JPS58705B2 - tv jiyeonji yuzouki - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a television receiver, and an object of the present invention is to improve image quality by modulating the scanning speed of an electron beam on a phosphor screen using an auxiliary deflection yoke.

Conventionally, a pulse signal corresponding to a change in the level of a video signal is used as a drive signal, and this signal is used to apply a voltage to an electrostatic deflection plate installed in a cathode ray tube, modulating the scanning speed of the electron beam on the phosphor screen, and improving the image quality. There are known methods that attempt to improve this, but this method requires the use of a cathode ray tube with a new electrostatic polarizing plate installed inside, which requires a higher applied voltage.

The present invention drives two Swisswung elements with pulses corresponding to the rise and fall level changes of a video signal, generates a resonant current, and adjusts the scanning speed of the electron beam on the phosphor screen to the vicinity of the electron gun of the cathode ray tube. The image quality is improved by modulating the speed using a deflection yoke for speed modulation installed in the yoke.

Regarding video signals, if we consider the pattern of black and white dots shown in Figure 1, if the video signal corresponds to the pattern shown in Figure 1, which originally has steep rises and falls, the image quality will be poor. However, due to the frequency characteristics of the receiver, the video signal has a slow rise and fall as shown in (2).

Therefore, currently, television receivers differentiate the video signal twice and superimpose the signal shown in ■ onto the original signal to obtain the video signal shown in ■, emphasizing the rising and falling edges and improving the image quality. I'm letting you do it.

In this case, the luminance at the rising and falling white levels increases more clearly than in case (2).

In other words, the larger the electron beam current flows, the larger the beam spot becomes, resulting in too much emphasis on white.

The present invention aims to eliminate the above-mentioned problems, and one embodiment thereof will be described below with reference to the drawings.

FIG. 2 shows the circuit configuration of the main parts of the television receiver according to the present invention, and FIG. 3 shows the current or voltage waveforms of each part obtained by this circuit.

In Figure 2, A is a video signal input terminal, 1 is a video amplifier, 2 is a buffer amplifier, 3 is a differentiating circuit consisting of a capacitor 31 and a resistor 32, 4 is a pulse amplifier, and 5 is a delay The circuit 6 is an output circuit for obtaining a resonant current for speed modulation.

This output circuit 6 consists of two NPN and PNP transistors Tr0. Tr2 is used, and the collector of Tr1 is connected to the power supply B via a resistor R1, and a capacitor C for resonance.
1 and the auxiliary deflection yoke DY, and connect R to Tr2 in the same way.
,2,C2,D.

Connect Y. The emitters of Trl and Tr2 are commonly grounded, and resistors R3 and R4 and capacitors C3 and C4 are connected.

Now, the video signal in FIG. 3 1 is amplified by a video amplification circuit 1, passed through a buffer amplifier 2, and then sent to a differentiating circuit 3 to generate a pulse signal H in the same diagram corresponding to the rise and fall times of the video signal I. becomes.

This pulse signal is amplified by an amplifier 4 and then further amplified by a delay circuit 5.
and the transistors Tr1. Applied to Tr2.

This pulse signal is applied to the capacitor 31. As a result obtained from the differentiating circuit including the resistor 32, the rising edge of the video signal becomes a positive pulse, and the rising edge becomes a negative pulse.

Accordingly, the switching transistors Tr1. Inductance of deflection coils D and Y for speed modulation and resonance capacitance C1 that drive Tr2 and are provided near the electron gun of the cathode ray tube.
, C2 as switches for the respective resonant circuits to obtain the resonant current shown in FIG.

That is, there is no signal pulse and the transistor Tr1. Tr
2 is cut off, capacitor C1 is connected to power source B, C
2 is charged from one power source B through damping resistors R1 and R2, and is Trl.

When Tr2 reaches saturation or active region, respectively,
The resonance current shown in FIG. 3 can be obtained by the charges stored in the capacitors C1 and C2 and the inductance of the auxiliary deflection yokes D and Y.

The portions corresponding to the rise and fall of this resonant current are 180 degrees out of phase.

Note that for video signals with steep rises and falls, the resonant period does not match that of the differential pulse signal, so almost no resonant current flows.

Furthermore, if the time constant of the differentiating circuit 3 is set so that the differential pulse becomes small in extremely slow rising and falling parts of the video signal, Trl and Tr2 will not switch and no problem will occur.

Therefore, as a result, the resonant current shown in FIG. 3 becomes a current of approximately one cycle in the rising and falling parts of a video signal having a certain range of rising and falling times.

