JPS60174578A - Horizontal deflecting circuit of television receiver - Google Patents

Abstract

PURPOSE:To generate two horizontal deflection scanning frequencies by providing the 1st switching means which generates a saw-tooth wave current at a deflecting coil and the 2nd switching means which switch two windings of the deflecting coil between a series and a parallel connection. CONSTITUTION:An NP transistor (TR) 4 constitutes the 1st switching means together with a damper diode 5 to generate the saw-tooth wave current at the deflecting coil. The horizontal winding 8 of the deflecting coil is connected to a resonance capacitor 6 in parallel through a series-parallel means 9, and also connected to a DC stopping capacitor 10 in series. Further, DC electric power is supplied through a choke coil or fly-back transformer 7. The means 9 switches the two coils of the deflecting coil between the series and parallel connections through its associative switch 11. Thus, horizontal deflection scanning frequencies of, for example, 15.75kHz and 31.5kHz are generated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a horizontal deflection circuit for a television receiver that performs horizontal deflection scanning using a deflection coil.

2. Description of the Related Art Structures of Conventional Examples and Their Problems In recent years, in the field of video display equipment industry centered on television receivers, high-definition video display equipment has been commercialized. One of its characteristics is that the horizontal deflection scanning frequency fH is around 31.5 KHz. This frequency is approximately twice the horizontal deflection scanning frequency fH of a normal television receiver.

Incidentally, in the horizontal deflection circuit of a television receiver, a method has generally been adopted in which a sawtooth current 1 is passed through the horizontal winding of a deflection coil, as shown in FIG. Furthermore, the horizontal winding of the deflection coil consists of two coils 2 and 3 in FIG.
As shown in Figures a and b, it does not matter whether they are connected in series or in parallel.

Now, the relationship between the sawtooth current i flowing through the coil 2.3 and the voltage V generated across the coil is expressed as follows. Here, L is the inductance value of the coil 2.3. By integrating equation (g), we obtain: Here, ■DC is a direct current voltage applied to the coil.

The peak value fp of the sawtooth current is expressed by the following equation.

Here, tH is the horizontal deflection scanning period a, which is the reciprocal of the horizontal deflection frequency amount H.

What is the deflection angle δ due to the deflection coil of the electron beam scanning inside the cathode ray tube?

δ-ized iP ...... defined by (4).

Substituting equation (3) into equation (4), we get becomes.

From equation (6), it can be seen that the angle of deflection of the electron beam, ie, the partial deflection angle δ, is defined by the power supply voltage vDc, the inductance L of the deflection coil, and the period tH of the horizontal deflection scan.

If left as is, the higher the horizontal deflection scanning frequency (1/1H) becomes, the smaller the deflection angle δ becomes, and as a result, the horizontal amplitude becomes smaller. For example, if the horizontal deflection scanning frequency fH is twice the original frequency fHO, the horizontal vibration 1] will theoretically be %.

Conversely, this means that the original horizontal deflection scanning frequency fH
To obtain a normal image horizontal width for a frequency twice as high as O, either double the power supply voltage Dc, or increase the inductance of the deflection coil to a value of This means that it needs to be lowered.

Therefore, in a conventional television receiver, two or more different horizontal deflection scanning frequencies 'H1
, 'H2 ('H2 is approximately twice the frequency of fHl), which can receive an image while maintaining an appropriate image has not yet been realized. This is because it was not easy to greatly change the values of the power supply voltage/voltage Dc and the inductance L of the deflection coil.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional problems, and provides a horizontal deflection circuit for a television receiver that can receive images having two horizontal deflection scanning frequencies, the ratio of which is doubled. The purpose is to provide.

