JPH0470266A - Display device - Google Patents

Abstract

PURPOSE:To display various video signals in correct aspect ratio by correcting the current value of a deflection current in accordance with the flyback period of an input video signal. CONSTITUTION:In a cathode ray tube 2, even in the case that the ratio of a scanning period TSV to the flyback period TBV is different, in respect of a vertical direction, a display picture of prescribed size can be displayed at a prescribed position. On the contray, in a horizontal deflection yoke 4, a collector pulse FB generated by the ON-OFF operation of a horizontal output transistor 30 is impressed, and a horizontal deflection current IM is supplied. Since in the horizontal deflection current IM, the output voltage of DC power supply 40 is switched together with the contacts of switch circuits 48, 50 based on the pulse width TBM of a horizontal blanking pulse SBM, the deflection current IM rises suddenly in a sub scanning period TSM, and after that, it falls gradually in the flyback period TBM. Thus, in the horizontal deflection current IM, the amplitude value ix of the scanning period TSM is corrected so as to be a constant value and in a horizontal direction too, the display picture of the prescribed size can be displayed at the prescribed position of the cathode ray tube 2.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a display device, and is particularly applicable to a display device that switches and displays various input video signals having different deflection frequencies.

B. Summary of the Invention The present invention corrects the current value of the deflection current in accordance with the retrace period of the input video signal in a display device, thereby correcting various input video signals without readjusting the aspect ratio. Can be displayed in aspect ratio.

C. Prior art Conventionally, in this type of display device, various video signals with different deflection frequencies can be displayed by switching the frequency of the deflection current according to the horizontal deflection frequency and vertical deflection frequency of the video signal. is being done.

D Problems to be solved by the invention By the way, in a video signal, not only the deflection frequency but also
The ratio of the scan period and retrace period may be different.

That is, as shown in FIG.
)tz) of the navigation system.

(Fig. 5(A)), 30.4 [μsec
) scanning period, blanking period is 9.88 rμsec
] has been selected.

On the other hand, the NTSC video signal 5813. (5th
In Figure (B)) (consisting of a horizontal deflection frequency of 15.75 [k7]), the retrace period is 10 to 11 [μsec] for the scanning period of 53.5 to 52.5 Cu5ec 3.
has been selected.

For this reason, there is a problem in that simply switching the deflection frequency does not allow display with the correct aspect ratio, but the aspect ratio must be readjusted as the video signal is switched.

The present invention has been made in consideration of the above points, and aims to propose a display device that can display various video signals at the correct aspect ratio without readjusting the aspect ratio.

8 Means for Solving the Problems In order to solve the problems, in the present invention, in the display device 1 that forms a display image of the input video signal SIH on the cathode ray tube 2, a deflection waveform is determined based on the input video signal srs. Deflection waveform generation circuit (10, 16) to generate
, (4, 10, 30, 32, 34, 38, 40, 42)
Based on the deflection waveform, a deflection current of 1 V, I is applied to the deflection yoke 6.4.

Deflection yoke drive circuit (26), (4, 10,
30, 32, 34, 38, 40, 42) and the retrace period TIV% TIN of the human-powered video signal SIN, and based on the detection results, the deflection current Iv, 1. The current value ia,i
Deflection current correction circuit (14, 20, 22) that corrects X
, (14, 40, 4 days, 50).

By detecting the retrace period T my-, 'rsN of the F-action input video signal SIN and correcting the deflection current ■7 and the current values iA and iO based on the detection results, the retrace period T mv, T
Even when □ is different, a display image of a predetermined size can be displayed at a predetermined position on the cathode ray tube 2, and thus various video signals can be displayed with the correct aspect ratio without readjusting the aspect ratio.

G example An embodiment of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, l indicates the display device as a whole, and the video signal SIN is converted into a color signal by a video signal processing circuit (not shown), and then applied to the cathode of the cathode ray tube 2 via a predetermined video amplification circuit. As a result, the cathode ray tube 2
The desired video signal SIN is displayed on the screen.

Furthermore, at this time, the deflection currents III and Iv flowing through the deflection yokes 4 and 6 are determined according to the deflection frequency of the video signal SIN.
In addition to switching the frequency of the deflection current according to the retrace period. and Iv current values are corrected, thereby displaying the video signal SIN with a correct aspect ratio.

That is, in the display device f1, the high voltage generation circuit 7 generates driving power for the anode, focus, etc. necessary for driving the cathode ray tube 2, and supplies it to the cathode ray tube 2.

At this time, the high voltage generation circuit 7 is driven separately from the horizontal deflection circuit.
By generating a source, the voltage of the drive power source is maintained at a predetermined value even if the horizontal deflection frequency of the video signal SIN changes.

As shown in FIGS. 2 and 3, the blanking pulse separation circuit 8 separates the horizontal blanking pulse SI from the video signal S IN.
M (Fig. 2 (A) and (D)) and vertical blanking pulse S□ (Fig. 3 (A) and (C)) are separated, and the oscillation circuit 10 and the blanking pulse width detection circuit 14 Output to.

