JP3223485B2 - Deflection circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Table of Contents] The present invention will be described in the following order. INDUSTRIAL APPLICATIONS Conventional technology (FIG. 3) Problems to be solved by the invention (FIGS. 4 to 11) Means for solving the problems (FIG. 1) Action (FIG. 1) Embodiment (FIG. 1) effect

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deflection circuit, and more particularly, to a deflection circuit suitable for application to a horizontal deflection circuit for bidirectional deflection.

[0003]

2. Description of the Related Art Conventionally, in a deflection circuit of this kind, a horizontal deflection coil is driven by using a drive signal whose signal level changes symmetrically before and after a predetermined time such as a sine wave signal. A driving deflection circuit (hereinafter referred to as a bidirectional deflection deflection circuit) has been proposed (U.S. Pat.
No. 72,449).

According to this deflection circuit, scanning from the left to the right of the screen (hereinafter referred to as forward scanning) and, conversely, scanning from the right to the left of the screen (hereinafter referred to as returning scanning) are performed. Both can form a display image and reduce the deflection frequency by half. Further, since a sudden change in the deflection current such as a sawtooth signal can be prevented, unnecessary radiation and the like can be reduced, and the load on the deflection circuit element can be reduced.

In particular, if the deflection circuit is formed by a resonance circuit and the deflection coil is driven by a sinusoidal current as shown in FIG.
(A) and (B)), the power required for deflection can be reduced with a simple configuration (Japanese Patent Laid-Open No. 3-72783).

[0006]

However, when driving a deflection coil by supplying a pure sinusoidal current as described above,
Deflection current I period near the peak of _L shown by oblique lines in FIG. 3, by Riniaritei changes, forced to not give not drive the deflection coils so as to eventually Obasukiyan,
During this oblique line, there is a problem waste supplies the deflection current I _L. In practice, when using the cathode ray tube of a conventional 34-inch this period corresponds to a period of the entire approximately 38 [%] of the deflection current I _L of about 17 [%] min in terms of the amplitude waste Will be supplied to

[0007] As one method of solving this problem, by manipulating the time axis of the video signal, without supplying wasteful deflecting current I _L, it is considered a method of improving Riniaritei.

However, in this method, the configuration of the video signal processing circuit becomes complicated, and it is necessary to change the beam current in accordance with the operation of the time axis in order to keep the brightness of the entire screen uniform. The entire configuration becomes complicated. There is also a problem that the beam shape and the like change with the change of the beam current.

On the other hand, as shown in FIG. 4, a method of forming the deflection current I _L (FIGS. 4A and 4B) so as to eliminate useless portions can be considered. Accordance connexion to the operation principle shown in this case Figure 5, by driving the deflection coils, it is possible to drive the deflection coil L in such a deflection current I _L.

That is, the deflection circuit 1 connects the capacitor C1 to the deflection coil L via the selection circuit 2, and forms a resonance circuit with the capacitor C1 and the deflection coil L. If this state is left as it is, a deflection current having a sinusoidal waveform flows in the deflection coil L. If there is no loss in the resonance circuit, the deflection current continuously flows without attenuation.

[0011] Selection and to the deflecting current I _L that varies in this manner, the deflection circuit 1, (made in i.e. deflection voltage) terminal voltage of the deflection coil L V _L falls to a predetermined voltage V _M at time t1 The contact of the circuit 2 is switched to the capacitor C2 side. Here equal the capacitance of the capacitor C1 and C2, and the capacitor C2 that is charged to the voltage -V _M, the deflection voltage V _L is under stood from the voltage V _M at time t1 rapidly to the voltage -V _M is after One changes from the voltage -V _M sinusoidally.

The deflection voltage V which changes sinusoidally in this manner
Against _L, the deflection circuit 1 rises to the voltage -V _M at the deflection voltage V _L is subsequently time t2, switch the contacts of the selection circuit 2. Thereby, the deflection circuit 1 is connected to the capacitor C2
Disconnected from the terminal voltage is connected to the capacitor C1 which is held at a voltage V _M, the deflection voltage V _L, after One rising from the voltage -V _M to the voltage V _M, it varies sinusoidally.

Thus, the two capacitors C1 and C2
Are alternately switched at a predetermined timing and connected to the deflection coil L, and the switching voltages V _M and −V _M are selected to predetermined values, and no unnecessary deflection current is supplied.
Linearity can be improved.

[0014] In practice, it is possible to form a deflection current I _L of this kind in the deflection circuit 4 as expressed by an equivalent circuit in FIG. That is, the deflection circuit 4 forms a resonance circuit with the capacitor C and the deflection coil L via the selection circuit 6.

