JPH04326694A - Convergence drive - Google Patents

Abstract

PURPOSE:To reduce the power consumption of a convergence driving device by detecting the phase and the voltage of a maximum induced voltage induced in a correction coil and changing the supply voltage, the phase, and the frequency characteristic of the transistor of a current amplifying part. CONSTITUTION:A horizontal synchronizing signal is applied to an input terminal 1 and is supplied to a correction waveform generating part 2. The correction waveform is amplified by a current amplifying part 3, to which the signal from the correction coil is fed back, and is given to the correction coil. The terminal voltage applied to the correction coil is proportional to differential of the correction current. A synchronizing signal is supplied to a power generating part 4, and a voltage having a large absolute value is generated only in the fly-back period and is given to the amplifying transistor of the current amplifying part 3. By this constitution, the supply voltage is reduced to a minimum required value, and the convergence driving circuit of low power consumption and small loss is obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for correcting convergence in color television receivers and the like, and more particularly to a highly accurate convergence drive device that consumes low power and does not cause color shift at the periphery of the screen.

0002

2. Description of the Related Art Generally, in color television receivers and the like, convergence correction is performed so that electron beams of three primary colors are converged into one beam. In (Fig. 15),
1 is a synchronization signal input terminal, 2 is a convergence correction waveform generation section, and 3 is a current amplification section. Normally, in convergence correction, as shown in FIG. 15, a correction waveform generating section 2 generates a convergence correction waveform, the current amplification section 3 amplifies the current signal, and sends the signal to a correction coil. If the terminal voltage applied to the convergence correction coil is V, the flowing current is i, and the inductance of the coil is L, then there is a relationship of V≒L (di/dt), so in order to flow the convergence correction current, , it is necessary to apply a value proportional to the differential of the current as the terminal voltage of the convergence correction coil. As a result, the steeper the change in the correction current, the greater the applied voltage needs to be. In particular, since the change in convergence current is often steep during the retrace period, it is necessary to amplify the current with a power supply voltage that is large in absolute value during this period. However, during the effective scanning line period, it was possible to amplify even a small power supply voltage in absolute value in the current amplification section. Therefore, during the effective scanning line period, the convergence current changes more slowly than during the flyback period, resulting in a large power loss. Furthermore, the more finely the convergence correction is made by dividing the screen into smaller parts, the more steeply the change in the convergence correction current becomes, and the voltage applied to the correction coil becomes higher, so it is necessary to increase the power supply voltage. This further led to an increase in power loss, leading to an increase in power consumption. As a conventional convergence drive device for reducing the power consumption of such a current amplification section, for example, Japanese Patent Application Laid-Open No. 1-320
It is shown in the No. 891 publication.

FIG. 16 shows a circuit diagram of this conventional convergence drive device. (Fig. 16), 51 is a horizontal deflection output circuit, 52 is a choke transformer,
53 is a drive circuit, and 54 is an output circuit.

In the conventional convergence drive device configured as described above, the horizontal deflection output circuit 51 is connected to the primary coil of the choke transformer 52 to generate a horizontal pulse voltage. Further, a drive circuit 53 and a DC voltage 55 are connected to the secondary side of the choke transformer 52. The convergence correction waveform is applied to the drive circuit 53, amplified, and then supplied to the output circuit 54. The output circuit is single-ended push-pull (SE
PP) circuit and drives a correction coil. In the choke transformer 52, a horizontal pulse from the horizontal deflection circuit is superimposed on the DC voltage from the DC power supply 55, and this is supplied as a power source to the SEPP circuit. As a result, a DC voltage is generated during the scanning period of one horizontal scanning period, a superimposed voltage in which a horizontal pulse voltage is superimposed on the DC voltage is generated during the blanking period of one horizontal scanning period, and a superimposed voltage is generated during the blanking period of one horizontal scanning period. A power supply circuit is provided that supplies the SEPP circuit with a power supply voltage that is larger in absolute value than the effective scanning period.

[0005]

[Problems to be Solved by the Invention] However, in the above configuration, since the horizontal pulse voltage obtained from the transformer is superimposed on the power supply of the current amplifying transistor,
If the output voltage or phase of the pulse voltage output cannot be adjusted, and when considering a multi-scan TV, etc., the phase between the induced voltage generated in the correction coil and the pulse voltage output does not match, resulting in saturation of the induced voltage. There was a problem in that the correction accuracy in the peripheral area decreased.

