JPH0244191B2 - BIIMU * PENETOREESHONINKYOKUSENKANYOKODENATSUKARAASUITSUCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high voltage color switch for a beam penetration cathode ray tube, and more particularly to a high voltage color switch for a beam penetration cathode ray tube.
The present invention relates to a color switch having a first mode for sequential display of color information and a second mode for random display of color information.

Beam penetration color CRTs (cathode ray tubes), as they are commonly known, are display devices having a fluorescent plate on which images or text can be drawn. One or more phosphor layers on the inner surface of the phosphor plate can be selected to emit visible light at most desired wavelengths. If two layers of phosphor are provided on the inner surface of the phosphor plate, two or more different colors can be created by varying the depth of penetration of the electron beam into the phosphor layer. .
Since the electron beam emitted by the cathode in the neck of the CRT impinges on the phosphor layer at a speed that is primarily influenced by the voltage level of the accelerating cathode, changes in the voltage level applied to the accelerating anode affect the phosphor layer of the two layers. This causes a corresponding change in the proportion of light emitted by the body layers. In other words, a penetration CRT has two layers of phosphors that emit different types of light.
Up to four colors can be displayed by changing the DC voltage level applied to the accelerating anode placed near the front of the CRT.

A significant limitation encountered in the use of penetration CRTs is related to the length of reset time between successive exposure periods. Since the DC voltage level of the accelerating anode must be changed during the reset time, the length of the reset time is primarily determined by the capacitance of the accelerating anode. Because the accelerating anode has a relatively large size and therefore an inherently large capacitance, it accumulates a significant amount of charge during the imaging time. Of course, the addition of capacitors, especially large capacitors often used in high voltage power supplies, increases the capacitance in the high voltage circuit and further lengthens the reset time. As this charge increases or decreases as the accelerating anode voltage level changes, the reset time separating successive imaging times is related to the charge/discharge rate determined by the total capacitance seen by the high voltage power supply.

Other limitations found in known color switches used in beam penetration CRTs are:
It is related to the switching order of colors displayed on a CRT fluorescent plate. 3 to 2-layer penetration CRT
Although it is possible to display a color or four distinct colors, some high voltage color switches must operate in a specific order. In other words, the high voltage color switch applies one preselected voltage level to the accelerating anode during successive imaging times. That is, the anode voltage is, for example, from 10kV to
to 14kV, from 14kV to 18kV and finally to 18kV
to the first 10kV. At each successive imaging time, the image or character written by the electron beam appears only in a color corresponding to the voltage level applied to the accelerating anode. If an image or character is to appear in one color, say red, during a particular rendering time, the next time the red color information after the completion of that rendering time, the high voltage color switch will change its preselected voltage level. It cannot appear until the imaging time when a voltage level corresponding to the red color is applied to the accelerating electrode again.

Reference may be made to U.S. Pat.
There is number 3906333. This patent specification describes a switching high voltage power supply for use in beam penetration type cathode ray tubes.
In this power supply, the secondary winding of a high voltage step-up transformer is connected in series with the accelerating anode of the cathode ray tube. The primary winding of this transformer is connected to ground through a capacitor to generate a DC voltage level. The voltage across this capacitor is applied to the regulation input of the baseline DC high voltage power supply. The color switching power supply of the present invention is an improvement on that described in this patent.

Other patents to refer to include the May 30, 1975 patent titled “Switch-operated High Voltage Power Supply System.”
There is a date US Pat. No. 4,092,556. This patent describes a high voltage power supply for fast switching of high voltage applied to the anode of a beam penetration type color cathode ray tube. The energy for fast transitions between voltage levels is stored in two inductors, one for the upward transition and one for the downward transition. When it is desired to change the voltage applied to the cathode ray tube, the appropriate one of the storage inductors is connected to the anode through a control switch to rapidly change the voltage applied to the anode. The voltage increases until it reaches the desired upper voltage corresponding to the desired color, at which point the switch is turned off and the storage inductor is recharged. Once a predetermined voltage level is reached, the high voltage power supply maintains the anode at that voltage level by a tracking action.

An object of the present invention is to provide a beam penetration cathode ray system in which the rendering times of various colors are switched in a first mode in a predetermined switching order, and in the second mode the rendering times can be randomly switched to reveal a desired color. The purpose of the present invention is to provide a dual mode high voltage color switch for tubes.

