JPS62219771A - Horizontal deflection circuit - Google Patents

Abstract

PURPOSE:To suppress the loss of an active element in a horizontal deflection output circuit at the minimum level, and to improve reliability for a device, by providing a voltage control circuit which controls a power source voltage supplied to an excitation circuit, so as to lower as a horizontal deflection frequency goes high. CONSTITUTION:A voltage regulator 15 is interposed between the other end of the primary side winding 3a of a transformer 3, and a DC power source circuit 4, and a voltage Eb11 in which the output voltage Eb1 of the DC power source circuit 4 is controlled corresponding to the output voltage Eb21 of a voltage regulator 12, is impressed on the primary side winding 3a of the transformer 3. An excitation current Ib1 is excessive when a horizontal deflection cycle Th is short, and is insufficient when it is long, therefore, to dissolve the problem, the voltage Eb11 outputted from the voltage regulator 15 is set low when the horizontal deflection cycle Th is short, and set high when it is long. Thus, by changing the value of the voltage Eb11 corresponding to a horizontal deflection frequency fH, and the output voltage Eb21 of the voltage regulator 12, the optimum excitation current can be supplied to the base of a transistor 5, even when the horizontal deflection frequency fH is varied, and the loss of the transistor 5 can be minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a horizontal deflection circuit for horizontally deflecting an electron beam of a cathode ray tube such as a picture tube in response to different horizontal deflection frequencies.

(Prior Art) Video information reproducing devices that reproduce video information using cathode ray tubes (picture tubes such as cathode ray tubes) include, for example, television receivers, display devices used as terminal devices for various information devices, etc. There is.

In such a video information reproducing apparatus, in order to reproduce video information on the picture tube, it is necessary to deflect the electron beam of the picture tube in the vertical and horizontal directions according to a predetermined scanning method, as is well known.

By the way, for example, the predetermined scanning method as mentioned above in a television receiver differs depending on which standard television method the video information to be reproduced is transmitted according to, and also as a terminal device of various information devices. Since the scanning method is usually set for each display device used, the scanning method is usually different for each display device.

As mentioned above, when the scanning methods are different, the deflection circuits such as the horizontal deflection circuit and the vertical deflection circuit will of course have different configurations, but in response to the different scanning methods, it is necessary to use a video information reproducing device dedicated to each scanning method. However, in the past, various types of deflection circuits that were configured to operate in accordance with multiple scanning methods were used. What has been proposed is well known.

An example of a conventional horizontal deflection circuit will be explained with reference to the circuit diagram of FIG.

In Fig. 4, 1 is a pre-stage circuit such as a synchronous separation circuit (4th
An oscillation circuit that oscillates a square wave signal R in response to a synchronization signal @P with a horizontal deflection frequency f, which is supplied from a device (not shown in the figure); 2 is a square wave signal R output from the oscillation circuit 1; 3 is a transformer for the moving part, 4 is a DC power supply circuit, 5 is an NPN transistor for horizontal deflection output, 6 is a diode for a damper, 7 is a capacitor for retrace resonance, 8 is a deflection coil, 9 is a capacitor for figure 8 correction, 10 is a flyback transformer, 11
12 is a voltage regulator, 13 is a DC power supply circuit, and 14 is a horizontal deflection output circuit.

The oscillation circuit 1, which is supplied with a synchronization signal P as shown in FIG. 5(A) from a pre-stage circuit such as a synchronization separation circuit, outputs a square wave signal R as shown in FIG. 5(B). Since the wave signal R is supplied to the base of the transistor 2, the collector-emitter of the transistor 2 becomes conductive or non-conductive in response to the square wave signal R.

The collector of the L transistor 2 is connected to one end of the primary open winding 3a of the transformer 3, and the other end of the negative winding 3a is grounded via the DC power supply circuit 4.

Therefore, the collector current 1cd of the I-transistor 2 as shown in FIG. 5(C) is supplied to the primary winding 3a of the transformer 3 in accordance with the state of the transistor 2.

One end and the other end of the secondary winding 3b of the transformer 3 are connected to the base and emitter of the transistor 5, respectively.

Since the base of the transistor 5 is supplied with a base current 1b as shown in FIG. , the collector of the transistor 5 has a horizontal orientation period Th
A flyback pulse Vp is generated.

Also, transistor 5, diode 6, capacitor 7,
The circuit consisting of the deflection coil 8 and the capacitor 9 is a well-known horizontal deflection output circuit 14, and its operation will not be explained here.
As a result, a sawtooth waveform flow S having a horizontal deflection frequency fH flows through the deflection coil 8, so that the electron beam can be horizontally deflected by the deflection coil 8 driven by the sawtooth waveform flow S.

