JPH03229591A - Horizontal deflection circuit and projection type display adopting same - Google Patents

Abstract

PURPOSE:To realize the improvement of a focusing characteristic (improvement of picture quality) by controlling a switching means connected to junction between serially connected capacitors to constitute an S-shape correction capacitor by the output voltage of a pulse width modulation circuit. CONSTITUTION:S-shape correction quantity is changed for every horizontal period by changing continuously the ratio of a period (t1 to t2) and the period (t1 to t4) by a pulse width control circuit 92 in an S-shape control circuit 24. A horizontal saw tooth wave generation circuit 25 in the pulse width control circuit 92 generates the horizontal saw tooth wave of the horizontal period from a fly back pulse FBP inputted from a fly back pulse input terminal 2, and outputs it to a square wave generation circuit 27. The square wave generation circuit 27 generates the square wave by comparing the horizontal saw tooth wave outputted from the horizontal saw tooth wave generation circuit 25 with a vertical parabolic wave outputted from an inverting amplification circuit 26, and making them cut each other.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a horizontal deflection circuit for deflecting an electron beam in a cathode ray tube display. The present invention relates to a horizontal deflection circuit including a correction circuit that corrects pincushion distortion and horizontal linearity.

Additionally, the present invention relates to an improvement in a horizontal deflection circuit that is particularly effective (high image quality) when applied to a projection display using three cathode ray tubes: R (red), G (green), and B (blue). It is.

(Prior Art) As a method of correcting side pin distortion and horizontal linearity in each cathode ray tube screen constituting a projection display, as shown in Japanese Patent Application Laid-Open No. 58-215886,
There is a method using a convergence correction circuit. Specifically, N cathode ray tubes are provided with N convergence yokes, and the convergence yokes generate a magnetic field for correcting the side pin distortion and horizontal linearity, thereby performing the correction.

Furthermore, as a conventional technique for correcting the horizontal linearity of a screen in a cathode ray tube receiver, etc., in which the retrace period is set to be approximately constant for each television signal having a different horizontal deflection frequency, there is As shown in Publication No. 24626, by switching the capacitance value of the 5-character correction capacitor connected in series with the horizontal deflection coil, appropriate horizontal linearity is always ensured against differences in horizontal deflection frequency, etc. There is a way to do it.

[Problems to be Solved by the Invention] A projection display generally includes red, green, and blue cathode ray tubes (hereinafter referred to as projection tubes). The arrangement of each projection tube is usually with green light in the center, which emits light that is most likely to offend the human eye, and red and blue lights at the ends.

FIG. 4 shows a configuration diagram of the projection display.

In Fig. 4, 101 is a deflection circuit, 102 is a convergence correction circuit, 103 is an electromagnetic focus circuit, and 104.10
5.106 is a focus magnet, 107 108.
109 is convergence yoke, 110, lit, 11
2 is a deflection yoke, 113114.115 is a projection tube, 11
Reference numerals 6, 117, and 118 are projection lenses, and 119 is a fluorescent screen of the projection tube.

In addition, 104, 107, 110, 113.116 are for red projection tubes, 105, 108, 111, 114.117 are for green projection tubes, 106, 109112.115, 118
is for the blue projection tube.

The feature of the projection display shown in FIG. 4 is that electromagnetic focusing is performed using focus magnets 104, 105, and 106 as lenses for focusing the electron beam of the projection tube. As a result, the aperture of the lens can be made larger than in the case of electrostatic focusing, which is widely used in direct-view displays and the like. Therefore, the spot diameter of the electron beam on the projection tube surface can be reduced, and the focusing characteristics (image quality) can be improved.

At this time, the closer the focus magnet is mounted to the fluorescent screen 119 of the projection tube, the lower the magnification of the electromagnetic lens and the smaller the diameter of the bonnet of the electron beam on the tube surface, which further improves the focus characteristics. Improvements can be made.

Therefore, the deflection circuit corrects vertical and horizontal pin distortion and near-tee, and the convergence yoke 108 for the green projection tube
If it is possible to eliminate this as unnecessary, the focus magnet 105 can be brought closer to the fluorescent screen of the projection tube to lower the magnification, which is considered to be effective in improving image quality.

However, convergence yaws 107 and 109 for red and blue projection tubes cannot be removed because of the original convergence correction, so the focus magnet cannot be brought close to the phosphor screen. Even if 108 is removed and the focus magnet is brought closer to the phosphor screen, the image quality will be greatly improved.

