JP2571818B2 - Color shift correction circuit for projection display - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color shift correction circuit for a projection display.

[Conventional technology]

In a projection type display, generally, three projection tubes for red, green, and blue are horizontally arranged along with a projection lens to project and synthesize a color image on one screen.

FIG. 10 is an explanatory diagram showing a relationship between a projection lens in a general projection type display and an image projected on a screen.

In FIG. 10, 100 is a projection lens, 110 is a screen, and ω is the inclination of blue light with respect to green light.

As shown in Fig. 10, when projecting and combining color images,
Since the red and blue images are projected obliquely to the screen, vertical trapezoidal distortion (trapezoidal distortion in which the lengths of two vertical sides are different) is generated based on the projection geometry. This results in color misregistration. The magnitude of this color shift is about 10 times as large as the color shift in the non-projection type direct-view display. Therefore, conventional techniques based on the principle of nonlinear magnetic saturation (Japanese Patent Application Laid-Open Nos. 58-144453 and 63-8428).
In some cases, it cannot be erased.

In order to correct this color shift, for example, Japanese Patent Application Laid-Open No. Sho 62-92
As described in Japanese Patent No. 595, a convergence yoke (hereinafter abbreviated as CY) for electron beam assisted deflection similar to a deflection yoke (hereinafter abbreviated as DY) is mounted on a neck portion of a projection tube. Then, the output from the convergence amplifier is applied to the CY to correct the color shift.

The main cause of color misregistration due to such a projection optical system (projection lens or the like) is the above-described vertical trapezoid (hereinafter abbreviated as V-KS. V-KS is a vertical key storage).
ne is an abbreviation for ne. ) In addition to distortion, horizontal linearity (hereinafter abbreviated as H-LIN. H-LIN is horizontal
Al Linearity. ) Distortion.

FIG. 11 shows a positional relationship between a projection tube and DY and CY in a general projection type display.

In FIG. 11, 16 is a projection tube, 17 is DY, 18 is CY, and 19 is an electron gun.

The deflection sensitivity of DY17 and CY18 can be represented by the deflection distance of the electron beam with respect to the unit electromagnetic energy input, and is proportional to the effective magnetic path length of each yoke (the length direction of the neck portion).

On the other hand, the effective magnetic path length of CY18 is DY17, as shown in FIG.
About 1/2 of that of The reason is that there is a dimensional restriction for preventing an adverse effect of the CY18 on the electron lens portion of the electron gun 19 adjacent to the left of the CY18.

Therefore, the deflection sensitivity of CY18 is about 1 /
2 and bad.

[Problems to be solved by the invention]

As described above, the deflection sensitivity of CY is about 1 /
In the conventional technology, the color shift is corrected by such a CY having such a poor deflection sensitivity, and the power consumed for the color shift correction becomes large. was there.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a color misregistration correction circuit that can solve the above-mentioned problems of the related art and can perform color misregistration correction with low power consumption.

[Means for solving the problem]

In order to achieve the above object, according to the present invention, there are provided three projection tubes for emitting monochromatic lights of three primary colors, and three projection tubes arranged one by one on each of the right and left ends of one projection tube. A tube, a total of three projection lenses arranged on the front surface of each projection tube, and a total of three sets of horizontal deflection coils arranged on each projection tube and deflecting the electron beam of each projection tube And a color misregistration correction signal generating means for generating and outputting a color misregistration correction signal in a projection type display including a total of three sets of vertical deflection coils and a deflection circuit for supplying a deflection current to each deflection coil; Amplifying means for amplifying and outputting the color misregistration correction signal from the color misregistration correction signal generating means, wherein the three sets of vertical deflection coils are connected in series with each other, and the projection tube located at the center of the Supported vertical deflection carp Instead, a correction current corresponding to the output signal from the amplifying means is applied to two sets of vertical deflection coils corresponding to the two projection tubes located at the left and right ends from a connection point of the two sets of vertical deflection coils. , As currents of opposite polarities,
Transformer coupling means for coupling via a transformer between the coupling point and the output of the amplifying means so as to be superimposed on the vertical deflection current, and wherein the waveform of the correction current is a horizontal period sawtooth wave. The color misregistration correction circuit of the projection type display is configured as a waveform obtained by multiplying by a sawtooth wave having a vertical period.

