JPS62171280A - Power supply circuit for horizontal output circuit - Google Patents

Abstract

PURPOSE:To offer a power supply with low power and small size by applying the control of a distortion correction voltage to a switching regulator system DC-DC converter directly so as to fluctuate directly the output voltage in a horizontal output circuit with keystone distortion correcting function and a power supply circuit. CONSTITUTION:The switching regulator system DC-DC converter 2-1 uses a negative feedback loop comprising resistors 58, 59 and a coil 52 and a reference voltage generating circuit 57 to decide its output voltage and stabilize it. Further, a picture distortion correction signal forming circuit 3-1 and is provided to set the frequency response of the said negative feedback loop lower than the frequency of a distortion correction signal and the fluctuation according to the period of the picture distortion correction signal is caused in the output voltage of the converter 2-1 by superimposing the distortion correction signal on the said negative feedback loop or the reference voltage and the output voltage of the converter 2-1 is applied to the horizontal output circuit 4 as a power voltage. Thus, a transistor circuit applying serial control operation is not used as the power supply circuit of the circuit 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a means for controlling the output voltage of a power supply circuit in an analog manner according to a predetermined cycle, and particularly to a horizontal deflection circuit of a flat-screen television that requires Rask distortion correction. The present invention relates to a power supply circuit suitable for.

[Conventional technology]

As an example of means for increasing the efficiency and reducing the power consumption of the horizontal output power supply circuit, as described in Japanese Patent Application Laid-Open No. 124572/1982, it is possible to perform horizontal deflection port one-way cleaning without using a voltage stabilization circuit. A self-stabilizing horizontal deflection circuit has already been proposed in which a stable DC power supply is supplied and the horizontal deflection circuit itself is stabilized. In addition, a series control type power supply circuit is used in the horizontal output voltage control circuit applied to the line operation system, and the output voltage of the voltage control circuit is controlled at a predetermined rate by detecting increases and decreases in the horizontal output circuit load current during high voltage fluctuations. descending,
A rasterization correction means that increases
This has already been proposed in No. 4274.

However, in these conventional technologies, the output voltage of a high-efficiency DC-DC converter for the horizontal output circuit power supply is controlled at a predetermined cycle, and image distortion such as keystone distortion when using a flat Brakun tube is corrected. The means are not indicated.

The configuration shown in FIG. 2 is known as a keystone distortion correction means for a horizontal output circuit that drives a flat Brakun tube. That is, FIG. 2 consists of an unregulated DC power source 1 such as a battery, a high efficiency DC-DC converter of the switching regulator type, a keystone distortion correction circuit indicated by a broken line, and a horizontal output circuit indicated by a broken line 4.

As shown in FIG. 3, a horizontal and vertical deflection coil 8
If the tube is deflected in the same manner as a normal straight plaque/tube, a trapezoidal raster indicated by ABC'D' will be obtained with the center of deflection S as the center. That is, a raster with keystone distortion is obtained, but it is necessary to correct it to the correct raster shape as shown by <ABCD. To do this, for example, the horizontal deflection current amplitude may be modulated with vertical synchronization, and the horizontal deflection current amplitude may be controlled to be small at the beginning of the vertical scan and large at the end of the vertical period. In general, the horizontal deflection coil is a passive element and its inductance value cannot be changed, so the control of the deflection current amplitude described above is
This is done by controlling the 'i4M voltage value of the horizontal deflection circuit as shown in the figure.

In FIG. 2, the horizontal output circuit A includes a drive signal input terminal 9, an output transistor 10, a damper diode 11,
It consists of a common camera capacitor p12, a horizontal deflection coil 8H, a DC blocking capacitor f13, and a DC power supply voltage is applied from the 0 point via an f-yoke coil 14. The DC power supply voltage at point 0 is obtained by controlling the constant output voltage (point P) of the DC-DC converter by the output transistor 15 of the keystone distortion correction circuit 3.

The keystone distortion correction circuit 3 provides an input terminal 16 with a sawtooth voltage waveform that changes with a vertical period, which is inverted and amplified by a transistor 17, and then further inverted and amplified by a transistor 20 via a collector f18 and a resistor 19.

At the output of the transistor 20, the sawtooth voltage obtained at the collector of the transistor 17 is connected to a resistor 21 and a capacitor 22.
After being low-passed and converted into a parabolic voltage, it is added via the transistor 3 forming a differential pair with the transistor 20. The collector output voltage of the transistor 20 is applied to the base of the output transistor 150 via the transistor 24 and the diode 5. It is used to make it easy to obtain a large pressure change.