According to the invention, beam penetration
A dual mode high voltage color switch for a CRT includes a high voltage power supply connected to the accelerating anode of the CRT through the secondary winding of a transformer. The primary winding of the transformer is connected to the output of the drive circuit through a switch. In the first of the two modes (sequential display), the feedback path detects the DC voltage level related to the dynamic drive waveform applied to the accelerating anode of the CRT through the transformer and drives the DC voltage level to zero. do. A suitable DC voltage is returned to the CRT by adjusting the reference input to the high voltage power supply,
This changes the level of high voltage output applied to the accelerating anode of the CRT. 2nd mode (random/
display), the above feedback path is deactivated and the beam penetration
The CRT can be randomly switched to display a desired non-base color during a rendering time not exceeding a predetermined duration. Also, in this second mode, when the magnetizing current in the transformer is reset after each imaging time, a path for returning energy is created through a pair of diodes.

By using the dual mode color switch of the present invention, color information can be displayed on a beam penetration CRT in two modes that can be switched by a pair of switches under the control of a color processor.

CRT for beam penetration according to the invention
For the above and other purposes of high voltage color switch,
The features and advantages will become clearer in the following description of preferred embodiments thereof with reference to the drawings.

First, referring to FIG. 1, a dual mode beam penetration CRT according to the present invention is shown.
One embodiment of a color switch is shown. A high voltage power supply 10 of known type is provided and connected by conductors 12 to one side of a secondary winding 14 of a transformer 16. The other side of the secondary winding 14 is connected by a conductor 18 through a damping resistor 20 to a beam penetration CRT (cathode ray tube) 22. As is well known, the CRT 22 includes an anode 24 to which a high voltage is applied which directs a beam of electrons emitted by a cathode (not shown) located in the neck of the tube to a cathode 24 located in front of the CRT 22. Accelerate toward the fluorescent plate 25 located.
The interior surface of the phosphor plate 25 is typically provided with at least two layers of phosphor, each layer emitting a different wavelength or wavelength of light in response to stimulation by the electron beam. For purposes of explaining the invention, it will be assumed that the inner surface of the phosphor plate 25 is provided with one green phosphor layer and one red phosphor layer; It will be appreciated that a light body may be used. Additionally, more than two phosphor layers may be used if more than about four colors are to be displayed on the phosphor plate 25. Anode 24 is CRT2
The CRT 22 is made of a highly conductive material placed around the periphery of the CRT 22 near the front of the CRT 22. Because of its large size, anode 24 has a relatively large capacitance and is shown as a capacitor in FIG. 1 for ease of illustration.

The transformer 16 also has a primary winding 26, and the turns ratio of the primary winding 26 to the secondary winding 14 is tailored to the required voltage swing characteristics, as is well known. For example, if the turns ratio is 1:1000, a 4V change in the voltage across the primary winding 26 will cause the secondary winding 14 to change.
The voltage across it will change by 4kV.
This voltage swing, if symmetrical with respect to ground potential, would result in a swing from -2kV to +2kV in the secondary winding. In this embodiment, one end of the primary winding 26 is connected to ground, and the other end is connected to the conductor 26.
8 to one side of the switch 30. The other side of the switch 30 is connected by a conductor 32 to the output of a drive circuit 34. The input to drive circuit 34 is essentially an analog signal having discrete levels, each level specifying a separate color as will be explained in more detail below.

One feature of the invention is that in its second mode, the color switch includes a feedback path from transformer 16 to a low voltage power supply for drive circuit 34;
Energy can be returned during the reset time. The feedback path includes a pair of diodes 42 and 44 connected in opposite polarity between conductor 28 and a positive potential terminal 46 and a negative potential terminal 48 of the low voltage power supply. A low voltage power supply (not shown) is of well known type and provides positive and negative potentials to dynamic circuit 34 through terminals 46 and 48, respectively. Typical voltage levels applied to drive circuit 34 are +25V DC to -25V DC
is within the range of The anode of the diode 42 is the conductor 2
8 and its cathode is connected to terminal 46, while the cathode of diode 44 is connected to conductor 28 and its anode to terminal 48.