Further, in the color shift correction circuit of the projection display, a second color shift correction signal generating means for generating and outputting a second color shift correction signal, and a color shift from the second color shift correction signal generating means. A second amplifying means for amplifying and outputting the correction signal, wherein the three sets of horizontal deflection coils are connected in parallel with each other, but are not the horizontal deflection coils corresponding to the projection tube located at the center of the three sets. Two sets of horizontal deflection coils corresponding to the two projection tubes located at the left and right ends thereof are connected to a second point corresponding to an output signal from the second amplifying means from a connection point of the two sets of horizontal deflection coils. A second transformer coupling unit that couples the coupling point and the output of the second amplifying unit via a transformer so that the correction currents flow as currents of opposite polarities superimposed on the horizontal deflection current. Comprising, and said second The waveform of the correction current, as it is parabolic shaped signal waveform of the horizontal period planarizing the horizontal blanking period, to constitute a color shift correction circuit of another projection type display.

[Action]

In general, when trying to flow current from two different power sources to one load, current from one power source flows into the other power source, and the power consumption of both power sources increases. However, according to the present invention, as described above, the transformer coupling means includes two sets of vertical deflection coils connected in series with each other or two sets of vertical deflection coils connected in parallel with each other.
Since the two sets of horizontal deflection coils are connected so that currents of opposite polarities are supplied as correction currents, the deflection current flowing the deflection current to the two sets of vertical deflection coils or the two sets of horizontal deflection coils is used. The correction current does not flow into the supply means. Further, the deflection current supply means is provided in the 2nd.
Since the deflection current flows through the set of vertical deflection coils or the two sets of horizontal deflection coils in the same phase, the deflection current does not flow into the amplification means via the transformer coupling means. Therefore, the power consumption in the deflection current supply means and the amplification means does not increase.

Further, according to the present invention, the color shift between the three primary colors caused by the projection optical system can be corrected by the DY deflection coil having deflection sensitivity approximately twice as high as that of CY. The power consumed for the correction can be reduced to almost half of the conventional power.

〔Example〕

FIG. 1 shows a first embodiment of the present invention. This embodiment is a color shift correction circuit for correcting the V-KS distortion described above.

In FIG. 1, 1 is a sawtooth signal of 1V (one vertical scanning cycle), 2 is a sawtooth signal of 1H (one horizontal scanning cycle), 3 is a negative feedback amplifier for vertical deflection, and 4, 5, and 6 are green, respectively. (G) vertical deflection coils of a deflection yoke (DY) for colors, red (R) colors, and blue (B) colors, 7 is a deflection current detection resistor for negative feedback, 8, 9, and 10 are green, respectively. DY parallel resistors for red and blue (especially 9, 10 are for differential application of color shift correction signal), 11 is a transformer, 12 is a multiplier, 13 is a filter, 14
Is a color shift correction negative feedback amplifier, 15 is a correction current detection resistor,
20 is an output signal of the multiplier 12.

 Next, the operation of the present embodiment will be described.

The 1V sawtooth signal 1 input to the amplifier 3 and the multiplier 12 and the 1H sawtooth signal input to the multiplier 12 are generated and generated in a conventional general projection display, respectively.
It is a well-known one used.

The amplifier 3 supplies the vertical deflection current to the vertical deflection coils 4, 5, and 6, and the waveform of the vertical deflection current detected by the detection resistor 7 is similar to the waveform of the input 1V sawtooth signal 1. Thus, the negative feedback operation is performed. Here, the parallel resistances 8, 9, and 10 are set to values that are about 10 times or more the parasitic resistances of the vertical deflection coils 4, 5, and 6, respectively, and equal to each other.

On the other hand, the multiplier 12 receives the input 1V sawtooth signal 1
And a 1H sawtooth wave signal 2 to generate a color shift correction signal. Here, the frequency component of the color misregistration correction signal includes a high frequency horizontal scanning cycle component and its sideband.
Next, the color misregistration correction signal is input to the amplifier 14 via the filter 13 for compensating the frequency characteristics of the subsequent portion.

The amplifier 14 supplies the correction current to the primary side (lower side in FIG. 1) of the transformer 11 and also converts the waveform of the correction current detected by the detection resistor 15 into the color shift correction signal input from the filter 13. Negative feedback operation is performed so as to be similar to the waveform.

Also, the transformer 11 corrects the correction current supplied to the primary side from the secondary side (the upper side in FIG. 1) to the vertical deflection coils 5 and 6.
Pour into

Here, the vertical deflection current supplied from the amplifier 3 flows through the vertical deflection coils 4, 5, and 6 in the same phase, so that no current flows through the primary side of the transformer 11; Do not shed.