Structure of the Invention A horizontal deflection circuit for a television receiver according to the present invention includes: a first switching means capable of generating a sawtooth wave current in a horizontal deflection coil; two horizontal deflection windings located above and below the deflection coil; and a second switching means for switching connections, the second switching means being means for switching the connection of the two windings of the deflection coil between series and parallel, and a switching means for switching the connection of the two windings of the deflection coil. Depending on the means, the ratio can be doubled or 2
This makes it possible to receive images at more than one horizontal deflection scanning frequency.

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

First, when receiving a video signal having a horizontal deflection scanning frequency of 15.7 KHz, two deflection coils 2 and 3 are connected in series as shown in FIG. 2a. The inductance value of the deflection coil at this time is assumed to be Ls.

From the above equation, the deflection angle 1δ1 is given by: Here, tHl is, for example, 15.75
It is assumed that the reciprocal number R1 of KHz is 63.5 μsec.

Next, when receiving a video signal having twice the horizontal scanning frequency of 31.5 KHz, the period is lH2=31
．． 75 p Sec, but at this time, 2 of the deflection coil
The two coils 2.3 are connected in parallel as shown in FIG. If the inductance value of the deflection coil in this case is LP, then LP:LS/4, and the deflection angle 1δ'1 is the DC applied voltage ■ Dc is constant = 1δ1 (7) become.

Fig. 3 is an explanation in which the deflection angle 1δ1 is replaced with the deflection current, and Fig. 3a shows the period tH1 and the slope ■DC/μJin.
It is a sawtooth current defined by tHl. Figure 3 shows
The current waveform of the deflection coil when only the period is increased to 3A (that is, the frequency is doubled) without changing the connection method of the deflection coil.
Since the slope does not change, the peak value of the current is halved. This means that the deflection angle is halved.

FIG. 3C shows the case where the two coils 2 and 3 of the deflection coil are connected in parallel from series as in the present embodiment described above. μ7・lH2・(-DO, competitive ball・tIse)
It is a sawtooth wave current defined by . The peak value of the current in this deflection coil is the same as in FIG. 3a, and can be kept constant without reducing the deflection angle.

FIG. 4 shows a specific circuit configuration of an embodiment of the present invention. In this example, as shown in FIG. 4a, the first switching means for forming a sawtooth wave current in the deflection coil is This uses an NPN transistor 4. The damper diode 6 assists the operation of the switching transistor 4. 6 is a resonant capacitor, 7 is a choke coil or flyback transformer connected to a DC power supply, and the horizontal winding 8 of the deflection coil is connected via a series-parallel connection switching means 9, and is connected in series with the DC blocking capacitor 10. Connections have been made.

FIG. 4 shows an example of a specific configuration of the above-mentioned series-parallel connection switching means 9, and here the interlocking mechanical switch 11 is shown.
The connection method of the two deflection coils 2.3 is switched between series and parallel. When the switch 11 is on the FLJ side, the deflection coils are connected in series, which is suitable for receiving image signals with a relatively low horizontal deflection scanning frequency. For example, a video signal having a horizontal deflection scanning frequency of 15.75 KHz can be received. Switch 11 is I[J
When the deflection coils are on the side, the deflection coils are connected in parallel and are suitable for receiving image signals with a relatively high horizontal deflection scanning frequency. For example, a video signal having a horizontal deflection scanning frequency of 31.5 KHz can be received.

According to this configuration, it is possible to receive video signals having two or more horizontal deflection scanning frequencies whose ratio is approximately twice that of the other, by a simple means, and to obtain an inexpensive and power-efficient horizontal deflection circuit. I can do it.

In the above example, an interlocking mechanical switch was used as the series-parallel switching means 9 for the coils 2 and 3 of the two horizontal windings of the deflection coil, but a relay or a semiconductor switch may also be used. Of course, it is useless.

Furthermore, in the above example, the case where the ratio is doubled as two different horizontal deflection scanning frequencies has been mainly explained, but this is the optimum condition, that is, the condition that can bring out the maximum effect, and the present invention is not a necessary condition. The conditions under which the effects of the present invention are effective are that the ratio of the two horizontal scanning frequencies is 1:1.
．． Yes, if the ratio is S or more, and preferably 1:3 or less.