Furthermore, since the cut-off frequency of the drive circuit cannot be controlled, if you try to widen the band of the drive circuit, the peak value of the induced voltage in the convergence coil will increase, making it necessary to increase the power supply voltage of the current amplification transistor, Another problem was that the inductance value of the correction coil had to be lowered.

In view of this, the present invention detects the phase and voltage value of the maximum induced voltage induced in the correction coil, and adjusts the power supply voltage, phase, and frequency characteristics of the transistor of the current amplification section according to the detected signal. The purpose of the present invention is to provide a convergence drive circuit that supports multi-scan with low power consumption by changing the power consumption.

[0008]

[Means for Solving the Problems] In order to solve the above problems, a first invention provides a correction waveform generating means for generating a convergence correction waveform, and a feedback type current source for applying the correction waveform to a correction coil. The present invention is characterized in that it comprises a driving means, and a power generating means set to a high level only during the retrace period of the signal, and the power source is inputted to the driving means.

[0009] A second invention also includes a correction waveform generating means for generating a correction waveform for performing convergence correction, a driving means for a feedback type constant current source for applying the correction waveform to a correction coil, The apparatus further includes a band control means for setting the frequency characteristics of the driving means to be different between a retrace period and an effective scanning period.

0010

[Operation] According to the first invention, the voltage and phase of the maximum induced voltage induced in the coil are detected, and the power supply and correction waveform of the current amplification section are controlled based on this detection signal, thereby supporting multi-scanning. It is possible to reduce loss and power consumption in the drive circuit and improve correction accuracy in the peripheral area.

Further, according to the second invention, by setting the frequency characteristics of the amplifying section during the retrace period to be different from the effective scanning period, the induced voltage during the retrace period can be suppressed to the minimum level, and the consumption can be reduced. Power consumption can be reduced.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of a first embodiment of the present invention. In (Fig. 1), 1 is an input terminal that inputs a horizontal synchronization signal synchronized with the deflection, 2 is a correction waveform generator that generates a convergence correction waveform in synchronization with the input synchronization signal, and 3 is a convergence correction signal that is supplied. A current amplifying section 4 that amplifies the waveform is a power generating section that generates power to be supplied to the current amplifying section, and the current amplifying section 3 is of a feedback type in which the output is fed back. The output is also fed back to the power generation section 4. (Figure 2) is (
FIG. 2 is a waveform diagram showing voltage and current waveforms at various parts in the circuit of FIG. 1).

The operation of the first embodiment configured as shown in FIG. 1 will be explained below. When a horizontal synchronizing signal as shown in FIG. 2(a) is applied to the input terminal 1, it is supplied to the correction waveform generator 2. The correction waveform generating section 2 generates, for example, a parabola correction waveform as shown in FIG. 2(b) in synchronization with the synchronization signal. The correction waveform is supplied to the current amplification section 3 which feeds back the signal from the correction coil, and is current-amplified. The current amplified signal is supplied to a correction coil. Here, since the terminal voltage applied to the correction coil is proportional to the differential of the correction current, it is shown as (FIG. 2(c)). The synchronization signal is supplied to the power generation section 4, and (
As shown in FIG. 2(d) and FIG. 2(e), a voltage with a large absolute value is generated only during the retrace period, and is supplied to the current amplifying transistor of the current amplifying section 3.

As described above, according to this embodiment, when a large induced voltage is generated in the absolute value only during the retrace period in the convergence correction coil (FIG. 2(b)), the power source of the power source generator 4 is By supplying the current amplifying transistor to the current amplifying transistor of the current amplifying section 3, the power supply voltage can be suppressed to the necessary minimum, and a convergence drive circuit with low power consumption and low loss can be realized.

(FIG. 3) shows a block diagram for explaining the power generation means of the present invention. In (FIG. 3), parts corresponding to those in (FIG. 1) are given the same numbers. (Figure 4)
3 is a waveform diagram showing voltage waveforms at various parts in the circuit of FIG. 3. FIG.

