JP3384145B2 - Vertical deflection circuit - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical deflection circuit suitable for application to a cathode ray tube device for various television receivers.

[0002]

2. Description of the Related Art In a cathode ray tube (CRT) used in a television receiver or the like, since vertical pincushion distortion occurs, a means for correcting this is usually provided in a vertical deflection circuit.

FIG. 10 shows such a conventional example, in which a vertical sawtooth wave signal (voltage) output from the vertical oscillator circuit 12 is shown.
Vo is supplied to the vertical output circuit 16 via the feedback differential amplifier 14. The vertical output circuit 16 includes a pair of transistors Q.
The vertical deflection coil 20 is connected to the connection point p of the SEPP structure composed of 1 and Q2.

A pincushion distortion correction circuit 22 is connected on the current path of the vertical deflection coil 20. Correction circuit 2
2 is a well-known LC resonance circuit driven in a horizontal cycle. In the correction circuit 22, a sawtooth voltage having a horizontal cycle is formed. This sawtooth voltage is further modulated by a vertical sawtooth current.

A capacitor 24 for AC coupling the vertical output signal VOUT is further provided on the current path of the vertical deflection coil 20. And capacitor 24
A resistor 26, which is a current detection element, is connected between the ground and the ground. A current iR obtained by superposing the vertical pincushion distortion correction current iP on the vertical sawtooth wave current iS flows through the resistor 26 (FIG. 11C).

In the case of such a configuration, by connecting the vertical sawtooth wave signal Vo shown in FIG.
Is a vertical output signal VOUT having a waveform as shown in FIG.
(Voltage) is obtained. A vertical deflection current iDY having the same waveform as the current iR described above flows through the vertical deflection coil 20, and the vertical pincushion distortion is dynamically corrected.

As shown in FIG. 11C, the resistor 26 has a vertical sawtooth wave current iS and a vertical pincushion distortion correction current iP.
Since a current iR which is the sum of the above, flows as a feedback correction signal (voltage) VFB and is fed back to the negative terminal of the differential amplifier 14, a vertical saw having the same waveform as the vertical sawtooth wave signal Vo output from the vertical oscillation circuit 12 is obtained. Wave current i
Feedback control is performed so that s flows to the vertical deflection coil 20.

[0008]

As shown in FIG. 11C, in addition to the vertical sawtooth wave current iS, the current iR in which the upper and lower pincushion distortion correction currents iP are superimposed flows through the resistor 26 described above. A feedback correction signal (voltage) VFB similar to the current iR is fed back to the differential amplifier 14. Therefore, since the upper and lower pincushion distortion correction voltages appear at the connection point p, a horizontal period parabolic wave signal having an amplitude as shown in FIG. 11B is superimposed on the vertical output signal VOUT.

When the parabolic wave signal of the horizontal period is superposed, the output amplitude of the connection point p during the scanning period is increased by the superposed parabolic wave signal, so that the vertical output circuit 16 uses its power supply voltage + B. The amplitude component of the parabolic wave signal must be increased. Since this amplitude increase ΔB is usually about 2 volts, a power loss of about 4 volts (about 0.8 W) occurs.

In order to eliminate this power loss, a configuration as shown in FIG. 12 has been proposed. This is an LC resonance circuit 27 that resonates at a horizontal frequency is connected between the connection points p and q, and the upper and lower pincushion distortion correction currents are bypassed so that the current does not flow to the resistor 26 and the connection point. The parabolic wave upper and lower pincushion distortion correction voltages are not fed back from q to the vertical output circuit 16 side.

However, even with this configuration, in the LC resonance circuit 27, the high frequency component of the upper and lower pincushion distortion correction current flows to the resistor 26 side, so this high frequency component together with the vertical sawtooth wave signal side to the vertical output circuit 16 side. And the output amplitude at the connection point p becomes slightly larger, though not so much as in the conventional case. As a result, the power supply voltage + B of the vertical output circuit 16 must be set to a high value, which causes power loss.

Therefore, the present invention solves such a conventional problem and proposes a vertical deflection circuit in which a sawtooth wave signal having a horizontal period is not fed back to the vertical output circuit side.