The oscillation circuit 10 locks the oscillation frequency by inputting a horizontal blanking pulse SIN and a vertical blanking pulse S□ to the vertical oscillation circuit and the horizontal oscillation circuit, respectively.
Horizontal blanking pulse Sl, I and vertical blanking pulse S
A horizontal oscillation signal SON and a vertical oscillation signal S synchronized with sv. Outputs V.

The blanking pulse width detection circuit 14 detects the pulse widths TIN and TmV of the horizontal blanking pulses S, H and the vertical blanking pulse S□, and based on the detection results, the blanking pulse width detection circuit 14
Correct currents IN and I9.

That is, in the deflection waveform creation circuit 16, constant current: r
At i20, a charging current rev is applied to the charging/discharging capacitor 18, and at the same time, a constant current source 22 releases a tt current from the charging/discharging capacitor 18. V is discharged, and at this time the vertical oscillation signal S is generated.

By switching the switch circuit 24 to the OFF state in synchronization with V, the flow of the released tt flow IDV is controlled to be stopped intermittently.

As a result, the deflection waveform generating circuit 16 changes the terminal voltage of the charging/discharging capacitor 18 in a sawtooth waveform to form a vertical deflection waveform synchronized with the vertical blanking pulse Smv.

Further, the deflection waveform generating circuit 16 drives the vertical deflection yoke 6 with the vertical deflection waveform via the amplifier circuit 26.

The deflection waveform creation circuit 16 includes the blanking pulse width detection circuit 1
Based on the detection result of step 4, the constant current sources 20 and 22 are controlled to switch and control the charging current XCV and the discharging current LvO value.

That is, at the rising and falling points of the vertical blanking pulse S□, the values of the charging current ICV and the discharge t) JLI Of are switched am so that the vertical deflection waveform reaches a predetermined signal level.

As a result, the pulse width T'' of the vertical blanking pulse SIV
When sv is wide (Fig. 3 (C)), when it is narrow (Fig. 3 (C))
A)) Compared to
The value of is increased to maintain the peak value of the vertical deflection waveform at a predetermined value.

This causes the vertical deflection current Iv (Fig. 3 (B) and (D
)), the wave height (!!iA) is held at a constant value,
The current value and its change during the scanning period T3v are held constant.

Therefore, by holding the driving voltage of the cathode ray tube 2 at a constant voltage by the high voltage generation circuit 7, the cathode ray in the vertical direction is A display image of a predetermined size can be displayed at a predetermined position on the tube 2.

The horizontal output transistor 30 is configured with a common emitter circuit and receives a horizontal oscillation signal S. , I repeats the on/off operation.

Further, the collector of the horizontal output transistor 30 is grounded through a damper diode 32 and a main resonant capacitor 34, and also through a series circuit of a horizontal deflection yoke 4, a distortion correction transformer 36, and a three-figure correction capacitor 38. , a predetermined DC power source 4o is inputted via a dummy transformer 42.

Therefore, in the collector of the horizontal output transistor 30, a collector pulse FB (FIGS. 2B and 2E) having a predetermined peak value H is induced in response to the on/off operation.

As a result, in the display device 1, it is possible to supply the horizontal deflection yoke 4 with a horizontal deflection current M (FIGS. 2C and 2D) whose current value changes in a sawtooth waveform.

Here, in the DC power supply 40, the pulse width T of the horizontal blanking pulse SIN detected by the blanking pulse width detection circuit 14. The output voltage is switched based on the retrace period T. When HP decreases, the pressure voltage is increased accordingly to maintain the peak value HP at a constant value.

On the other hand, in addition to the main resonant capacitor 34, auxiliary resonant capacitors 46 and 48 are connected to the collector of the horizontal output transistor 30 via switches 5° and 52, and the horizontal retrace line By switching the contacts of the switch circuits 50 and 52 based on the pulse width TIH of the erase pulse SIN, as the blanking period TIN increases, the pulse width P of the collector pulse FB increases accordingly. It is designed to increase the size of the image.

Therefore, in the horizontal deflection current (8), as the blanking period T increases, the deflection current 1 increases rapidly during the scanning period TsN, and then gradually decreases during the blanking period T@H. As a result, the amplitude [i
It is designed to hold X at a constant value.

Therefore, in the cathode ray tube 2, even in the horizontal direction,
Similarly to the vertical direction, a display image of a predetermined size can be displayed at a predetermined position on the cathode ray tube 2.

As a result, in the display device 1, even if not only the deflection frequency but also the ratio of the scanning period T, v and blanking period TBv are different, the display image can be displayed at the correct aspect ratio without readjusting the aspect ratio. be able to.

By the way, instead of correcting the deflection current in this way, as shown in FIG.
) may be used to correct the deflection current.

However, in this method, the change in scanning period (ΔT
), resulting in wasted deflection current ΔIK (Δiy) being consumed.

Therefore, according to this embodiment, the useless deflection current ΔI11
(Δty) consumption can be effectively avoided and the display image can be displayed with the correct aspect ratio.

