JPS59161178A - Electrostatic image read-out device - Google Patents

Abstract

PURPOSE:To prevent attenuation of a charge in a photocondutive body, and to obtain a stable electrostatic image by a charge of an insulating layer, by placing a primary electrostatic charging means, a means for irradiating an electromagnetic wave, a secondary electrostatic charging means and a scanning means, etc. on an electrostatic image holding body which has an insulating layer, a semiconductor layer having conductivity, and a conductive body layer. CONSTITUTION:An image holding body 1 is constituted of a conductive layer 11, a semiconductor layer 12 having conductivity,and an insulating layer 13, and this holding body 1 is rotated in the direction as indicated with an arrow. A primary electrifier 2, a uniform exposure lamp 3 for irradiating an electromagnetic wave uniformly at the almost same time as the primary electrostatic charging, and a secondary electrifier 5 which has the opposite polarity to the primary electrostatic charging or is AC electrostatically charged are placed on this holding body 1. Also, an image exposure optical system 4 for irradiating an electromagnetic wave of a picture information at the almost same time as the secondary electrostatic charging, the whole surface exposure lamp 6, and a scanning optical system 9 for scanning an electrostatic image formed by each means, by the electromagnetic wave are provided. In this way, an electric signal at a scanning position is read by a roller electrode 7, attenuation of a charge in the conductive layer 11 is prevented, and a stable electrostatic image is read by a charge of the insulating layer 13.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for electrostatically recording image information on an electrostatic image carrier and reading out the recorded electrostatic image as an electrical signal.

A device that records an image as an electrostatic image on an image carrier and reads out the electrostatic image as a time-series electric signal is disclosed in, for example, Japanese Patent Laid-Open No. 54
It is described in the publication No.-31219.

As disclosed in the above-mentioned publication, a conventionally known electrostatic image reading device is formed and held on an insulating layer of an electrostatic image holder having a structure in which an insulating layer and a photoconductive layer are sandwiched between conductive layers. This device discharges an electrostatic image by optically scanning it, and reads out the discharge current as a signal.

During the electrostatic latent image forming process in such a device, the electrostatic image formed on the insulating layer and the photoconductive layer will degrade over time because the dark resistance of the photoconductive layer is finite. The charge of is neutralized and attenuated.

In order to prevent this, the entire surface is exposed by light point scanning to eliminate the charge on the photoconductive layer, and only the insulating layer is charged, thereby creating an electrostatic image that is stable over time.

However, since the insulating layer is in contact with the conductive layer, sufficient stability cannot be obtained. In addition, the entire surface exposure by light spot scanning is 4
, a very bright light source is required to image a large area image carrier in a short time. In addition, the scanning light point is
It has to be made smaller. Therefore, the scanning optical system becomes large.

The present invention has been made for the purpose of eliminating the above-mentioned drawbacks of conventional devices.

In order to achieve this object, the present invention provides a primary charging means 2 for charging an electrostatic image carrier l having an insulating layer 13, a semiconductor layer 12 which is excited by electromagnetic waves and becomes conductive, and a conductive layer 11. , means 3 for uniformly irradiating electromagnetic waves substantially simultaneously with the -order charging, secondary charging means 5 for charging with opposite polarity or alternating current to the -order charging, and electromagnetic waves for image information almost simultaneously with the secondary charging. means 4 for irradiating electromagnetic waves, means 6 for irradiating the entire surface with electromagnetic waves, means 8 and 9 for scanning electrostatic images formed by the above-mentioned means with electromagnetic waves, and electrodes 7 for reading electrical signals at the scanning positions. An electrostatic image reading device characterized by comprising:

FIG. 1 shows an embodiment of an electrostatic image reading device to which the present invention is applied.