[0013]

In order to solve the above problems, in the invention described in claim 1, a correction circuit for correcting pincushion distortion is connected on a vertical deflection current path flowing through a vertical deflection coil, This pincushion distortion correction signal superimposed on the vertical sawtooth wave signal is fed back to the vertical output circuit as a feedback correction signal, and the voltage obtained at the connection point between the vertical deflection coil and the correction circuit is applied to the bandpass filter. By extracting the anti-phase component of the pincushion distortion correction signal and adding the extracted anti-phase pincushion distortion correction signal to the feedback correction signal, only the vertical sawtooth wave signal corresponding to the vertical deflection current is obtained. It is characterized by being fed back to the vertical output circuit.

[0014]

In the bandpass filter 30 shown in FIG. 1, the reverse phase component (extraction signal VBP) of the upper and lower pincushion distortion correction voltages is extracted (FIG. 5G), which is the feedback correction signal VF of FIG. 4E.
It is added to B '. This addition process cancels the upper and lower pincushion distortion correction voltages, so the feedback correction signal VFB
Is a sawtooth signal with a vertical cycle only (FIG. 5H). Therefore, only the vertical output signal VOUT (FIG. 5I) in which the upper and lower pincushion distortion correction signals are not superposed is obtained at the connection point p, whereby power loss due to the upper and lower pincushion distortion correction signals can be avoided. The power supply voltage can also be set low.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a case where an example of a vertical deflection circuit according to the present invention is applied to the above-mentioned television receiver,
A detailed description will be given with reference to the drawings.

FIG. 1 shows a concrete example of a vertical deflection circuit 10 used in a television receiver. The basic structure of this structure is the same as that of the conventional example shown in FIG. Therefore, the pincushion distortion correction circuit 22 generates a horizontal period parabolic wave current, which is modulated in the vertical period and flows through the vertical deflection coil 20. Then, a part of the voltage across the resistor 26 becomes a feedback correction signal (voltage) VFB and is fed back to the vertical output circuit 16 side.

In the present invention, a bandpass filter 30 is provided at the connection point r between the vertical deflection coil 20 and the correction circuit 22, and the signal (voltage) VBP extracted by this filter 30 is obtained at the connection point q as a feedback correction signal VFB. ′ And the matrix circuit 28. This feedback correction signal VFB subjected to the addition processing is fed back to the vertical output circuit 16 via the differential amplifier 14.

The above-mentioned correction circuit 22 is shown in FIG. 2 or FIG.
It is possible to use the one having the configuration as shown in The correction circuit 22 shown in FIG. 2 is a two-terminal circuit and includes a capacitor 32 and a coil 3.
Bidirectional switching means 3 in parallel resonance circuit with 3
4 are provided. The switching means 34 is controlled by a horizontal pulse (for example, a horizontal flyback pulse H · FBP), and a sawtooth voltage having a horizontal cycle is modulated by a vertical sawtooth current flowing through two terminals.

FIG. 3 shows a two-terminal circuit structure using a saturable reactor, which is composed of a core 35 and a rod-shaped magnet (permanent magnet) 36 as shown in FIG. A, and has a primary coil 38a and a secondary coil on the core 35. The coils 38b and 38c are wound.
FIG. 9B is an equivalent circuit thereof. A horizontal pulse (H · FBP) is supplied to the primary coil 38a, and the same modulation as described above is performed.

The band-pass filter 30 is for extracting only the voltage component corresponding to the upper and lower pincushion distortion correction voltage from the voltage Vr obtained at the connection point r, and its frequency characteristic is the attenuation near the vertical frequency fV. The amount is large, and the frequency characteristic in the horizontal frequency fH region is selected to be -6 dB / OCT. Due to the inclination of the frequency characteristic, the parabola-shaped correction voltage VPC generated by the correction circuit 22 is output from the bandpass filter 30 in a completely integrated state. The details will be described later.

Now, the operation of the vertical deflection circuit 10 having such a structure will be described with reference to FIG. The vertical output signal VOUT (voltage) of FIG. 4B is obtained at the connection point p by the sawtooth wave signal Vo (voltage) of the vertical cycle shown in FIG. 4A. However, this vertical output signal VOUT is a waveform before correction. As shown in FIG. 4C, a sawtooth voltage having a horizontal cycle is modulated by a vertical sawtooth current iS at both ends of the corrector circuit 22 by a vertical deflector current iDY flowing through the vertical deflector coil 20, and a correction signal (voltage) VPC in the form of a bow tie. Is obtained.