The first power generation means will be explained below (FIG. 3).
) will be used to explain in detail. A feature of the first power generation means is that the power supply voltage is optimally set according to the induced voltage. (FIG. 3), 11 is a feedback amplifier circuit, 12 is a drive circuit, 13 is a current/voltage conversion circuit that converts the correction current supplied to the correction coil into voltage, 14 is a control circuit, 15 and 17 are voltage generation circuits, Reference numeral 16 denotes a switching circuit, which controls the power supply voltage according to the induced voltage.

In FIG. 3, when a synchronization signal is input from the input terminal 1, a convergence correction waveform is generated in the correction waveform generating section 2. This convergence correction waveform is supplied to the feedback amplifier circuit 11. Feedback amplifier circuit 1
1 is composed of an operational amplifier as shown in FIG. 5, for example. For the feedback signal, the signal supplied to the correction coil is converted into a current/
A voltage signal converted by the voltage conversion circuit 13 is used. This current/voltage conversion circuit 13 is, for example, a resistor 1 in (FIG. 5).
It is configured as shown in 8. The reason why a feedback type amplifier circuit is used here is that the convergence correction circuit is required to have about half the stability of the scanning line in terms of resolution. The convergence correction waveform amplified by the feedback amplifier circuit 11 is supplied to the drive circuit 12, where the current is amplified. For example, a SEPP circuit is used as the drive circuit 12. The power generation unit 4 supplies power to the drive circuit 12. The signal converted by the current/voltage conversion circuit 13 is shown, for example, as shown in FIG. 4(b). The converted signal is sent to the control circuit 14, which generates a first voltage generating circuit 15 that generates both positive and negative power supply voltages with a large absolute value corresponding to the retrace period, and a first voltage generating circuit 15 that generates a voltage of both positive and negative power supplies with a large absolute value corresponding to the effective scanning period. The respective power supply voltage values of the second voltage generation circuit 17 which generates small voltages of both power supplies are controlled. Here, the voltage VS1 of the first voltage generation circuit 15 is controlled by the control circuit 14 so that VS1≧V1 when the output of the current/voltage conversion circuit 13 is shown as shown in FIG. 4(b). be done. Here, V1 is the highest value of the output of the current/voltage conversion circuit 13 during the entire period including the blanking period and the effective scanning period. Further, the voltage VS of the second voltage generation circuit 17
2 is controlled by the control circuit 14 so that VS2≧V2. Here, V2 is the highest value of the output of the current/voltage conversion circuit 13 during the effective scanning period. For the voltage generation circuits 15 and 17, for example, a series controlled constant voltage power supply as shown in FIG. 6 is used. In FIG. 6, 19 is an input terminal, 20 is a variable impedance element, 21 is an output terminal, 14 is a control circuit, and 22 is an error amplification circuit. In this circuit, by controlling the voltage drop caused by the variable impedance element, a power supply voltage corresponding to the control signal obtained from the control circuit 14 can be extracted from the output terminal 21. Here, as the variable impedance element, for example, a transistor is used. The voltage generated by the first voltage generation circuit 15 and the second voltage generation circuit 17 is controlled by the switching circuit 16 so that the first voltage generation circuit 15 is connected to the power supply of the drive circuit 12 during the retrace period, and during the effective scanning period. connects the second voltage generation circuit 17 to the power supply of the drive circuit 12.

Next, the reason why power consumption can be reduced will be explained in detail. For example, in (Fig. 4(c)), 1
Consider the case of a signal source in which the blanking period tr is 20% and the effective scanning period ts is 80% of the horizontal scanning period t1H. At this time, the power supply voltage of the drive circuit in the current amplification section is set such that the voltage VS2 during the retrace period is set to 12V, and the power supply VS1 during the effective scanning period is set to 24V, so that the average current of the power supply voltage is 0.
An example of calculating power consumption at 5A is shown. In this case, the power consumption Pc1 during the entire scanning period is Pc1 = (24V x 0.5A x 0.2) + (12V
×0.5A×0.8) =7.2W In addition, power consumption Pc2 during the entire scanning period when not following the example
is Pc2=(24V×0.5A×1.0)=12W, and by implementing the present invention, it is possible to reduce power consumption by about 40%.

By the above operation, the power supply voltage value of the drive circuit changes as shown in FIG. 4(c), and it is possible to reduce power consumption and loss in the power supply section of the drive circuit.