On the other hand, the correction current supplied from the amplifier 14 via the transformer 11 flows through the vertical deflection coils 5 and 6 in opposite phases, so that no current flows to the amplifier 3. That is, independence and orthogonality are maintained between the amplifiers 3 and 14 (that is, there is no signal leakage).

In general, when trying to flow current from two different power sources to one load, current from one power source flows into the other power source, and the power consumption of both power sources increases. However, in this embodiment, as described above, the vertical deflection current supplied from the amplifier 3 is
Since the correction current supplied from the amplifier 14 does not flow into the amplifier 3, the power consumption of the amplifiers 3 and 14 does not increase.

In addition, according to the present embodiment, the color shift can be corrected by the vertical deflection coil of DY having deflection sensitivity approximately twice as high as that of CY. Can be reduced by almost half.

Now, at the end of the description of the present embodiment, the configuration of the filter 13 will be described a little.

Primary side of transformer 11 from amplifier 14 (lower side in FIG. 1)
If the correction current flowing through the vertical deflection coils 5 and 6 due to this is I ₁ and I ₅ and I ₆ , the following equation is established.

Here, p = jω (complex angular frequency) M = mutual inductance of transformer 11 L ₂ = inductance on the secondary side of transformer 11 R ₀ = resistance value of parallel resistors 9 and 10 L _D = vertical deflection coils 4,5, Inductance of 6 By transforming the above equation, The second term on the right side of the above equation, that is, 1 / (1 + 1 /
τp) means frequency characteristics.

FIG. 2 is a circuit diagram showing a specific example of the filter 13 of FIG.

In FIG. 2, 82 and 83 are resistors, 84 is a capacitor, 85
Is an operational amplifier.

The frequency characteristic as described above is obtained by configuring the filter 13 of FIG. 1 using an operational amplifier 85 as shown in FIG.
The resistance of 3 is R ₁ and R ₂ , respectively, and the capacitance of capacitor 84 is C ₂
Is compensated by selecting a time constant so that R ₁ = R ₂ , R ₂ C ₂ = τ.

Now, an example of actual constants in the case of a vertical scanning frequency of 60 Hz is shown below. Note that _RD is the resistance value of the parasitic resistance of the vertical deflection coils 4, 5, and 6, and _RS is the resistance value of the detection resistor 15.

L _D = 2 mH, R _D = 4 Ω, R ₀ = 100 Ω, L ₂ = 5 mH, M = 500 μH, R ₁ = R ₂ = 1 kΩ, C ₂ = 120 nF, R _S = 5 Ω After the description of the embodiment, a second embodiment of the present invention is shown in FIG.

3, the same components as those in FIG. 1 are denoted by the same reference numerals. In addition, 2 'is a signal obtained by differentiating the 1H sawtooth signal 2 shown in FIG. 1, 21 is a filter,
Reference numerals 22 and 23 denote bleeder resistors for voltage detection, and reference numeral 24 denotes a DC blocking capacitor.

In the embodiment of FIG. 1 described above, the amplifier 14 performs a negative feedback operation so that the waveform of the output current (that is, the correction current) is similar to the waveform of the color shift correction signal to be input, that is, the so-called current feedback system. However, in the present embodiment, the amplifier 14 performs a negative feedback operation so that the waveform of the output voltage (that is, the correction voltage) becomes similar to the waveform of the input color shift correction signal. A so-called voltage feedback system is adopted.

That is, in the present embodiment, the operation of the amplifier 14 is as follows.
The correction voltage is applied to the primary side of the transformer 11 and the waveform of the correction voltage detected by the bleeder resistors 22 and 23 is
The negative feedback operation is performed so as to be similar to the waveform of the color misregistration correction signal input from the filter 21.

Further, in this embodiment, the output voltage of the amplifier 14 (i.e., correction voltage) when the the E _1, the correction current I _5, I ₆ flowing due to the vertical deflection coils 5 and 6 is expressed by the following equation .

Here, n = turn ratio of the transformer 11 L = equivalent inductance when the transformer 11 is viewed from the primary side and is substantially equal to L _D / (2n ² ) C = capacitance value of the capacitor 24 The first term, n / pL
_D is an integration factor of the inductance of the vertical deflection coil. As shown in FIG. 3, this is a pulse obtained by differentiating one input signal of the multiplier 12 from the 1H sawtooth signal 1 shown in FIG. This is compensated for by making the signal 2 'like a circle.