A sawtooth-shaped vertical sawtooth current iS flows through the capacitor 24, and this is integrated to generate a parabolic wave signal (voltage) VC having a vertical cycle as shown in FIG. 4D at both ends of the capacitor 24. Bowl 2
The current (referred to as detection signal iR) shown in FIG. The detection signal iR is a vertical sawtooth wave current iS superimposed with the upper and lower pincushion distortion correction current iP, and the voltage across the resistor 26 obtained by the detection signal iR is the feedback correction signal VFB for the vertical output circuit 16. ′
Used as.

Therefore, at the connection point r between the vertical deflection coil 20 and the correction circuit 22 described above, these three signals (VP
A combined voltage Vr (FIG. 5F) of C, VC, VFB ') will be generated. Then, the vertical pincushion distortion is dynamically corrected by the vertical deflection current iDY, which is a combination of the vertical sawtooth wave current iS and the horizontal cycle upper and lower pincushion distortion correction current iP, and a distortion-free raster screen is obtained.

The correction voltage Vr at the connection point r shown in FIG. 5F is also applied to the bandpass filter 30. As is clear from the frequency characteristics shown in the curve L of FIG. 6A, the bandpass filter 30 has a large attenuation amount in the vicinity of the vertical frequency fV, and the frequency characteristics in the horizontal frequency fH region have a slope of −6 dB / OCT. Has been selected for.

With such a bandpass characteristic, the amount of attenuation near the vertical frequency fV is large.
The vertical period parabolic wave signal VC and the vertical period sawtooth wave signal shown in D are neither output. Therefore, FIG. 4C
The correction signal VPC (sawtooth wave signal of the horizontal period) and the upper and lower pincushion distortion correction current iP of the horizontal period superimposed on the sawtooth wave current iS shown in FIG.

Here, the voltage value of the both-end voltage VPC of the correction circuit 22 is about 60 VP-P, while the voltage value of the upper and lower pincushion distortion correction current iP is about 50 mVP-P, which can be ignored and extracted. It can be said that only the voltage VPC (integral value) is applied.

The high band side of the band pass filter 30 is -6d.
Since it has been selected for the frequency characteristics such as B / OCT,
The correction signal VPC of FIG. 4C is integrated and output. Therefore, the extraction signal VBP shown in FIG. 5G is obtained from the bandpass filter 30. This extraction signal VBP is added in-phase with the feedback correction signal VFB 'in the matrix circuit 28.

Since the parabolic wave signal (upper and lower pincushion distortion correction signal) superimposed on the feedback correction signal VFB 'and the extraction signal VBP have an opposite phase relationship with each other, the result of the in-phase addition is a parabolic wave-shaped upper and lower waveform. The pincushion distortion correction signal is completely canceled, and the feedback correction signal VFB from the matrix circuit 28 is only the sawtooth signal having the vertical cycle shown in FIG. 5H. Since this is fed back to the vertical output circuit 16 via the differential amplifier 14, the vertical output signal VOUT shown in FIG. 5I is finally obtained at the connection point p.

Since the horizontal output parabolic wave signal is not superimposed on the vertical output signal VOUT, the power supply voltage + B can be lowered by the amplitude of the parabolic wave signal. As mentioned above, when the amplitude of the parabolic wave signal is about ± 2 volts,
When the amplitude value of the vertical sawtooth wave current iS is 1.2 AP-P, power of about 0.8 W is lost due to superimposition of the parabolic wave signal, but the present invention can prevent this power loss.

In the above-mentioned bandpass filter 30, as shown in FIG. 6B, the horizontal frequency fH and the spectrum centered on its high frequency component (the frequency interval thereof is fV) are -6 dB / OCT. Since the relationship between the horizontal frequency and the frequency characteristic on the high frequency side is selected, the bow-tie-shaped signal component shown in FIG. 4C among the voltage components at the connection point r is completely integrated and output. The circuit 28 performs a cancellation process including the high frequency component of the parabolic wave signal. Therefore, there is no possibility that the high frequency component remains without being canceled and is fed back to the vertical output circuit 16 side as in the conventional case.

