JPS60120265A - Surface potentiometer - Google Patents

Abstract

PURPOSE:To make it possible to reduce the superposition of the driving signal of a piezoelectric element to an electric signal, by allowing the driving piezoelectric element of a vibrator for intermittently shielding an electric field to the position in the side opposite to an object to be measured with respect to a plane including an electrode. CONSTITUTION:The free end side of a vibrator 5 is formed so that a piezoelectric element 6 is arranged in the side opposite an object to be measured with respect to a plane L including at least the measuring surface of a measuring electrode 3. For example, the free end side of the vibrator 5 is bent at a right angle. By this arrangement, the drive signal to the piezoelectric element 6 is directly incident to the measuring electrode 3 in cooperation with the arrangement effect of an internal shield 2 to reduce action for generating disturbance to measured potential. Therefore the possibility such that the drive signal of the piezoelectric element 6 is directly incident to the measuring electrode 3 as compared with such a case that the piezoelectric element 6 is positioned in the side of the object to be measured from the plane including the front surface of the measuring electrode 3. By this mechanism, the more accurate measurement of surface potential is enabled without affecting the influence of the piezoelectric element 6 upon a electric field to be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface potential A1 for measuring the surface potential of an object to be measured, and more particularly to a surface potential meter that detects the potential on the surface of a photoreceptor in a copying machine or the like and extracts it as an alternating current signal. It is something.

Generally, photoreceptors using photoconductive materials used in electronic copying machines etc. are prone to sensitivity shifts due to changes over time, etc.
It is desirable to add a means for controlling the surface potential of the photoreceptor so that the surface potential is always set within a certain range. That's my enemy,
A surface electrometer is required to measure the photoreceptor surface potential.

As a surface electrometer, by intermittently shielding the electric field generated between the object to be measured and the potential measurement electrode directly facing it,
There is a known method in which an AC signal having an amplitude proportional to the voltage difference between the surface of the object to be measured and the measurement electrode is induced in the measurement electrode to perform measurement.

The surface electrometer described above consists of a potential measuring electrode circuit section and a chop section that intermittently shields between the measuring electrode and the object to be measured6.Both are made of metal to prevent the influence of external electric fields and noise. It is surrounded by a shield. This metal seal has a
A measurement window for potential measurement is formed, and the potential of the photoreceptor is measured through this measurement window. Although there is one that uses a DC motor (Japanese Unexamined Patent Publication No. 54-6447) for the tilting section, one that uses a piezoelectric element has been proposed because it is small and easy to manufacture.

However, the conventional one had a configuration as shown in Figure 1,
Since the drive signal for the piezoelectric element 6 is extremely thick compared to the surface potential signal induced in the measurement electrode 3, the piezoelectric element drive signal is likely to be superimposed on the surface potential signal in the positional relationship shown in FIG.

An object of the present invention is to provide a surface electrometer configured to reduce superimposition of a piezoelectric element drive signal on a surface potential signal.

In order to achieve the above object, the present invention positions a driving piezoelectric element of a vibrator that intermittently shields an electric field on the opposite side of the object to be measured with respect to a plane including the electrode.

Hereinafter, the present invention will be described in detail with reference to the illuminated surface. 1st
The figure is a cross-sectional view of an example of the surface electrometer in a completed assembled state, as seen from the detection surface side.

l is the outer shield, 2 is the inner shield, 3 is the measurement electrode,
4 is a substrate, 5 is a vibrator, 6 is a piezoelectric element, and 7 is a base that supports the piezoelectric chopper. A measurement window is formed in the external shield at a position corresponding to the measurement electrode, and the electric field generated between the measurement object and the object to be measured, which is placed in front in Figure 1, enters the shield through the measurement window and reaches the measurement electrode. However, other parts of the external shield 1 are not affected because the external shield 1 is attached to the board by screws and is in contact with the ground pattern of the board.

Furthermore, the inner shield 2 is connected to the measuring electrode 3. This is because the AC potential signal induced in the measurement electrode 3 is too small compared to the drive signal of the piezoelectric element 6 in the chop section, so the external electric field and noise cannot be suppressed by the external shield. However, since the influence of the drive signal of the piezoelectric vibrator on the potential signal cannot be suppressed, the inner shield 2 can suppress the above-mentioned influence.

FIG. 2 is a front view showing only the chop portion, and FIG. 3 is a top view. The vibrator is divided into two parts as indicated by 5 in FIG. 2, and a piezoelectric element 6 is bonded to each fulcrum side with a conductive adhesive. The fulcrum of the piezoelectric vibrator 5 is bottle-shaped and embedded in the base 7 as shown in FIG. 3, and is bent downward relative to FIG. 2 and exposed to the outside. Further, the lead bin 8.9 is also embedded in the base 7 as shown in FIG. 3, and is bent downward with respect to FIG. 2 and exposed to the outside from the base.