Reference numeral 1 denotes an electrostatic image holder having a conductive layer 11, a semiconductor layer 12, and an insulating layer 13 laminated, which is formed into a drum shape and rotates in the direction of the arrow. The conductive layer 11 is made of aluminum, for example, the semiconductor layer 2 is made of a photosensitive material such as CdS or Se, and the insulating layer 13 is a transparent plastic sheet such as Mylar sheet (trade name). Conductive layer 11 is grounded. 2 is a primary charging means, which is composed of a corona charger, and is located at approximately the same exposure position as the exposure lamp, which is the means 3 for uniformly irradiating electromagnetic waves.
It applies a primary charge to the position. 4 is a means for irradiating electromagnetic waves for image information, and is composed of an optical system, and the document 0 on the document table 14 is
image is formed on an image carrier. Reference numeral 5 denotes a corona charger as a secondary charging means, which charges with an alternating current or with a polarity opposite to that of the -order charging substantially simultaneously with the image exposure. 6 is an exposure lamp which is a means for irradiating the entire surface with electromagnetic waves. More
Electrophotography uses a photoreceptor whose surface is covered with an insulating layer.
) are the same as the electrostatic latent image forming means, and are well known, so detailed explanations will be omitted. 8.? consists of a scanning optical system 9 for scanning the axial direction of the photosensitive drum with a laser emitted from a laser light source 8 by scanning means using electromagnetic waves. The scanning optical system 9 includes, for example, a polygon mirror and an f/θ lens. A mirror may be attached to the rotating shaft of the galvanometer.

Reference numeral 7 denotes a roller electrode for reading electrical signals, which is transparent. As shown in FIG. 4, the roller electrode 7 has a Nesa film 18 provided on the surface of the glass cylinder 17, and the Nesa film layer 18 serves as a conductive electrode that comes into contact with the photosensitive drum 1. Cylinder 1
Both sides of the board 19 are supported by the board 19, and the board 1
9 rotates in the direction of the arrow.

Also, 10 is a transparent roller electrode, and 15 is an exposure lamp that illuminates the contact position of the roller electrode.

The operation of an electrostatic image reading device having such a configuration when recording and reading an image will be described below.

FIG. 2 shows the state of charge in each operation step.

As shown in (a), the surface of the image carrier 1 is irradiated with the light L1 by the uniform exposure chamber 3, and at the same time, the surface of the image carrier 1 is uniformly charged negatively by the charger 2. Next, when the image exposure optical system 4 irradiates the image exposure light L2 and at the same time positive or alternating current AC charging is applied by the charger 5, an electrostatic image of charges as shown in (b) is formed.

Next, when uniform exposure L3 is applied using the lamp 6, the charge of the electrostatic image is retained in the insulating layer 13, as shown in (C).

This electrostatic image is read out as shown in (d).

When the roller electrode 7 is brought into contact and the position is scanned with the laser beam L4 emitted from the laser light source 8, a current corresponding to the electrostatic charge is output from the roller electrode 7. When this small current is amplified by the operational amplifier 20, a signal as shown in FIG. 6 is output as an image information signal. In the figure, the vertical axis is current I or voltage V, the horizontal axis is time t, 30 is the output in the dark area, 3
1 represents the output of the intermediate tone, and 32 represents the output of the bright area.

Note that the residual charge on the image carrier is removed by bringing the electrode 10 into contact with the image carrier while uniformly exposing it with the exposure lamp 15.

In such an electrostatic image reading device, since the insulating layer 13 is not in contact with a conductive substance, the uniform exposure step (second
(C)), there is no need to perform scanning exposure as in the conventional method.
Full-surface exposure is sufficient. Therefore, the scanning mechanism can be omitted. Further, since the charges held in the insulating layer 13 do not come into contact with conductive substances, an electrostatic image can be held stably for a long time without attenuation, and the performance as an image memory is greatly improved.

The latent image reading device of the present invention can be widely applied not only to recording and reading visible light images but also to images generated by electromagnetic waves such as X-ray images. When forming an X-ray image, a subject is irradiated with X-rays projected from an X-ray source, and an electrostatic image is formed on an image carrier using the transmitted X-rays. Therefore, in order to prevent the X-ray image from spreading, it is necessary to place the subject and the image carrier close to each other. Therefore, it is necessary to place the subject on the side of the conductor free from obstacles such as a charger and irradiate the X-ray image. An example of this is shown in FIG. The image holder 1 is not drum-shaped as in the previous example, but has a planar shape or a shape with both sides open.

As shown in FIG. 2A, primary charging is performed by a planar needle-like electrode 21 while uniformly exposing the surface of the image carrier 1 to light. As shown in FIG. 7, this planar needle-like electrode 21 has a structure in which a large number of wires 25 are embedded in a transparent conductor base 24.