On the other hand, in the projection display shown in FIG. 4, in order to correct the field curvature of the optical lenses (projection lenses 116, 117, 118), the fluorescent screen 119 of the projection tube has a convex shape toward the electron gun. It has a curvature so that

As a result, when conventional distortion correction and linearity correction are performed using the deflection circuit as described above, the following problems occur.

Although this problem occurs in both vertical deflection circuits and horizontal deflection circuits, the case of the horizontal deflection circuit related to the present invention will be explained here using FIG. 5.

FIG. 5 shows pin distortion and linearity projected onto the screen of a projection display. In FIG. 5, (a) shows the case without pin distortion correction and linearity correction, and (b) shows the case with conventional pin distortion correction and linearity correction. 80, 81, 82, 83 in Figure 5.
84 indicates a vertical line signal displayed at regular intervals.

Conventional pin distortion correction (side pin correction) methods include modulating the power supply voltage of the horizontal deflection output circuit,
A common method is to use a side pin correction transformer.

In addition, in conventional linearity correction (horizontal linearity correction), the value of the figure-8 correction capacitor connected in series with the horizontal deflection coil of the horizontal deflection circuit is adjusted to obtain the optimal horizontal linearity ( However, the following explanation will ignore the left-right asymmetry of horizontal linearity caused by the resistance bones of the circuit.) However, when this conventional method is used for correction in the projection display shown in Fig. 4, Since the phosphor screen of the projection tube has a convex curvature, even if the connecting lines at both the left and right ends of the screen (80.84 in Figure 5) are corrected to a straight line,
Vertical line 81 on the left center. and the vertical line 83 at the center right is the fifth
It is curved as shown in Figure (b). In other words, the horizontal linearity is different between the top and bottom of the screen and the center.

On the other hand, by continuously changing the capacitance value of the figure-8 correction capacitor within the vertical period, it is possible to maintain optimal horizontal linearity.

As a conventional technique for changing the capacitance value of the figure-8 correction capacitor, there is a method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 1-24626.However, in this method, the capacitance value of the figure-8 correction capacitor is changed intermittently. It is not possible to change the three-character correction amount continuously within the vertical period.

An object of the present invention is to provide a deflection circuit that can perform side pin correction and horizontal linearity correction by continuously changing the three-character correction amount within the vertical period, even when using a projection tube with a convex curvature on the phosphor screen. As a result, the conventionally required convergence yoke can be removed from the green projection tube, and the focus magnet can be moved closer to the phosphor screen, resulting in projection with improved focus characteristics (image quality). The object of the present invention is to provide a horizontal deflection circuit that is effective for realizing a shaped display, and to provide the above-mentioned projection display.

[Means to solve the problem]

In order to achieve the above object, in the horizontal deflection circuit of the present invention,
The figure-8 correction capacitor was constituted by a plurality of capacitors connected in series, a switching means was connected between the connection point of the capacitors and the ground potential, and a pulse width modulation circuit was connected to the control terminal of the switching means.

In the projection display of the present invention, the horizontal deflection circuit as described above is employed in the green projection tube.

(Function) In the horizontal deflection circuit of the present invention, the switching means connected to the connection points of the series-connected capacitors constituting the figure-8 correction capacitor is turned on and off within the horizontal period. By controlling the on/off period within one horizontal period by the output voltage of a pulse width modulation circuit connected to the control terminal of the switching means, the figure-8 correction amount is equivalently changed for each horizontal period. I can do it.

Therefore, it is possible to continuously change the 8-character correction amount within the vertical period.

Furthermore, in the projection display of the present invention, since the horizontal deflection circuit as described above is employed in the green projection tube, the convergence yoke that is conventionally required can be omitted. As a result, in the case of a green projection tube, the focus magnet can be brought closer to the phosphor screen by that amount, and the focus characteristics can be improved (improvement of image quality).

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

In each figure, the same numbers are used to indicate the same functions.

FIG. 1 is a circuit diagram showing a first embodiment of a horizontal deflection circuit according to the present invention.

