JPH07222023A - Dynamic focus circuit - Google Patents

Abstract

PURPOSE:To control continuously a phase of a horizontal parabolic wave voltage superimposed on a focus DC voltage in response to a frequency of a horizontal synchronizing signal. CONSTITUTION:The circuit is provided with an F/V converter 1 converting a frequency of a horizontal synchronizing signal HSYC into a voltage, a time constant setting capacitor C1, a monostable multivibrator M1 receiving the horizontal synchronizing signal HSYC and a horizontal drive pulse Hr>, a horizontal parabolic wave generating circuit 11 generating a horizontal parabolic wave voltage HVP in response to an output pulse P1 of the monostable multivibrator M1 and a transistor (TR) controlling a charging current of the capacitor C1 with an output voltage of the F/V converter l.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic focus circuit for generating a voltage applied to a focus electrode of a cathode ray tube.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing the configuration of a conventional dynamic focus circuit used in, for example, a monitor display (model CMT-A17UM5) manufactured by Sanyo Electric Co., Ltd. Horizontal sync signal H _SYC is F / V (frequency / voltage)
It is input to the converter 1 and the horizontal oscillation circuit 2. The output voltage of the F / V converter 1 is the horizontal oscillation circuit 2 and the switching signal generation circuit 6
Is input to. Horizontal driving pulse signal H _D output by the horizontal oscillation circuit 2 is input to the horizontal drive circuit 3. The output voltage of the horizontal drive circuit 3 is input to the horizontal output circuit 4, the horizontal output pulse H _P output from the horizontal output circuit 4 is input to the horizontal parabolic wave generating circuit 5. Parabolic wave voltage H _PV output from the horizontal parabolic wave generating circuit 5 are input to the parabolic gain switching circuit 7.

The output voltage of the switching signal generating circuit 6 is input as a switching signal to a parabola wave gain switching circuit 7 and a phase switching circuit 8 having a differentiating circuit. The horizontal parabolic wave voltage output from the parabolic wave gain switching circuit 7 is input to the phase switching circuit 8, and the horizontal parabolic wave voltage H _PVi output from the phase switching circuit 8 is input to the dynamic focus output circuit 9. The vertical parabolic wave voltage V _PV is input to the dynamic focus output circuit 9, and the horizontal parabolic wave voltage H _PV0 and the vertical parabolic wave voltage V _PV output by the dynamic focus output circuit 9 are _{stored in} the capacitor C ₃
The DC voltage for focusing obtained from the variable resistor VR via the variable resistor VR is applied to the focus electrode of a cathode ray tube (not shown).

Next, the operation of the dynamic focus circuit will be described with reference to FIG. 4 which shows a waveform diagram of signals at various parts.
Horizontal sync signal H _SYC is F / V converter 1 and horizontal oscillation circuit 2
When input to the F / V converter 1, the F / V converter 1 converts the frequency of the horizontal synchronizing signal H _{SYC into} a voltage with a linear frequency-voltage characteristic, and _supplies the converted voltage to the horizontal oscillation circuit 2. As a result, the horizontal oscillator circuit 2 oscillates in synchronization with the horizontal synchronizing signal H _SYC .

From the horizontal oscillation circuit 2 to the horizontal drive path
Loose signal H_DOutput to the horizontal drive circuit 3
The horizontal drive circuit 3 receives the input horizontal drive pulse signal.
Issue H _DDrive pulse signal H_DThe water
Input to the flat output circuit 4. As a result, the horizontal output circuit 4
Horizontal output pulse H shown in Fig. 4 (a)_POutput the horizontal parameter
Input to the Bora wave generation circuit 5. Horizontal parabolic wave generation circuit
5 is resonance using inductance and capacitor
It consists of a circuit, and the input horizontal output pulse H_PTo
Use horizontal parabolic wave voltage H_PVOccurred and occurred
Horizontal parabolic wave voltage H_PVParabolic wave gain switching circuit 7
To enter.