On the other hand, the second term of the denominator on the right side of the equation, that is, 1 / P ² LC
Is Can be ignored if the value of is selected to be sufficiently larger than one horizontal scanning period (1H).

The second term of the numerator on the right side of the equation, that is, 1 / (1
+ R ₀ / pL _D ) is the same as the second term on the right-hand side of the above equation, that is, 1 / (1 + 1 / τp), although the time constant value is different.
Therefore, compensation can be achieved by forming the filter 21 in the same type as that shown in FIG.

The other operations in this embodiment are the same as those in the embodiment shown in FIG. 1, and the description thereof will be omitted.

Therefore, also in this embodiment, the same effects as in the embodiment of FIG. 1 described above can be obtained.

 This concludes the description of the embodiment of FIG.

Next, as a third embodiment of the present invention, the above-described H-LI
A color shift correction circuit for correcting N distortion will be described.

 FIG. 4 shows a third embodiment of the present invention.

In FIG. 4, 25 is a horizontal drive pulse, 26 is a horizontal output transistor, 27 is a damper diode, 28 is a resonance capacitor, and 29, 30, and 31 are DYs for green, red, and blue, respectively.
Horizontal deflection coil, 32 is a choke coil for power supply, 33
Is a bypass capacitor for blocking DC, 34 is a deflection current detection resistor, 35 is a multiplier, 36 is a maximum value detector, 37 is a changeover switch, 38 is a negative feedback amplifier, 39 is a transformer, and 40 is a correction current detection resistor. . The components other than 35 to 40 belong to the well-known horizontal deflection output circuit technology.

FIG. 5 is a waveform diagram showing signal waveforms of main parts in FIG.

In FIG. 5, a, b, c, and d denote signal waveforms of the same reference numerals in FIG. 4, respectively, and BL denotes a horizontal blanking period.

 Now, the operation of the present embodiment will be described.

The horizontal output transistor 26 receives the horizontal drive pulse 25, and turns on in the latter half of the horizontal scanning period. The resonance capacitor 28 resonates with the inductance components of the horizontal deflection coils 29, 30 and 31 during the horizontal retrace period, generates a flyback pulse as shown in FIG. , 31, a horizontal deflection current of a sawtooth wave flows.

Therefore, this horizontal deflection current is detected by the detection resistor 34,
A sawtooth signal as shown in FIG. 5b is obtained and input to the multiplier 35. The multiplier 35 squares the input sawtooth signal and outputs a parabolic signal as shown in FIG.
It is input to one input of the maximum value detector 36 and the changeover switch 37. The maximum value detector 36 is composed of, for example, a diode and a capacitor, detects the maximum value of the input parabolic signal, and inputs the same to the other input of the changeover switch 37.

The switching of the changeover switch 37 is controlled by the input pulse signal 2 'shown in FIG.
The switch is turned to the α side only during the horizontal retrace period, and the switch is turned to the β side during the other periods. Therefore, its output is
A signal having a waveform as shown by a solid line in FIG. 5d is obtained. The signal output from the changeover switch 37 is input to the amplifier 38 as a color shift correction signal.

The amplifier 38 supplies the correction current to the primary side (lower side in FIG. 4) of the transformer 39, and the correction current waveform detected by the detection resistor 40 is changed by the color shift correction signal Negative feedback operation is performed so as to be similar to the waveform of.

Here, the reason why a signal obtained by flattening the horizontal blanking period portion as shown by the solid line in FIG. 5d is used as the color misregistration correction signal is as follows.

That is, assuming that a signal showing a steep waveform change as shown in FIG. 5C is used as it is as a color shift correction signal, a current showing a steep waveform change as its input current is supplied to the transformer 39. Will be entered. However, since the transformer 39 is an inductive load, when a current showing such a sharp waveform change is input, an excessive voltage is required, so that a high power supply voltage is required for the amplifier 38 and power consumption is reduced. It is because it becomes excessive.

Next, the transformer 39 supplies correction currents of opposite polarities to the horizontal deflection coils 30 and 31 as in the embodiment of FIG.
In the embodiment of FIG. 1 described above, three vertical deflection coils are connected in series, whereas in the present embodiment, three horizontal deflection coils are connected in parallel. ing.

The above-described horizontal deflection current is supplied to the horizontal deflection coils 29, 3
Since the current flows in the same phase to 0 and 31, no potential difference occurs between both ends of the transformer 39 on the secondary side.