In Figure 1, 1 is a horizontal drive pulse input terminal, 2 is a flyback pulse input terminal, 3 is a vertical parabolic wave input terminal, 4 is a drive voltage input terminal, 5 is a three-figure control voltage output terminal, and 6 is a power supply voltage input terminal. Terminal, 7.10.14 is resistance, 8
．． 11 is a capacitor, 9 is a drive transistor, 12
is a drive transformer, 13 is a diode, 15 is a horizontal output transistor, 16 is a damper diode, 17 is a resonant capacitor, 18, 19.20 is a horizontal deflection coil, 21
is the first figure-8 correction capacitor, 22 is the second figure-8 correction capacitor, 23 is the choke coil, 24 is the S-shaped control circuit, 25 is the horizontal sawtooth wave forming circuit, 26 is the inverting amplifier circuit, and 27 is the rectangular wave forming circuit. circuit, 28 is switching means, 2
9 is a side pin correction circuit, 92 is a pulse width modulation circuit, 9
3 is a horizontal deflection drive circuit, and 94 is a horizontal deflection output circuit.

In FIG. 1, the horizontal deflection drive circuit 93 has a resistor of 7.10
, 14, capacitor 8.11, drive transistor 9
, a drive transformer 12, and a diode 3, and the horizontal deflection output circuit 94 includes a horizontal output transistor 15, a damper diode 16, and a resonant capacitor 1.
7, horizontal deflection coils 18, 19, 20, a first figure-eight correction capacitor 21, a second figure-three correction capacitor 22, and a choke coil 23.

Further, the pulse width modulation circuit 92 is a horizontal sawtooth wave forming circuit 2.
5. It is composed of an inverting amplifier circuit 26 and a rectangular wave forming circuit 27, and the S-shaped control circuit 24 is composed of a pulse width modulation circuit 9.
2. It is constituted by a switching means 28.

In the embodiment described below, a case will be explained in which a power MO3FE, T is used as the switching means 28, but a bipolar transistor and a diode (however, since the power MO8FET has a built-in diode between the source and drain, this diode is (not required) may be used.

Hereinafter, before explaining the operation of the first embodiment of the horizontal deflection circuit according to the present invention shown in FIG. 1, the basic principle of the horizontal deflection circuit according to the present invention will be explained.

In the horizontal deflection circuit, generally, the larger the capacitance value of the figure-8 correction capacitor, the smaller the figure-8 correction amount, and the smaller the capacitance value of the figure-8 correction capacitor, the larger the figure-8 correction amount. In the horizontal deflection circuit of the present invention, a plurality of (two in the embodiment shown in FIG. 1) figure-8 correction capacitors are connected in series, and one of them is connected in series.
The figure-8 correction amount is switched by short-circuiting both ends of the figure-8 correction capacitors.

However, simply performing a switch (for example, short-circuiting both ends of one of the series-connected figure-8 correction capacitors only once within a vertical period) is not the same as the conventional technology. , it is not possible to change the three-character correction amount continuously within the vertical period. Therefore, in the horizontal deflection circuit of the present invention, the short-circuit period of the 5-character correction capacitor is limited to an appropriate period within the horizontal cycle, and by continuously changing this short-circuit period, the 3-character correction amount is continuously adjusted. It is changing to

Hereinafter, this specific circuit operation will be explained with reference to FIG. 3 as well.

FIG. 3 is an operational waveform diagram illustrating the operation of the horizontal deflection circuit as an embodiment of the present invention shown in FIG.

In FIG. 3, (a) shows the collector voltage vcpg type of the horizontal output transistor 15, and (b) shows the switching means 28 (
Here, the power M including the built-in diode shown by the broken line
OS FET) gate voltage VSG waveform, (C) is the drain voltage VSD waveform of the switching means 28, (d)
is the horizontal deflection current IDY waveform.

In addition, tl and t4 are the times when the switching means 28 is turned off, and t2 is the time when the switching means 28 is turned on (however, when using a power MO3FET, the time when the built-in diode shown by the broken line between the source and drain is turned on), t3 indicates the time when the current flowing through the switching means 28 is reversed (the time when the current starts flowing from the drain to the source of the power MO3FET). Note that the period (tl to t4) corresponds to one horizontal period.

In FIG. 3, during the period (tl-m2), the switching means 28 in the S-shaped control circuit 24 shown in FIG. 1 is in an off state. Therefore, the horizontal deflection current IDY is divided between the first figure 3 correction capacitor 21 and the second figure 8 correction capacitor 2.
2. Therefore, the capacitance value of the series circuit of the first 3-character correction capacitor 21 and the second 8-character correction capacitor 22 is smaller than when each 5-character correction capacitor is used alone. Therefore, this period (tl~t2
), the amount of 3-character correction is large.