The deflection circuit 4 in this state, (made during the period that is, from time point t2 in FIG. 4 to time t1) during the period to launch a deflection voltage V _L to or higher than the voltage -V _M, contact of the selection circuit 6 And the DC power supply 8 of 2 V _M is inserted into this resonance circuit. Thus during the period from the time point t2 to time point t1, the DC level of the deflection voltage V _L is shifted by a voltage 2V _M, may drive the deflection coil L by the deflection voltage V _L shown in FIG.

More specifically, as shown in FIG. 7, a selection circuit 6 (FIG. 6) is formed by a semiconductor switch with respect to a resonance section 10 of a capacitor C and a deflection coil L, and an energy supply section 12 is connected. Thus, a configuration that compensates for the loss of the resonance unit 10 can be considered. That is, the deflection circuit 14 connects the series circuit of the field effect transistors Q3 and Q4 in parallel with the DC power supply VB, and connects the resonance section 10 via the capacitor C3 and the coil L1 from the connection point of the field effect transistors Q3 and Q4. Is supplied with a driving power supply Va.

Here, as shown in FIG. 8, the deflection circuit 14 alternately switches the field effect transistors Q3 and Q4 on and off, and thereby the deflection voltage _VL and deflection current I of the deflection coil L to be generated. _At a period synchronized with _L (FIGS. 8A and 8B), the midpoint voltage Va of the field-effect transistors Q3 and Q4 rises (FIG. 8C).
Supply drive power.

Further, the deflecting circuit 14 connects a series circuit of field effect transistors Q1 and Q2 in parallel with the DC power supply 8, and these field effect transistors Q1 and Q2 respectively.
2 and diodes D1 and D2 are connected in parallel. Further, the deflection circuit 14 connects the capacitor C to a connection point between the field effect transistors Q1 and Q2, and forms the selection circuit 6 by the field effect transistors Q1 and Q2 and the diodes D1 and D2.

Thus, the deflection circuit 14 forms a series resonance circuit of the deflection coil L and the capacitor C by holding the field effect transistor Q2 connected to the ground side in an on state, and the resonance current is reduced by the deflection coil L. By holding the field effect transistor Q2 connected to the DC power supply 8 side in the ON state, the DC power supply 8 can be inserted into the series resonance circuit of the deflection coil L and the capacitor C. Thus, the deflection circuit 14 can drive the deflection coil L under the conditions described above with reference to FIG. 4 by switching the connection of the selection circuit 6 at times t1 and t2.

With respect to the switching of the selection circuit 6, the deflection circuit 14 switches the connection of the selection circuit 6 as a whole by controlling the timing at which the field effect transistors Q1 and Q2 are turned off. That deflection circuit 14, when the deflection voltage V _L at time t2 rises to the voltage -V _M, switch the field effect transistor Q2 in the OFF state (FIG. 8 (G)). As a result, in the deflection circuit 14, the voltage Vb (FIG. 8 (H)) at the midpoint of the connection between the field effect transistors Q1 and Q2 is changed to the deflection current I.
_The voltage rises rapidly at _L , and the diode D1 is instantaneously switched to the ON state (FIG. 8D), so that the connection of the switch circuit 6 can be switched from the earth side to the DC power supply 8 side.

[0021] After switching the field effect transistor Q1 in the ON state in this state, when the deflection voltage V _L at time t1 falls to a voltage V _M, the deflection circuit 14, the field effect transistor Q1 in the OFF state Switch (Fig. 8
(E)). Thus, in the deflection circuit 14, rapidly falling voltage Vb deflection current I _L of the connection point of the field effect transistors Q1 and Q2, momentarily diode D2 is switched to the ON state (FIG. 8 (F) ), The connection of the switch circuit 6 can be switched from the DC power supply 8 side to the ground side.

By the way, in the deflection circuit 14, it is understood that the DC power supply 8 hardly supplies power.
That is, in the DC power supply 8, when the diode D1 is turned on, a current flows through the diode D1. Conversely, the field-effect transistor Q1
Is switched to the ON state and the midpoint voltage Vb starts dropping, the DC power supply 8
The current flows out via 1.

[0023] The current value is different between during discharge and during charging, changes in deflection current I _L in the forward scan and the backward scan becomes different, the display image becomes unsightly.

As shown in conjunction with associated circuitry in this order 9, be replaced by the direct current power supply 8 in a capacitor CS, is considered to be driving the deflection coil L in deflection current I _L described above with reference to FIG. 4 . Here, the deflection circuit 20
Detects the deflection voltage _VL in the voltage detection circuit 22, and drives the field effect transistors Q3 and Q4 in the drive circuit 24 based on the detection result.