If the above-mentioned two frequency ratio is 1.6 times or less, it is not advantageous to switch the connection of the two windings of the deflection coil from series to parallel. In other words, it is clear that it is better to deal with the problem by changing the DC voltage without changing the connections. Further, for two frequencies whose ratio exceeds three times, the amount of correction by other means becomes large. For example, when the two windings of the deflection coil are connected in series, 16.75KFI
If it is optimally designed to receive a video signal having a horizontal deflection scanning frequency of 29.6 KH2 or 33.
To receive a video signal with a horizontal deflection scanning frequency of 6KHz,
Great effects can be expected by connecting two horizontal deflection coil windings in parallel. Considerable effects can also be expected in the reception of video signals with horizontal deflection scanning frequencies of 27 KHz and 35 KHz. However, in the case of receiving a video signal with a horizontal deflection scanning frequency such as 23.5 KHz or 47 KHz, a large effect cannot be expected. Needless to say, this is only true if the design is optimized for a horizontal deflection scan frequency of 16.75 KHz for the series connection of two windings of the deflection coil, and for a horizontal deflection scanning frequency of 23.5 KHz. This does not mean that the effects of the present invention cannot be achieved absolutely depending on the scanning frequency.

Furthermore, in the above example, the explanation has been made on the assumption that the ratio of inductance values when connecting in series and when connecting in parallel is 4:1 when switching the connection of the two windings of the deflection coil, but this is also not an essential condition of the present invention. . Tolerances during the manufacturing of coils are usually not met, so the ratio of 4:1 is limited to ideal cases and is usually somewhere in the middle such as 4.2:1 or 3.7:1. can be the value of It is clear that even under such conditions, the effects of the present invention are not lost at all.

Regarding the ratio of inductance values when the two horizontal windings of the deflection coil are connected in series and in parallel, the condition that limits the effectiveness of the present invention is that the ratio of the inductance value L3 when connected in series and the inductance value LP when connected in parallel is Although a ratio of 2:1 to 8:1 is allowed, in reality, even if there is a horizontal auxiliary winding for the deflection coil, the ratio of Ls:LP is from 3:1 to 6:1.
It is set within the range of 1. Even when the ratio of Ls:LP is 3:1 or 6:1, the effects of the present invention remain the same.

According to the present invention, it is possible to receive video signals having two or more horizontal deflection scanning frequencies, the ratio of which is approximately double, by simple means and at low cost. , a horizontal deflection circuit with good power efficiency can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a waveform diagram for explaining the operation of the horizontal deflection circuit of a television receiver in an embodiment of the present invention, and Fig. 2 a and b are wiring diagrams showing mutually different connection states of the two coils. , Figure 3a. 4b and 4c are waveform diagrams for explaining the formation of sawtooth wave current flowing through the horizontal deflection coil, and FIGS. 4a and 4b are connection diagrams showing the configuration of an embodiment of the present invention. 2.3...Horizontal deflection coil, 4...
...First switching means, 9, 11... Second switching means. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure @Figure 2 (and λ non (b)) 381 L, -t, 92- Figure 4

Claims (3)

[Claims] (1) At least a cathode ray tube, a deflection coil, and a first and second
switching means, the deflection coil scans the electron beam of the cathode ray tube; the second switching arm forms a sawtooth current in the deflection coil; A horizontal deflection circuit for a television receiver, characterized in that the means switches the connection of the two windings of the deflection coil between series and parallel. (2) A horizontal deflection circuit in which 3LP≦Ls≦6LP is established between the inductance value Ls when the deflection coils 15 are connected in series and the inductance value LP when the deflection coils 15 are connected in parallel by the second switching means. (3) The horizontal deflection circuit for a television receiver according to claim 1, wherein the second switching means is constituted by a mechanical switch, a relay, or a semiconductor switch.