On the other hand, during the period (t2 to t4), since the switching means 28 is in the on state, the state is equivalent to that in which both ends of the second figure-8 correction capacitor 22 are short-circuited. Therefore, the horizontal deflection current IDY flows only through the first three-figure correction capacitor 21. Therefore, compared to the period (tl to t2), the capacitance value of the 5-character correction capacitor is large and the 3-character correction amount is small.

In the horizontal deflection circuit of the present invention, the pulse width control circuit 92 in the S-shaped control circuit 24 shown in FIG.
The three-character correction amount is changed for each horizontal period by continuously changing the ratio of the period D2 to t2) and the period D2 to t, 4). The operation of this pulse width control circuit 92 will be explained below.

The horizontal sawtooth wave forming circuit 25 in the pulse width control circuit 92 shown in FIG. It is output to the circuit 27. In addition, the inverting amplifier circuit 26 in the pulse width control circuit 92 receives a vertical parabolic wave input from the vertical parabolic wave input terminal 3 (a parabolic waveform is created as it is suitable for side pin distortion and horizontal linearity correction). Vertical period parabolic waveform) Invert and amplify the voltage Vp,
It is output to the rectangular wave forming circuit 27.

In the rectangular wave forming circuit 27, the horizontal sawtooth wave forming circuit 25
A rectangular wave (gate voltage VSG of the switching means 28) is formed by comparing and cutting off the horizontal sawtooth wave output from the inverting amplifier circuit 26 and the vertical parabolic wave output from the inverting amplifier circuit 26.

As a result, the gate voltage VSG has a rectangular wave whose average value is pulse width modulated in the form of a parabolic wave with a vertical period. Therefore, the on/off timing of the switching means 28 (the period (tl to t2) in FIG. 3 and the period (t2 to t2)
4) can be continuously changed for each horizontal period.

Switching means 2 in the S-shaped control circuit 24 explained above
8 and the pulse width modulation circuit 92, it becomes possible to change the three-character correction amount continuously within the vertical period. Specifically, at the beginning and end of the vertical scanning period (top and bottom of the screen), the period (tl-t2.) is shortened to 8.
Reduce the amount of character correction during the vertical scanning period! ! In lI (the center of the screen), the period (tl - t2) is lengthened to increase the size of the S-shaped correction product.

For example, if (b), (c), and (d) in FIG. 3 are the operating waveforms at the beginning and end of the vertical scanning period, the operating waveforms at the middle of the vertical scanning period are (e) and (f).

(g) (However, in this case, each symbol is represented by adding a dash °).

The side pin correction circuit 29 in FIG. 1 is a side pin correction circuit using a power supply voltage control method, and changes the voltage of the horizontal deflection output circuit 94 in a parabolic manner with a vertical period. By using this side pin correction circuit 29 in combination with the S-shaped control circuit 24, the vertical lines on the screen can be adjusted as shown in FIG.
As shown in c), all (connections 80, 81, 82,
83.84) Can be corrected linearly.

Again, in this way, on the side of the horizontal deflection circuit, the horizontal deflection circuit that has realized the side pin distortion correction and horizontal linearity correction by circuit means is used for the green projection W in the projection display shown in FIG. 114, the convergence yoke 108 can be removed and the focus magnet 105 can be brought closer to the phosphor screen, and it is expected that the focus performance as a projection display and the image quality will be improved.

Next, a specific circuit example of the S half control circuit 24 and the side pin correction circuit 29 shown in FIG. 1 is shown in FIG.

In Figure 2, 30.31 is a DC voltage input terminal, 33.37
．． 3B, 40, 41, 44, 45, 48°50.57.
5B, 61, 62, 63, 64, 65.68, 70.7
1 is a resistor, 34.39 67 is a diode, 35, 36
．． 59, 60.6672 is a transistor, 42 is a Zener diode, 43.46, 47, 52, 56.73 is a capacitor, 49 is an operational amplifier, 51, 53, 55.69
is a variable resistor, and 54 is a comparator.