(FIG. 7) shows a block diagram for explaining the second power generation means of the present invention. A feature of the second power generation means is that the phase of the power supply corresponding to the retrace period is optimally set according to the induced voltage. In (FIG. 7), parts corresponding to those in (FIG. 1) are given the same numbers. (FIG. 8) is a waveform diagram showing the operation of each part in the circuit of (FIG. 7), and (FIG. 9) shows the frequency characteristics of the current amplification section.

The second power generation means will be explained below (FIG. 7).
) will be used to explain in detail. (FIG. 7), 23 is a comparator, 25 is a timing control circuit, 24 is a timing control section composed of the comparator 23 and the timing control circuit 25, and 26 is a voltage generation circuit, which controls the power source according to the induced voltage. The phase of the voltage blanking period is controlled.

In (FIG. 1), from input terminal 1 (FIG. 8
When the synchronization signal (a) is input, a convergence correction waveform is generated in the correction waveform generating section 2. This convergence correction waveform is supplied to the current amplifying section 3 (FIG. 7), and a correction current having a parabolic waveform (FIG. 8(b)) flows through the correction coil. The induced voltage induced in the correction coil is generated when the current/voltage conversion circuit 13 converts the correction current into voltage, and is expressed as shown in FIG. 8(c). As shown in FIG. 9, the frequency characteristics of the current amplification section 2 are fc1 when the correction current is large amplitude, and fc1 when the correction current is small amplitude.
c2, the band changes depending on the gain, and its characteristics are those of a low-pass filter. Therefore, (Fig. 8
A correction waveform is generated based on the rising edge of the input synchronization signal in (a)), but a phase difference of a fixed time delay amount DL1 occurs in the correction current flowing through the correction coil due to the factor of band limitation. Therefore, a synchronization signal synchronized with the deflection (FIG. 8(a)) is supplied to the power generation section 4 (FIG. 8(a)).
(d) Generates the bipolar power supply voltage of drive circuit 1
Supply to 2.

In this case, a delay amount DL1 occurs between the retrace period t1 of the power supply voltage (FIG. 8(d)) and the phase timing of the induced voltage (FIG. 8(c)), so that the induced voltage is lower than the power supply voltage. is delayed, and color shift occurs due to saturation of the induced voltage near the retrace period. Therefore, in the second power generation means, the level of the induced voltage (FIG. 8(c)) is compared with the reference potential (Vref) by the comparator 23, and this comparison signal is supplied to the timing control circuit 25. (Figure 8(e)
) generates a power supply voltage during the retrace period t2.

Next, when a synchronization signal having a different scanning frequency is input from the input terminal 1 (FIG. 8(f)), a convergence correction waveform is generated in the correction waveform generating section 2. This convergence correction waveform is supplied to the current amplification section 3, and a horizontal parabola correction current (FIG. 8(g)) flows through the correction coil. The induced voltage induced in the correction coil is generated when the current/voltage conversion circuit 13 converts the correction current into voltage.
An induced voltage as shown in FIG. 8(h) is generated. (Figure 8 (
A correction waveform is generated based on the rising edge of the input synchronization signal in f)), but a phase difference of a fixed time delay amount DL1 occurs in the correction current flowing through the correction coil due to the factor of band limitation. Therefore, a synchronization signal synchronized with the deflection (FIG. 8(f)) is supplied to the power supply generator 4 (FIG. 8(f)).
i) The drive circuit 12 generates the bipolar power supply voltage of
supplied. In this case, a delay amount DL1 occurs between the retrace period t3 of the power supply voltage (FIG. 8(i)) and the phase timing of the induced voltage (FIG. 8(h)), so that the induced voltage lags behind the power supply voltage. As a result, color shift occurs at the periphery of the screen due to saturation of the induced voltage near the retrace period. (Figure 8 (
c) The induced voltage of) is set to the reference potential (Vref) by the comparator 23.
This comparison signal is supplied to the timing control circuit 25 to generate the power supply voltage for the retrace period t4 (FIG. 8(e)). As mentioned above, a certain amount of delay DL1 occurs due to the band limitation in the current amplification section 3. Therefore, when considering multi-scan support with different scanning frequencies, the retrace period of the power supply voltage and the maximum induced voltage depend on the scanning frequency. The phase difference between them will change significantly. Therefore, the level at which the induced voltage increases is detected, and the phase of the retrace period of the power supply voltage is controlled by this detection signal, so that the induced voltage is always set within the retrace period of the power supply voltage.
By eliminating the saturation of the induced voltage, it is possible to significantly improve convergence accuracy in the peripheral area and reduce power consumption.