The lead wire from the piezoelectric element is attached to lead pin 8 as shown in Figure 2.
, 9 are soldered. Further, the lead pin of the vibrator 5 is grounded. When a voltage is applied to the piezoelectric element 6 in the thickness direction, that is, in the vertical direction in FIG. 2, distortion occurs in the plane direction. Therefore, due to the distortion of the piezoelectric element, each side of the vibrator causes vertical vibration as shown in Figure 2, and the tip of each side of the vibrator is parallel to the measurement electrode 3 in Figure 1 so that it can shield the electrode 3. It has a shape. The vibrator 5 itself is grounded and vibrates in front of the electrode 3, so the electrode 3 is connected from the object to be measured through the measurement window.
The total area to which the electric field is applied varies 1. #At the same frequency as the vibration frequency of A mover 5.

An alternating current signal having an amplitude proportional to the potential difference between the object to be measured and the electrode 3 is induced in the electrode 3.

This chop part is located between A and A' in FIG. 2, for example.
Insert the vibrator 5 and lead pins 8.9 into 7a from below in Fig. 3, bend them downward as seen in Fig. 2, and glue 7b from above in Fig. 3. is formed. With this configuration, the work of mounting the chop part on the board 4 together with other transistors, resistors, etc. and soldering the lead wires after screwing the chop part as in the conventional work can be replaced with a soldering bath. By just passing it through, you can fix the chop part to the board and connect it to the printed pattern at the same time.

In FIG. 4, which is a cutaway plan view of this surface electrometer, the outer shield l has a potential measurement window 1' at a position where the measurement electrode 3 faces the part to be measured, and the detection circuit 11 formed on the substrate 4 is , are shielded by an inner shield 2. Here, a chop section including a vibrator 5 is disposed at a position that intermittently blocks the electric field formed between the measurement electrode 3 and the object to be measured (located below in this figure).

In this embodiment, the surface potentiometer is designed to reduce the superimposition effect on the surface potential signal of a nine-degree detection pair as a detection pair. As in the second embodiment, the piezoelectric element 6 is located on the side of the free end of the vibrator 5 on the opposite side of the object to be measured (located in the direction indicated by the arrow) with respect to the plane that includes at least the measurement surface of the electrode 3. .

As a result, the drive signal to the piezoelectric element 6 is transmitted to the inner shield 2.
Together with the effect of the arrangement, the effect of directly entering the measurement electrode 3 and causing disturbance in the measurement potential' is reduced. In the embodiment shown in FIG. 6, the free end of the vibrator 5 is bent at a right angle and positioned on the opposite side of the plane containing the measurement electrode from the electrode to be measured. In the second embodiment shown in FIG. Although the bending angle of the vibrator is smaller than that of the first embodiment, the gist of the present invention can be fully implemented even in this case.

Since each of the above embodiments is configured as described above, the drive signal of the piezoelectric element can be directly transmitted, compared to the case where the piezoelectric element is located on the side of the object to be measured from the plane including the front surface of the measurement electrode adopted in the conventional type. This has a remarkable effect on reducing the possibility that the sample will be incident on the measurement electrode.

The present invention focuses on the driven piezoelectric element as a cause of measurement errors in surface electrometers, and enables more accurate surface potential measurement without the driven piezoelectric element affecting the measurement electric field.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a known surface electrometer in a fully assembled state as seen from the foot to be measured side, Fig. 2 is a front view of the electrometer shown in Fig. 1 with only the chop section taken out, and Fig. 3 is a , FIG. 4 is a cutaway plan view of the surface electrometer, FIG. 5 is a top view showing the positional relationship between the vibrator and the measuring electrode in the conventional surface electrometer, and FIG. Figures 6 and 7 are
5 is a diagram similar to FIG. 5 of a first and second embodiment of a surface electrometer, respectively, using shielding means according to the invention; FIG. l...External shield 1'...Measurement window 2...
Internal shield 3...Measuring electrode 4...Substrate 5
... Vibrator 6 ... Piezoelectric element 7 ... Base 8 ... Lead bin 9 ... Lead pin 10 ・
... Lead wire 11 ... Detection circuit ant 1 No. 2 Figure 4 Figure 5 Figure 6 Figure 7 Procedure amendment (method) % formula % 1. Indication of incident 1982 Patent application No. 228383
No. 2, Name of the invention Surface electrometer 3, Person making the amendment Relationship to the case Applicant (+00) Canon Co., Ltd. 4, Representative J Address 1-9-20-5 Akasaka, Minato-ku, Tokyo Date of amendment order Shipping date: February 28, 1982

Claims (1)

[Claims] A surface electrometer including a sensing body having a sensing surface directly facing the measuring object, and a vibrator that intermittently blocks an electric field formed between the sensing surface and the measuring object, the driving of the vibrator. A surface electrometer comprising a piezoelectric element (1) on a side opposite to the object to be measured with respect to a plane including a sensing surface of an electrode of the sensing object.