SU892341A1 - Method of measuring electrophotographic layer sluggishness - Google Patents

Description

The invention relates to the field of measuring the parameters of semiconductor devices, in particular, to the area of measuring a constant time, and can be used to derive the properties of electrophotographic and iconic layers. The known method of measuring the transient response of photoresistors consists in illuminating the photoresistor with a U-shaped light pulse, measuring its resistance after a certain period of time and calculating the value of the constant time of resistance variation based on the measured resistance values and time interval 1. The disadvantage of this method is low measurement accuracy when applied to the measurement of the inertia of the photodiagram of electrophotographic and vidicon layers, due to the presence of x layers of dark discharge. A known method for determining the inertia of the photodischarge of electrophotographic layers is to study the rate of decline of the surface electric potential of electrophotographic layers after illumination with a light pulse recorded on an oscilloscope screen and subsequent theoretical calculations 2. The disadvantage of the method is the accuracy due to errors in the visual observation of the photodischarge curve on the oscilloscope screen, and the inability to automate the measurement process by devices that implement this method. The purpose of the invention is to improve the accuracy and enable the automation of measurements of the inertia of the photodischarge of electrophotographic layers. The goal is achieved by the fact that in the method of measuring the inertia of electrophotographic layers containing a measurement of the rate of change of the surface electric potential of an electrophotographic layer, after illuminating it with a U-shaped radiation pulse, the velocity of the dark discharge of the electrophotographic layer is also measured before it is illuminated. radiation

The value of the surface electric potential and the beginning of the reference time are recorded, and when the potential decay rate is equal to the initial speed of the dark discharge, the electric potential value and the end of the reference time are recorded before illumination.

FIG. 1 shows flow charts for measuring the inertia of an electrophotographic layer; in fig. Fig. 1a shows a graph of a sync pulse (control pulse controlling the initial discharge rate of the electrophotographic layer; Fig. 1b shows a graph controlling the source of illumination; Fig. 1c shows a U-shaped pulse of a certain intensity, Wave, and slope fronts; Fig. 1 graph of changes in the surface electric potential (1 curve of that layer discharge, 2 curve of layer discharge under the action of a U-shaped optical radiation pulse, point B - the beginning of the action of the optical radiation pulse, C-ko irradiation of the potential of the layer of radiation from the point of B to the right of the dark discharge of the layer of the illumination pulse, 3-curve of the photodischarge of the layer under the action of semi-infinite radiation); Fig. 1 d plot of the rate of change of the electrical potential of the output signal The speed meter unit in Fig. 1e is a graph of the rate of dark discharge of a layer at the output of a memory unit (e.g., a peak detector); Fig. 1 g is a plot of potential changes at both inputs of a coincidence unit; the moment of coincidence of speeds is indicated by a dot in Fig. 1 3 is a graph of the electric potential of the layer on the memory element at the time of the termination of the radiation pulse; in fig. 1 and - plot of the electric potential of the layer at the time of coincidence of the velocities; in fig. 1 to the graph of the absolute value of the voltage difference during the inertial descent of the potential of the layer in FIG. 1 L is a graph of the time interval in seconds of the inertial descent of the surface potential of the layer in FIG. 2 is a block diagram of a device for implementing the method.

The device contains (Fig. 2) a translucent, conducting signal electrode 1, a measured sample (semiconductor layer) 2, a conductive substrate 3 layers, a charge meter 4, a compensation amplifier 5 / blocks b and 8 control sync pulses, a source 7 of pulses the illumination unit 9, the measuring instrument of the rate of change of the potential, the unit 10 of the controlled peak detector, the unit 11 of coincidence, the meter 12 of the time interval, the unit 13 of the controlled peak detector, the controlled unit 14 of the recording of the potential and the subtracting unit 15.

The device works as follows.

The pre-charged layer 2 is placed under the transparent electrically conductive signal electrode 1. At the output of charge meter 4, we obtain a voltage proportional to (R D induced on the signal electrode 1. The voltage from the output of the charge gauge 5 is amplified by a compensation amplifier 5, the output of which connected to the conductive substrate 3 of the measuring layer 2. As a result, a voltage equal to the surface electric potential of the layer 2 is obtained on the conductive substrate01 6 of the measuring layer.

A graph of the surface electric potential of a layer and its measurement under the action of radiation (light, X-ray, etc.) is shown in FIG. 1 g, curve 2. The output of the compensation amplifier 5 is connected to the conductive substrate 3, to the input of the block 9, the measuring rate of change

potential to the input controlled

an electric potential detection unit 14; and a controlled peak detector unit 13. From the output of the compensation amplifier 5 signal

5 is fed to the input of block 9 of a potential change rate meter (a potential differentiator can serve as a potential change rate meter, the circuits of which are well known).

0 From the output of block 9 of the speed meter, the signal is fed to the input of the controlled block 10. peak detector 1 (it can be a peak detector), which is switched on for a short time by a clock pulse from the output of block b (fig. 1 a) and this moment is indicated on the graph by a dot And in FIG. 1 g and the point H in the graph of the change in velocity of the electric potential (FIG. 1 d).

 At the input of block 10 of the peak de-tector, we obtain a voltage value proportional to the rate of change of the potential at the time of arrival of the clock pulse (Fig. 1 a and Fig. 1 d),

5a, its graph is shown in FIG. 1 e. From the output of the control block b with a certain delay, the sync pulse arrives at the input of the control block 8 of the radiation source 7

Q (Fig. 1 b and Fig. 1 c).

The change in the surface electrolytic potential of a layer under the action of a radiation pulse is shown in Fig. 1 g curve 2, the rate of change in this potential is shown in

FIG. 1 d. At the moment of termination of the radiation pulse, the temporal potential meter 12 is started (the first pulse on the 1 l plot) and the control unit 13 of the controlled peak detector, which stores the value of the electric potential at the time of the termination of the radiation pulse (Fig. 1 h). After the cessation of the radiation pulse, the surface electric potential of the layer will change for some time (Fig. 1 g, curve 2, section SB).

As the rate of change of the surface electric potential of the layer decreases, and when it reaches the initial rate of dark discharge (Fig. 1, point D), the block 11 coincides with a short pulse (Fig. 1), which will stop the meter 12 interval and will include a controlled electric potential recording unit, which registers the value of the electric potential when the dark discharge layer coincides with the exposure and exposure time (Fig. 1 and). At the output of subtracting unit 15, we obtain the value of the voltage difference uU U4-Uy (Fig. 1k).

In this way, the time interval of the inertial change (the interval between pulses

FIG. 1 l) and the absolute value after the fall of the surface electric potential of the layer (Fig. 1 K).

Claims (2)

1. Olesk A.O. Photoresistors. M.-L., Energie, 1966, p. 13-20. 2. Hyde, V.I., Markevich, N.N., Montrimas, E.A. Physical processes in electrophotographic layers. Vilnius, 1968, p. 178-187.