Next, in order to explain the correction waveform generating section in detail, the block diagram shown in FIG. 10 will be used. The feature of the correction waveform generator is that by shifting the phase of the correction waveform according to the induced voltage, the position of the maximum induced voltage induced in the correction coil and the phase of the deflection blanking period are made to be the same. It is.

In (FIG. 10), parts corresponding to those in (FIG. 1) are given the same numbers. (FIG. 11) shows voltage waveforms of various parts for explaining the first-term correction waveform generating part. In FIG. 10, 27 is a pulse shift circuit, 28 is a correction waveform generation circuit, and 29 is a phase comparator.

When the synchronization signal (FIG. 11(a)) is input from the input terminal 1, a convergence correction waveform is generated in the correction waveform generating section 2. This convergence correction waveform is supplied to the current amplification section 3 and sent to the correction coil (Fig. 11(b)
)) horizontal parabola correction current flows. The induced voltage induced in the correction coil is obtained by the current/voltage conversion circuit 13, and is shown in FIG. 11(c). A correction waveform is generated based on the rising edge of the input synchronization signal (Fig. 11(a)), but the current flowing through the correction coil has a phase difference of a certain amount of delay due to the factor of band limitation. Become. In this case, a delay amount DL2 occurs at the phase timing of the synchronization signal (FIG. 11(a)), which is the retrace period synchronized with the deflection, and the induced voltage (FIG. 11(d)), so the delay amount DL2 occurs during the retrace period. In comparison, the induced voltage is delayed, and color shift occurs at the periphery of the screen due to saturation of the induced voltage near the retrace period. The waveform of the induced voltage (Fig. 11(c)) was shaped (Fig. 11(c)).
(d)) and (FIG. 11(a)) are phase-compared by a phase comparator 29, and this comparison signal is supplied to the pulse shift circuit 27, (FIG. 11(a))
The pulse shift circuit 27 is controlled so that the rising period of the synchronizing signal shown in ) coincides with the rising period of the waveform-shaped induced voltage shown in FIG. 11(d) (FIG. 11(d)).

The pulse shift circuit 27 is composed of, for example, a monostable multivibrator, and by changing the time constant according to the control signal from the phase comparator 27, (
As shown in FIG. 11(e), the phase of the deflection synchronization signal is advanced by the phase delay DL2 of the convergence correction waveform in the current amplification section 3. By supplying this phase-advanced synchronization signal to the correction waveform generation circuit 28, a convergence correction waveform is output. This convergence correction waveform is supplied to the current amplification section 3, but the current amplification section 3 has a limited band and is delayed by DL2. As a result, the convergence correction waveform supplied to the correction coil (Fig. 11(
The waveform becomes as shown in f)). Then, (Fig. 11(g
An induced voltage as shown in )) is induced from the correction coil. By performing such an operation, the phases of the input synchronization signal and the induced voltage match. As a result, the induced voltage is set so that it always falls within the retrace period of the horizontal synchronization signal, eliminating saturation of the induced voltage, greatly improving convergence accuracy at the periphery of the screen, and reducing power consumption.

As described above, the first power generation means controls the power supply voltage, the second power generation means controls the phase and width during the retrace period of the power supply, and the retrace period synchronized with the deflection. The case where the phase of the correction waveform is controlled has been described above. In order to further enhance the effects of the present invention, the present invention can be achieved by first controlling the phase of the correction waveform, second controlling the power retrace period, and third controlling the power supply voltage. effect can be activated.

As described above, according to this embodiment, the induced voltage from the correction coil is detected, and the induced voltage is reduced by setting the power supply voltage of the current amplifying section to be large only during the retrace period when the induced voltage is large. This eliminates color saturation, eliminates color shift at the periphery of the screen, and creates a convergence drive circuit with low power consumption and low loss.

(FIG. 12) shows a block diagram of a second embodiment of the present invention. The difference from the first embodiment is that the frequency characteristics of the effective scanning period and blanking period are made different. In (FIG. 12), parts corresponding to those in (FIG. 1) and (FIG. 3) are given the same numbers. Also, (Figure 13
) shows the voltage waveform of each part in (FIG. 11), and (FIG. 14) shows the frequency characteristics of the convergence drive circuit.