The deflection circuit 20 further includes a voltage detection circuit 22
Is output to the AFC circuit 26, and the horizontal synchronization signal S
The drive circuit 28 drives the field effect transistors Q1 and Q2 based on the result of comparison between the YNC and the voltage detection result, thereby synchronizing the operation of the entire deflection circuit 20 with the horizontal synchronization signal SYNC.

Further, the deflection circuit 20 connects the pin distortion correction circuit 29 to the capacitor CS, and corrects the pin distortion by changing the terminal voltage of the capacitor CS in a parabolic manner in synchronization with the vertical synchronization signal.

Thus, according to the configuration shown in FIG. 9, the linearity can be improved without supplying a useless deflection current, and the entire configuration can be simplified by replacing the DC power supply 8 with the capacitor CS. Conceivable.

[0028] However, in the case of this configuration, there is a problem that deflection current I _L in the forward path and the backward path is changed slightly, there is a problem that the image quality of the minute display screen is degraded. That is, as shown in FIG. 10, the deflection circuit 20 includes a field-effect transistor Q1, a diode D1, and a field-effect transistor Q2.
And the diode D2 are connected to switch circuits 30 and 3, respectively.
2 and can be represented by an equivalent circuit.

As can be seen from this equivalent circuit, the deflection circuit 2
0 indicates that the capacitor CS forms a part of the resonance circuit when the switch circuit 30 switches to the ON state, whereas the switch CS switches to the ON state when the switch circuit 32 switches to the ON state.
The capacitor CS is disconnected from the resonance circuit. As a result, in the deflection circuit 20, the resonance frequency changes between the forward path and the return path, and the deflection current changes differently between the forward path and the return path.

In this case, as shown in FIG. 11, there is a problem that the display position is displayed differently between the forward path and the return path, and the displayed image is difficult to see. One way to solve this problem is to increase the capacitance of the capacitor CS. However, if the capacitance of the capacitor CS is increased,
It becomes difficult to correct pin distortion and is not practical.

The present invention has been made in view of the above points, and proposes a deflection circuit capable of effectively avoiding deterioration of image quality and improving linearity without supplying a useless deflection current. It is assumed that.

[0032]

According to the present invention, a first switch circuit 30 that repeats an on / off operation based on a drive signal output from a predetermined drive circuit 28, and two terminals are provided. One is connected in series with one end of the first switch circuit 30, and the second switch circuit repeats on / off operation at a complementary timing with the first switch circuit 30 based on a drive signal output from the drive circuit 28. 32, a series circuit including a horizontal deflection coil L and a resonance capacitor C connected between the connection point of the first switch circuit 30 and the second switch circuit 32 and the ground, and a first switch circuit 30. A first capacitor CS1 connected in series between the other end of the switch and ground, and when the first switch circuit 30 is closed, resonates with the series circuit to turn the screen from left to right and Deflection current I for scanning
A first resonance circuit that supplies L3 to the horizontal deflection coil L;
A second capacitor connected in series between the other terminal of the second switch circuit and the ground, the second switch circuit having a second capacitor connected in series with the capacitor having a capacitance substantially equal to that of the first capacitor; And a second resonance circuit for supplying a deflection current IL4 to the horizontal deflection coil L for resonating with the series circuit and scanning the screen from right to left when closed. In the past, the deflection current IL3 for scanning and the deflection current IL4 for scanning the screen from right to left were made substantially equal.

In the present invention, the first switch circuit 30 includes a first transistor Q1 and a first diode D1.
The second switch circuit 32 is formed by a parallel circuit of a second transistor Q2 and a second diode D2.

Further, in the present invention, the resonance capacitor C
A predetermined voltage is supplied at a predetermined timing through a power supply series circuit including a power supply capacitor C3 and a power supply coil L1 connected to a connection midpoint of the horizontal deflection coil L. Energy supply units 22, 2 for compensating for the loss due to the first resonance circuit or the second resonance circuit.
4, VB, Q3 and Q4.

Energy supply units 22, 24, VB, Q3
And Q4, a third transistor Q3 and a fourth transistor Q4 are connected in series between a DC power supply VB for supplying a predetermined voltage and ground, and a voltage VL at a connection midpoint between the resonance capacitor C and the horizontal deflection coil L is used as a reference. Thus, the third transistor Q3 and the fourth transistor Q4 are alternately turned on and off.