Therefore, also in this embodiment, the same effects as in the embodiment of FIG. 1 described above can be obtained.

In the present embodiment, an example of actual constants in the case where the projection display is an ultra-high definition display having a horizontal scanning frequency of about 64 kHz is shown below. L _D is a horizontal deflection coil
29, 30 and 31 of the inductance, capacitance value of C _r is a resonant capacitor 28,
C _S is the capacitance value of the bypass capacitor 33, L ₁ is the inductance, L ₂ of the primary side of the transformer 39 is the secondary inductance, R ₀ is the resistance of the detecting resistor 40, the transformer 39.

L _D = 2000 μH, C _r = 4 μF, C _S = 0.4 μF, L ₁ = 20 μH, L ₂ = 2 mH, R ₀ = 0.5Ω Also in this embodiment, a filter having the same configuration as FIG. Is arranged on the input side of the amplifier 38, the influence of the parasitic loss of DY can be compensated for in the same manner as described above.

Further, as a modification of the present embodiment, it is obvious that an example in which the voltage feedback system is adopted for the amplifier 38 can be realized similarly to the relationship of the embodiment of FIG. 3 with respect to the embodiment of FIG.

The method of differentially driving DYs for red and blue has been described for the three embodiments. Further, by adding a similar circuit, the DY for green and the DY for red can be similarly differentially driven. Alternatively, a method of differentially driving two sets of DY for green and red and DY for green and blue can be adopted.

This concludes the description of the color misregistration correction circuit that corrects V-KS distortion and H-LIN distortion, which are the main causes of color misregistration due to the projection optical system (projection lens and the like).

By the way, in addition to the above-described V-KS distortion and H-LIN distortion, the three primary colors are displaced in parallel due to the direction variation of the projection optical system or the electron gun inside the projection tube. And distortion. In the prior art, in order to correct such a distortion, a method in which a correction current such as a DC current is applied to CY has been used. But,
As described above, since the CY has a low deflection sensitivity, a large amount of power consumption is required to perform the correction.

Therefore, next, as a fourth embodiment of the present invention, a description will be given of a color misregistration correction circuit capable of correcting not only the above-described H-LIN distortion but also a distortion in which three primary colors are shifted in parallel in the horizontal direction. I do.

 FIG. 6 shows a fourth embodiment of the present invention.

6, the same components as those in FIG. 4 are denoted by the same reference numerals. In addition, 41, 42, 43 are choke coils, 44
Is a variable power supply for horizontal translation of a green screen, 45 is a first color shift correction signal, 46 is a second color shift correction signal, 47 and 48 are low frequency amplifiers, 49 and 52 are negative feedback amplifiers, 50 and 50. 53 is a transformer, 51 and 54 are subtractors, 55 and 56 are DC blocking capacitors,
It is.

 Now, the operation of the present embodiment will be described.

In the present embodiment, a method of differentially driving two sets of DY for green and red and DY for green and blue is adopted.

The amplifier 49 includes, as the first color misregistration correction signal 45, a signal for translating the red screen in the horizontal direction with respect to the green screen, a signal for correcting the H-LIN distortion, and the like. As the second color shift correction signal 45, a signal for horizontally moving the blue screen with respect to the green screen, a signal for correcting the H-LIN distortion, and the like are input.

Therefore, the amplifier 49 transmits the correction current to the amplifier 47 and the transformer.
The signal is supplied to the primary side of the color shift register 50, and a negative feedback operation is performed so that the waveform of the output voltage of the subtracter 51 becomes similar to the waveform of the first color misregistration correction signal 45. Similarly, the amplifier 52 supplies the correction current to the amplifier 48 and the primary side of the transformer 53,
The negative feedback operation is performed so that the waveform of the output voltage of the subtractor 54 is similar to the waveform of the second color misregistration correction signal 46.

On the other hand, the variable power supply 44 is used for horizontal translation of the green screen, and controls the current flowing through the horizontal deflection coil 29 of the green DY.

The inductance of each of the choke coils 41, 42, and 43 is selected to be an AC high impedance that is approximately 20 times the inductance of the horizontal deflection coils 29, 30, and 31, respectively.
Therefore, the choke coils 41 and 43 respectively include the amplifier 4
7, out of the correction current supplied from the amplifier 48, a high-frequency current in the horizontal scanning period, that is, a signal component for correcting the H-LIN distortion flows only slightly, but the DC current and the low-frequency current in the vertical scanning period The current, that is, a signal component for horizontally moving the screen in a horizontal direction, sufficiently flows. Also, the DC current and the low-frequency current in the vertical scanning period sufficiently flow from the current supplied from the variable power supply 44 to the choke coil.