One end of the primary winding 10a of the flyback transformer 10 is connected to the collector of the transistor 5, and the other end is grounded via a voltage regulator 12 and a DC power supply circuit 13 connected in series.

As described above, the flyback pulse Vp with the horizontal deflection period Th is generated in the collector of the transistor 5, so a high voltage pulse vh, which is the boosted flyback pulse Vp, is generated in the secondary winding 10b of the flyback transformer 10. However, the high-voltage pulse vh is rectified by the high-voltage rectifier circuit 11 and output as a DC high-voltage voltage ■Elf□.

By the way, since the horizontal deflection circuit shown in FIG. 4 has a configuration that corresponds to various horizontal deflection frequencies +H, the above-mentioned square wave signal R1 flyback pulse Vp1 becomes sawtooth waveform as the horizontal deflection frequency changes. Flow S must also change.

By the way, the output voltage of the voltage regulator 12 is Eb21
．． If the length of the deflection scanning period is Ts and the inductance of the deflection coil 8 is Ly, then It)D=Et)2+・TS
/L'l/. Here, it is necessary to keep the peak-to-peak value 1pp of the sawtooth-wave current S constant, but since the scanning period Ts also changes corresponding to the change in +l1ITh for horizontal deflection, the peak-to-peak value 1ppρ of the sawtooth-wave current S is kept constant. In order to maintain the output voltage of the voltage regulator 12 (EE)
2+ or the inductance Ly of the deflection coil 8, but since it is difficult to change the inductance L'l/ of the deflection coil 8,
The output voltage Eb21 of the normal voltage regulator 12 will be changed.

That is, the DC voltage Eb2 may be controlled by the voltage regulator 12 to change the DC voltage Eb2+ in inverse proportion to the scanning period TS.

By the way, in the horizontal deflection circuit shown in FIG. 4, when the horizontal deflection 11DTh is short (for example, the deflection period The)
The operation is shown in Fig. 5(A) to Fig. 5(E), and the operation when +1Th for horizontal deflection is long (for example, deflection period Th2) is shown in Fig. 6(A) to Fig. 6(E). show.

FIG. 5(B) corresponds to the synchronization signal P shown in FIG. 5(A).
A square wave signal R as shown in FIG. The collector current 1cd becomes as shown in FIG. 5(C).

In FIG. 5(C), the period TS+ is the accumulation period of the transistor 2, and from the position where the accumulation period TS+ ends and the amplitude of the collector current 1cd becomes zero, the base current 1b of the transistor 5 changes as shown in FIG. 5(D). The current begins to flow as shown in FIG. 2, and continues to flow until the collector current 1 cd of transistor 2 begins to flow again.

Initial value 1b of base current Ib of transistor 5.

The collector current LED of the transistor 2 is determined by the energy stored in the inductance of the primary winding 3a of the transformer 3, and the base current 1b of the transistor 5 decreases exponentially with time. The amplitude becomes zero at the position where the collector current lcd starts flowing.

In addition, the collector current IC of the transistor 5 continues to flow for an additional accumulation period T82 of the transistor 5 after the conduction period in which the transistor 5 conducts due to the base current Ib, and as shown in FIG. It becomes an electric current.

Therefore, when the base current Ib of the transistor 5 decreases to the final value 1b+ as shown in FIG. 5(D), the collector current 1c of the transistor 5 reaches near the maximum value (Icp), It is necessary to set the initial value 1bo to a relatively large value so that the final value 1k)+ of the base current tb can be set at a sufficiently large margin even at this point, and the transistor 5 can be brought into a saturated state.

Next, as shown in FIG. 6(A), when the horizontal deflection period Th is long (for example, deflection period Th2), the repetition period becomes large, but the period of the square wave signal R shown in FIG. 6(B) is It cannot be easily made longer, and the Q of the primary winding 3a of the transformer 3 cannot be set too high to prevent the transformer 3 from becoming large.Also, even if Q could be set high, Also, the winding resistance Ro of the primary winding 3a of the transformer 3 is lowered because there is a possibility that the collector voltage of the transistor 2 increases so much that it exceeds the withstand voltage of the transistor 2 when the transistor 2 is turned off and the transistor 2 is turned off. It becomes impossible to ignore the value of .

Therefore, when the pulse of collector current 1 cd of transistor 2 shown in FIG. 6(C) ends, the current amplitude value 1 c
dI is mainly determined by the value of the power supply voltage Eb+ and the value of the primary winding resistance RO of the transformer 3, and has little effect on the deflection period Th2 and pulse width. Therefore, there is almost no difference between the value 1cd1 of the collector current 1cd of the transistor 2 shown in FIG. 5(C) and the value 1cd2 of the collector current 1cd of the transistor 2 shown in FIG. 6(C).