The other elements on the keystone distortion correction circuit are used for setting the amplification level, DC voltage setting, etc., and individually do not have any special significance for keystone distortion correction. That is, the purpose of the keystone distortion correction circuit is to
- Control of the output transistor 15 for converting the constant DC power supply voltage obtained at the output point P of the DC converter into the DC °4 source voltage at the 0 point controlled by the vertical period required by the horizontal output circuit 4 The amount and control is to form the hourglass shape as desired. With the circuit configuration shown in Figure 2, the third
The correct raster shape shown by ABCD in the figure can be obtained. In Fig. 2, the low voltage at the Q point, which is the output voltage of the - Unlike the keystone correction output section for horizontal output, which requires a relatively high voltage, this is to further reduce power consumption in the small signal shaping processing section, which can be driven with a single low voltage like normal signal processing. .

Now, if we look at the operating voltage waveform and power consumption of the circuit configuration shown in FIG. 2 for correcting keystone distortion on the flat platen tube, it is as shown in FIG. 4. That is, when the vertical axis represents the voltage and the horizontal axis represents the time from the ground potential (GND), the voltage waveforms at the 0 point and the P point are shown as Eo and Ep, respectively. To give an example of specific numerical values, Eo repeats a range from a minimum value of 10V to a maximum value of 20V in a vertical period, and Ep is constant at 25V. Time t1 represents the start of vertical scanning, time t2 represents the end, and retrace scanning is performed between t2 and 15. The amplitude of the deflection current flowing through the horizontal deflection coil 8H varies in proportion to the change in the voltage FJo at the 0 point, and the (average) value of the load current on the horizontal output circuit is also proportional to the voltage go.

Therefore, it can be considered that the power consumption as a horizontal output circuit considered from point P is proportional to the product of go and Ep.

That is, in the circuit configuration shown in FIG. 2, the output transistor 15 on the keystone distortion correction circuit can be considered to constitute an output transistor of a so-called series-controlled power supply circuit, and the collector-emitter voltage of the output transistor 15 The corresponding voltage (Ep-Eo) in FIG.
is wasted by

Further, the overall purpose of the keystone distortion correction circuit 1 may be considered to be a circuit for forming a control signal for the output transistor 150 for performing the series control.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology does not consider minimizing power consumption in the horizontal deflection circuit that requires keystone distortion correction and its power supply circuit, and therefore, the battery life is short, especially in the case of battery drive. There was a problem with that.

An object of the present invention is to provide a circuit configuration with low power consumption for a horizontal deflection circuit that requires correction of image distortion such as keystone distortion and its power supply circuit.

[Means for solving problems]

For the above purpose, 1, without using a transistor circuit that performs series control operation as a power supply circuit for a horizontal output circuit that requires keystone distortion correction, the output voltage 1 voltage of a switching regulator type DC-DC converter can be directly used as a power supply circuit for a horizontal output circuit. An image distortion correction signal forming circuit is provided which generates a correction signal to be used as a voltage and further corrects image distortion such as keystone distortion, and supplies the image distortion correction signal to a DC-DC converter as an output voltage control signal. This is achieved by controlling the output voltage of the DC-DC converter according to the signal.

[Effect]

The image distortion correction signal forming circuit generates an image distortion correction signal for correcting keystone distortion and the like. For example, for correction of keystone distortion, a sawtooth wave voltage signal with a predetermined vertical period is generated.

The image distortion correction signal is supplied to a DC-DC converter,
The DC-DC converter changes the output voltage according to this image distortion correction signal. Therefore, when a keystone distortion correction signal is input, the output voltage of the DC-DC converter becomes a sawtooth wave according to the correction signal, the deflection current amplitude in the horizontal output circuit changes, and the keystone distortion can be corrected.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. This embodiment relates to a circuit for correcting keystone distortion, and a keystone position correction voltage signal output from a keystone distortion correction circuit 3-1 is transferred to a DC-DC converter 2-1.
The output voltage of the DC-DC converter is changed by inputting the voltage to the reference voltage terminal of the DC-DC converter.