As a result, DC current and low frequency current of vertical scanning cycle,
That is, the signal components for horizontally moving the screen in the horizontal direction are supplied to the DY horizontal deflection coils 29, 30, and 31, respectively, and the horizontal movement of the green screen and the red movement with respect to the green screen are referred to. The horizontal translation of the screen and the blue screen is performed with low power loss.

Further, the transformer 50 converts the correction current supplied to the primary side from the secondary side into horizontal deflection coils 29, 30 for green DY and red DY.
The transformer 53 supplies the correction current supplied to the primary side to the green DY and blue DY horizontal deflection coils 29 and 31 from the secondary side so that they have opposite polarities. Pour into

The horizontal deflection current flows through the horizontal deflection coils 29, 30, 31 in the same phase as in the embodiment of FIG.

Here, two windings are wound on the secondary sides of the transformers 50 and 53, respectively, and half of the current flows through the winding connected to the horizontal deflection coil 29 of the green DY. Is set to twice the other. Further, each of the two resistors disposed between the two windings is a current detection resistor, and the resistance value is similarly set to a ratio of 1: 2.

By doing so, each of the horizontal deflection coils 29, 30,
The horizontal deflection current flowing in the same phase 31 does not generate a voltage at the outputs of the subtractors 51 and 54, and only the correction current flowing in the opposite phase generates a voltage. Therefore, the correction current can be detected by the current detection resistors of the transformers 50 and 53 and the subtracters 51 and 54, and the negative feedback operation of the amplifiers 49 and 52 can be realized. In addition, each horizontal deflection coil 29, 30, 31
Does not generate a potential difference at both ends of the transformers 50 and 53 on the secondary side.

As described above, according to the present embodiment, not only the H-LIN distortion but also the distortion in which the three primary colors are shifted in parallel in the horizontal direction can be corrected by the DY as the color shift correction. The coil for horizontal auxiliary deflection in CY can be omitted at all.

Next, as a fifth embodiment of the present invention, the aforementioned V-KS
A description will be given of a color misregistration correction circuit that can correct not only distortion but also distortion in which three primary colors are shifted in parallel in the vertical direction.

 FIG. 7 shows a fifth embodiment of the present invention.

7, the same components as those in FIG. 1 are denoted by the same reference numerals. In addition, 61 is a first color misregistration correction signal, 62
Is a second color shift correction signal, 63 is a third color shift correction signal,
64 is a subtractor, 65 and 67 are low-frequency amplifiers, 66 and 68 are choke coils, 69 and 73 are negative feedback amplifiers, 70 and 74 are transformers, 71 and 75.
Is a current detection resistor, 72 and 76 are subtracters, and 77 and 78 are DC blocking capacitors.

 Now, the operation of the present embodiment will be described.

In the present embodiment, a method of differentially driving two sets of DY for green and red and DY for green and blue is adopted.

As the first color misregistration correction signal 61, a signal (low-frequency signal) for translating the green screen in the vertical direction (substantially moving the screen of all three primary colors in the vertical direction) is subtracted 64. , The feedback voltage of the amplifier 3 becomes insufficient by that amount.
An in-phase current corresponding to the first color misregistration correction signal flows through the vertical deflection coils 4, 5, and 6 of the DY, and the parallel movement of the entire three primary colors is achieved. Even if a high-frequency signal is supplied to the subtractor 64 as the first color misregistration correction signal 61, since the amplifier 3 originally handles a low-frequency signal of about 60 Hz, the amplifier 3 does not work effectively. Absent.

On the other hand, a signal for translating the red screen in the vertical direction, a signal for correcting V-KS distortion, and the like are input to the amplifier 69 as the second color shift correction signal 62, and the amplifier 73 is As the third color shift correction signal 63, a signal for moving the blue screen in parallel in the vertical direction, a signal for correcting V-KS distortion, and the like are input.

Therefore, the amplifier 69 supplies the correction current to the amplifier 65 and the capacitor 77, and performs a negative feedback operation so that the waveform of the output voltage of the subtractor 72 becomes similar to the waveform of the second color shift correction signal 62. . Similarly, the amplifier 73 supplies the correction current to the amplifier 67 and the capacitor 78, and performs a negative feedback operation so that the waveform of the output voltage of the subtractor 76 becomes similar to the waveform of the third color shift correction signal 63. I do.

