JPS599044B2 - Document transport type electronic copying machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an original document transport type electronic copying machine that scans a sheet original by itself and a thick original by placing it on a transparent carrier while transporting the original on an original glass.

Generally, in the copying machine described above, the projection optical system is adjusted so that the projection optical system is focused on the surface of the original sheet when the original sheet is being conveyed.
Therefore, when transporting thick originals or sheet-like originals by placing them on a transparent carrier such as an acrylic or glass plate,
Since the optical path length changes by the thickness of the transparent carrier, it was necessary to correct the optical path length. Moreover, at this time, not only the optical path length changed, but also the amount of exposure light reaching the exposed area due to surface reflection and absorption of the transparent carrier varied considerably. In order to solve these drawbacks, when using a transparent carrier, there were some that required removing or retracting not only the transport rollers and document holding plate for sheet documents, but also the document glass for sheet documents. However, the structure and operation of the device are complicated, and the illumination optical system is contaminated by dust. The amount of change (1) in the optical path length during transport of the transparent carrier is 1=--(1) where d1: thickness of the carrier n1: refractive index of the carrier, and the optical path length is increased by the above (1).

The thickness (D2) of the transparent member for correcting this amount of change (1) may be set as N2: refractive index of the transparent member.

By using a transparent member for optical path length correction in this way, it is possible to obtain a clear image using a transparent carrier for thick originals without retracting the original glass for sheet originals. Since there is a loss of light amount due to absorption and reflection of light by the carrier and the transparent correction member, there is a drawback that there is a difference in the amount of exposure light when the transparent carrier is used and when the transparent carrier is not used.

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned drawbacks, and to use a document transport type electronic copying machine in which a sheet document is carried alone and a thick document is placed on a transparent carrier and conveyed on a document glass, when copying a thick document, a transparent A member that optically corrects changes in optical path length due to the carrier is positioned between the original glass and the projection lens to correct the optical path length.
An object of the present invention is to provide an original document transport type electronic copying machine that corrects the exposure light amount by positioning a member for correcting changes in the exposure light amount between a light source and the document glass.

Hereinafter, embodiments of the present invention will be described based on the drawings.
4 through 4 show the present invention applied to an electrostatic latent image transfer type electrophotographic copying machine.

In the drawing, a copying machine main body 1 includes a paper feeding device 2, a photosensitive drum 3, a developing device 4, and a pair of aperture rollers 5, 6.
A transfer paper conveyance path is formed from the and suction belt 7 to the upper surface of the main body 1, while the document conveyance device 8 and the device 8
An image forming optical system 9 that forms an optical path from the photoreceptor drum 3 to the photoreceptor drum 3 is formed.

This optical system 9 includes an illumination lamp 10 provided at the bottom of the document conveyance device 8, and reflectors 11 and 12 that refract the optical path.
It is composed of an imaging lens 13 provided between the reflecting mirrors 11 and 12. The reflective shade 14 is formed into an ellipsoid and is provided on the back side of the illumination lamp 10, and the light shielding case 16 is provided under the document conveyance device 8 together with the flat auxiliary reflective plate 15.
It is set in. A dustproof glass 17 is fixed to the lower part of the light shielding case 16, and an optical path length correction glass 18 made of heat ray absorbing glass or the like and having a thickness that satisfies the formula (2) is provided to the upper part of the case 16. There is. The optical path length correction glass 18 is rotatably supported by a frame holding member 21 (not shown) of the main body 1, and is positioned at the opening of the reflective shade 14 as shown in FIG. 3 when copying a sheet-like original 19. However, when copying a thick original 20, it is configured to be located in the optical path from the thick original 20 to the imaging lens, as shown in FIG. In the document conveyance device 8, conveyance rollers 22 and 23 for conveying a sheet-like document 19 are rotatably provided on the frame of the main body 1 (not shown), and driven rollers 24 and 25 rotate following the rollers 22 and 23. It is rotatably provided on a side plate (not shown) fixed to the cover 26 of the carrier device 8 .

Moreover, the conveyance roller pairs 22, 24, . Between 23 and 25, the original glass 27 is attached to the frame of the main body 1, and the guide plate 2
8 are provided on the side plates of the cover 26, respectively. The cover 26 is supported by a rotating means provided between one end of the cover 26 and the frame of the main body 1 so as to be openable and closable. The cover 2
6 is opened, the transparent carrier 29 made of a transparent member passes over the transport rollers 22 and 23 and the original glass 27, and the transport roller 2
It is configured to be movable at a predetermined speed by rotation with 2 and 23. Next, to explain the operation of the present invention, when copying the sheet-like original 19, the cover 26 is used in a closed state.

The sheet-like original 19 is sandwiched between the transport rollers 22 and 24, passes between the original glass 27 and the guide plate 28, and is exposed to direct light from the illumination lamp 10 or from the reflector 14 or the auxiliary reflector 15 on the original glass 27. Illuminated by reflected light, the image of the sheet-like original 19 is formed on the photoreceptor drum 3 by the imaging lens 13 . The sheet-like original 19 that has passed over the original glass 27 is transferred to the main body 1 by conveyance rollers 23 and 25.
discharged outside. At this time, part of the document illumination light from the illumination lamp 10 is lost due to surface reflection and absorption of the correction glass 18. On the other hand, when the thick original 20 is placed on the transparent carrier 29 and copied, the cover 26 is first opened, and the transparent carrier 29 with the thick original 20 placed thereon is placed on the transport rollers 22 and 23 and transported.

At this time, the thick original 20 on the transparent carrier 29 is illuminated in the same way as the sheet-like original 19, and an image is formed on the photoreceptor drum 3. Changes in the optical path length due to the presence of the transparent carrier 29 are corrected by positioning the correction glass 18 in the optical path, and the photosensitive drum 3 due to surface reflection and absorption of the transparent carrier 29 and absorption by the correction glass 18 Changes in the amount of exposure light that occur are corrected during copying of the sheet-like original 19 by absorption and surface reflection of the correction glass 18 that is tilted in the optical path between the illumination lamp 10 and the original 19. Note that the amount of surface reflection of the correction glass 18 can be changed by appropriately selecting the angle of inclination between the illumination light directed toward the original 20 from the illumination lamp 10 and the correction glass 18. FIG. 5 shows another embodiment of the present invention, in which the correction glass 18 provides a fixed light amount loss in the width direction of the document in the embodiments of FIGS. 3 and 4. In the embodiment, the holding member for the correction glass provides light loss, so that the amount of light loss can be partially changed.

The correction glass 18 is attached to a holding member 31 provided on the rotating shaft 30,
32, and is rotatably provided around a rotating shaft 30. This holding member 32 blocks part of the light from the illumination lamp 10 when copying the sheet-like original 19, and
It does not obstruct illumination and exposure during copying, and when blocking light from an illumination lamp, it is shaped to block more light at the center in the width direction of the document and less at both ends. The fan 33 forms a ventilation path for cooling the illumination lamp 10 and the original glass 27 through an opening 34 in a portion of the reflector 14 that does not contribute to illumination and an opening 35 near the original glass 27. Since the configuration other than the above-mentioned configuration is almost the same as the embodiment shown in FIGS. 3 and 4, the explanation will be omitted.

When copying a sheet-like original or a thick original, the correction glass 18 rotates around the rotating shaft 30 together with the holding members 31 and 32 to move forward and backward into the optical path, correcting the optical path length change caused by the transparent carrier 29, and holding the original. The member 32 corrects the loss of light due to the transparent carrier 29 and the correction glass 18, and corrects the change in the amount of exposure light due to the switching.

Furthermore, by changing the shape of the holding member 32 according to the characteristics of the optical system or illumination, the amount of illumination light in the width direction of the document can be adjusted and made uniform. Furthermore, with the above-described configuration, the cover 26 and the like cover the original glass 27 when copying the sheet-like original 19, and the disadvantage that the original glass 27 becomes hot due to convection heat from the illumination lamp 10 is avoided when the correction glass 18 is illuminated. This can be prevented by blocking the upper openings of the lamp 10 and the reflective shade 14. In addition, since the cover 26 on the original glass 27 is removed when copying a thick original, heat dissipation from the original glass 27 is good, and no measures against the heat of the illumination lamp 10 are required. Furthermore, the correction glass 18 can also be rotated in conjunction with the opening and closing of the cover 26 of the document conveying device 8 for conveying the transparent carrier 29, and the material is not limited to heat ray absorbing glass. .

Furthermore, the member for adjusting the amount of illumination light may be provided separately from the correction glass 18 as long as it is provided to block light during conveyance of a sheet-like original.

In the above embodiment, the present invention is applied to an electrophotographic copying machine, but the present invention is not limited to this and can be applied to other copying machines.

As described above, the present invention is an electronic document transport type copying machine in which sheet-like originals are placed alone and thick originals are placed on a transparent carrier and transported over the original glass. The optical path length is corrected by placing a component that corrects the change in exposure light amount between the light source and the document glass when copying a sheet document. Since this electronic copying machine is characterized by correcting the amount of exposure light by adjusting the amount of exposure light, it is possible to obtain clear images without being affected by changes in optical path length caused by copying sheet-like originals or thick originals. This eliminates the need for adjusting changes in exposure light amount due to carrier transport.

Furthermore, since the transparent member also serves as the light amount correcting means, and the light amount correcting means consists of a holding member for the transparent member, the exposure light amount can be corrected with a simple configuration.

Furthermore, since the transparent member is provided so as to be movable in conjunction with the switching operation of the document conveying device during transport of the transparent carrier, the switching operation of the transparent member can be easily performed.

Furthermore, since the transparent member is made of a heat ray absorbing member, overheating of the transparent plate can be prevented.

[Brief explanation of the drawing]

FIG. 1 is an external view of a copying machine to which the present invention is applied, FIG. 2 is a sectional view of FIG. 1, FIGS. 3 and 4 are sectional views of an embodiment of the present invention, and FIG. 5 is another embodiment. FIG. 1...Main body, 8...Document transport device, 9
...Optical system, 10...Illumination lamp, 1
1, 12... Reflecting mirror, 13... Imaging lens, 14... Reflecting shade, 15... Auxiliary reflecting plate, 16...・Light-shielding case, 18゜゜゜゜゜“Correction glass, 19...Sheet original, 20
・・・・・・Thick manuscript, 22, 23, 24, 25...
... one roller one 26 ... cover, 27 ...
...Original glass, 28...Guide plate, 29...
...Transparent carrier, 30 ... Rotating shaft, 31
, 32... Holding member.

Claims (1)

[Scope of Claims] 1. In an electronic document transport type copying machine in which a sheet original is carried alone and a thick original is placed on a transparent carrier and transported on the original glass, when copying a thick original, optical path length changes due to the transparent carrier are optically detected. The optical path length is corrected by placing a component that corrects the change in exposure light amount between the light source and the document glass when copying a sheet document. An original document transporting type electronic copying machine is characterized in that the amount of exposure light is corrected by adjusting the amount of exposure light. 2. The document transport type electronic copying machine according to claim 1, wherein the member for correcting the optical path length change also serves as a member for correcting the exposure light amount change. 3. The document transport type electronic copying machine according to claim 2, wherein the member for correcting changes in optical path length corrects changes in exposure light amount by surface reflection thereof. 4. The document transport type electronic copying machine according to claim 1, wherein the member for correcting the change in exposure light amount comprises a holding member for the member for correcting the change in optical path length. 5. The member for correcting the optical path length change is located at a first position between the illumination light source and the original when a sheet-shaped original is transported, and is movable to be located at a second position between the imaging lens and the original when a thick original is transported. 4. A document transporting type electronic copying machine according to claim 2 or 4, wherein the copying machine is provided in a document transporting type electronic copying machine. 6. The document conveying type according to claim 5, wherein the member for correcting the optical path length change is provided movably in conjunction with a switching operation of the document conveying device during conveyance of the transparent carrier. Electronic copy machine. 7. The document transport type electronic copying machine according to claim 5, wherein the member for correcting the optical path length change is made of a heat ray absorbing member.