The power supply circuit of this embodiment includes an unregulated power supply 1 such as a battery, a switching regulator type I) C-DC converter 3
-1, Keystone distortion correction circuit top -1, horizontal circle force circuit 4
It consists of In this figure, the same reference numerals are used for parts indicating the same contents as in FIG. 2, and detailed illustrations are omitted.

A keystone distortion correction voltage waveform similar to that of the collector of transistor 20 in FIG. 2 is obtained at the collector of transistor 20 in keystone distortion correction circuit 1-1.

1) The C-DC converter 2-1 includes a switching transistor 50. Flywheel diode 51. Choke coil 52. The output voltage is determined by the configuration of the smoothing conductor f53.

Zener diode for setting reference voltage 54. A reference voltage formed by a series circuit consisting of a bias undercurrent supply resistor 55 is applied to the negative terminal of a comparator 57 (specifically, for example, NJM2903) via a resistor 56, and the output voltage is divided by resistors 58 and 59. After being applied, it is applied to the positive terminal of the comparator 57 via the resistor 60. The output voltage of the DC-DC converter is determined by the voltage difference between the DC voltages applied to the plus and minus terminals of the comparator 57. That is, the rated output voltage can be adjusted to a predetermined voltage by selecting the voltage determined by the Zener diode 54 or the dividing ratio of the resistors 58 and 59. - Also, resistor 58.59 comparator 57. Output transistor 50. Since the loop formed by the choke coil 52 constitutes a negative feedback loop, it has a function of always keeping the output voltage of the DC-DC converter constant. In addition,
The resistor 61 is a resistor for setting the charging current of the capacitor 620, and conducts the output transistor 50 according to a time constant determined by its resistance value and the capacitance value of the capacitor, and a repetition period determined by the charging and unloading of the capacitor 62 by the comparator 57. Control non-conduction. The output voltage of the DC-DC converter 2-1 is applied as a power supply voltage to the horizontal output circuit 4.

Now, in Fig. 1, in addition to the configuration of the above-mentioned normal switching regulator EDC-DC converter, a resistor 5
A collector f65 is connected to the connection point of 8 and 59, forming a low-pass filter. That is, if the fluctuation in the output voltage is transmitted to the positive input terminal of the comparator 57 without time delay, the effect of the negative feedback loop will be controlled to cancel the fluctuation in the output voltage. Since the desired vertical periodic fluctuation of the DC-DC converter output voltage cannot be achieved, a time delay is provided due to the low-pass effect of the collector f63. Alternatively, it may be considered that the average DC voltage is applied to the positive terminal due to a sufficient low-pass effect.

Note that even in a normal configuration, there is a certain degree of low-pass effect due to the capacitor 62, but the vertical period is A low-pass filter was constructed separately that can set a sufficient time delay for both.

The low-pass filter formed by the capacitor 63 is formed by the f-yoke coil 52. The capacitor 56 may be omitted as long as a sufficient low-pass effect can be obtained.

Moreover, the effect of the negative feedback loop is sufficient if it can generate a sufficient negative feedback effect against input voltage fluctuations over a relatively long period of time, such as voltage fluctuations of the unregulated DC power supply 1 due to battery exhaustion. , there is no problem at all even if it cannot respond to fluctuations in the vertical period.

Further, in FIG. 1, a keystone distortion correction voltage signal is superimposed from the collector of the transistor 20 via the collector +70 on the reference DC voltage applied to the negative terminal of the comparator 57. As mentioned above, the output voltage of the DC-DC converter is determined by the difference voltage applied to the plus terminal and the minus terminal of the comparator 57, so the output voltage of the DC-DC converter 2-1 is determined according to the superimposed keystone distortion correction voltage signal. It is easy to understand that the output voltage of That is, at the DC-DC converter output terminal O point in FIG. 1, the output voltage waveform exactly the same as that at point 0 in FIG. 2, and Eo in FIG. 4, is obtained. Furthermore, in the case of Fig. 1, the output voltage of the high-efficiency switching regulator E DC-DC converter is used as the power supply voltage of the horizontal output circuit that requires keystone distortion correction, rather than the low-efficiency power supply circuit such as series control. Therefore, the power consumption of the entire set can be significantly reduced. In addition, the output circuit parts such as the high voltage/large current output transistor 15 that were necessary in the configuration shown in Figure 2 are all unnecessary, and design structural parts such as heat sinks are also no longer required, resulting in low gravity and low cost. A horizontal deflection circuit with a keystone distortion correction function and its electromagnetic circuit can be obtained.