The convergence drive circuit has a frequency characteristic as shown in FIG. 14(a) due to the action of a correction coil and the like. In this embodiment, the cutoff frequency is changed from fc4 to fc3 by lowering the high frequency characteristics during the retrace period.
It is changing to By reducing the high frequency characteristics during the retrace period, where the convergence correction waveform changes sharply, changes in this period are smoothed out, thereby reducing the peak of the induced voltage from the correction coil. As a result, the power supply voltage value of the drive circuit can be amplified to a small absolute value, and a convergence drive device with low power consumption and low loss is realized.

In FIG. 12, 40 is a band control unit that limits the frequency band of the current amplification unit, 41 and 43 are switching circuits, 42 is a low-pass filter that controls the band, and 44
is a control circuit that controls the frequency characteristics of the switching circuits 41 and 43 and the low-pass filter from the induced voltage converted by the current/voltage conversion circuit. Since the operations other than the bandwidth control section 40 are the same as those of the corresponding parts in the first embodiment, the bandwidth control section 40 will be described in detail here.

When a horizontal synchronizing signal as shown in FIG. 13(a) is input to the input terminal 1, the correction waveform generating section 2 generates a convergence correction waveform. Feedback amplifier circuit 11
The convergence correction waveform amplified by is supplied to the switching circuit 41. The switching circuit 41 is controlled by a control circuit 44, and the control circuit 44 is controlled by a signal from the current/voltage conversion circuit 13. During the blanking period when the convergence correction waveform changes sharply, the convergence correction signal is supplied to the low-pass filter 42, and during the effective scanning period when the change is relatively gradual, the convergence correction signal is supplied to the switching circuit without passing through the low-pass filter 42. Supply to 43. When the low-pass filter is not passed through the entire period, the induced voltage of the correction coil is (Fig. 13(b)
The waveform is as shown in )). However, by passing the signal through a low-pass filter only during the retrace period, the change in the convergence correction waveform during the retrace period can be made gentler. At this time, since the signal is not passed through a low-pass filter during the effective scanning period, even if the correction waveform changes, it is amplified with high accuracy. As a result, as shown in FIG. 13(c), without affecting the correction waveform during the effective scanning period,
The peak of the induced voltage from the correction coil can be reduced, and the power supply voltage value of the drive circuit can be amplified to a small absolute value, realizing a convergence drive device with low power consumption and low loss.

As described above, according to this embodiment, by band-limiting the frequency characteristics of the current amplifying section only during the retrace period when the induced voltage from the correction coil is large, the peak of the induced voltage during the retrace period can be suppressed. It is possible to reduce power consumption by reducing the size of the current amplification unit so that it can be amplified with a small power supply voltage, and at the same time, it is possible to reduce the saturation of the induced voltage and improve the correction accuracy in the peripheral area of the screen.

In the first and second embodiments, the case of driving convergence correction has been described, but it goes without saying that the present invention is also effective for driving devices with other correction waveforms.

Furthermore, in the first and second embodiments, a case has been described in which control is performed only during the retrace period during which the induced voltage is at its maximum, but control may be performed during periods other than the retrace period depending on the correction waveform. .

Furthermore, in the first and second embodiments, the case where the induced voltage is detected to control the voltage generator voltage, the phase of the retrace period, and the phase of the correction waveform has been described, but it is also possible to detect the correction waveform. It may be controlled by

In addition, in the first embodiment, three systems of control were described in which the induced voltage is detected and the voltage of the voltage generator, the phase of the retrace period, and the phase of the correction waveform are controlled.
Various combinations of systems or independent control may be used.

Further, in the first embodiment, the positive and negative voltage values generated by the voltage generating circuit are equal in absolute value, but the positive and negative voltage values may be changed.

Furthermore, in the first embodiment, a case has been described in which power is generated in two systems for the retrace period and the effective scanning period, but a larger number of systems may be used.

In the second embodiment, the case where the frequency characteristics are controlled by switching the low-pass filter has been described, but it can also be done by changing the value of the damping resistor connected in parallel to the correction coil. good.

Furthermore, although the case of switching the low-pass filter in the second embodiment has been described, the cut-off frequency of the low-pass filter may be changed by the induced voltage.

Furthermore, in the second embodiment, the case where a constant power supply voltage is supplied to the drive circuit has been described;
It goes without saying that the first embodiment may also be adopted.