On the other hand, the switching signal generating circuit 6 generates a switching signal which becomes H level or L level according to the frequency of the horizontal synchronizing signal H _SYC by the voltage converted by the F / V converter 1, and serves as a switching signal. Input to the wave gain switching circuit 7 and the phase switching circuit 8. As a result, the gain of the parabolic wave gain switching circuit 7 is switched according to the switching signal,
The parabolic wave gain switching circuit 7 outputs a horizontal parabolic wave voltage of a predetermined level. Then, the horizontal parabolic wave voltage having a predetermined level is input to the phase switching circuit 8. As a result, the phase switching circuit 8 switches the time constant of the differentiating circuit in accordance with the switching signal input from the switching signal generating circuit 6 to adjust the phase of the horizontal parabolic wave voltage.

Then, the phase-adjusted horizontal parabolic wave voltage H _PVi shown in FIG. 4B is input to the dynamic focus output circuit 9. This dynamic focus output circuit 9
A vertical parabolic wave voltage V _PV is input to the dynamic focus output circuit 9 amplifies the horizontal and vertical parabolic wave voltages. The outputs horizontal parabolic wave voltage H _PV0 showing the dynamic focus output circuit 9 in FIG. 4 (c), by superimposing on a DC voltage for the focus obtained from the variable resistor VR through the capacitor C _3, is not shown It is applied to the focus electrode of the cathode ray tube. The amplified vertical parabolic wave voltage V _PV is also superimposed on the focusing DC voltage.

By the way, as shown in FIG. 4C, the horizontal parabolic wave voltage H _PV0 output from the dynamic focus output circuit 9 is input to the dynamic focus output circuit 9 as the frequency of the horizontal synchronizing signal H _SYC increases. the phase delay becomes large with respect to the horizontal parabolic wave voltage H _PV shown in FIG. 4 (b) to be. Therefore, the phase switching circuit 8 is used for the operation shown in FIG.
As shown in FIG. 4, the phase is advanced, and the time constant of the differentiating circuit in the phase switching circuit 8 is switched according to the frequency of the horizontal synchronizing signal so that the horizontal parabolic wave voltage H _PVi shown in FIG. enter to from dynamic focus output circuit 9, and adjusted to output a horizontal parabolic wave voltage H _PV0 shown in FIG. 4 (e) there is no phase delay with respect to the horizontal output pulse H _P shown in FIG. 4 (a) There is.

[0009]

However, as described above, the conventional dynamic focus circuit adjusts the voltage level and the phase of the horizontal parabolic wave voltage by switching by the switching signal according to the frequency of the horizontal synchronizing signal. Therefore, the voltage level and phase of the horizontal parabolic wave voltage cannot be continuously adjusted with respect to the frequency of the horizontal synchronizing signal. Further, in order to adjust the voltage level and the phase corresponding to various frequencies of the horizontal synchronizing signal, it is necessary to increase the number of stages for switching the voltage level and the phase, which causes a problem that the circuit becomes complicated.

Since there is a horizontal parabolic wave voltage generation IC capable of making the voltage level of the horizontal parabolic wave voltage constant with respect to the frequency of the horizontal synchronizing signal, the phase of the horizontal parabolic wave voltage is eventually changed to There is a problem that it cannot be continuously changed according to the frequency of the horizontal synchronizing signal. The present invention has been made in view of the above problems, and an object thereof is to provide a dynamic focus circuit capable of continuously controlling the phase of a horizontal parabolic wave voltage according to the frequency of a horizontal synchronizing signal.

[0011]

A dynamic focus circuit according to the present invention converts a frequency of a horizontal synchronizing signal into a voltage, controls a horizontal oscillation circuit by the converted voltage, and outputs a horizontal drive pulse synchronized with the horizontal synchronizing signal. Generate
In a dynamic focus circuit that generates a horizontal parabolic wave voltage to be applied to the focus electrode, a monostable multivibrator that has a time constant setting capacitor and that receives the horizontal drive pulse and generates a pulse synchronized with the horizontal drive pulse, A horizontal parabolic wave generation circuit that generates a horizontal parabolic wave voltage in relation to the pulse, and a current control circuit that controls the charging current of the time constant setting capacitor according to the converted voltage are provided. Accordingly, it is configured to control the phase of the horizontal parabolic wave voltage.