In the first mode, the dual-mode color switch according to the present invention switches in a predetermined switching order through a series of color extraction times and uses high voltage to accommodate duty cycle variations during a particular color extraction time. A DC feedback loop is provided to adjust the output voltage level from power supply 10. The DC feedback loop includes a resistor 50 connected to conductor 28 on one side. The other side of resistor 50 is connected to capacitor 5 by conductor 52.
4 and the other side of this capacitor is connected to ground. Resistor 50 and capacitor 54 act as a low pass filter that integrates the voltage waveform on conductor 28 to primary winding 26 of transformer 16. The operational amplifier 56 has one input terminal connected to the conducting wire 52 in order to detect the DC component of the signal waveform applied to the primary winding 26 . The other input end is connected to ground. The output terminal of the operational amplifier 56 is connected to the drive circuit 34 via a conductor 58.
is connected to the input end of the

A resistor 60 is connected to one side of the capacitor 64 by a conductor 37 on one side and by a conductor 62 on the other side so that the DC voltage level output from the high voltage power supply 10 can be varied. The other side of capacitor 64 is connected to ground. Conductor 6
2 is also connected to the reference input terminal of the high voltage power supply 10. Resistor 60 and capacitor 64 integrate the signal waveform applied to drive circuit 34 to form a DC voltage level that proportionally changes the output voltage level from high voltage power supply 10. A switch 66 is connected between conductor 62 and ground and is controlled by color processor 36 and serves to disable the integration function in the second mode.

Also, as a feature of the invention, means are provided for creating a focus voltage that dynamically tracks the high voltage level applied to the anode. In the preferred embodiment, this means includes a first potentiometer 70 connected to the output of the high voltage power supply 10. This output is separate from the output used to supply the anode voltage and has a DC voltage level lower than the anode voltage. The first potentiometer 70 is connected to the second potentiometer 74 through a winding 72 that is added to the transformer 16 . A potentiometer 74 is used to dynamically adjust the voltage applied to a focusing electrode 76 located near the front of the electron gun (not shown). Typically, the focusing voltage level applied to the focusing electrode is a level of a fixed percentage of the voltage applied to the anode 24. An advantage of this focusing system is that it requires a minimum of additional components, namely two potentiometers 70,
74 and an additional winding of the transformer 16. The first potentiometer 70 adjusts the DC baseline voltage level, while the second potentiometer 74 adjusts the dynamic output to the level applied to the focusing electrode 76.

Referring now to FIG. 2, the manner in which the dual mode color switch according to the present invention operates in the first mode (sequential mode) will now be described.
In this first mode, the color switch performs four steps by applying a step voltage waveform to the accelerating anode 24.
The rendering time for each color is switched in a predetermined switching order. In other words, the voltage level applied to the anode 24 goes from 10kV to 12kV, from 12kV to 16kV,
It changes from 16kV to 18kV and finally returns from 18kV to the initial 10kV. In the anode voltage waveform of the duty cycle shown in the left half of Fig. 2,
Since each imaging time is approximately equal in length, the overall DC voltage level of this waveform does not change with time.

However, in the waveform shown in the right half of FIG. 2, one of the rendering times is longer than the others. In other words, an asymmetric voltage waveform is applied to the anode 24,
This asymmetric voltage waveform has an average DC voltage level. Since switch 66 is open in this mode, resistor 60 and capacitor 64, drive circuit 3
It acts as a low pass filter that integrates the voltage waveform applied to 4. This voltage level is applied to the reference input terminal of high voltage power supply 10 to adjust the high voltage output level on conductor 12. Switch 30 is
While the dual mode color switch is in this first mode, it remains in the closed position.

Referring now to FIG. 3, the manner in which the dual mode color switch according to the present invention operates in the second mode (random access mode) will now be described. In this second mode, the color switch can switch the rendering time to display any of the available colors, but the description will be given for switching the rendering time to display yellow and red. In this mode, a baseline color such as orange is normally used to display information on the fluorescent plate 25 of the CRT 22, but if necessary,
It is particularly suitable, for example, if it is desired to display certain information on a phosphor in a non-baseline color, such as yellow or red, in order to emphasize that information.

Referring to the left half of FIG. 3, a process is shown in which the rendering time is changed to appear yellow. At time t ₀ a binary signal from an external signal source indicates that the yellow rendering time is to begin. Switch 66 closes in response to a control signal from color processor 36, bringing the DC voltage across capacitor 64 to ground potential. Switch 30 remains closed during this brewing period.
At time t ₁ when the reset is initiated, switch 30 opens in response to a control signal from color processor 36 and transfers power from drive circuit 34 to primary winding 26 of transformer 16.
interrupting the flow of current to. The magnetic flux within the transformer 16 begins to decrease toward zero, and a voltage is induced accordingly. Depending on the polarity of the primary current, one of the two diodes 42 or 44 begins to conduct. A feedback path is provided from the transformer to the low voltage power supply through the conduction diode. Also,
At time _t1 , the output voltage of the drive circuit 34 returns to its original level according to the voltage waveform from the color processor 36, and the anode voltage is at a voltage level lower than that of the baseline color, in this example.
Changes to 10kV. By time _t2 , the magnetizing current in transformer 20 has completely disappeared, and by time _t4 , at the end of the reset time, switch 30 is closed, allowing current to flow from drive circuit 34 to secondary winding 26. Form a route. Accordingly, the voltage level on the anode 24 is returned to the voltage level of 14 kV for the baseline color, orange in this example.