A second embodiment of the present invention is shown in FIG. 5 and will be described in detail.

In this embodiment, the output of the -DC converter is changed by superimposing the correction signal from the keystone distortion correction circuit 3-2 on the feedback signal of the negative feedback loop of the DC-DC converter 2-2. In the same drawing, elements showing the same content as in FIG. 1 are given the same reference numerals. In FIG. 5, unlike in FIG. 1, the polarity of the vertical periodic sawtooth voltage waveform applied to the terminal 16 is reversed. Therefore, the keystone distortion correction voltage is applied from the collector of the transistor 20 to the positive terminal of the comparator 57. Also, resistance 58, 59, 60
゜The voltage of the output voltage stabilization negative feedback loop of the DC-DC converter including the collector f65 is not directly applied to the positive terminal of the differential amplifier 57, but is superimposed on the keystone distortion correction voltage via the transistors 25 and 20 for negative feedback. There is. Therefore, in FIG. 5, the control signal based on the keystone distortion correction voltage is applied to the DC-DC converter in a form including a direct current component.

The feedback voltage input to the positive input terminal of the converter 57 varies in a sawtooth manner according to the keystone distortion correction signal, and the output voltage of the DC-DC converter also varies in a sawtooth manner accordingly.

Similar to the embodiment shown in FIG. 1, the embodiment shown in FIG. 5 also provides a horizontal output circuit with a keystone distortion correction function and its power supply circuit that is smaller, lower cost, and lower in power than the prior art shown in FIG. 2. .

As explained above, in order to perform low-voltage kakistone distortion correction according to the present invention, the specific configuration methods such as the polarity of various feedback loops and control loops, whether DC coupling or AC coupling, etc. are variously modified. can do. In addition, the specific circuit configuration of the key distortion correction circuit, its correction amount, polarity, etc. are matters that should be appropriately designed depending on the deflection angle, flatness, deflection polarity, etc. of the Braun tube used.

In addition, regarding the specific circuit configuration of the DC-DC converter, various modifications are possible, such as whether to use a PNP type or NPN type for the output transistor, and whether to use pace grounding or collector grounding. In addition to the step-down switching regulator shown in FIG. 5, it is also possible to construct a step-up switching regulator using a transformer.

In the above description, keystone distortion correction has been taken as an example, but it is clear that the present invention can also be applied to image distortion such as pincushion distortion.

〔Effect of the invention〕

According to the present invention, in a horizontal output circuit with a keystone distortion correction function and a power supply circuit, control using a keystone distortion correction voltage is controlled by a switching regulator type DC with high conversion efficiency.
- Since it is directly added to the DC converter and directly changes the output voltage of the DC-DC converter, there is less power loss than in the past (lower power and smaller power supply for horizontal output circuits can be provided).

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of the first embodiment of the present invention, FIG. 2 is a circuit diagram of a conventional horizontal output circuit with keystone distortion correction function, and FIG.
The figure is a schematic diagram showing a flat cathode ray tube for explaining the present invention, FIG. 4 is an operating waveform diagram of the circuit of FIG. 2, and FIG. 5 is a circuit diagram of a second embodiment of the present invention. 1...Unregulated DC power supply 2...DC-DC converter 3...Keystone distortion correction circuit 4...Horizontal output circuit 7...Flat cathode ray tube 63 Capacitor Patent attorney Katsutoshi Ogawa [Ko I Akira Figure 2 Figure 3 Box 4 Figure 5 j, -z

Claims (1)

[Claims] 1. In a horizontal output circuit power supply circuit comprising a switching regulator type DC-DC converter that determines and stabilizes the output voltage by an output voltage stabilization negative feedback loop and a reference voltage generation circuit, and a horizontal output circuit, An image distortion correction signal forming circuit that generates an image distortion correction signal is provided, and the frequency response characteristic of the output voltage stabilization negative feedback loop of the DC-DC converter is set to be lower than the frequency of the image distortion correction signal, The distortion correction signal is
Causes the output voltage of the DC-DC converter to fluctuate according to the image distortion correction signal period by superimposing it on the output voltage stabilization negative feedback loop of the converter or the reference voltage,
A power supply circuit for a horizontal output circuit, characterized in that an output voltage of the DC-DC converter is applied to the horizontal output circuit as a power supply voltage.