JPS5854357A - Copying device - Google Patents

Abstract

PURPOSE:To copy an original with a good variable contrast reproducibility, by providing an exposure means due to a transmitted light in the side of one face of an original, and providing an exposure means due to a reflected light in the side of the other face, and performing the exposure for an ordinary original with a reflected light source, and performing the exposure for a light-transmissive original with a transmitting light source. CONSTITUTION:A platen cover part 30 is provided with a light diffusing plate 5 in the face facing to a transparent glass 1 and is provided with a transmitted light source 31 which is moved synchronously with the rotation of a photoreceptor, and an original is inserted to a platen after raising the platen cover part 30. In case that an untransmissive original is copied, is reflected light source 4 in the lower part is lit, and an optical system unit 28 is moved forward in the direction of an arrow to perform the exposure scan. In case that a light-transmissive original is copied, the reflected light source 4 is not lit but a light source 6 of a transmitted light source unit 31 is lit, and the unit 31 is moved forward in the direction of an arrow alone or together with the unit 28 to perform the exposure.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a copying apparatus such as an electrophotographic copying apparatus, and more particularly to a copying apparatus in which an exposure means for irradiating an original is improved.

Some originals to be copied by a copying device are light-transmissive. The optically transparent original refers to a film that has both images on a Km bright 7' ilm, such as an X-ray photographic film or a silabene film for an overhead projector. A light-transmitting original is irradiated with −ts=e and the light −
When exposing an image carrier (photoreceptor) to light, different images are obtained depending on whether the irradiation light is reflected light or transmitted light. Figure 1 (~ shows the cross section of a light-transmissive original when it is irradiated with reflected light. Original glass (transparent glass) 1
A light-transmissive original T is placed on top of L1 and is held down by a platen cover 3 with a white surface and highly reflective skewer, and the original TK is irradiated with a reflective light source 4 from the same source as the photoreceptor (II not shown). do. On the other hand, FIG. 1(b) shows a cross section of a light-transmissive original irradiated with transmitted light.
A light-transmissive original T is placed on top of the LS, and a light-diffusing white 7 tarryl ablative plate C (hereinafter simply referred to as a light-diffusion plate) 5
The transmitted light source 6 illuminates the original T from the side opposite to the photoreceptor (gJ not shown).

Figure 2 shows the density (γ) curve for the original density of a manuscript with the same light transmittance, and Figure 112 (&)
Figure 1(a) shows the r curve when the reflected light shown in K is irradiated, and Figure 12(b) shows the curve when the transmitted light shown in Figure 1 is irradiated. When reflected light is irradiated as shown in Figure 1 (&), it passes through the document τ twice, and the amount of light attenuation due to the document TK is as shown in Figure 1 (b).
Compared to the case of transmitted light irradiation that passes through the inside only once, the amount of light attenuation due to the document T is twice as large. Therefore #! Figure 2 (&
), in the case of the reflected light side light, the intermediate density is reproduced at a higher density than that of the transmitted light 115t, and the intermediate density is reproduced at a high density with nr, and the intermediate tone reproduction is not good.However, as shown in Fig. 2(b), In the case of a transparent image, the intermediate tones are also more accurately reproduced, resulting in a better image.

The present invention uses transmitted light like an X-ray photographic film to perform ordinary copying of originals, which is commonly done with a reflected light source, and also reproduces multi-tone reproduction of light-transmissive originals. The purpose of this invention is to provide a copying apparatus that can make copies with good quality. The first unified means of overcoming
and a second line light means that resists irradiation of 1!12 digits of the original document on the side opposite to the first exposure means for the ige+ and uses the reflected light to cause the image carrier to become redundant. It is traced by a copying device that is

Hereinafter, the present invention will be described in detail with reference to the drawings. Figure 3 schematically shows the structure of an electrophotographic copying apparatus of a fixed original table type according to an embodiment of the present invention. A charging electrode 12, an electrostatic developing device 13, a transfer electrode 14, a separation electrode 15, and a cleaning device 16 are arranged around the photosensitive drum 11 rotating in the direction of the hour hand. After the photoreceptor drum's 11th circumference is uniformly charged by Teiden electrode twisting, the original image is charged with static electricity by a 1° stage consisting of a reflective or transmitted light source and an optical system (mirror, lens). Form a latent image.

The electrostatic latent image on the circumferential surface of the photoreceptor drum 11 is developed into a toner image by the developing device i13, and the toner adheres to the circumferential surface of the photoreceptor drum 11 according to the image. On the other hand, the transfer paper r in the magazine is fed to the left in the diagram in synchronization with the rotation of the photoreceptor drum 11, and the transfer electrode 14 transfers the toner image on the photoreceptor drum ll onto the transfer paper a. Transcribe. After the transfer, the transfer paper P is separated from the circumferential surface of the photoreceptor drum 11 by the separation electrode 15, sent further to the left in the figure, fixed by the fixing device 117, and then discharged from the device.

Here, the 111 original means for forming an original image on the image carrier will be explained. Transparent glass on the manuscript table! A document T can be placed on top, and after the document is placed, it is pressed by a document holding member (platen cover S) I. There is a reflected light source 4 such as a halogen lamp inside the main body of the copying apparatus, which irradiates the original T from the same side as the photosensitive drum 11. Original illuminated by reflected light source 4!
After passing through the light distribution adjustment slit 21, the reflected light first forms a slit image of the document T on the photoreceptor drum II. The embodiment shown here is a document table fixing part, so
As is already well known, when copying, an optical system consisting of a reflective light source 4, an era adjustment slit, and a first reflecting mirror 4 is used.
28N When moving in the direction of the arrow 1 or l in the figure, the second
The mirror unit of the third reflecting mirror 1L moves in the direction of the arrow 1 or l along the optical guide shirt 27 at a speed of m/2, and scanning is performed in synchronization with the rotation of the photosensitive drum 11).

FIG. 3 is a diagram of the main part of the light source as seen from the direction of the main building. In particular, as shown in FIG. 4, a halogen lamp 41 is used as a reflective light source, a light diffusing plate 5 is provided on the transparent surface, and a document presser spring presses the document uniformly to prevent scratches on the document. It is designed to prevent floating.There is a transmissive light source that moves or is synchronized with the rotation of the photoreceptor but is driven separately from the reflective light source unit: L=nit 3, and the transmissive light source is YTM unit 31 K 11 A transmitted light source 6 such as a fluorescent lamp or a halogen lamp is installed.Transmitted light source unit) 31
-4G moves along the transmitted light source guide shaft.
In addition, in this embodiment, the insertion of the document onto the document table is performed using the transmitted light source guide shaft 33 (which also serves as a rotation shaft) and the part of the platen cover (equipment) that has the transmitted light source unit and light diffusing plate 5. After lifting it upwards, he decided to actually do it. The light diffusing plate 5 has the role of diffusing and uniformly applying light to the original when the original is irradiated with a transmitted light source, and serves as a white plate on the back of the original when using a reflective light source.

Now, when copying an opaque original, the reflective light source 4 is turned on, and the optical second lens 2) 2B is moved forward in the direction of the arrow, thereby projecting the copying knife K11l onto the photosensitive drum 11. In addition, when copying a light-transmitting original, use the "X-ray film copy" button (not shown) provided on the copying machine's control panel in advance, and press the copy start button after properly translating the transmitted light source. The transmitted light source 6 is turned on while the light source 4 is not lit, and the transmitted light source unit (31) is an optical system unit.By moving the pot and the co-movement unit independently in the direction of the arrow, the halftone of the KIN document on the photoreceptor drum 11 is adjusted. A faithfully reproduced original image is projected. especially! Although not shown, power is supplied to each light source via sliding contacts or a flexible power cord.

Fig. 5 shows an example in which a surface light such as electro/l/l nescence is provided on a part of the platen cover of the embodiment shown in Figs. The effective surface is divided into mXn segments by pressing down. It is also possible to illuminate the entire surface of a document with one-dimensional transparency.
L2) It is configured so that it lights up sequentially in the direction of the arrow in response to the forward movement of 28, or illuminates only the portion corresponding to the document size or paper feed size.6. EIK shows an embodiment of the present invention in which the document table is movable, and since the document table moves, the optical system's reflective mirror 43 and the reflective light source 4. The transmitted light source 6 remains fixed. Therefore, the original platen fixing MW shown in FIG.
There is no need for a large-scale transmitted light source like in an I-copying device, and there is no need for a device for reciprocating the transmitted light. Therefore, when a transmitted light source is added to a document platen moving plate copying device, one simple device is sufficient and the transmitted light source portion can be detachably constructed. However, since a normal opaque platen cover cannot be used, the light diffusing plate shown in the previous embodiment is used for the platen cover itself.

Of course#! A light diffusing plate may be provided integrally with the transmitted light source cover 311 directly under the transmitted light source that is detachably fixed as shown in FIG.

Furthermore, 117w1 shows a modification of the embodiment in which the present invention is applied to the document table moving unit shown in No. 6 WJ. When using a reflective light source, the 1st column is removed from the manuscript table. This is an example in which a cylindrical light diffusing member 51 rotatably provided around the transmitted light source 6 is configured to also serve as a document holder on a movable document table. In this case, it is preferable that the light diffusing member is a cylinder made of white acrylic resin or the like, with a flexible light-transmitting rubber or the like attached to the outer surface of the cylinder.

The original is moved by the light diffusing member 5 as the original table moves (in the direction of the arrow).
The rotation of step 1 also rotates forward and reverse in synchronization with the movement of the document table, so it can be carried out neatly without any scratches on the document.

The present invention can be carried out regardless of whether the document table of the copying device is moved or fixed, and copies with good gradation can be achieved not only for normal opaque documents but also for light-transmissive documents such as X-ray film.

[Brief explanation of the drawing]

Figure 1 is a T cross-sectional view showing reflected illumination and transmitted illumination, and Figure 2 shows the reflected density relative to the original density.
1W shows a part of the platen cover of another embodiment, and FIG. 6 shows an embodiment of the document table movable type according to the present invention. Figure 7 is the 61st
6I shows a modification of the embodiment 1. 6I: Light diffuser plate Muha: Transmitted light source 11...
...Photoreceptor drums 22.23, 24.26...Reflector b.
...Optical lens magazine...Reflected light source 2) (Capital)...Platen cover part 31...Transmitted light source 2) 61L...
Surface light source representative Kuwahara -mi @ Figure 1 (α) (b) Figure 2 (α) (b) Original 3M shoes
Orysia Ishi 5jI 51st! 1st 41st (α) Kabuto Imako'@5th edition (α) (b)

Claims (1)

[Claims] (1) A first 1Il beam that illuminates the original provided on one side of the original and uses the transmitted light to move the image carrier.
1 light means, and a second exposure means provided on the opposite side of the original to the exposure means III for irradiating the original and exposing the image carrier by the reflected light. copying equipment. Q) The first exposure means is a light source for transmission exposure installed on the original holding member of the original table so as to be scannable, and the second exposure means is a light source for scanning the image carrier 11 on the original table. A copying apparatus according to claim HJIIJJ, characterized in that the light source for reflective exposure is installed in a light source for reflective exposure, and both light sources are provided in a switchable manner.