In addition, the initial value 1bo of the base current 1b of the transistor 5
is determined by the energy stored in the primary winding 3a of the transformer 3, so if the values of the collector currents lad of 1-transistor 2 are similar, the initial value IbO of the base current of transistor 5 is also approximately It becomes the same.

Since the value of the base current ib of the transistor 5 decreases exponentially as described above, in the case of the deflection FI]TF12 with a long horizontal deflection period Th, the duration of the base current 1b becomes longer, as shown in FIG. As shown in (D), the final value Ib11 of the base current becomes smaller than the final value Ib1 of the base current shown in FIG. 5(D).

Therefore, at the final value Ib++ of the base current Ib of the transistor 5 shown in FIG. 6(D), it becomes difficult to sufficiently saturate the transistor 5 and allow the collector current 1c to flow.
Therefore, the voltage drop between the emitter and collector of transistor 5 increases, and internal loss increases. In order to prevent this, the final value IbI+ of the base current shown in FIG.
If it is set to be sufficiently large, the final value 1b+ of the base current shown in FIG.
The problem is that the fall time Tf becomes longer and the loss in this part increases.

As mentioned above, in the horizontal deflection circuit shown in FIG. 4, if the horizontal deflection frequency fn is changed, the optimum excitation condition cannot be satisfied over the entire frequency range, so the loss of the output transistor 5 increases and the reliability is reduced. There was a problem in that the value decreased.

Therefore, in order to solve the above-mentioned problems, the present invention variably controls the power supply voltage of an excitation circuit that excites the horizontal deflection output circuit so that it decreases as the horizontal deflection frequency increases. An object of the present invention is to provide a horizontal deflection circuit that can improve reliability by setting excitation conditions for the horizontal deflection output circuit suitable for R and minimizing loss in active elements of the horizontal deflection output circuit. .

(Means for Solving the Problems) The present invention provides a horizontal deflection circuit having a configuration as shown in FIG. 1 in order to solve the above-mentioned problems. The horizontal deflection circuit shown in FIG.
An oscillation circuit 1 that outputs an oscillation signal R synchronized with the oscillation signal R, an excitation circuit (transistor 2.1 to lance 3) that amplifies the oscillation signal R and excites the subsequent circuit, and a deflection coil that deflects the electron beam in the horizontal direction. Excitation circuit (transistor 2,
and a horizontal deflection output circuit 14 which is driven by a deflection current whose peak-beak value is always constant regardless of the horizontal deflection frequency in response to the signal output from the excitation circuit (transistor 3). 2. A voltage control circuit (voltage regulator 15) is provided to control the power supply voltage E b ++ supplied to the transformer 3) so as to decrease as the horizontal deflection frequency increases.

(Function) By supplying the power supply voltage Et) ++, which is lowered as the horizontal deflection frequency increases, to the excitation circuit (transistor 2, transformer 3), the horizontal deflection output circuit is supplied with excitation conditions. It can be set optimally for the frequency.

(Embodiment) FIG. 1 is a block diagram of an embodiment of a horizontal deflection circuit according to the present invention. Components in FIG. 1 that are the same as those in FIG. 4 are given the same reference numerals and their explanations will be omitted.

In FIG. 1, reference numeral 15 denotes a voltage regulator, which is inserted between the other end of the primary winding 3a of the transformer 3 and the DC power supply circuit 4, and converts the output voltage Eb1 of the DC power supply circuit 4 into the output voltage of the voltage regulator 12. A voltage E'D u controlled in accordance with Eb2+ is applied to the primary winding 3a of the transformer 3.

By the way, since the voltage Eb21 can be changed in inverse proportion to the Ts during the scan lv1 as described above, the horizontal deflection frequency f. As shown by the solid line in FIG. 2, the curve changes approximately linearly in proportion to the horizontal deflection frequency fH.

On the other hand, as mentioned above, the excitation current It)+ becomes excessive when the horizontal deflection period Th is short (l; i same period TF1+), and becomes insufficient when the horizontal deflection period Th is long (deflection period Th2). To solve this problem, the device E b ++ composed of the voltage regulator 15 may be set low when the horizontal deflection period Th is short, and set high when the horizontal deflection period Th is long.

That is, the horizontal deflection frequency f may be controlled so that the voltage E b n decreases as the horizontal deflection frequency f11 increases, as shown by the broken line in FIG.

