil 10 during the forward and backward scans, the beam of the cathode ray tube 2 can be changed in response to the switching of the scanning directions even when the scanning directions are switched between the forward and backward paths. The scanning speed of can be accelerated or decelerated.

[0019]

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

(1) Structure of the 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, as shown in FIG.
In order to deal with this bidirectional deflection, the horizontal synchronizing signal and the vertical synchronizing signal are separated from the sequentially input video signal SV and output to the bidirectional deflecting circuit 3 and the vertical deflecting circuit 5 (FIG. 2A). ) 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 (FIG. 2 (B)). 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 and backward scans, and converts the video signal S.
V1 is generated, and the drive circuit 8 drives the cathode ray tube 2 based on the video signal SV1.

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 modulation coil 10 formed of a pair of upper and lower coils is arranged, and a modulation magnetic field is formed by this modulation coil 10 so that velocity modulation can be performed. Therefore, the monitor device 1
The video signal SV1 output from the time axis inverting circuit 7 is applied to the inverting amplifier 11 and the non-inverting amplifier 12, where the video signal SV1 is amplified and output with gains of 1 and -1, respectively.

That is, as shown in FIG. 3, the inverting amplifier 11
Is a grounded-emitter amplifier circuit composed of resistors 13 to 15 and a transistor 16, which amplifies a video signal with a gain of 1 and outputs a video signal whose polarity is inverted from the collector of the transistor 16. Has been done.
On the other hand, as shown in FIG. 4, the non-inverting amplifier 12 is a grounded-emitter amplifier circuit formed by resistors 17 to 19 and a transistor 20, and outputs the emitter output of the transistor 16 to obtain a gain of 1 Amplify with
Moreover, the video signal having the same polarity as the input is output.

The phase correction circuits 22 and 23 receive the output signals of the inverting amplifier 11 and the non-inverting amplifier 12, respectively,
Here, after the phase correction, the DC component of the video signal is cut and output via the capacitors 24 and 25. The selection circuit 21 inputs the capacitors 24 and 25, and switches the contacts in synchronization with the forward scan and the backward scan to alternately select and output the output signals of the inverting amplifier 11 and the non-inverting amplifier 12.

As a result, the monitor device 1 makes the video signal SV input to the monitor device 1 in the forward scan.
A video signal SV2 having the same polarity as that of is generated and output to the speed modulation circuit 26 (FIG. 2C). On the other hand, during the period T1 of forming the effective display screen in the backward scanning period, the selection circuit 21 selectively outputs the output signal of the inverting amplifier 12, whereby the monitor device 1 receives the output signal during this period T1. , A video signal SV whose polarity is inverted with respect to the video signal SV
2 is generated and output to the speed modulation circuit 26.

The speed modulation circuit 26 receives the sequentially input video signal SV as in the case of the speed modulation of normal raster scanning.
A differential signal is generated from 2, and the modulation coil 10 is driven by using this differential as a signal reference. As a result, the monitor device 1
Regarding forward scanning, when the signal level of the video signal SV sharply rises, the scanning speed can be accelerated and decelerated before and after the rising, and conversely, when the signal level of the video signal SV sharply falls. The scanning speed can be decelerated and accelerated before and after the trailing edge, whereby the contrast of the display screen can be emphasized.

On the other hand, in the case of the backward scan, as shown in FIG. 5, the video signal SV2 (FIG. 5B) whose polarity is inverted with respect to the video signal SV (FIG. 5A) is differentiated. By forming the differential signal S1 by
On the contrary to the case of the outward path, when the brightness level of the display screen rises and falls sharply (FIG. 5C), the differential signal S1 (FIG. 5D) where the signal level falls and rises can be obtained. Note that, in FIG. 5, the scanning direction and the time axis are inverted to correspond to FIG. 11.

As a result, the monitor device 1 can form a modulation magnetic field having a polarity opposite to that of the outward path in the backward scan, and when the brightness level of the display screen suddenly rises in the same way as in the outward path, before and after the rise. The scanning speed can be accelerated and decelerated by, and on the contrary, when the brightness level sharply falls, the scanning speed can be decelerated and accelerated before and after the fall, thereby enhancing the brightness of the display screen. (Figs. 5 (E) and (F)). As a result, the monitor device 1 can use the raster scanning speed modulation circuit to perform speed modulation with a simple structure in which only the inverting amplifier 12 and the selection circuit 21 are added, and thus the monitor device 1 can be applied to bidirectional modulation with a simple structure. The focus characteristics of the display screen can be improved.

(2) Effects of the Embodiments According to the above configuration, the polarity is switched in the forward path and the backward path and the video signal is supplied to the speed modulation circuit, so that the selection circuit and the inverting amplifier are simply added. It is possible to improve the image quality by applying speed modulation to the case of bidirectional deflection.

(3) Other Embodiments In the above embodiment, the inverting amplifier and the non-inverting amplifier are used to switch the polarity of the video signal in advance between the forward path and the backward path, thereby changing the modulation magnetic field applied to the modulation coil. Although the case of switching between the forward path and the return path has been described, the present invention is not limited to this. For example, the polarity of the differential signal may be switched to switch the modulation magnetic field applied to the modulation coil between the forward path and the return path. The polarity of the drive signal to be applied may be switched to switch the polarity of the modulation magnetic field between the forward path and the return path.

[0031]

As described above, according to the present invention, by switching the polarity of the modulation magnetic field in the forward and backward paths, it can be applied to the case of bidirectional deflection and speed modulation can be performed to improve the image quality. A monitor device having a configuration can be obtained.

[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 signal waveform diagram showing processing of the video signal.

FIG. 3 is a connection showing an inverting amplifier.

FIG. 4 is a connection showing a non-inverting amplifier.

FIG. 5 is a signal waveform diagram for explaining modulation magnetic field formation.

FIG. 6 is a signal waveform diagram showing a video signal.

FIG. 7 is a signal waveform diagram for explaining velocity modulation of raster scanning.

FIG. 8 is a schematic diagram for explaining raster scanning.

FIG. 9 is a schematic diagram for explaining bidirectional deflection.

FIG. 10 is a signal waveform diagram for explaining a case where velocity modulation of raster scanning is applied to bidirectional deflection.

[Explanation of symbols]

1 ... Monitor device, 2 ... Cathode ray tube, 3 ... Bidirectional deflection circuit, 10 ... Modulation coil, 11 ... Inversion amplifier, 12
...... Non-inverting amplifier, 21 …… Selection circuit, 26 …… Velocity modulation circuit.

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

Claims (3)

[Claims] 1. A monitor device for repeating forward and backward scanning on the basis of a predetermined video signal to form a display screen of the video signal on a cathode ray tube, wherein a scanning speed of a beam of the cathode ray tube is accelerated and decelerated. A modulation coil that forms a modulation magnetic field and a differential signal that is obtained by differentiating the video signal, generates a drive signal based on the differential signal, and applies the drive signal to the modulation coil to drive the modulation coil. The monitor device is characterized in that the speed modulation means switches the polarity of the drive signal applied to the modulation coil during the forward scan and the backward scan. 2. The speed modulation means receives the video signal in an inverting amplifier circuit and a non-inverting amplifier circuit and selectively differentiates output signals of the inverting amplifier circuit and the non-inverting amplifier circuit to generate the differentiated signal. The monitor device according to claim 1, wherein the polarity of the drive signal applied to the modulation coil is switched by performing the forward scan and the backward scan. 3. The monitor device according to claim 1, wherein the video signal is a video signal whose time axis is inverted in the scanning of the forward and backward paths.