[0012]

The horizontal output pulse output from the horizontal output circuit based on the horizontal drive pulse output from the horizontal oscillator circuit is delayed from the phase of the horizontal drive pulse, and the delay increases as the frequency of the horizontal synchronizing signal increases. When the frequency of the horizontal synchronizing signal is high (low), the charging current of the time constant setting capacitor decreases (increases), and the pulse width of the pulse output by the monostable multivibrator becomes wide (narrow). A horizontal parabolic wave voltage is generated in synchronization with this pulse, and the phase of the horizontal parabolic wave voltage changes according to the frequency of the horizontal synchronizing signal. Thereby, the phase of the horizontal parabolic wave voltage can be continuously controlled according to the frequency of the horizontal synchronizing signal.

[0013]

The present invention will be described in detail below with reference to the drawings showing the embodiments thereof. FIG. 1 is a block diagram showing the configuration of a dynamic focus circuit according to the present invention. Horizontal sync signal H _SYC
Is input to the F / V (frequency / voltage) converter 1 for converting the frequency into a voltage in proportion to the linear frequency-voltage characteristic and the horizontal oscillation circuit 2. The horizontal drive pulse signal H _D output from the horizontal oscillation circuit 2 is an IC for the monostable multivibrator in the monostable multivibrator M ₁ forming the horizontal drive circuit 3 and the phase control circuit 10.
Input to input terminal A of IC _M1 . The output of the horizontal Doibu circuit 3 is input to the horizontal output circuit 4, the horizontal output circuit 4 is the horizontal output pulse H _P is output.

The output voltage of the F / V converter 1 is the horizontal oscillation circuit 2
And to the base of the transistor TR, which is a current control circuit forming the phase control circuit 10, via the resistor R ₂ . In the phase control circuit 10, the connection between the resistor R ₁ and the resistor R ₂ is connected to the base of the transistor TR,
The emitter of is connected to the terminal of the resistor R ₁ on the side to which the resistor R ₂ is not connected via the resistor R ₃ . The collector of the transistor TR is connected to the trigger terminal T ₂ of the monostable multivibrator IC IC _M1 . The trigger terminal T ₂ is connected to the trigger terminal T ₁ via the time constant setting capacitor C ₁ . The connection between the resistors R ₁ and R ₃ is connected to the input terminal B of the monostable multivibrator IC IC _M1 and also to the trigger terminal T ₂ via the resistor R ₄ .

The phase control circuit 10 comprises a monostable multivibrator M ₁ having a time constant setting capacitor C ₁ , a transistor TR, and resistors R ₁ , R ₂ , R ₃ and R ₄ . The connection between the resistors R ₁ , R ₃ , R ₄ and the input terminal B is connected to the power supply V _CC . The output pulse P ₁ of the output terminal Q of the monostable multivibrator for IC IC _M1 is inputted in the monostable multivibrator M ₂ to the input terminal B of the monostable multivibrator for IC IC _M2. The input terminal A of the monostable multivibrator IC IC _M2 is grounded, and the time constant setting capacitor C ₂ is interposed between the trigger terminal T ₂ and the trigger terminal T ₁ . The connecting portion between the trigger terminal T ₂ and the capacitor C ₂ is the capacitor C _2
Is connected to the power supply V _CC through a resistor R ₅ which determines the charging current of the power supply.

The output pulse P _{2 from} the output terminal Q of the monostable multivibrator IC IC _M2 is a horizontal parabolic wave generation circuit.
Is input to 11, the horizontal parabolic wave voltage H _PV output from the horizontal parabolic wave generating circuit 11 is inputted to the dynamic focus output circuit 9. This horizontal parabolic wave generation circuit 11
A known parabolic wave generation IC that can keep the voltage of the horizontal parabolic wave voltage constant is used. The horizontal parabolic wave voltage output from the dynamic focus output circuit 9 is superimposed on the DC voltage for focus obtained from the variable resistor VR via the capacitor C ₃ and applied to the focus electrode of the cathode ray tube (not shown). It has become. The vertical parabolic wave voltage V _PV is input to the dynamic focus output circuit 9, and the vertical parabolic wave voltage output from the dynamic focus output circuit 9 is also superimposed on the DC voltage for focusing.

