JPS5826614B2 - Yuuki Film Tartar Getstogata Sou Sahen Kankan Youmo Do Kirikaesouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an operation mode switching device for a two-electron gun type scan conversion tube using an organic film target.

The outline of the two-electron gun type scan converter tube using the organic film target is described in, for example, Nikkei Electronics, No. 19747-15 (A86.)j, but its operation will be briefly described here. .

This is characterized in that the target part is composed of a metal mesh and an organic film, and the organic film has a thickness of 2 to 3 μm.
It consists of a polyimide film of m.

This polyimide film can be obtained by applying a liquid polyimide film to one side of a metal mesh and curing it at a certain high temperature.

Compared to conventional silicon targets, this organic film target has the advantage of being very inexpensive.

As shown in Figure 1, the secondary electron emissivity characteristics of such a polyimide film are such that when the first crossover voltage is 60 to 70V,
It shows a higher value than cases such as S i02.

A two-electron gun type scanning conversion tube using this organic film as a target has two electron guns facing each other with the organic film target T in the middle, as shown in FIG.

The image signal is applied to the first grid G1 of the writing electron gun, and the electron beam is modulated and scanned to accumulate and form a two-dimensional charge pattern on the organic film surface.

Next, based on this charge image, a potential image of an electric field protruding from the holes in the mesh controls and modulates the readout beam scanning the mesh side.

A controlled electron flow is extracted from the mesh electrode as an output signal.

In the erase mode, the target voltage is set to 100 V, which is the range of δ>1 in FIG. 1, and in the write mode, the target voltage is set to 30 V, which is the range of δ<1.

In the erase mode, the unmodulated electron beam on the write side scans the organic film surface by several frames of standard television scanning.

In this case, since δ>1, all of the accumulated charges on the organic film surface are released, resulting in a state where there is no charge pattern.

In one writing mode, a writing electron beam modulated by a video signal scans the organic film surface.

In this case, since δ<1, negative charges proportional to the electron beam are accumulated, and a charge pattern corresponding to the video signal is formed.

During readout, by scanning the target on the readout side with an unmodulated beam, it is possible to extract a signal output proportional to the charge pattern accumulated on the surface of the writing individual organic film.

The present invention provides a mode switching device most suitable for a two-electron gun type scan conversion tube using an organic film target as described above.

That is, in the erase mode, the target voltage is set to 100V, and in the write mode, the target voltage is set to 30V.

Generally, it is best to use a relay for such switching, but if the erasing time is to be made very short, the access time of the relay becomes a problem.

Therefore, the present invention provides a transistor-type switching device that can shorten the erasing time by f minutes, and that also better matches the characteristics of the organic film target.

Here, the erasing operation of the organic film target type two-electron gun type scan converter tube will be explained once again with reference to FIG.

In the write mode, when the target voltage is 30 V, the charge image formed on the organic film surface has a maximum potential of -30 Vt on the polyimide surface with respect to the target.

When the erase mode is set after such a state, the polyimide surface potential becomes 100V, and the potential difference with the previously formed charge image becomes (-30V) - (-100V) = 70V, which is the same as in Figure 1. In the graph of secondary electron emissivity, δ〉1
It is found that the data is within the range of □, and a predetermined erasing operation is performed.

However, if we consider a case where the switching time of the target voltage, especially the time to switch from 30V to 100V, is long, as shown in ■ in Figure 3, the target voltage changes instantaneously from 30V to 70V, and then 100Vt
Let's assume that it changes gradually.

That is, when the erase beam current starts flowing when the target voltage is 70V, the polyimide surface potential is -70V when the target voltage is 70V, and therefore the potential difference with the previously formed charge image is (-30V). )-(-70
V) 40V.

This is in the range δ<1. This state is in write mode, so the polyide surface is storing charge rather than releasing it, and it is stored at 1 to -70V.

Therefore, even if the target voltage becomes 100V after this, the potential difference on the surface of the polyide is (-70v) - (
-100v)=30v, which is still 11 in the range of δ<1.

Therefore, a charge equal to -100V is accumulated on the surface of the polyimide, and what was intended to be an erase operation ends up being an accumulation of charges.

In such a state, normal function can no longer be expected.

For the reasons mentioned above, it is necessary for the switching device to have a short transition time when changing from write mode to erase mode.

The present invention fully satisfies these conditions, and at the same time, can lower the impedance of the target in the erase mode, allowing the target current in the erase mode to be much higher than the target current in the write mode. , it is possible to flow efficiently and the erasing operation can be carried out reliably.

Next, a description will be given with reference to FIG. 4, which is an embodiment of the present invention.

In the figure, TR1 and TR2 are transistors for mode switching, and a control signal is applied to the base of transistor TR1 such that a positive voltage is applied in the erase mode and 0 in the write mode.

In erase mode, positive pressure is applied to one transistor TR1.
When the base voltage of the transistor TR1 and TR2 are both turned on, 100V is applied to the target through the emitter and collector of the other transistor TR2.

At this time, the load impedance of the target becomes the saturation resistance of the transistor TR2 and becomes extremely small.

R1 and R2 are bias resistors of the transistor TR2.

Further, R3 is a target load resistance in write mode.

The housings R, , and R5 are dividing resistors for dividing the voltage of 100V to make the target voltage 30V in the write mode.

That is, in the write mode, transistors TR1,
Since both TR2 are turned off, a voltage of 30V obtained by dividing by resistors R4 and R5 is applied to the target through load resistor R3.

Here, 01 is a coupling capacitor, and load resistance R3
The signal components obtained at both ends of are extracted and the video amplification circuit A
It is intended to supply

As explained above, according to the configuration of the present invention, mode switching is performed by turning transistors TR1 and TR2 "ON"""OFF.
This can be done simply by simply switching the switch, and the switching speed is controlled only by the switching speed of the transistor, making it extremely fast.

Furthermore, in the erase mode, the impedance of the target can be made much smaller than in the write mode, making it possible to perform a more reliable erase operation.

[Brief explanation of the drawing]

Figure 1 is a graph showing the secondary electron emissivity of the organic film target, Figure 2 is a block diagram showing the operation of the organic film target 2 electron gun type scan conversion tube, and Figure 3 explains the operation of the organic film target. FIG. 4 is a wiring diagram of an organic film target type scan conversion mode switching device according to an embodiment of the present invention. TR1, TR2...Transistor, R3s R
4sR5...Resistance.

Claims (1)

[Claims] 1 A transistor is inserted between an organic film target and a power source that applies an erasing voltage, with a collector electrode connected to the target and an emitter electrode connected to the voltage source, and a transistor that divides the voltage of the power source for writing. A voltage dividing resistor is provided to serve as a voltage source, and a resistor is connected between the write voltage source and the target, and a signal is supplied to the base of the transistor to turn the transistor ON-OFF. Features: Mode switching device for organic film target type scan converter tubes.