In Fig. 2, the horizontal sawtooth wave forming circuit 2 shown in Fig. 1
5 are resistors 33, 37, 38, 40 . diode 34,
39, transistors 35, 36, and a capacitor 46, and the inverting amplifier circuit 2G includes resistors 41, 44, 45.
．． 48, 50, Zener diode 42, capacitor 43
．． 47, a variable resistor 51, and an operational amplifier 49, and the rectangular wave forming circuit 27 includes a comparator 54, a variable resistor 53, and a capacitor 52.

In addition, the side pin correction circuit 29 shown in FIG. 1 includes variable resistors 55 and 69, capacitors 56 and
, resistance 57, 58, 61, 6263.64, 65, 68
,70,715. Transistors 59, 60, 66.
72 and a diode 67.

In FIG. 2, in the horizontal sawtooth wave forming circuit 25, a capacitor 46 and a constant current? J! j (constructed using a transistor 36) and a transistor 35 that switches based on the flybank pulse input from the flybank pulse input terminal 2 and discharges the charge of the capacitor 46, to generate a horizontally periodic sawtooth wave. is forming.

Further, in the inverting amplifier circuit 2G, the vertical parabolic wave voltage inputted from the vertical parabolic wave input terminal 3 is input to the operational amplifier 49.
is used for inversion amplification. At this time, the variable resistor 51 functions to adjust the amplification factor of the vertical parabolic wave. Further, the rectangular wave forming circuit 27 is configured using a comparator 54, and includes a horizontal sawtooth wave forming circuit 25 and an inverting amplifier circuit 2.
By comparing the output voltages of 6, a rectangular wave is formed. Note that the variable resistor 53 functions to adjust the DC level of the vertical parabolic wave voltage input to the comparator 54.

Next, the operation of the side pin correction circuit 29 in FIG. 2 will be explained. This side pin correction circuit B29 is constituted by a differential amplifier circuit consisting of transistors 59 and 60. In this differential amplifier circuit, the base voltage of the transistor 60 (the emitter voltage of the transistor 72) is
, 70, obtained by dividing the voltage by the variable resistor 69) is
It operates to be equal to the vertical parabolic wave voltage input to the base of transistor 59. As a result, the emitter voltage of the transistor 72 (the power supply voltage of the horizontal deflection output circuit 94) changes in a parabolic manner with a vertical period, and side pin correction becomes possible.

By using the first embodiment of the present invention described above,
The three-character correction amount can be changed continuously within the vertical period. Therefore, even when using a projection tube with a convex curvature on the phosphor screen, side pin correction and horizontal linearity correction can be performed in the deflection circuit side, and as mentioned earlier, green projection Convergence for tubes: It is possible to improve focusing characteristics by removing the rays and concomitantly bringing the focusing magnet closer to the phosphor screen side.

Next, a second embodiment of the horizontal deflection circuit according to the present invention will be described using FIG. In Figure 6, 3" is an S-shaped correction signal input terminal, 3P is a side pin correction signal input terminal,
90 is an arbitrary waveform generation circuit.

In FIG. 6, an arbitrary waveform generation circuit 90 has a function of generating an arbitrary waveform.
A digital convergence correction circuit, etc. used in the I, etc.) can be used. In other words, it is a circuit that stores data constituting a desired waveform in a ROM in advance and generates the desired waveform by reading the data.

By using this arbitrary waveform generation circuit 90, when the convex shape of the phosphor screen of the projection tube is aspherical (by making the convex shape of the phosphor screen aspherical, the correction for the curvature of field can be optimized in each part of the screen). It is possible to generate a waveform that enables accurate 3-character correction (horizontal linearity) and side pin correction even if the

Note that the S-shape correction signal and the side-pin correction signal inputted from the S-shape correction signal input terminal 3° and the side pin correction signal input terminal 3'' may both be the same signal, but they may be signals with independent optimal waveforms. By creating and generating this, it becomes possible to perform more accurate 3-character correction and side pin correction.

In the above explanation, we have described a system that has a phosphor screen with a convex curvature of the projection tube Q. However, even if the phosphor screen of the projection tube is flat, the same problem can occur in optical installation 1 of projection lenses, etc. (When performing sidepin correction and linearity correction using the conventional method, the vertical line on the screen
(as shown in Figure (b), it is curved). Even in this case, by applying the present invention, similar effects (improvement of focus characteristics by correcting the curvature of the vertical line in a circuit on the deflection circuit side and removing the convergence yoke for the green projection tube) can be achieved.