Now, the period T of the resonant current of the resonant circuit consisting of the inductance of the auxiliary deflection yokes D and Y and the capacitance C1 and C2 is the rise and fall time of the video signal, and is used to set and determine the time required for correction. The above-mentioned resonant current is caused by the magnitude of the input signal pulse in the transistor Tr1. T
The output impedance of r2 is different, and the amplitude of the resonant current of the resonant circuit is changed.

As a result of the above, when a signal pulse is obtained at the rising and falling portions of the video signal I, the switching transistor Tr1. Tr2 becomes a saturation region or an active region, and it is possible to obtain the horizontal scanning speed VH shown in FIG.

Figure 3 ■ shows the horizontal scanning speed of the electron beam raster L that is mounted on a cathode ray tube (described later) and is modulated by the speed modulation deflection yokes D and Y to which resonance current (■) is applied.
This indicates H.

In other words, when the resonant current is large, horizontal scanning is accelerated;
When it's small, slow down.

In other words, the horizontal scanning speed (■H) on the Rask is as shown in (■) in FIG.

When a video signal rises, the first half cycle is fast and the next half cycle is slow.

Also, in the falling portion, the speed is slow in the first half cycle and fast in the next half cycle.

Generally, the brightness on a screen is determined by the product of the horizontal scanning speed and the video signal level.

Therefore, if we look at Figure 3 (1) which shows the video signal level and (■) which shows the horizontal scanning speed, as shown in Figure 3 (■), the black level and white level in the rising and falling periods of the video signal are emphasized, and the black level The change in or vice versa becomes steep as shown in FIG. 3V, and the sharpness of the image is improved.

Incidentally, the damping resistors R1 and R2 are used for damping to prevent resonance from continuing as shown by the broken line in FIG. 3, when the signal pulse disappears.

Further, a resistor R1 indicated by a broken line is a damping resistor for preventing parallel resonance due to the inductance of the deflection yokes D and Y and their distributed capacitance.

Figures 4 and 5 show the main parts of a cathode ray tube equipped with the aforementioned auxiliary velocity deflection yokes D and Y, and Figure 6 shows the deflection yokes D and Y.
This shows the coil core of Y.

In Figures 4 and 5, 51 is a deflection coil core for speed modulation, 52 is a purity magnet, 53 is a pole piece,
54 is a cathode ray tube glass, 55 is a focus electrode, 56
57 is the second grid, 57 is the first grid, 58 is the cathode, and 59 is the deflection coil core for speed modulation. Two cores 59 are mounted outside the focus electrode 55 of the cathode ray tube.

A velocity modulation deflection coil 60 is wound around this core 59 in a toroidal shape to constitute a velocity modulation deflection yoke.

As described above, the television receiver of the present invention uses two transistors, each of which is operated separately according to the rising and falling signals of the video signal, and is installed near the cathode ray tube electron gun. A series resonant circuit consisting of two resonant capacitances connected in series with a velocity modulation deflection coil is formed, and a series resonant circuit is formed in the neck of the cathode ray tube.
To improve image quality with a relatively simple configuration by providing an auxiliary deflection yoke to modulate the electron beam scanning speed on the fluorescent screen of a cathode ray tube without being affected by horizontal and vertical deflection magnetic fields. I can do it.

[Brief explanation of drawings]

Figures 1 - 2 are explanatory diagrams of the conventional method for correcting brightness signals, Figure 2 is a circuit diagram of the main parts of an embodiment of the television receiver of the present invention, and Figures 3 I - A signal waveform diagram obtained from the circuit shown in the figure, FIG. 4 is a structural cross-sectional view of the main part of the cathode ray tube in the same television receiver, and FIG.
A line sectional view, FIG. 6I is a front view of the speed modulation core, and ■ is a side view of the same. 3... Differential circuit, 6... Output circuit, Trl. Tr2...Transistor, C1, C2...Resonance capacitor, D, Y...Deflection yoke for speed modulation, R1, R2
...damping resistance.

Claims (1)

[Claims] 1 An auxiliary deflection yoke installed at the neck of the cathode ray tube, two transistors of different polarity driven by signals obtained in response to predetermined level changes in the video signal, and connections to the output terminals of these transistors. and a resonant circuit constituted by an inductance of the auxiliary deflection yoke and the auxiliary deflection yoke, and a resonant current obtained by controlling the resonant circuit by the two 1-channel yoke is passed through the auxiliary deflection yoke to produce a phosphor screen. A television receiver characterized by modulating the scanning speed of an electron beam on the television receiver.