JPH0261816B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a selective driving circuit, and particularly to a circuit for selectively driving needle electrodes of an electrostatic recording device using multi-needle electrodes.

An electrostatic recording device records and creates an electrostatic latent image on a recording medium by applying electrical signals to multi-needle electrodes in a calligraphic pattern. In this recording, the recording speed can be increased by scanning the signal that provides the needle pole without scanning the needle pole, so this recording method has been exclusively used recently. By the way, according to this recording method, it is necessary to apply a predetermined high voltage to the needle pole selected at high speed, and it is necessary that the selection drive circuit has a circuit configuration with low power consumption due to its integration.

However, this type of conventional selection drive circuit has the disadvantage that the rise of the output electric signal relative to the control input is slow. In order to control the output state of a high-voltage electrical signal using a micro-voltage control input, a switching element circuit of some kind is required, but due to the characteristics of this switching element circuit, the output electrical signal This is because its influence appears in

FIG. 1 shows an example of the circuit configuration of a conventional selection drive circuit of this type. According to this, when the transistor TR1 is in the on state, a Zener voltage is applied to the base of the transistor TR2 by the Zener diode D1, and its emitter is reversed with respect to the base by _V2 applied through the diode D2. It is in a biased state and the transistor TR2 is in an off state. On the other hand, when the transistor TR1 is in the off state, the base current is supplied to the base of the transistor TR2 from the power supply _V1 via the resistor R1.
Transistor TR2 is turned on. In this case, when the transistor TR2 changes from the off state to the on state, that is, when the voltage value at the intermediate connection point O between the diodes D2 and D3 changes from _V2 to _V1 , the current supplied to the base of the transistor TR2 is the resistor R1. Moreover, the existence of the diode D3 limits the speed-up of the switching operation of the diode D3.

The present invention has been made in view of the above points, and in order to perform high-speed switching at the above-mentioned point O, it is possible to supply a high-speed rising pulse by removing diode D3 and inserting a diode between the emitter and base of transistor TR2. The purpose of the present invention is to provide a selection drive circuit that performs the following.

A preferred embodiment circuit of the present invention is shown in FIG. As shown in the figure, a diode D4 was inserted between the emitter and base of the transistor TR2. As a result, when the transistor TR2 goes from off to on, that is, when the transistor TR1 goes from on to off, a current is supplied through the resistor R1, and a current is supplied through the diode D4 for transient phenomena of TR1, D1, and TR2. We achieved a faster switching circuit that supplies current and prevents high potential reverse bias from being applied between the base and emitter when TR2 is off.

As a result, the Zener voltage of the Zener diode in the circuit shown in Figure 1 is 5V, _V1 is 400V, and _V2 is 7V.
In this case, the rise from about +6 V to +400 V at point O took about 5 μ seconds, but by using the circuit configuration shown in FIG. 2, it took about 3 μ seconds. Furthermore, by adopting the configuration shown in Fig. 3 in which a capacitor C1, which is an energy storage element, is connected to both ends of the Zener diode D1, and supplying energy from the capacitor C1 during a transition during switching of the transistor, the power is controlled by the characteristics of the Zener diode D1. A _high -speed switching circuit has _been realized that is less likely to cause problems.
A very high-speed switching circuit has been realized, which is reduced to seconds.

Of course, the same effect can be obtained by using a series connection of diodes or resistance division to obtain a constant voltage instead of using the Zener diode D1 as the constant voltage source.

Also, even if you change it to a transistor, FET, VMOS,
The same is true even if an equivalent circuit is formed using SMOS or the like.

Further, although the present invention has been described by taking a multi-stylus drive circuit for electrostatic recording as an example, it is of course applicable to a wide variety of circuit configurations that perform switching.

As explained above, an extremely high-speed switching circuit has been realized with a simple circuit configuration.

[Brief explanation of drawings]

FIG. 1 is an example of a conventional circuit, FIG. 2 is a selection drive circuit diagram of this embodiment, and FIG. 3 is a selection drive circuit diagram of another embodiment. In the figure, D1... Zener diode, D2
~D4...Switching diode, TR1, TR
2...Transistor, C1...Capacitor, R1~R
5...Resistance.

Claims (1)

[Claims] 1 The collector of the emitter grounded transistor circuit is connected to the power supply via a Zener diode and a first resistor, and the base of the collector grounded transistor circuit is connected to the power supply via a second resistor from the connection point of the Zener diode and the first resistor. The anode terminal of the first diode is connected to the emitter of the collector grounded transistor, and the cathode terminal of the first diode is connected to the base of the transistor. A constant voltage is supplied to the emitter of the collector grounded transistor through a second diode so that the emitter of the collector grounded transistor is connected in a forward direction when the emitter grounded transistor is turned on. A selection drive circuit characterized by having a configuration for taking out an output.