JPH02114788A - Color television camera - Google Patents

Abstract

PURPOSE:To suppress sufficiently a change in a centering state and a convergence state in a deflection system due to a change in ambient temperature by detecting a fluctuation of a centering voltage and a fluctuation of a convergence voltage from a deflection voltage respectively efficiently and feeding back the fluctuation negatively to control the deflection system. CONSTITUTION:A deflection output voltage from output terminals 10, 11 is given to a centering voltage detection section 27 in a negative feedback loop system relating to centering voltage fluctuation suppression and after a sawtooth wave voltage is eliminated by resistors 28a, 28b and a capacitor 29, only a DC voltage is extracted and inputted to a subtraction circuit. In the negative feedback loop system relating to convergence voltage fluctuation suppression, the deflection output voltage from the output terminals 10, 11 is inputted to a flux control voltage detection section 33, compared with a convergence control input voltage VP, amplified and the result of comparison is outputted as an error voltage. Then the voltage is inputted to a centering control voltage input terminal 9a of a positive deflection voltage generator 1 and a centering control voltage input terminal 9b of a negative deflection voltage generator 2.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a multi-tube color television camera using an electrostatic deflection type image pickup tube, and in particular to image difference suppression Ht in a deflection focusing system and a centering system. This is related to this.

[Requirement of the invention]

In a photoconductor image pickup tube such as a vidicon, an image signal is obtained by scanning a photoconductive target with an electron beam. For example, 70 to 250
The electron beam is deflected by applying a sawtooth deflection voltage of approximately Vpp.

By the way, at this time, in order to adjust the position of the image, a direct current centering voltage is superimposed on each pair of deflection electrodes in addition to the sawtooth waveform deflection voltage described above. Furthermore, since this deflection electrode also functions as a focusing electrode for the electron beam, a direct current voltage for electrostatic focusing is also applied in a superimposed manner, and the deflection electrodes facing each other are The average value of the voltages applied to each of them becomes the focusing voltage, and the difference between the positive polarity deflection potential and the negative polarity deflection potential at the center of the scanning period becomes the centering voltage.

Therefore, when the deflection voltage changes, the focusing voltage and centering voltage change, resulting in a decrease in resolution and registration accuracy, resulting in deterioration of image quality.

In the present invention, the above-mentioned fluctuations in the deflection voltage are detected, and thereby negative feedback control is applied to the deflection operation, thereby suppressing deterioration of image quality.

[Conventional technology]

As a deflection system for a color television camera using an electrostatic deflection type image pickup tube, a circuit configuration shown in FIG. 2 has been known.

In this figure 2, ■ is a positive polarity deflection voltage generator, 2 is a negative polarity deflection voltage generator, 3 is a positive polarity sawtooth wave generator,
4 is a negative polarity sawtooth wave generator, 5a and 5b are centering control voltage amplifiers with a gain of 1, 6a and 6b are focusing control voltage amplifiers with a gain of 1, and 7a and 7b are adders that generate the sawtooth wave voltage, the centering voltage, and the focusing voltage. 8a and 8b are centering control voltage input terminals, 9a and 9b are focusing control voltage input terminals, 10.11 is a deflection voltage output terminal, 12 is an inverting amplifier with a gain of 1, and 13 is an external centering Control voltage input terminal 14 is an external focusing control voltage input terminal, and 15 is an eccentric polar pair of the image pickup tube. Note that this deflection electrode pair 15 is composed of both horizontal and vertical deflection electrode pairs, and correspondingly both horizontal and vertical deflection circuit systems are required, but only the horizontal deflection system will be described here.

Positive polarity sawtooth wave generator 3 and negative polarity sawtooth wave generator 4
The sawtooth wave voltages generated by the two waveforms have the same amplitude, but the phases are reversed (that is, as time passes, the voltage of one wave increases and the voltage of the other waveform decreases).

The centering control voltage applied to the external centering control voltage input terminal 13 is directly applied to the positive polarity deflection voltage generator 1, and is applied to the negative polarity deflection voltage generator 2 via the inverting amplifier 12. , terminals 8a and 8b, respectively.
However, the focusing control voltage applied to the external focusing control voltage input terminal 14 is directly input to both terminals 9a and 9b.