Next, the dynamic fo
The operation of the focus circuit will be described. Power supply V_CCVoltage of each part
Supply. Then, water is fed to the F / V converter 1 and the horizontal oscillation circuit 2.
Flat sync signal H_SYCIs input, the F / V converter 1 is
Sync signal H_SYCConvert the frequency of to voltage. And convert
The applied voltage is applied to the horizontal oscillation circuit 2. This allows horizontal
The oscillation circuit 2 has a horizontal synchronization signal H._SYCOscillates in synchronization with
Horizontal drive pulse signal H_DOutput and horizontal drive
Circuit 3 and monostable multivibrator IC IC _M1Input
Input to terminal A. Horizontal drive pulse signal H_DIs horizontal
It is amplified by the drive circuit 3 and input to the horizontal output circuit 4.
From the horizontal output circuit 4 to the horizontal output pulse shown in Fig. 2 (a).
H_PIs output.

The voltage converted by the F / V converter 1 is the resistance R
₂Is input to the base of the transistor TR via. That
The voltage converted by the F / V converter 1 is the horizontal sync signal H._SYCof
The higher the frequency, the higher the frequency. Thereby the transistor TR
Horizontal sync signal H is applied to the collector. _SYCInversely proportional to the frequency of
The current of the current value flows. And a capacitor for setting the time constant
C₁Charging current is horizontal sync signal H_SYCThe higher the frequency of
The monostable multivibrator becomes smaller and is shown in Fig. 2 (c).
IC IC_M1Output pulse P₁The pulse width of the
Issue H_SYCThe higher the frequency, the wider. This output pulse P
₁Is a monostable multivibrator IC IC_M2Input terminal B
Input to the IC IC for monostable multivibrator_M2In the
Output pulse P shown in Fig. 2 (d) with a constant width₂Occurs
Let This output pulse P₂Is a horizontal parabola wave generation circuit 11
Input to the horizontal parabolic wave generation circuit 11 and output pulse P
₂Horizontal parabolic voltage H shown in Fig. 2 (e) synchronized with_PVTo
Generate and output the dynamic focus output circuit 9
Is input to. And the dynamic focus output circuit
The delayed horizontal parabolic wave voltage is delayed by 9
Output from the focus focus output circuit 9.

By the way, the horizontal drive pattern shown in FIG.
Loose signal H_DAnd the horizontal output pulse H shown in Fig. 2 (a)_PWhen
The phase difference φ of the horizontal synchronizing signal H_SYCHigh frequency (low
The larger the value, the larger (smaller) the relationship is. Therefore the phase
Horizontal output pulse H from control circuit 10_PFigure 2 more advanced
Output pulse P shown in (c)₁Is output. And horizontal
Sync signal H_SYCIf the frequency of the
The collector current is small and the capacitor C₁Charge current is reduced
IC IC for monostable multivibrator_M1Will output
Output pulse P shown in Fig. 2 (c)₁The pulse width of
This output pulse P ₁For monostable multivibrator
IC IC_M2Input to the input terminal B of the output pulse P₁To
Output pulse P that is output in synchronization₂Is the horizontal sync signal
Issue H_SYCIt will be delayed according to the frequency.

This output pulse P₂Generated horizontal parabolic wave
Input to circuit 11, horizontal parabolic wave generation circuit 11 outputs
Pulse P₂The horizontal parabolic wave electric wave shown in Fig. 2 (e) in synchronism with
Pressure H _PVGenerate. This horizontal parabolic wave voltage H_PVThe da
Input to the dynamic focus output circuit 9
It is amplified by the focus output circuit 9 and
Horizontal output pulse H is delayed by the waste output circuit 9_PIn phase with
The horizontal parabolic wave voltage H shown in Fig. 2 (f)_PVThe die
Output from the namic focus output circuit 9.