The correction current supplied to the amplifier 65 is
And the DC current and the low frequency current of the vertical scanning period (ie,
Signal component for moving the red screen in parallel in the vertical direction)
Only the DY vertical deflection coil 5 for red
Flows so that the direction of the white arrow α is positive. This is because a constant current always flows in the opposite direction of the white arrow α due to the negative feedback operation of the amplifier 3 as described above. Thus, only the red screen can be translated in the vertical direction with respect to the green screen and the blue screen.

Similarly, from the correction current supplied to the amplifier 67, only the DC current and the low-frequency current of the vertical scanning cycle (that is, the signal component for moving the blue screen in the vertical direction) are similarly extracted by the choke coil 68. And then for green
DY vertical deflection coil 4 and red DY vertical deflection coil 5
Flows so that the direction of the white arrow β is positive. As a result, the green screen and the red screen are translated in the vertical direction with respect to the blue screen. For example, the green screen and the red screen are translated upward by a certain amount with respect to the blue screen. This is equivalent to shifting the blue screen downward by that amount with respect to the green screen and red screen, so that only the blue screen is parallel to the green screen and red screen in the vertical direction. Can be moved.

The correction current supplied to the capacitors 77 and 78 is such that only the high-frequency current of the horizontal scanning period (that is, the signal component for correcting the V-KS distortion) passes therethrough,
The four primary sides are each supplied. Subsequent operations can be easily inferred from the embodiment shown in FIG.

As described above, according to this embodiment, not only the V-KS distortion but also the distortion in which the three primary colors are shifted in parallel in the vertical direction can be corrected by the DY as the color shift correction. The coil for vertical auxiliary deflection in CY can be omitted at all.

In addition, by using this embodiment together with the embodiment of FIG. 6 described above, it is possible to obtain, as a correction current, a current in all the necessary frequency bands (a DC current, a low-frequency current in a vertical scanning cycle, and a horizontal scanning cycle). The color shift can be corrected by high-frequency current), and in this case, the CY itself can be deleted. Therefore, not only can the power consumption be reduced, but also the electron gun can be made more DY by changing the structure of the projection tube itself shown in FIG.
By moving closer to the side, the magnification of the electron lens can be reduced to improve the focus.

An example of actual constants in the embodiment of FIG. 7 is shown below.
Vertical deflection coil 4,5,6 (2mH), parallel resistance 8,9,10 (100
Ω), the detection resistor 15 (2Ω), and the transformers 70 and 74 are the same as those in the embodiment of FIG. In addition, the current detection resistors 71 and 75 are 8Ω, the choke coils 66 and 68 are 20 mH, and the DC blocking capacitors 77 and 78 are 5 μF.

The parallel resistors 8, 9 and 10 in FIG. 7 can be replaced by three choke coils 8 ', 9' and 10 'electromagnetically coupled to each other in FIG. If the constant value is selected to be 30 mH, which is about 5 times the total of 6 mH of the vertical deflection coils 4, 5, and 6, the shunt loss of the vertical deflection current, which is an in-phase component, can be suppressed to about 20%. On the other hand, with respect to the high-frequency correction current, currents of opposite polarities flow through the choke coils 9 ′ and 10 ′ and the magnetic fluxes cancel each other, so that the correction current can be efficiently applied to the vertical deflection coils 5 and 6.

 FIG. 9 shows a sixth embodiment of the present invention.

In FIG. 9, the same components as those in FIGS. 7 and 8 are denoted by the same reference numerals. In addition, reference numeral 80 denotes a coil constituting a choke transformer together with the choke coils 8 ', 9', and 10 ', and 81 denotes a choke coil.

An upper and lower pincushion distortion correction signal output from an unshown upper and lower pincushion distortion correction amplifier is applied to the coil 80.

Here, the upper and lower pincushion distortion is a raster shape distortion common to the three primary colors, which is not directly related to the distortion which causes color shift according to the present invention, and four corners of the screen are over-deflected in the diagonal corner direction. The distortion looks like it is being done.

This distortion is corrected by flowing an appropriate correction current in the same phase to the vertical deflection coils 4, 5, 6 via the choke coils 8 ', 9', 10 'constituting the choke transformer by the above-mentioned correction signal. be able to.

Here, the appropriate correction current is shown in FIG.
This is a current having a waveform obtained by multiplying the 1H parabolic signal and the 1V sawtooth signal 1 shown in FIG. 1 by a separate multiplier.