[0036]

[0037]

When the first switch circuit is closed, the first switch circuit resonates with the series circuit via a first capacitor connected in series between the other end of the first switch circuit and ground. And supplying a deflection current IL3 for scanning the outward path from the left to the right of the screen to the horizontal deflection coil L. When the second switch circuit 32 is closed, the other terminal in the second switch circuit 32 is connected to the ground. Resonating with the series circuit via a second capacitor CS2 having a capacity substantially equal to that of the first capacitor CS1 connected in series between the first capacitor CS1 and the deflection current IL4 for scanning the return path from the right to the left of the screen. Since the horizontal deflection coil L can be supplied to the horizontal deflection coil L in a state substantially equal to the deflection current IL3 in the forward path, the first capacitor CS1 and the second capacitor CS2 are passive elements. It is possible to improve the Riniaritei without with the display position in the forward and backward can be effectively avoided different image quality degradation, supplying wasteful deflecting current with.

In the present invention, the first switch circuit 30 includes the first transistor Q1 and the first diode D1.
One parallel circuit, and the second switch circuit 32
Of the first transistor Q1 by forming a parallel circuit of the transistor Q2 and the second diode D2.
Further, the first switch circuit 30 and the second switch circuit 32 can be easily turned on / off by controlling the ON / OFF of the second transistor Q2.

Further, in the present invention, the energy supply units 22, 24, VB, Q3 and Q4 are provided with a power supply capacitor C3 and a power supply capacitor C3 connected to a connection point between the resonance capacitor C and the horizontal deflection coil L. By supplying a predetermined voltage at a predetermined timing through a power supply series circuit including the coil L1, the loss due to the first resonance circuit or the second resonance circuit can be efficiently compensated.

Energy supply units 22, 24, VB, Q3
And Q4, a third transistor Q3 and a fourth transistor Q4 are connected in series between a DC power supply VB for supplying a predetermined voltage and ground, and a voltage VL at a connection midpoint between the resonance capacitor C and the horizontal deflection coil L is used as a reference. By alternately turning on and off the third transistor Q3 and the fourth transistor Q4 in this way, it is possible to generate a driving power supply Va having a different output level with a simple configuration.

[0041]

[0042]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

In FIG. 1 in which the same reference numerals are given to parts corresponding to those in FIG. 9, reference numeral 40 designates a deflection circuit as a whole, in which a capacitor CS1 is arranged in place of the capacitor CS, and a capacitor CS2 is additionally arranged. .

That is, in the deflection circuit 40, a capacitor CS1 is connected to the anode side of the diode D1 with respect to the diodes D1 and D2 forming a part of the first and second switch circuits, respectively, and the capacitor CS1 is grounded. I do. Further, in the deflection circuit 40, a capacitor SC2 is connected to the cathode side of the diode D2 symmetrically with the capacitor CS1, and the capacitor CS2 is grounded.

Thus, as shown in an equivalent circuit in FIG.
In the deflection circuit 40, a first resonance circuit is formed by the switch circuit 30 (that is, composed of the field effect transistor Q1 and the diode D1), the resonance capacitor C, the deflection coil L, and the capacitor SC1. outputting a resonance current of the first resonance circuit as the deflecting current I _L3 in the outward deflection coil L.

On the other hand, a switch circuit 32 (that is, a field effect transistor Q2 and a diode D2).
Are the resonance capacitor C, the deflection coil L and the capacitor S
A second resonance circuit is formed together with C2, and the deflection circuit 40
The resonance current of the second resonance circuit is output as the deflection current _{IL4 on} the return path of the deflection coil L.

Here, the deflection circuit 40 includes a capacitor CS1
, And CS2 are set to be small, so that the pin distortion can be easily corrected by the pin distortion correction circuit.

[0048] Thus the deflection circuit 40 can generate forward and set equal to obtain the frequency of the backward path deflecting current I _L, a deflection current I _L to exhibit the same changes in the forward path and backward path.

[0049] accordance connexion in deflection circuit 40, give avoids effectively the image degradation of a display screen by driving the deflection coil L in this deflection current I _L, thus the transistors Q1 and Q2
Is switched off at a predetermined timing, thereby effectively avoiding deterioration of image quality and improving linearity without supplying a useless deflection current.

Further, since the capacitors CS1 and CS2 can be reduced in capacity, a pin distortion correction circuit can be connected to correct the screen distortion of the display screen with a simple configuration.

