JPS6337372B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an impedance measuring device for a recording medium used in an electrostatic recording device, which is capable of always maintaining a constant level of image quality even when environmental conditions change, and particularly relates to an impedance measurement device for a recording medium used in an electrostatic recording device. In order to accurately measure the impedance of a recording medium, the volume resistance or surface resistance of the recording medium is measured, and recording conditions are controlled based on the measurement results. Impedance measurement of a recording medium improves the accuracy of an electrostatic recording device. Suggest a device.

2. Description of the Related Art Conventionally, in electrostatic recording apparatuses, it has been known that changes in the external environment such as temperature and humidity cause abnormal images such as ghosts to occur, or to affect image density and contrast, thereby degrading image quality.

In order to prevent the adverse effects of such changes in the external environment, electrostatic recording apparatuses that detect temperature, humidity, etc. and control recording conditions in accordance with the results are conventionally known.

However, with such conventional electrostatic recording devices,
It is difficult to grasp changes in the impedance of the recording medium, and it is also related to the time it takes for the recording medium to adapt to changes in environmental conditions, making it impossible to accurately detect the state of the recording medium during actual recording operation. , it was impossible to perform efficient control.

Therefore, in order to eliminate such inconveniences, the recording medium impedance measurement device of the present invention has the following features:
That is, in order to accurately measure the impedance of a recording medium, its volume resistance or surface resistance is measured, and recording conditions can be controlled based on the measurement results.

In general, a recording medium used for electrostatic recording is composed of two layers: a recording layer made of a dielectric layer and a base layer called a low resistance layer provided below the recording layer. is greatly influenced by. For example, when the humidity is high, the impedance of the base layer decreases, making the dielectric layer more likely to be charged, and when the humidity is low, the impedance increases, making it difficult to charge.

In this way, recording conditions vary and image quality changes depending on environmental conditions such as changes in humidity or temperature.

In order to accurately measure the impedance of a recording medium, the recording medium impedance measurement apparatus of the present invention is capable of measuring the volume resistance or surface resistance of the recording medium.

FIGS. 1A and 1B are perspective views showing one embodiment of a multihead for measuring the impedance of a recording medium in the impedance measuring apparatus of the present invention. In the drawing, 1 is a guard electrode, 2 is a detection electrode, 13 and 14 are a guard electrode and a detection electrode used as counter electrodes, and the dashed-dotted line A-A' is a cross-sectional view shown in the following Figure 2. Show part.

FIG. 2 is a diagram showing an embodiment of the electrode configuration and connection circuit in the impedance measuring device of the present invention. The symbols in the drawing are the same as in FIG. 1, and 3 is Teflon (registered trademark), 5 is a recording medium, 5A is its dielectric layer, 5B is its base layer, 6 is an impedance measuring device, and 7 is a DC power supply,
15 is an insulator such as Teflon, and SW1 to SW4 are interlocking switches.

Each electrode 1, 2, 13, 14 of the measuring head is shown in cross-section along line A-A' shown in FIGS. 1A and B, between which a recording medium 5 is arranged. .

The first impedance measurement electrode is
Consisting of a detection electrode 2 and a guard electrode 1, the detection electrode 2 is separated from the guard electrode 1 around it by an insulator 3.
They are mutually insulated by holes, etc., and
The second impedance measurement electrode, that is, the counter electrode, is composed of a detection electrode 14 and a guard electrode 13, and a DC voltage is applied between the detection electrode 14 and the guard electrode 13 by a DC power supply 7.

First, when measuring volume resistance, the detection electrodes 2 and 14 of the measurement head are used. In this case, the interlocking switches SW1-SW4 are connected to the upper terminals as shown.

In this way, a voltage of about 10 to 100 V is applied from the DC power supply 7 to one detection electrode 14, and a current flows from the other detection electrode 2 to the impedance measuring device 6 via the recording medium 5. Therefore, by picking up this current value, the volume resistance of the recording medium 5 can be detected. Note that guard electrodes 1 and 1
3 is grounded GND.

Next, when measuring the surface resistance of the dielectric layer 5A of the recording medium 5, the interlocking switches SW1 to SW4 are connected to the center terminal.

In this case, a voltage is applied from the DC power source 7 to the detection electrode 2, a current flows from the guard electrode 1 to the impedance measuring device 6 via the surface of the dielectric layer 5A, and its surface resistance is measured. Note that the guard electrode 13 and the detection electrode 14 on the base layer 5B side are grounded.

Furthermore, to measure the surface resistance of the base layer 5B,
A detection electrode 14 and a guard electrode 13 are used, and in this case, the interlocking switches SW1 to SW4 are connected to the terminals at the lower end.

For this purpose, a DC voltage is applied to the detection electrode 14 on the base layer 5B side, a current flows from the guard electrode 13 to the impedance measuring device 6 via the surface of the base layer 5B, and its surface resistance is measured. In this case, the guard electrode 1 and the detection electrode 2 on the side of the dielectric layer 5A are grounded.

By using a circuit as shown in FIG. 2, it is possible to measure not only the volume resistance of a recording medium but also its surface resistance.