The choke coil 81 is provided to prevent the correction current of the above-mentioned upper and lower pincushion distortion from flowing back to the amplifier 3 side, and has a capacitance of about 12 mH.

〔The invention's effect〕

According to the present invention, the color shift between the three primary colors caused by the projection optical system can be corrected by the DY whose deflection sensitivity is about twice as good as that of the CY. The consumed power can be reduced to almost half compared with the conventional one, and the cost can be reduced. In addition, since the power consumption is reduced to about half, the amount of heat generated due to the power consumption is also reduced by half, so that the internal temperature in the projection display device can be reduced and the reliability is improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention, FIG. 2 is a circuit diagram showing a specific example of the filter 13 of FIG. 1, and FIG. 3 is a second embodiment of the present invention. FIG. 4 is a circuit diagram showing a third embodiment of the present invention, FIG. 5 is a waveform diagram showing signal waveforms of main parts in FIG. 4, and FIG. 6 is a fourth embodiment of the present invention. FIG. 7 is a circuit diagram showing a fifth embodiment of the present invention, FIG. 8 is a circuit diagram showing a choke coil used in place of the parallel resistors 8 to 10 in FIG. 7, and FIG. FIG. 10 is a circuit diagram showing a sixth embodiment of the present invention. FIG. 10 is an explanatory diagram showing a relationship between a projection lens in a general projection type display and an image projected on a screen.
Fig. 11 Projection tube and DY, C in general projection type display
FIG. 6 is a side view showing a positional relationship with Y. Description of reference numerals 3,14,38,49,52,69,76 …… Negative feedback amplifier, 4,5,6 …… Vertical deflection coil, 11,39,50,53,70,74 …… Transformer, 12, 35…
... Multiplier, 13,21 ... Filter, 16 ... Projection tube, 17 ... D
Y, 18 CY, 29, 30, 31… Horizontal deflection coil, 36… Maximum detector, 37… Changeover switch.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Sachi Ikeda 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture New Media Factory, Hitachi, Ltd. (72) Inventor Toshiyuki Kimoto 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa New Media Factory, Hitachi, Ltd.

Claims (2)

(57) [Claims] 1. Three projection tubes that emit monochromatic light of three primary colors, three projection tubes arranged one at each of the left and right ends of one projection tube, and each of the projection tubes A total of three projection lenses arranged on the front surface, and arranged on each projection tube to deflect the electron beam of each projection tube;
In a projection type display including a total of three sets of horizontal deflection coils and a total of three sets of vertical deflection coils, and a deflection circuit for supplying a deflection current to each deflection coil, a color for generating and outputting a color shift correction signal is provided. A shift correction signal generating means, and an amplifying means for amplifying and outputting the color shift correction signal from the color shift correction signal generating means, wherein the three sets of vertical deflection coils are connected in series with each other. The two vertical deflection coils corresponding to the two projection tubes located at the left and right ends of the two vertical deflection coils are not provided at the center of the vertical deflection coil corresponding to the projection tube, but from the connection point of the two sets of vertical deflection coils. The coupling point and the output of the amplifying means are coupled via a transformer so that correction currents corresponding to the output signals from the amplifying means are superimposed on the vertical deflection current and flow as currents of opposite polarities. Comprising a transformer coupling means, and the waveform of the correction current is, the color shift correction circuit of the projection type display, which is a waveform in which a sawtooth wave of the sawtooth wave and the vertical period of the horizontal period is obtained by multiplying. 2. A color shift correction circuit for a projection display according to claim 1, wherein said second color shift correction signal generating means generates and outputs a second color shift correction signal, and said second color shift correction signal generating means. A second amplifying means for amplifying and outputting the color shift correction signal from the shift correction signal generating means, wherein the three sets of horizontal deflection coils are connected in parallel with each other, and a projection located at the center of the three sets. Instead of the horizontal deflection coils corresponding to the tubes, two sets of horizontal deflection coils corresponding to the two projection tubes located at the left and right ends thereof are provided from the connection point of the two sets of horizontal deflection coils to the second amplifying means. Through a transformer between the junction and the output of the second amplifying means so that the second correction current corresponding to the output signal of Second transformer coupling means for coupling Provided, and the waveform of the second correction current, the color shift correction circuit of the projection type display, which is a parabolic shaped signal waveform of the horizontal period planarizing the horizontal blanking interval.