FIG. 7 shows a specific example of the bandpass filter 30, which can be achieved by a cascade connection of a primary lowpass filter 42 and a highpass filter 44. The frequency characteristic of the low pass filter 42 is selected as shown in FIG. 8A, and the cutoff frequency side is selected to be -6 dB / OCT. The frequency characteristic of the high-pass filter 44 is selected as shown in FIG. 9B and is set so that the attenuation amount in the vertical frequency region is large.
Therefore, the total frequency characteristics of them are shown in Fig. C.
become that way. FIG. 6A is an enlarged view of FIG. 6C.

FIG. 9 shows a more specific example of FIG.
The primary low-pass filter 42 is composed of an RC series circuit of a resistor Ra and a capacitor Ca, and has a high-pass filter 44.
Is composed of a capacitor Cb and an RC series circuit of a pair of resistors Rb and Rc. The resistor Rc is for level adjustment.
Thus, the bandpass filter 30 can be realized with a very simple structure.

The vertical deflection circuit of the present invention can be applied to cathode ray tube devices for various television receivers and OA equipment. The use does not matter.

[0034]

As described above, in the vertical deflection circuit according to the present invention, the vertical pincushion distortion correction component is canceled and only the vertical sawtooth wave signal is fed back to the vertical output circuit.

According to this, since the vertical pincushion distortion correction component including the high frequency component is not superimposed on the vertical output circuit, it is necessary to increase the power supply voltage of the vertical output circuit by the amplitude increase due to this correction component. Disappear. As a result, power consumption corresponding to the increase in the amplitude due to the correction component is not wasted, so that power saving can be achieved.

Since the number of circuits to be increased is only a band pass filter and the configuration thereof is very simple, it is possible to achieve power saving without increasing the cost. Therefore, the present invention is compact and power saving such as a vehicle-mounted television receiver. It is extremely suitable to be applied to a television receiver that is required to meet the requirements.

[Brief description of drawings]

FIG. 1 is a connection diagram showing an example of a vertical deflection circuit according to the present invention.

FIG. 2 is a connection diagram of upper and lower pincushion distortion correction circuits.

FIG. 3 is a connection diagram of upper and lower pincushion distortion correction circuits.

FIG. 4 is a waveform diagram (1) of a vertical deflection operation.

FIG. 5 is a waveform diagram (part 2) of the vertical deflection operation.

FIG. 6 is a frequency characteristic diagram of a bandpass filter.

FIG. 7 is a configuration diagram of a bandpass filter.

FIG. 8 is a characteristic diagram thereof.

FIG. 9 is a connection diagram showing a specific example of a bandpass filter.

FIG. 10 is a connection diagram of a conventional vertical deflection circuit.

FIG. 11 is an operation waveform diagram thereof.

FIG. 12 is another connection diagram of the conventional vertical deflection circuit.

[Explanation of symbols]

12 Vertical oscillation circuit 14 Differential amplifier 16 Vertical output circuit 20 Vertical deflection coil 22 Vertical pincushion distortion correction circuit 26 Current detector 30 bandpass filter

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04N 3/23 H04N 3/16

Claims (5)

(57) [Claims] 1. A correction circuit for correcting pincushion distortion is connected on a vertical deflection current path flowing through a vertical deflection coil, and the pincushion distortion correction signal superposed on a vertical sawtooth wave signal is used as a feedback correction signal in a vertical output circuit. And the voltage obtained at the connection point between the vertical deflection coil and the correction circuit is applied to the bandpass filter to extract the negative phase component of the pincushion distortion correction signal, and the extracted negative phase pin A vertical deflection circuit characterized in that only a vertical sawtooth wave signal corresponding to a vertical deflection current is fed back to the vertical output circuit by adding the cushion distortion correction signal to the feedback correction signal. 2. The vertical deflection circuit according to claim 1, wherein the correction circuit is composed of an LC parallel resonance circuit that is switched in a horizontal cycle. 3. The vertical deflection circuit according to claim 1, wherein the correction circuit is composed of a saturable reactor. 4. The bandpass filter according to claim 1, wherein the bandpass filter has a large amount of attenuation near a vertical frequency and a frequency characteristic in a horizontal frequency region of −6 dB / OCT. Vertical deflection circuit. 5. The vertical deflection circuit according to claim 1, wherein the bandpass filter includes a first-order lowpass filter and a highpass filter.