Next, as shown in FIG. 3(b), from the conductor 11 side
Electrostatic charges are removed using the needle electrode 22 while irradiating Lx. In this case, the base 24 of the needle electrode 22 does not have to be transparent. The conductor 11 is made of an X-ray transparent material such as thin AI or acrylic with a Nesa film attached to the semiconductor layer side, and the object 2
The X-rays that have passed through the semiconductor layer 1 (the right part of the figure (b))
2 are made conductive and an electrostatic image is formed. Next, as shown in (C), the entire surface is exposed to light so that the electrostatic image is retained in the insulating layer 13.

The electrostatic image is read out using the electrode 7 while optically scanning as shown in (d).

The transparent roller electrode 7 in the above example has a glass cylinder 17 as its base body, as shown in FIG. 4, in order to eliminate the effect of lens action.

When this cylinder 17 is a glass pipe with an outer diameter of 8 mm and an inner diameter of 6 mm, if the diameter of the laser spot imaged by the fθ lens of the scanning optical system 8 is set to 80 JLm, the transparent roller electrode 7 The increase in spot diameter at the position of contact with is about 10%.

FIG. 5 shows another embodiment of the roller electrode 7, in which a collimator lens is provided in the scanning optical system 9 to introduce parallel light into the roller electrode 7. The base of the roller electrode 7 is a transparent rod 26 having a circular cross section, and a transparent electrode 18 such as a Nesa film is provided on the surface. This is an example in which the roller electrode 7 itself is part of the imaging lens. If the bar is made of glass with a cross-sectional diameter of 30 mm, 5■
When the parallel beam of
The image is formed into a spot of 50#Lm at the position where it makes contact with.

FIG. 8 shows another embodiment of the roller electrode 7. In FIG.

The roller electrode 7 and the conductive layer 11 of the carrier multiplier 1 are connected to the semiconductor layer 1
2 and the surface insulating layer 13, a capacitor is formed during electrostatic image reading.

Therefore, the smaller the contact area between the electrode 7 and the insulating layer 13, the smaller the electrical capacitance, the smaller the electrical time constant, and the faster the readout speed of the electrostatic latent image. Therefore, the embodiments shown in Figures (a), (b), and (C) are all examples in which the contact area is smaller than that of a cylindrical roller. (
In a) and (b), the contact surface is approximately dotted.
(c) is an example in which the contact area is reduced by making it gear-shaped. (
As in the examples a) and (b), high-speed rotation, spot light,
There is no need to synchronize with each other.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of an electrostatic image reading device to which the present invention is applied, Fig. 2 is an explanatory diagram of the operation of the image holder, Fig. 3 is an explanatory diagram of the operation of another embodiment, and Figs. 4 and 5. 6 is a side view showing an embodiment of a roller electrode, FIG. 6 is a diagram showing an output signal, FIG. 7 is a perspective view of an embodiment of a planar needle electrode, and FIG. 8 is a perspective view of another embodiment of a roller electrode. It is. 1 is an image carrier, 2 is a primary charger, 3 is a uniform exposure lamp,
4 is an image exposure optical system, 5 is a secondary charger, 6 is a full-surface exposure lamp, 7 is a roller electrode, 9 is a scanning optical system, 11 is a conductive layer,
12 is a semiconductor layer, and 13 is an insulating layer. 1 470- Unexamined Japanese Patent Publication No. 59-161178 (5) Fig. 6 Iff) 1 Fig. 5, Fig. 7, continuation of page 1 0 Inventor: Takashi Yozaki - 3-30-2 Canon, Shimomaruko, Ota-ku, Tokyo Co., Ltd. 473-

Claims (1)

[Claims] (1) A primary charging means that charges an electrostatic image holder having an insulating layer, a semiconductor layer excited by electromagnetic waves to become conductive, and a conductive layer, and a uniform electromagnetic wave applied almost simultaneously with the secondary charging. a means for irradiating an electromagnetic wave with image information, a means for irradiating an electromagnetic wave for image information substantially simultaneously with the secondary charging, a means for irradiating the entire surface with an electromagnetic wave; An electrostatic image reading device comprising: means for scanning an electrostatic image formed by each means with electromagnetic waves; and an electrode for reading an electric signal at the scanning position.