[0046]

As explained above, according to the first invention, the voltage and phase of the maximum induced voltage induced in the correction coil are detected, and the power supply and correction waveform of the current amplification section are optimized using this detection signal. By controlling the voltage, it is possible to eliminate the phase shift between the induced voltage and the pulse voltage output, prevent saturation in the current amplification section, and suppress the power supply voltage supplied to the amplification transistor of the current amplification section during the effective scanning period. It is possible to reduce loss and power consumption in the drive circuit, and improve correction accuracy in the peripheral area. In particular, in a multi-scan compatible display device that can support a signal source of any scanning frequency, the optimum conditions can be automatically set, so multi-scan compatible can be easily realized, and its practical effects are very large. Generally, in a convergence drive device, there is a conflicting relationship between bandwidth and power consumption. For example, a digital convergence device that arranges multiple adjustment points on the screen and generates an arbitrary correction waveform by interpolating the correction data of each adjustment point requires a wider band and greater power. By implementing the invention, power consumption can be reduced, and its practical effects are significant.

Further, according to the second invention, by setting the frequency characteristic of the amplifying section during the retrace period to be narrower than that of the effective scanning period, the induced voltage during the retrace period can be suppressed to the minimum level, and the consumption can be reduced. Power consumption can be reduced.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a convergence drive device in a first embodiment of the present invention.

FIG. 2 is an operational waveform diagram of the same embodiment.

FIG. 3 is a block diagram of a first power generation circuit of the same embodiment.

FIG. 4 is an operation waveform diagram for explaining the operation of the same embodiment.

FIG. 5 is a circuit diagram of an example of a feedback amplifier circuit and a current/voltage conversion circuit of the same embodiment.

FIG. 6 is a circuit configuration diagram of a first power generation circuit of the same embodiment.

FIG. 7 is a block diagram of a second power generation circuit of the same embodiment.

FIG. 8 is an operation waveform diagram for explaining the operation of the same embodiment.

FIG. 9 is a frequency characteristic diagram of the current amplification section of the same embodiment.

FIG. 10 is a block diagram of a correction waveform circuit of the same embodiment.

FIG. 11 is an operation waveform diagram for explaining the operation of the same embodiment.

FIG. 12 is a block diagram of a convergence drive device in a second embodiment of the present invention.

FIG. 13 is an operation waveform diagram for explaining the operation of the same embodiment.

FIG. 14 is a frequency characteristic diagram of the same embodiment.

FIG. 15 is a block diagram of a first conventional convergence drive device.

FIG. 16 is a block diagram of a second conventional convergence drive device.

[Explanation of symbols]

1 Input terminal 2 Correction waveform generation section 3 Current amplification section 4 Power generation section 40 Bandwidth control section 11 Feedback amplifier circuit 12 Drive circuit 13 Current/voltage conversion circuit 24 Timing control section 15, 17 Power generation circuit 14, 44 Control circuit 27 Pulse shift circuit 29 Phase comparator

Claims (6)

[Claims] 1. A correction waveform generating means for generating a correction waveform for convergence correction of a color television receiver, and a feedback type constant current source driving means for applying the correction current waveform to a correction coil. and a power generating means for generating a high power only during the retrace period of a signal, and the power is inputted to the driving means. 2. The convergence drive device according to claim 1, wherein the generating means detects the induced voltage induced in the coil during the retrace period, and sets the power supply voltage in accordance with this detection signal. . 3. A claim characterized in that the generating means detects the position of the maximum induced voltage induced in the coil, and controls the blanking period width and phase of the power supply voltage in accordance with this detection signal. 1. The convergence drive device according to 1. 4. The generating means detects the position of the maximum induced voltage induced in the coil, and the phase of the correction waveform generating means is controlled so that this detection signal is the same as the deflection retrace period of the receiver. The convergence drive device according to claim 1, characterized in that the convergence drive device is configured as follows. 5. Correction waveform generation means for generating a correction waveform for convergence correction of a color television receiver, and means for driving a feedback type constant current source for applying the correction current waveform to a correction coil. and a convergence drive device comprising a band control means for setting the frequency characteristics of the drive means to be different between a retrace period and an effective scanning period. 6. The convergence drive device according to claim 5, wherein the band control means sets the frequency characteristic of the blanking period narrower than that of the effective scanning period.