In addition, although we have so far described a system using electromagnetic focusing, the same effect can be achieved even when using electrostatic focusing (by removing the convergence yoke for the green projection tube, the electrostatic lens is moved closer to the phosphor screen, and the magnification is lowered). (improving focus characteristics).

[Effects of the Invention] According to the present invention, in the horizontal deflection circuit, the three-character correction amount can be changed continuously within the vertical period. Therefore, even when using a projection tube with a convex curvature on the phosphor screen,
Side pin correction and horizontal linearity correction can be performed circuit-wise on the deflection circuit side. Therefore, if such a horizontal deflection circuit is used in a green projection tube, the convergence yoke can be removed, and the focus magnet can be moved closer to the phosphor screen, thereby improving the focus characteristics of the projection display. (improvement of image quality).

[Brief explanation of drawings]

1 is a circuit diagram showing a first embodiment of the horizontal deflection circuit according to the present invention, FIG. 2 is a specific circuit diagram of an S-shaped control circuit and a side pin correction circuit, and FIG. 3 is a circuit diagram showing a first embodiment of the horizontal deflection circuit according to the present invention. The operating waveform diagram of the first embodiment is shown in the fourth example, the configuration diagram of a projection display as an example to which the present invention is applied, and FIG. 5 is a diagram showing the vertical lines on the screen to explain side pin distortion and horizontal linearity. FIG. 6 is a circuit diagram showing a second embodiment of the horizontally deflecting circuit according to the present invention. Explanation of symbols 21...First 8-character correction capacitor, 22...Second
8-character correction capacitor, 24...S-character control circuit, 28
...Switching means, 92...Pulse width modulation circuit, 29...Side pin correction circuit, 90...Arbitrary waveform generation circuit

Claims (1)

[Scope of Claims] 1. In a horizontal deflection circuit comprising a series connection circuit of a plurality of capacitors connected in series between a horizontal deflection coil and a constant potential as an S-shaped correction capacitor, the capacitor in the series connection circuit of capacitors a switching circuit connected in series between the connection point between the capacitor and the constant potential, and a switching circuit configured to vary the on/off period of the switching circuit within one horizontal scanning period. A horizontal deflection circuit comprising: a pulse width control circuit that varies an S-curve correction amount by applying a variable width pulse as an on/off drive signal. 2. In the horizontal deflection circuit according to claim 1, the pulse width control circuit includes a horizontal sawtooth wave forming circuit that generates a sawtooth wave in synchronization with the horizontal deflection period, and a vertical deflection circuit created for side pin distortion correction. An inverting amplifier circuit inputs a parabolic waveform synchronized with the period, inverts and amplifies it, and outputs it, and a sawtooth wave from the horizontal sawtooth wave forming circuit and an inverted parabolic wave from the inverting amplifier circuit are input, and a level comparison between the two is performed. A horizontal deflection circuit comprising a rectangular wave forming circuit that forms a rectangular wave and outputs it as an on/off drive signal to the switching circuit. 3. In the horizontal deflection circuit according to claim 1, the pulse width control circuit includes a horizontal sawtooth wave forming circuit that generates a sawtooth wave in synchronization with the horizontal deflection period, and a waveform of a desired arbitrary shape. A sawtooth wave from the horizontal sawtooth wave forming circuit and a waveform from the arbitrary waveform generating circuit are input, and a rectangular wave is formed by comparing the levels of the two, and the waveform is directed to the switching circuit. A horizontal deflection circuit comprising: a rectangular wave forming circuit that outputs on/off drive signals; 4. In the horizontal deflection circuit according to claim 3, the arbitrary waveform generation circuit not only outputs a waveform to be input to the rectangular waveforming circuit, but also separately creates a waveform for side pin distortion correction. 1. A horizontal deflection circuit comprising a waveform generation circuit that outputs a waveform. 5. The horizontal deflection circuit according to claim 1, 2, 3 or 4, which is used for electron beam scanning in a cathode ray tube in which the fluorescent screen has a curvature so as to be convex toward the electron gun. A horizontal deflection circuit characterized in that it is a horizontal deflection circuit. 6. In a projection display having three red, green and blue cathode ray tubes, by using the horizontal deflection circuit according to claim 1, 2, 3 or 4 as the horizontal deflection circuit in the green cathode ray tube. A projection display characterized by eliminating the convergence yoke in a green cathode ray tube and moving the focus magnet closer to the phosphor screen to improve focus characteristics.