On the contrary, when the frequency of the horizontal synchronizing signal H _SYC is low, the collector current of the transistor TR increases,
The charging current of the capacitor C ₁ increases, the pulse width of the output pulse P ₁ shown in FIG.
Phase ₂ will be advanced. And this output pulse P ₂
Is input to the horizontal parabolic wave generating circuit 11, a horizontal parabolic wave generating circuit 11 generates a horizontal parabolic wave voltage H _PV shown in FIG. 2 (e) in synchronism with the output pulse P _2. The horizontal parabolic wave voltage H _PV dynamic focus output circuit 9
Enter into amplified by dynamic focus output circuit 9, and the slow dynamic focusing output circuit 9, FIG. 2 in this case also became horizontal output pulse H _P in phase (f)
The horizontal parabolic wave voltage H _PV shown, outputs from the dynamic focus output circuit 9.

That is, the output pulse P of the phase control circuit 10
_1, is always a horizontal output pulse H _P from a phase leading the phase of the horizontal parabolic wave voltage H _PV dynamic focusing output circuit 9 and the slow dynamic focusing output circuit 9 outputs the horizontal output pulse H _P It can be in phase with the phase of. Further, since the frequency of the horizontal synchronizing signal H _SYC Ru high (low) if delays the phase of the horizontal parabolic wave voltage H _PV (is advanced), the horizontal parabolic wave voltage H _PV in accordance with the frequency of the horizontal synchronizing signal H _SYC it is possible to continuously change the phase, the horizontal output pulse H _P and the horizontal parabolic wave voltage H _PV, it always the same phase regardless of the frequency of the horizontal synchronizing signal H _SYC.

The horizontal parabolic wave voltage H _PV and the vertical parabolic wave voltage V _PV whose phases are controlled in this way are amplified and output from the dynamic focus output circuit 9, and the DC voltage for focusing obtained from the variable resistor VR. To the focus electrode of a cathode ray tube (not shown). Thereby, the image displayed on the cathode ray tube can be dynamically focus-controlled by the same function regardless of the frequency of the horizontal synchronizing signal.

The dynamic focus output circuit 9
Horizontal parabolic wave voltage H input to _PVAnd the phase of
The difference from the phase of the horizontal parabolic wave voltage output from
The dynamic focus output circuit 9 within the range
Adjust the horizontal output pulse H with a variable resistor (not shown)._P
And horizontal parabolic voltage H_PVAnd are adjusted to the same phase.

[0025]

As described in detail above, according to the dynamic focus circuit of the present invention, the phase of the horizontal parabolic wave voltage can be continuously controlled according to the frequency of the horizontal synchronizing signal. There is no need for a complicated switching circuit that switches in multiple stages according to the frequency of the horizontal synchronizing signal. Further, even if the frequency of the horizontal synchronizing signal is different, the horizontal output pulse and the horizontal parabolic wave voltage can always be in the same phase. Therefore, even if the frequency of the horizontal synchronizing signal is different, the function of the dynamic focus is not different. It has an excellent effect.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a dynamic focus circuit according to the present invention.

FIG. 2 is a timing chart of signals of respective parts.

FIG. 3 is a block diagram showing a configuration of a conventional dynamic focus circuit.

FIG. 4 is a timing chart of signals of respective parts.

[Explanation of symbols]

1 F / V (frequency / voltage) converter 2 Horizontal oscillation circuit 10 Phase control circuit 11 Horizontal parabolic wave generation circuit M ₁ , M ₂ Monostable multivibrator C ₁ Time constant setting capacitor

Claims (1)

[Claims] 1. The frequency of a horizontal synchronizing signal is converted into a voltage,
In the dynamic focus circuit that controls the horizontal oscillation circuit by the converted voltage to generate the horizontal drive pulse synchronized with the horizontal synchronization signal and generate the horizontal parabolic wave voltage to be applied to the focus electrode, the dynamic focus circuit has a time constant setting capacitor, A monostable multivibrator that receives the horizontal drive pulse and generates a pulse synchronized with the horizontal drive pulse, a horizontal parabolic wave generation circuit that generates a horizontal parabolic wave voltage in association with the pulse, and a monostable multivibrator that responds to the converted voltage. And a current control circuit that controls the charging current of the time constant setting capacitor,
A dynamic focus circuit, which is configured to control a phase of a horizontal parabolic wave voltage according to a frequency of a horizontal synchronizing signal.