JPS6238080A - Horizontal oscillator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to horizontal oscillation pulses for television receivers.

2. Description of the Related Art Conventionally, this type of horizontal oscillator had a configuration as shown in FIG. The oscillation waveform of the horizontal oscillation circuit 12 is synchronized with the horizontal synchronization signal by the AFC circuit 1o.

Therefore, the oscillation pulse has a fixed phase relationship with respect to the synchronization signal, and the pulse width is determined by the time constant of the capacitance and resistance value of the oscillation circuit 12.

Problems to be Solved by the Invention In such a conventional configuration, the phases of the synchronization signal and the horizontal oscillation pulse are fixed, making it difficult to adjust the phase shift in the horizontal screen position of the television receiver. there were. Furthermore, when scanning an input signal in which the phase relationship between the video signal and the synchronization signal contained therein is not normal, the screen position phase shift described above becomes large and adjustment becomes impossible. The present invention solves these problems, and even when receiving the above-mentioned non-regular input signal, the phase relationship between the video signal and horizontal scanning can be adjusted to the same level as when receiving a regular signal. The purpose of the present invention is to make it possible to adjust the phase shift of the screen position in the horizontal direction of the machine.
Instead of being used as a comparison voltage for the FC circuit, an output pulse obtained by switching the oscillation waveform at a certain reference voltage is used as a comparison voltage for the AFC circuit.

Operation With this configuration, by changing the reference voltage used for switching, the phase of the output pulse changes accordingly, and the phase of the horizontal output pulse with respect to the synchronization signal can be adjusted independently.

Embodiment In the block diagram of a horizontal oscillator according to an embodiment of the present invention shown in FIG. 1, the oscillation circuit 3 has a lower limit switching voltage (hereinafter referred to as ■L) and an upper limit switching voltage (
Charge/discharge oscillation is performed within the voltage range set by VH (hereinafter referred to as vH). This vL is set in two stages (hereinafter vL1.
■It is called L2. However, vL1≧L2. ) has been done. The oscillation pulse obtained from the oscillation circuit 3 is frequency-divided by the flip-flop 4, and the rectangular wave of this frequency-divided output is used to generate vL.
By switching l and vL2, an oscillation waveform in which the charging and discharging cycles differ for each -cycle is obtained. FIG. 2a shows this oscillation waveform. The shorter period is tl, the longer period is t2, vH5vL1. ■L2. There is a relationship between tl and t2. Here, f is a functional expression determined by the time constant of the oscillation circuit. The sum of tl and t2 is one period of the horizontal synchronization signal.

In FIG. 1, a horizontal AFC circuit 2 detects the phase difference between the rectangular wave obtained from the oscillation circuit 3 and the horizontal synchronization signal, and controls the oscillation frequency. Due to this AFC circuit 2, the phase of the oscillation waveform has a certain relationship with the phase of the horizontal synchronizing signal. By using this oscillation waveform as one input of the voltage comparator circuit 5, which is composed of a differential amplifier, and using the reference voltage (hereinafter referred to as vR) as the other input, a pulse as shown in Fig. 2d is generated. get the output. This pulse is frequency-divided by flip-flop Cff7 to obtain the pulse shown in FIG. 2e. This pulse becomes the horizontal output pulse. Therefore, the period (hereinafter referred to as T) and the pulse duty (hereinafter referred to as "T") of the horizontal output pulse can be expressed by the following equation.

'r=t, +t2 D=t1/(t1+t2) The amount of delay in the phase of the output pulse of the voltage comparison circuit 5 with respect to the phase of the oscillation waveform can be changed by changing the voltage value of the base voltage vR. For example, in FIG. 2a, when the comparison voltage vR is increased, the falling phase of the pulse shown in FIG. 2d advances.

Since the flip-flop 7 inverts the output at the falling edge of this pulse, the phase of the frequency-divided output pulse also advances.

Conversely, when the comparison voltage VR is lowered, the falling phase of the pulse shown in FIG. 2d is delayed, so that the phase of the horizontal output pulse is also delayed.

Since the oscillation waveform is matched with the phase of the horizontal synchronization signal by the AFC circuit 2, the amount of delay in the phase of the horizontal output pulse with respect to the phase of the horizontal synchronization signal can be changed according to the voltage value of the reference voltage vR. be. Furthermore, as shown in equation (1), since the charging/discharging time constants of tl and t2 are the same, the slope of the oscillation waveform is the same in the tl period and the t2 period. Therefore, the duty of the horizontal output pulse is kept constant regardless of the switching phase using the comparison voltage vR.

In the present invention, the lower limit switching voltage vL of the oscillation circuit 3 is set to v
Although switching is made between Ll and vL2, the same applies to switching the upper limit switching voltage vH.

Effects of the Invention As described above, according to the present invention, the phase of the horizontal output pulse having a constant pulse duty can be adjusted independently of the phase of the horizontal synchronization signal, thereby reducing the phase shift in the horizontal screen position of the television receiver. Furthermore, even when an input signal in which the phase relationship between the horizontal synchronization signal and the video signal is not normal is received, the horizontal screen position can be easily adjusted to the normal phase.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a horizontal oscillator according to an embodiment of the present invention, FIG. 2 is a waveform diagram of each part thereof, and FIG. 3 is a block diagram of a conventional horizontal oscillator. 4.7...Flip flop, 5...Voltage comparator circuit, 1,9...Horizontal synchronization signal input terminal,
2...AFC circuit, 3, 12...-Horizontal oscillator, 6...Reference voltage input terminal, 8, 13...
...Horizontal output pulse output terminal. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 (C

Claims (1)

[Claims] A flip-flop generates a rectangular wave signal that frequency-divides the pulse generated during charging and discharging of the oscillator circuit and switches the comparison voltage set in two stages for each cycle of charging and discharging, and the switched comparison voltage is used to generate one cycle. the oscillation circuit that generates oscillation waveforms having different charging and discharging times; a phase comparison circuit that compares the phase of the rectangular wave obtained from the oscillation circuit with a horizontal synchronization signal; It consists of a voltage comparator circuit that can change the switching phase by varying the reference voltage applied to one input of the voltage comparator circuit, and a flip-flop that divides the frequency of the pulse obtained from the voltage comparator circuit and generates an output pulse, A horizontal oscillator characterized in that the phase of an output pulse having a constant duty can be changed with respect to the phase of the oscillation waveform.