In electrostatic recording, the order of influence on recording conditions is the surface resistance of the base layer, the volume resistance, and the surface resistance of the dielectric layer. Therefore, the impedance measurement of such a recording medium can be performed under various environmental conditions. If the recording conditions are controlled based on the measurement results, even if the environmental conditions change,
If the recording conditions are controlled based on the measurement results, even if the environmental conditions change,
High quality recorded images can always be obtained.

FIG. 3 is a schematic diagram of the main parts of an electrostatic recording apparatus using the measurement head shown in FIG. 2 above. Reference numerals in the drawings are the same as those in FIG. 2, and 8A and 8B are impedance measurement sections, 9 is a calculation section, 10 is a control section, 11 is a recording electrode, and 12 is a back electrode.

As shown in FIG. 3, guard electrodes 1 and 13
For example, 10 detection electrodes 2 and 14 are respectively provided to measure the volume resistance at 10 locations on the recording medium 5, and the calculation unit 9 calculates the average value thereof. As shown in FIG. 3, by using a plurality of detection electrodes 2 and 14, it is possible to further improve the reliability of the measurement results.

Then, according to the calculation result, the control unit 10 controls to change the voltage, time, phase, etc. of the signal input to the recording electrode 11, the back electrode 12, or the auxiliary electrode.

For example, when the volume resistance is high, the applied signal voltage is increased, the application time is increased, or both values are increased. Alternatively, control is performed so that the phase is changed to increase the value of the time input at a voltage higher than the discharge start voltage. In this way, even when the volume resistance is high, it is possible to increase the amount of charge, and it is possible to maintain a constant image quality.

In addition, when the input signal is kept at a constant level and the recording operation is performed constantly, for example, by changing the relative speed ratio to the moving speed of the recording body 5, the contact time between the recording body and the developer can be controlled. Alternatively, the development efficiency can also be controlled by means such as applying a bias voltage to the development section.

Furthermore, it is also possible to measure surface resistance.

In FIG. 3, the measurement head as shown in FIG. 1 is placed on the dielectric layer 5A side of the recording medium 5, but it is not necessarily necessary to place it on the dielectric layer 5A in this way. It can be placed on the layer 5B side or on both sides.

In addition, in order to maintain good contact with each electrode 1, 2, 13, 14 of the recording body 5, each electrode 1, 2, 1
It is preferable to use connectors made of Si for the surfaces 3 and 14 that come into contact with the recording medium 5.

In the case of FIG. 3, since it is possible to measure not only the volume resistance of the recording medium but also its surface resistance, it is possible to more accurately grasp the impedance change of the recording medium 5, and each of these can be measured by multiple measurements. The result is detected, and the recording conditions are controlled based on the average value. Therefore, it is possible to perform a more reliable recording operation than with conventional recording apparatuses.

As explained in detail above, in the recording medium impedance measurement device of the present invention, among the recording conditions that affect the recorded image due to environmental conditions in an electrostatic recording device, such as changes in humidity and temperature, the recording medium impedance measurement device of the present invention Changes in impedance, especially volume resistance or surface resistance, are directly measured immediately before the recording operation, and based on the measurement results, recording conditions such as the magnitude, application time, or phase of the signal in the recording section can be controlled, and recording in the developing section can be controlled. The contact time between the body and the developer, the bias voltage, etc. are controlled.

In addition, impedances at multiple locations are measured using multiple detection electrodes, and highly reliable control is performed using the average value of these measurements.

Therefore, it is possible to always maintain stable recording conditions even when environmental conditions change.
An excellent effect is achieved in that a good recorded image with high density and high contrast can be obtained without the occurrence of ghosts or the like.

[Brief explanation of the drawing]

1A and 1B are perspective views showing one embodiment of a multihead for measuring the impedance of a recording medium in the impedance measuring device of the present invention, and FIG. 2 shows the electrode configuration and connection in the impedance measuring device of the present invention. FIG. 3, which shows one embodiment of the circuit, is a schematic diagram of the main parts of an electrostatic recording apparatus using the measuring head shown in FIG. 2. In the drawing, 1 is a guard electrode, 2 is a detection electrode, 3 is an insulator, 5 is a recording body, 6 is an impedance measuring device, 7 is a DC power supply, 8A and 8B are impedance measuring sections, 9 is a calculation section, and 10 is a control Part, 11
12 is a recording electrode, 12 is a back electrode, 13 and 14 are guard electrodes and detection electrodes used as counter electrodes, 1
5 is an insulator.

Claims (1)

[Claims] 1. A first detection electrode arranged at a position in contact with one surface of a recording medium, and a first guard electrode arranged around the first detection electrode and insulated from each other. an impedance measurement electrode, a second detection electrode disposed at a position in contact with the other surface of the recording medium and at a position opposite to the first detection electrode of the first impedance measurement electrode; a second detection electrode and a guard electrode arranged around the two detection electrodes and mutually insulated from each other;
an impedance measuring electrode, a DC power supply means for supplying voltage to the first and second impedance measuring electrodes, and a switch means, and by switching the switch means, a first impedance measuring electrode that contacts both surfaces of the recording medium is provided. The volume resistance of the first and second detection electrodes is measured by applying a DC voltage to the first and second detection electrodes.
Impedance measurement of a recording medium, characterized in that the surface resistance of the recording medium is measured by applying a DC voltage to either one of the detection electrode and the first guard electrode, or the second detection electrode and the second guard electrode. Device.