The centering control voltage and focusing control voltage taken out as the outputs of the amplifiers 5a, 5b, 6a, and 6b are output from the positive polarity deflection voltage generator 3 and the negative polarity deflection voltage generator 4 by the adders 7a and 7b, respectively. It is added to the sawtooth voltage and applied via the respective output terminal 10.11 to the horizontal deflection electrode pair 15 of the image pickup tube.

Next, the operation of this conventional example will be explained with reference to FIG.

First, FIG. 3 fa) shows the positive polarity deflection voltage 16 applied to the deflection electrode pair 15 when the imaging operation by the image pickup tube is in a predetermined centering state and a predetermined focusing state.
The negative polarity deflection voltage 17 is shown, and 18 represents the intersection point of the positive polarity deflection voltage 16 and the negative polarity deflection voltage 17. As shown in the figure, the vertical axis represents the deflection output voltage level, and the horizontal axis represents time.

As is clear from this figure, in a predetermined operating state, each positive polarity deflection voltage 16 and negative polarity deflection voltage 17 have a sawtooth waveform.
The intersection 1st is located at the center of the horizontal scanning period T.

Since the deflection electric field generated by the deflection electrode pair 15 appears symmetrically from left to right (or up and down in the case of a vertical deflection electrode pair) with this intersection point 18 as the center, in this case, the deflection electric field from the center of the image pickup tube ) is scanned symmetrically, resulting in the correct centering condition, so the external centering control voltage may be zero at this time.

Also, the deflection voltage output level at this intersection 18 is
This is the average value of the positive polarity deflection voltage 16 and the negative polarity deflection voltage 17 including the DC voltage component, and this becomes the focused voltage component by the deflection electrode pair 15.

Next, in FIG. 3(b), an external centering control voltage of a predetermined value Vc is applied to the input terminal 13, and the positive polarity deflection voltage 16 increases by the voltage Vc to become the positive polarity deflection voltage 19. On the other hand, since the external centering control voltage is inverted by the inverting amplifier 12, the negative polarity deflection voltage 17 drops by this voltage Vc and becomes the negative polarity deflection voltage 20. As a result, the intersection 18 moves to 21. In this way, when only the external centering control voltage is applied, the rising and falling values of both deflection voltages are equal, so the voltage level at the intersection 21 is the same as at the intersection 18, and from the voltage Therefore, although the time at the intersection is shifted by a predetermined time ΔT depending on the application of the external centering control voltage, the focusing voltage by the deflection system does not change.

As mentioned above, the scanning of the target surface by the electron beam is performed symmetrically (or downwardly) with respect to this intersection, so when the external centering control voltage Vc is applied in this way, this A shift of T appears at a predetermined time corresponding to the voltage, and as a result, the scanning area of the target surface by the electron beam is shifted from its center, and the position of the image is thereby moved, so that centering control can be obtained. Become.

Further, in FIG. 3(c), a focusing control voltage of a predetermined value is applied to the input terminal 14, thereby increasing the positive polarity deflection voltage 16 to 22
, and the negative polarity deflection voltage 17 changes to 23. In this case, the intersection 18 becomes 2.
Move to 4. That is, as described above, since the external focusing control voltage is input to the positive polarity deflection voltage generator 1 and the negative polarity deflection voltage generator 2 with the same polarity, the positive polarity deflection voltage and the negative polarity deflection voltage due to this voltage are changes appear the same,
Therefore, at this time, only the potential at the point where these voltages intersect changes, and the time does not change.

This means that the new focusing voltage V due to the new crossing point 24
FA is given, therefore, although the focusing voltage changes, the centering position does not change, and after all, according to the application of this external focusing control voltage, only the focusing voltage by the deflection electrode pair 15 can be independently controlled. become.

As described above, this conventional example allows centering control and focusing control in the deflection system to be performed independently and arbitrarily, and can be applied to a multi-tube color television camera to ensure sufficient registration. can be kept in good condition and provide excellent image quality.

Note that related devices of this type include, for example,
The description in JP-A-57-150281 can be mentioned.

[Problem to be solved by the invention]

The above-mentioned conventional technology does not take into account changes in the characteristics of the sawtooth voltage generator due to changes in ambient temperature, etc., or changes in the characteristics of other circuit elements, and there is a problem in maintaining stable operation.

To explain this with reference to FIG. 4, assume that, for example, the DC component of the positive polarity deflection voltage 16 changes, and this DC component increases by ΔVn to become a positive polarity deflection voltage as shown at 25 in the figure.

In this case, the intersection will be moved from 18 to 26.

This means that the focusing voltage fluctuates by 80 degrees and the centering position also shifts in response to the time change ΔTn.In the end, in the conventional technology, when the DC component of the deflection voltage fluctuates, the centering position changes. Both focusing is affected, and this causes overlapping of images in a multi-tube color television camera, that is, a decrease in accuracy of registration and a decrease in resolution, resulting in a significant loss of image quality.

The purpose of the present invention is to sufficiently suppress changes in the centering state and focusing state of the deflection system due to changes in ambient temperature, etc.
To provide a color television camera which can easily obtain high image quality with good registration accuracy.

[Means to solve the problem]

According to the present invention, the above object is to efficiently separate and detect the fluctuations in the centering voltage and the fluctuations in the focusing voltage from the deflection voltage, and to provide negative feedback to the control in the deflection system based on the detection results. This is achieved by

FIG. 5 is a diagram for explaining the present invention in detail.
1 shows the method of detecting the variation in the centering voltage from the deflection voltage, which is adopted in the present invention, Tbl in the same figure shows the method of detecting the variation in the focusing voltage from the deflection voltage, and FIG. 1 and 2 respectively show other methods of detecting fluctuations in the focusing voltage from the deflection voltage.

Now, the positive polarity deflection output voltage appearing at the output terminal 10 is expressed as ■(
++D, the negative polarity deflection output voltage appearing at the output terminal 11 is V(-). Then, V (+lD = e(+l + Vc+ Vy+
Vn(+)"""(1)V(-)D = e (-1 V, +V, 10V, -2......(2) Here, e
(4): Positive polarity sawtooth wave voltage appearing at the output terminal 10 e(-): Negative polarity sawtooth wave voltage appearing at the output terminal 11 c: Centering control voltage VF: Focusing control voltage V n (.): Positive polarity DC voltage variation VnL-) generated within the deflection voltage generator: This is the DC voltage variation generated within the negative polarity deflection voltage generator.

Therefore, first of all, in FIG. 5 1a), 27 is a centering voltage detection section, resistors 28a, 28b, and capacitor 2.
9. Resistors 30a, 30b, and amplifiers 31a, 31b
It consists of

The resistors 28a and 28b serve to reduce the influence on the deflection voltage generator 1.2, and in order to reduce their own power loss, resistors with a high resistance value of, for example, about 2 MΩ are used.

The capacitor 29 functions to cancel out the sawtooth voltage of positive polarity and the sawtooth voltage of negative polarity, and for this reason, the capacitance value is selected to exhibit a sufficiently low impedance with respect to the deflection scanning frequency, and This ensures that the sawtooth voltage generated in the circuit is suppressed to a negligible level.

The resistors 30a and 30b are for buffering purposes, and their resistance values are selected taking into consideration the influence on the circuits that will be connected later, for example, 1.
A resistance value of 00Ω is used. Note that the resistors 30a and 30b are not necessarily necessary, and may be unnecessary in some cases.

The deflection output voltage of the output terminal 10.11 is first applied to the resistor 28a.
, 28b and are short-circuited at the capacitor 29. Since the sawtooth wave voltage components in the deflection output voltage supplied from the output terminals 10 and 11 have inverted phases, they cancel each other out through the capacitor 29. Wave voltage is not generated, only the DC voltage component is generated.

The amplifiers 31a and 31b function as buffer amplifiers with a gain of 1, and their input voltages are
If (-)D is V (41n-V c + VF + Vn D)
・−・・−・(3)■8−) D −V. 10V F
+V 1161 (4) The outputs of these amplifiers 31a and 31b are sent to the output terminal 3 via a subtraction circuit.
Appears as the output of 2.

Therefore, if the output voltage of this output terminal 32 is 3□, then V 3 □ - Equation (3) - Equation (4) -" (+l II
V (-) D-2V(+V, , (+, Vn(-1
``・+・(5) Here, the equation (5) shows that the output voltage ■3t of the output terminal 32 is the centering control voltage VC applied from the outside and the DC voltage generated by the deflection voltage generator of each polarity. Effect of variation on centering control bone (V n (.

, −■ゎ, −, ).

Therefore, by comparing this output voltage V3□ (formula (5)) with the centering control voltage VC and feeding back the error voltage negatively to the centering control voltage input of each polarity, the centering fluctuation can be suppressed.

Next, FIG. 5 (bl shows an example of the focused voltage detection section 33, which is composed of three resistors 34a, 34b, and 35).

Resistors 34a, 34. b, Fig. 5 (al resistance 2
It is provided to perform the same function as 8.
Again, from the standpoint of loss, a high resistance value of about 2 MΩ is used, and it operates as a voltage adder.

The resistor 35 is for buffering, and similarly to the resistors 30a and 30b, a resistor 35 having a resistance value of about 100Ω is used.

Note that this resistor 35 is also not necessarily required.

The deflection output voltage from output terminal 10.11 is connected to resistor 34,
They are directly added at the connection point between a, 34b and the resistor 35, and as a result, the positive and negative sawtooth wave voltages whose phases are inverted are canceled out, and only the DC voltage component is extracted. However,
In this case, unlike the above-mentioned centering control, since direct addition is performed without providing a capacitor, the DC component is also added as is, so the output voltage V36 of the output terminal 36 is The above equation (3) and (4
) is the addition of the expressions. That is, V36=(Formula 31-1-(Formula 41-VF + 1/2 (Vnto +V11+-
1)...(6) Equation (6) shows that the output voltage V36 is the external focusing control voltage VF applied to the deflection control system and the DC voltage generated within the deflection voltage generator of each polarity. Effect of variation on focusing voltage Bone 1/
2(V-(., 10v., -,).

Therefore, by comparing the output voltage V36 of this output terminal 36 with the focusing control voltage VF and feeding back the error voltage negatively to the focusing control voltage input of the deflection voltage generator of each polarity, it is possible to suppress fluctuations in the focusing state. .

In addition, FIG. 5 (C1 shows another example of the focused voltage detection section, and this detection section is represented by 37, and is connected to four resistors 38a, 38b, 39a, 39b and a capacitor 41. It is equipped with an output terminal 40.

In this focused voltage detection section 37, instead of simply adding the positive polarity and negative polarity deflection output voltages from the output terminals 10.11 using a resistor, first, only the sawtooth wave voltage at the capacitor 41 is added and canceled. After that, a DC voltage is added via resistors 39a and 39b.

Therefore, the same voltage as the output terminal 36 in FIG. 5 (bl) can be obtained at the output terminal 41 by this focusing voltage detection section 37, and the focusing state can be maintained stably.

As described above, according to the present invention, the large-amplitude sawtooth voltages included in the positive polarity output voltage and the negative polarity deflection output voltage cancel each other out, so that the centering voltage included in the deflection output voltage Since it is possible to reliably detect the focusing voltage and the focusing voltage, it is easy to apply negative feedback to the deflection system using this voltage, and it is possible to maintain high precision registration in a multi-tube color television camera, resulting in high quality images. can be easily obtained.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS A color television camera according to the present invention will be explained in detail below using illustrated embodiments.

FIG. 1 shows an embodiment of the present invention. This embodiment has two negative feedback loops, namely, a negative feedback loop including a centering voltage detection section 27 for suppressing centering voltage fluctuations, and a focusing voltage fluctuation loop. A negative feedback loop including a focusing control voltage detecting section 33 is provided to suppress the negative feedback loop.

It goes without saying that embodiments of the present invention may include only one of these negative feedback loops, if necessary.

First, in the negative feedback loop system related to centering voltage fluctuation suppression, the deflection output voltage from the output terminal 10.11 is introduced into the centering voltage detection section 27, where the resistor 28a
, 28b and the capacitor 29, the resistors 30a, 30b and the amplifiers 31a, 31
Only the DC voltage is extracted via the differential amplifier 42 and the resistors 43a, 43b, 43c, 43d.
is input to a subtraction circuit consisting of.

The output of this subtraction circuit is taken out from the output of the differential amplifier 42, and is supplied to the inverting input side of a differential amplifier 44 having a relatively large gain GC, which constitutes a comparison circuit, and is supplied to the non-inverting input side of the differential amplifier 44. side, the centering control voltage Vc supplied from the input terminal 13 is compared and amplified, and the error voltage that is the result of this comparison is applied to the buffer gain 1.
The signal is outputted via the amplifier 45.

The output voltage of this amplifier 45 is directly inputted to the focusing control voltage input terminal 9a of the positive polarity deflection voltage generator 1 on the one hand, and the focusing control voltage of the negative polarity deflection voltage generator 2 via the inverting amplifier 12 on the other hand. It is input to the input terminal 9b.

Therefore, this forms a negative feedback loop regarding the centering voltage, and as will be explained in more detail later, it is possible to suppress fluctuations in the centering of the image and greatly improve the image quality.

In addition, in the negative feedback loop system related to focusing voltage fluctuation suppression,
The deflection output voltage from the output terminal 10.11 is input to the focusing control voltage detection section 33, and the voltage that is added by the resistors 34a and 34b to only the DC voltage component is further passed through the buffer resistor 35 to the high gain voltage detector 33. Differential amplifier 46 with GF
is supplied to the inverting input of the differential amplifier 46, and is thereby compared with the focusing control input terminal VF which is supplied from the external focusing control voltage input terminal 14 to the non-inverting input of the differential amplifier 46, and is amplified, and the result of this comparison is used as an error voltage. Output.

The output voltage of the differential amplifier 46 is supplied to the centering control voltage input terminal 9a of the positive polarity deflection voltage generator 1 and the centering control voltage input terminal 9b of the negative polarity deflection voltage generator 2, respectively. A negative feedback loop system for suppressing focusing voltage fluctuations is constructed, and as a result, focusing voltage fluctuations can be sufficiently suppressed as described later.

Next, the operation of the embodiment shown in FIG. 1 will be explained with reference to the circuit functional block diagram shown in FIG.

FIG. 6 shows the two systems of negative feedback loops described above, and the gains of the differential amplifiers 44 and 46 are set to Gc.
and GF, the DC voltage bone in the deflection output voltage appearing at the deflection output terminal 10.11. ,. 1, VD+-1 is Vn(+1...(7) VO(-1= Gc [Vc (
VO(-) VO(-1) Ko +GF
[VF (VO(+1+VO(-1))] +V
fi (-1...(8) where, ■,: Centering control voltage ■F: Focusing control voltage Vfil+l: Positive polarity DC voltage variation generated within the deflection voltage generator vfi, -,: Negative polarity From these equations (7) and (8), the DC voltage fluctuations generated within the polarization voltage generator are calculated as (Vo(+)+V).
), VO(+1=GC[VC(Vll++1 VO(-1
)] +GF [VF (VO(・)
+VO (-1) ] +(V o (・l +v
,,~))=2GF VF / (1+2CF)+, so (V, (.r + Vn+-+) / (1+ 2
GF ) (■.〈ya)'-Vfi+-1>#V
F...0υ...(9) (V, 1(4) V-+-+) #Vc
−・”02rOn the other hand, from equations (7) and (8), (V
o (-1V G (-1) is calculated as follows: (■0(・) VO(-1) = 2GCVC/ (1+2GC)+ (Vn+-, + V11+-1)/ (1+2GC)
・・・・・・α0) Here GF and G. can be made sufficiently large by the gain of the differential amplifier, and GF1・GC These 0υ equations and 0 equations are the focusing voltage (=V., 4. → -V n t-,) and the centering voltage (-V7°) V n (-)) is kept independent of DC voltage fluctuations in the output voltages of the positive polarity deflection voltage generator 3 and the negative polarity deflection voltage generator 4, which are
External control voltage ■, and ■, respectively. Therefore, according to this example, in a multi-tube color television camera using an electrostatic deflection/electrostatic focusing type image pickup tube, the centering state and the focusing state can be sufficiently maintained. It can be seen that stable and highly accurate registration can be easily obtained.

In addition, although the above embodiment describes a case in which both the negative feedback loop in the centering voltage control system and the negative feedback loop in the focusing voltage control system are applied, an embodiment in which only one of these is applied is also possible. Needless to say.

Furthermore, in the above embodiments, the application of the present invention to a horizontal deflection system was mainly explained, but it goes without saying that the present invention is similarly applicable to a vertical deflection system. Needless to say, it's a good thing.

〔Effect of the invention〕

According to the present invention, in a multi-tube color television camera using an electrostatic deflection/electrostatic focusing type image pickup tube, centering deviation due to DC voltage fluctuation in the deflection circuit system,
Since defocusing can be sufficiently suppressed, it is possible to easily provide a color television digital camera without the risk of deterioration of image quality due to a decrease in registration accuracy or a decrease in resolution.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing an embodiment of a color television camera according to the present invention, Fig. 2 is a circuit diagram showing a conventional example of a color television camera, and Fig. 3 (al, Tb), fc).
are waveform diagrams for explaining the operation, Figure 4 is a waveform diagram explaining the influence of DC voltage fluctuations in the deflection system, and Figure 5 is a waveform diagram for explaining the influence of DC voltage fluctuations in the deflection system.
, fbl, and (C) are circuit diagrams explaining the present invention in detail, and FIG. 6 is a functional block diagram of an embodiment of the present invention. 1... Positive polarity deflection voltage generator, 2...
Negative polarity deflection voltage generator, 3...Positive polarity sawtooth wave generator, 4...Negative polarity sawtooth wave generator, 5
a, 5b... Centering control voltage amplifier with a gain of 1, 6a, 6b... Focusing control voltage amplifier with a gain of 1, 7a, 7b... Adder, 8a, 8b...・
...Centering control voltage input terminal, 9a, 9b.
...Focusing control voltage input terminal, 10.11...
... Deflection voltage output terminal, 12 ... Inverting amplifier with gain of 1, 13 ... External centering control voltage input terminal, 14 ... External focusing control voltage input terminal,
15... Deflection electrode of image pickup tube, 27...
Centering voltage detection unit, 33...Focusing control voltage detection unit, 44...Differential amplifier having a relatively large gain GC, 45... constituting a comparison circuit.
・An amplifier with a gain of 1 for buffering.

Claims (1)

[Claims] 1. A plurality of electrostatic deflection type image pickup tubes are used, and a deflection voltage having an inverted phase is applied to one pair of deflection electrodes and the other of each of the plurality of image pickup tubes. A multi-tube color television camera that performs deflection includes an adder circuit means for adding the deflection voltages applied to one and the other of the pair of deflection electrodes of each image pickup tube, and the adder circuit means. A color television set comprising: comparison circuit means for generating an error voltage by comparing the output with a reference voltage; and the output of the comparison circuit means is configured to be negatively fed back to the focusing control system of each image pickup tube. john camera. 2. A method that uses a plurality of electrostatic deflection type image pickup tubes and performs deflection by applying a deflection voltage with an inverted phase to one pair of deflection electrodes of each of the plurality of image pickup tubes. In a tube-type color television camera, an AC coupling circuit means for coupling the deflection voltages applied to one and the other of the pair of deflection electrodes of each of the image pickup tubes to cancel out the alternating current components; and the AC coupling circuit. DC component detection circuit means for independently extracting a DC component from each deflection voltage whose AC component has been canceled by the means; arithmetic circuit means for subtracting the DC component of each deflection voltage extracted by the DC component detection circuit means; Comparison circuit means for generating an error voltage by comparing the output of the arithmetic circuit means with a reference voltage is provided, and the output of the comparison circuit means is configured to be negatively fed back to the centering control system of each image pickup tube. Color television camera.