According to the above configuration, the first and second resonance circuits for supplying the forward and backward deflection currents to the deflection coil are provided with capacitors of equal capacity, and the deflection voltage is biased by the capacitors. The change in the deflection current in the forward path and the return path can be held equal, whereby the first and second resonance circuits are switched at a predetermined timing, thereby effectively avoiding the deterioration of the image quality and supplying a useless deflection current. Without this, the linearity can be improved.

In the above embodiment, the case where the switch circuits 30 and 32 are formed by field effect transistors and diodes has been described. However, the present invention is not limited to this, and various semiconductor switch circuits and the like are widely applied. be able to.

[0053]

As described above, according to the present invention, when the first switch circuit is closed, the first capacitor connected in series between the other end of the first switch circuit and ground is connected. By supplying resonance to the horizontal deflection coil for scanning the outward path from the left to the right of the screen by resonating with the series circuit through the second switch circuit, when the second switch circuit is closed, the other The deflection for scanning the return path from the right to the left of the screen by resonating with the series circuit via a second capacitor connected in series between the terminal of Since the current can be supplied to the horizontal deflection coil in a state substantially equal to the deflection current in the forward path, the display position can be changed in the forward path and the return path using only the first capacitor and the second capacitor and the passive element. Together comprising such can effectively avoid image quality deterioration can be realized a deflection circuit capable of improving Riniaritei without supplying wasteful deflecting current.

[Brief description of the drawings]

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

FIG. 2 is a connection diagram showing an equivalent circuit thereof.

FIG. 3 is a signal waveform diagram for explaining bidirectional deflection.

FIG. 4 is a signal waveform diagram for explaining the improvement of the deflection current.

FIG. 5 is a connection diagram for explaining the operation principle.

FIG. 6 is a connection diagram showing an equivalent circuit of the actual configuration.

FIG. 7 is a connection diagram showing a specific configuration thereof.

FIG. 8 is a signal waveform diagram for explaining the operation.

FIG. 9 is a connection diagram showing a specific deflection circuit including an accompanying circuit.

FIG. 10 is a connection diagram showing an equivalent circuit thereof.

FIG. 11 is a schematic diagram for explaining the deterioration of the image quality.

[Explanation of symbols]

1, 14, 20, 40 ... deflection circuit, 2, 6, 30, 3
2. Switch circuit, C, C1 to C3, CS1, CS2
... capacitors, D1 to D4 ... diodes, L ... deflection coils, Q1 to Q4 ... field effect transistors.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References Table 2-82870 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 3/16 H04N 3/30

Claims (4)

(57) [Claims] (1)The drive signal output from the given drive circuit
On the basis ofFirst switch circuit that repeats on / off operation
When,One of the two terminals is directly connected to one end of the first switch circuit.
The driving signal output from the driving circuit connected to the column.
The first switch circuit is complementary to the first switch circuit based on the
In the mining The second switch circuit that repeats on / off operation
When,Connection between the first switch circuit and the second switch circuit
Connected between midpoint and ground With horizontal deflection coil
Vibration capacitorAnd a series circuit consisting of A series connection is made between the other end of the first switch circuit and ground.
A first capacitor connected to the first switch circuit.
When the road is closed, the screen resonates with the series circuit.
To scan once from left to right Horizontal deflection of deflection current
A first resonance circuit for supplying a coil,Select a value that has almost the same capacitance as the first capacitor.
And the other terminal of the second switch circuit is connected to the ground.
And a second capacitor connected in series between the
Note that when the second switch circuit is closed,
Resonating together and scanning the screen from right to left
For A second common electrode for supplying a deflection current to the horizontal deflection coil is provided.
With a vibration circuit,Deflection current for scanning the above screen from left to right
And deflection to scan the screen from right to left
Almost equal current A deflection circuit, characterized in that: 2. The first switch circuit is formed by a parallel circuit of a first transistor and a first diode, and the second switch circuit is formed by a parallel circuit of a second transistor and a second diode. The deflection circuit according to claim 1, wherein the deflection circuit is formed. 3. The resonance capacitor and the horizontal deflection coil.
Power supply capacitor connected to the midpoint of
And a power supply series circuit composed of a power supply coil and
By supplying a predetermined voltage at a predetermined timing,
Loss due to the first resonance circuit or the second resonance circuit
3. The deflection circuit according to claim 1, further comprising: an energy supply unit that compensates for the deviation. 4. An energy supply unit, comprising: a third power supply between a DC power supply for supplying the predetermined voltage and a ground;
And fourth transistors are connected in series, characterized in that the on-off control to alternately said resonant capacitor and the third transistor and the fourth transistor a voltage of connection midpoint on the basis of the horizontal deflection coil The deflection circuit according to claim 3, wherein