To take advantage of the dual mode color switch in the second mode, it is desirable to match the characteristics of transformer 16 to the longest rendering time of any one non-baseline color. This is because the voltage applied to the primary winding 26 by the drive circuit 34 increases the magnetic flux density within the iron core, but if this magnetic flux density reaches the saturation magnetic flux density, the level of the high voltage applied to the anode 24 drops. ,with this
This is because the color appearing on the fluorescent plate 25 of the CRT 22 changes. As will be appreciated by those skilled in the art, in order to increase the imaging time, larger transformers with higher saturation flux atomization must be used.
If a short imaging time is acceptable, a small transformer with a low saturation magnetic flux density can be used, and the drive circuit can also be small.

Next, referring to the right half of FIG. 3, there is shown a case where a voltage of 10 kV level is applied to the anode 24 in a pulsed manner for the red color rendering time. Time t ₅
Then, the color processor 36 gives a pulse to the drive circuit 34 in response to an external binary signal command.
This pulse is amplified by the drive circuit 34 and applied to the primary winding 26. By time t ₆ , the red rendering time has passed its maximum time and transformer 1
The magnetic flux density within 6 is close to the saturation magnetic flux density.
The reset time is initiated by the opening of switch 30 by a signal from color processor 36. As the magnetic flux decreases towards zero, a pulsed voltage of opposite polarity is induced in the transformer. diode 4
2 conducts, through which a feedback path from the transformer to the low-voltage power supply is formed. lastly,
By time t ₇ , when the anode voltage has reached a voltage level of 14 kV corresponding to the baseline color, the switch 30 is closed by a signal from the color processor 36 and the output of the drive circuit 34 and the primary winding 26 are connected. form a current path between the two.

While the invention has been illustrated and described with respect to preferred embodiments thereof, those skilled in the art will recognize that various changes may be made in form and detail without departing from the scope of the invention.

[Brief explanation of drawings]

FIG. 1 shows in block form a dual mode color switch for a beam penetration CRT according to the present invention. FIG. 2 is a diagram showing waveforms at various points in the embodiment of FIG. 1 in a first mode of the color switch. Figure 3 is the first
FIG. 6 is a diagram showing waveforms at various points in the illustrated embodiment in a second mode of the color switch; 10...High voltage power supply, 14...Secondary winding, 16
...Transformer, 20...Damping resistor, 22...
Beam penetration cathode ray tube (CRT), 2
4... Accelerating anode, 25... Fluorescent plate, 26... Primary winding, 30... Switch, 34... Drive circuit, 3
6...Color processor, 42, 44...Diode, 46, 48...Low voltage power supply terminal, 50...
Resistor, 54... Capacitor, 56... Operational amplifier, 60... Resistor, 64... Capacitor, 66...
...Switch, 72...Additional winding, 70, 74...
Potentiometer, 76...Focusing electrode.

Claims (1)

[Scope of Claims] 1. A first mode in which the rendering times of various colors are switched in a predetermined switching order, and a first mode in which the rendering times are changed randomly so that the baseline color is always displayed but a desired color is displayed. a high voltage color switch for a beam penetration cathode ray tube having a switchable second mode; a high voltage power supply means having an output of a voltage level; transformer means connected between an output of the high voltage power supply means and the cathode ray tube; and receiving at an input an input voltage having a color specifying waveform; drive circuit means for amplifying said transformer means to provide the voltage swing necessary to produce the desired color during imaging; and said drive circuit means having an open position and a closed position. first switch means connected between the output of the drive circuit means and the transformer means; and an integrator connected between the input of the drive circuit means and a terminal of the reference input of the high voltage power supply means. a second means connected to said integrating means and used to stop the integrating function in said second mode;
and switching means, in the first mode, the input voltage is applied as a DC voltage to the reference input terminal of the high voltage power supply means through the integrating means, so that the high voltage output level thereof can be adjusted accordingly. such that said second switch means are open and at the same time said first switch means are closed such that said input voltage can be applied to said transformer means via said drive circuit means, while said second A high voltage collar for a beam penetration cathode ray tube, characterized in that in the mode, the second switch means is closed to stop the integrating function of the integrating means, thereby allowing random switching of the exposure time. Switch.