Thus, in this embodiment, the oscillation circuit 10 and the deflection waveform creation circuit 16, based on the input video signal SIN,
The amplifier circuit 26 constitutes a deflection waveform generation circuit that generates a vertical deflection waveform, whereas the amplifier circuit 26 constitutes a deflection yoke drive circuit that supplies a deflection current 9 to the vertical deflection yoke 6 based on the vertical deflection waveform.

Further, a blanking pulse width detection circuit 14, a constant current source 20.
22 constitutes a deflection current correction circuit that detects the vertical return vA period TIV of the input video signal SIN and corrects the current value i of the deflection current Iv based on the detection result.

On the other hand, the horizontal deflection yoke 4, the oscillation circuit 10, the horizontal output transistor 30, the damper diode 32, the resonance capacitor 34.5 character correction capacitor 38, the DC power supply 40
, and the dummy transformer 42 constitute a deflection waveform generation circuit that generates a horizontal deflection waveform based on the human input video signal SIN, and supply a deflection current A to the horizontal deflection yoke 4 based on the horizontal deflection waveform. This constitutes the yoke drive circuit.

Furthermore, the blanking pulse width detection circuit 14, direct? The power supply 40
, resonance capacitors 48 and 50 constitute a deflection current correction circuit that detects the horizontal retrace period TI)l of the input video signal srH and corrects the current value ix of the deflection current ①8 based on the detection result.

In the above configuration, the high voltage generation circuit 7 independently generates a driving power supply, so that the cathode ray tube 2 is supplied with a driving voltage maintained at a constant voltage.

At this time, in the vertical deflection yoke 6, the waveform shaping circuit 1
6, and thereby supplies a vertical deflection current Iv whose current value changes in a sawtooth waveform in synchronization with the vertical blanking pulse S□.

In this state, at vertical deflection current 9, the pulse width of vertical blanking pulse SIV is T! Depending on v, constant current source 20
By switching the current values of and 22, the peak value ia is held at a constant value, and the current value and its change during the scanning period TsV are held at a constant value.

Therefore, in the cathode ray tube 2, not only the deflection frequency but also
Even when the scanning period TSV and blanking period TIVO ratio are different, a display image of a predetermined size can be displayed at a predetermined position in the vertical direction.

On the other hand, a collector pulse FB generated by the on/off operation of the horizontal output transistor 30 is applied to the horizontal deflection yoke 4, and this causes a horizontal deflection current of 1. is supplied.

At this time, in the horizontal deflection current IN, when the output voltage of the DC power supply 40 is switched together with the contacts of the switch circuit 48, 50 based on the pulse width T0 of the horizontal blanking pulse SIH, when the blanking period Ta1l increases, Accordingly, the deflection current A during the scanning periods T and H is 2. After getting up really hard, I went home! It gradually falls during the period TIN.

This results in a horizontal deflection current of 1. In, the scanning period T□
Amplitude at! L is corrected to a constant value, and thus a display image of a predetermined size can be displayed at a predetermined position on the cathode ray tube 2 in the horizontal direction as well as in the vertical direction.

Therefore, in the display device l, not only the deflection frequency but also the scanning period T3V, T3)1 and the retrace period T
Even if the lv ratio is different, the display image can be displayed at the correct aspect ratio without readjusting the aspect ratio.

According to the above configuration, by detecting the blanking period of the video signal and correcting the current value of the deflection current based on the detection result, even if the ratio of the scanning period TSV and the blanking period is different, the cathode ray tube A display image of a predetermined size can be formed at a predetermined position.

Therefore, various video signals can be displayed at the correct aspect ratio without readjusting the aspect ratio.

Note that in the above embodiment, the case where the horizontal deflection current and the separate drive ti are generated by the high voltage generation circuit has been described;
The present invention is not limited to this, and can be widely applied to cases in which drive power is generated simultaneously by a horizontal deflection circuit.

Further, in the above-described embodiment, a case has been described in which the current values of both the horizontal deflection current and the vertical deflection current are corrected, but the present invention is not limited to this, and the present invention is not limited to this. You may only correct it.

H Effects of the Invention As described above, according to the present invention, by correcting the current value of the deflection current according to the retrace period of the input video signal, various video signals can be processed without readjusting the aspect ratio. A display device capable of displaying images with a correct aspect ratio can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a display device according to an embodiment of the present invention, FIGS. 2 to 4 are signal waveform diagrams for explaining its operation, and FIG. 5 is a signal waveform diagram showing a video signal. 1...Display device, 2...Cathode ray tube, 4...Horizontal deflection yoke, 6...
Vertical deflection yoke, 8...Blanking pulse separation circuit, 10...Oscillation circuit, 14...Blanking pulse width detection circuit, 16... Deflection waveform creation circuit.

Claims (1)

[Scope of Claim] A display device that forms a display image of an input video signal on a cathode ray tube, comprising: a deflection waveform generation circuit that generates a deflection waveform based on the input video signal; A deflection yoke drive circuit that supplies a deflection current to the yoke; and a deflection current correction circuit that detects a retrace period of the input video signal and corrects the current value of the deflection current based on the detection result. A display device featuring: