JPS5826615B2 - Yuuki Film Targetsutogata Sou Sahenkankanyou Mod Kirikaesouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an operating 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, for example, in Nikkei Electronics, No. 1974.7-15 (A8611, etc.), but its operation will be briefly described here.

The feature of this is 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 is possible to use 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.

The secondary electron emissivity characteristics of such a polyimide film are as shown in Fig. 1 when the first crossover voltage is 60 to 70V and S
This value is higher than that of iO2, etc.

A two-electron gun type scanning converter tube using this organic film as a target is constructed using an organic film target T as shown in Figure 2.
The two electron guns are placed in the middle and facing each other.

The image signal is applied to the first grid G0 of the writing electron gun, and the electron beam travels while being modulated 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.

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

In the erase mode, the target voltage is in the range δ>1 in FIG.

100■, in write mode 3 which is in the range of δ<1
It is set to 0V.

In the erase mode, the unmodulated electron beam on the writing side
The organic film is scanned by several arrays 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 organic film on the writing side.

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

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

Accordingly, the present invention provides a transistor-type switching device that can sufficiently shorten the erasing time, and that also satisfies 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 -100μ, and the potential difference with the previously formed charge image is (-30V) - (-100V) = 70V, which is the same as shown in Figure 1. In the graph of secondary electron emissivity, δ〉1
is found to be within the range of , and a predetermined erasing operation is performed.

However, if the target voltage switching time, especially 30
Considering the case where it takes a long time to switch from V to 100V, the target voltage is 30V as shown in 2 in Figure 3.
It is assumed that the voltage changes instantaneously from to 70V, and then gradually changes to 100Vt.

In other words, if the erase beam current starts flowing when the target voltage is 70V, in the case of a target voltage of 70■,
The polyimide surface potential is -70V, so the potential difference with the previously formed charge image is (-30V) - (-70V
)=4. It becomes OV.

This is the range of δ<1.

This state is in write mode, so the polyimide surface is accumulating charges rather than emitting charges, which is -
It was accumulated in the past when it reached 70V.

Therefore, even if the target voltage becomes 1oov after this, the potential difference on the polyimide surface will be (-70V)
-(-100V) 30V, and is still within the range of δ<1.

Therefore, a charge equal to -100 V is accumulated on the polyimide surface, and what was intended to be an erase operation results in the 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. This enables efficient flow and ensures reliable erasing operation.

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

In the figure, TR1':J=- and TR2 are mode switching transistors, and on the other hand, a control signal is applied to the base of the transistor TR1 so that it becomes O in the erase mode.

When a positive voltage is applied to the base of one transistor TR1 in the erase mode, both transistors TR1 and TR2 are turned on, and 100V is applied to the target through the collector 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 for the transistor TR2.

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

The old R4 pR6 is a dividing resistor that divides the voltage of 100V to make the target voltage 30V in the write mode.

That is, in write mode, transistors TR0, T
Since R2 are both "OFF", a voltage of 30V obtained by dividing by resistors R4 and R5 is applied to the target through load resistor R3.

Here, C1 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 shown in FIG. 4, mode switching is achieved by turning transistors TR1 and TR2 ON
This can be easily done by simply switching the transistor F'', 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.

The present invention can also provide a further improved mode switching device.

That is, if the ratio of resistors R3 to R4 and R5 is carefully selected, the organic film target type scan converter tube can be used more reliably and safely.

Here, a fifth embodiment of a further improved mode switching device will be described.
5 and will be described below with reference to FIG.

The difference from FIG. 4 is that a capacitor C2 is added in parallel to the resistor R5, and the ratio of the resistors R3s, R4, and R5 is the crossover voltage of the polyide.

).

In the above configuration, by adding capacitor C2, the 30V voltage generation point (resistors R4 and R5
It is possible to reduce the ripple component at the connection point of

Furthermore, the resistance values of resistors R4 and R5 can be increased,
It is possible to reduce the output current of the 100 V supply power supply, and the 100 V supply power supply can be simplified.

However, in this case, the switching speed is slow when switching from erase mode to write mode due to capacitor C2.
Even if you intend to switch to write mode, the erase mode may temporarily continue during the transition state of switching, which may have an adverse effect.

Therefore, even in erase mode, the voltage at the junction of resistors R3, R4, and R5 is below the crossover voltage Ver, so even in the transient state when switching from erase mode to write mode, the values of resistors R3, R4, and R5 are set to the target value. The voltage is V
er or less, and switching is performed smoothly.

As explained above, according to the present invention, an organic film target type scan converter tube can be used extremely reliably and safely.

[Brief explanation of drawings]

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, and FIG. 5 is a wiring diagram showing another further improved embodiment of the present invention. . TR1, TR2...Transistor, R3, R4
, R5...Resistor, C2...Capacitor.

Claims (1)

[Scope of Claims] 1. A transistor inserted between an organic film target and a power source for applying an erasing voltage, with a collector electrode connected to the target side and a vine electrode connected to the power source side, respectively; Between the power supply and ground, connect the first
a voltage dividing resistor inserted in series with a second resistor connected to the ground side, and a third resistor connected between the connection point of the first and second resistors and the target. , a first capacitor connected in parallel to the second resistor, and the first, second, and third resistors (where ■cr is the secondary electron emissivity of the organic film target 1. A mode switching device for an organic film target type scan converter tube, characterized in that the mode switching device is selected to satisfy the voltage at which the voltage is "1".