In this way, by changing the value of the voltage Et) 11 in accordance with the horizontal deflection frequency fn and the output voltage Ebz+ of the voltage regulator 12, the optimum excitation current can be set for the transistor 5 even if the horizontal deflection frequency 1,000 □ changes. The loss of the transistor 5 can be minimized.

An example of a specific circuit of the voltage regulator 15 will be described below with reference to FIG.

In Fig. 3, 16 and 17 are resistors with resistance values R1 and R2, respectively, 18 is an NPN+- transistor, 19 is a resistor with a resistance value Re, 20 is an NPN transistor, and 21 is an l transistor 2o with a resistance value Rb. The base bias resistor 22 is a smoothing capacitor through which the ripple of the primary winding 3a of the transformer 3 flows.

The output voltage Eb21 of the voltage regulator 12 is connected to the resistor 16.
is supplied to the base of transistor 18 via. Further, the base of the transistor 18 is grounded via the resistor 17.

The emitter of transistor 18 is grounded via resistor 19, and the collector of transistor 18 is grounded via resistor 19.
The base of the transistor 20 is connected to the collector of the transistor 20 via the resistor 21, and the collector of the transistor 20 is connected to the DC power supply circuit 4 (third
(not shown in the figure). transistor 20
The emitter of is grounded via a capacitor 22 and connected to the other end of the primary winding 3a of the transformer 3.

With the configuration as described above, hfe of transistor 18.20
is large to some extent, and the base-emitter voltage is E b +
If it is sufficiently smaller than +, the following approximate expression holds true.

Eb22→Ebz+-R2/(R+-IR2) Also, if the base-emitter voltages of transistor 18.20 are Vt)e+ and Vbe2, respectively, then IC'=Ie=
(Ebzz-Vbe1)/ReEbn=Ebzz R
t)(IC+It))-Vbe2 or above, the equation becomes as follows.As shown in Fig. 2, if the voltage Ebz+ increases linearly as the horizontal deflection frequency fH increases, E b
++ can be set so that it tends to decrease linearly, and therefore, the Rn value 1t)+ of the base voltage 'a I b of the transistor 5 can be set to an optimal value corresponding to the horizontal deflection frequency ft1. It becomes like this.

In addition, in FIG. 1, DC power supply circuit 4 and DC power supply circuit 1 are
Although the explanation has been made as a different component from 3, it goes without saying that it is possible to use the same component depending on the design conditions.

(Effects of the invention) The present invention provides the above i! Since the configuration is as shown in L, the excitation conditions of the horizontal deflection output circuit are optimally set for the supplied horizontal deflection frequency, and the loss of the active elements of the horizontal deflection output circuit is minimized to improve reliability. It has the advantage of being able to

[Brief explanation of drawings]

FIG. 1 is a block system diagram of one embodiment of the horizontal deflection circuit according to the present invention, FIG. 2 is a diagram for explaining the operation of the horizontal deflection circuit shown in FIG. 1, and FIG. 3 is the same as that shown in FIG. A circuit diagram illustrating an example of the voltage regulator 15 of the horizontal deflection circuit shown in FIG.
The figure is a block diagram of an example of a conventional horizontal deflection circuit.
6A to 6E are diagrams for explaining the operation of an example of the horizontal deflection circuit shown in FIG. 4. FIGS. 1... Oscillation circuit for horizontal deflection, 2... 1-transistor for excitation, 3... Transformer for excitation, 4.13... DC power supply circuit, 5... Transistor for output, 8... Deflection coil, 10... Flyback transformer, 12.15... Voltage regulator, 14... Horizontal deflection circuit. Sai I Figure 2 Note t3a Ge

Claims (2)

[Claims] (1) An oscillation circuit that outputs an oscillation signal synchronized with a horizontal deflection frequency signal, an excitation circuit that amplifies this oscillation signal and excites the subsequent circuit, and a deflection coil that deflects the electron beam in the horizontal direction. and a horizontal deflection output circuit that is driven by a deflection current whose peak-to-peak value is always constant regardless of the horizontal deflection frequency in response to a signal output from the drive circuit, wherein the power supply voltage supplied to the excitation circuit is A horizontal deflection circuit comprising a voltage control circuit that controls the horizontal deflection frequency to decrease as the horizontal deflection frequency increases. (2) The voltage control circuit supplies the voltage to the excitation circuit as the power supply voltage of the horizontal deflection output circuit increases, which changes in order to maintain a constant peak-to-peak value of the deflection current that drives the deflection coil in accordance with the horizontal deflection frequency. 2. The horizontal deflection circuit according to claim 1, wherein the horizontal deflection circuit is configured such that the power supply voltage applied to the horizontal deflection circuit is reduced.