GB2152685A

GB2152685A - Image scanning and recording

Info

Publication number: GB2152685A
Application number: GB08500324A
Authority: GB
Inventors: Hiroichi Tada; Takashi Ohara; Masahide Ikeda
Original assignee: Dainippon Screen Manufacturing Co Ltd
Current assignee: Dainippon Screen Manufacturing Co Ltd
Priority date: 1984-01-12
Filing date: 1985-01-07
Publication date: 1985-08-07
Also published as: JPS60115248U; GB8500324D0; GB2152685B; DE3443583A1

Abstract

In a reflection-type image-scanning and recording apparatus in which an original mounted on a transparent rotary cylinder is illuminated at its front surface and is also illuminated at its back surface to erase edge shadows and prevent production of dots from the backing, the back illumination system comprises lamp 9, curved shutter 19 which has an inclined lower edge and is rotatable by handle 24 about pivot 26, lens 11 and mirror 17. The back illumination is variable by virtue of the rotatable inclined lower edge 21. <IMAGE>

Description

SPECIFICATION Light quantity control device The present invention relates to a reflection type image scanning and recording system having a transparent, rotatable cylindrical original mount, means for illuminating the front surface of the original and means for illuminating the back surface of the original, such as a back illumination lamp, having a device for controlling the quantity of light emitted therefrom, for use in scanning and recording an original.

Generally, in a process camera, as shown in Fig. 1, when an original 106 is bonded on a backing 108, shadows 107 are formed at the edges of the original 106. For the purpose of erasing the shadows 107 or of making the backing 108 brighter than the highlight portion of the original 106 to thereby prevent formation of dots in the reproduction of the backing 108, a back illumination lamp 109 is disposed below a transparent original mount 1 02. In this case, it is necessary to control the light quantity from the back illumination lamp 109 depending upon the thickness of the original 106 and the light transmission of the backing 108. This control has been conventionally accomplished by controlling the length of time during which the lamp 109 is lit.

It is conceivable that the quantity of light from lamp 109 may be adjusted by changing the voltage thereon. However, the color temperature of said lamp would change with the rise and fall of voltage. Further, if said lamp is a halogen lamp, there is an inconvenience that its life is reduced when the voltage is high.

Therefore, in making such adjustments of light quantity, variations of voltage on the light source must be avoided. To this end, in a process camera, the adjustment of back illumination is controlled with time.

In scanners, recently, images have been often scanned and recorded from originals supported on a backing. In such cases the same problem as in process cameras occurs.

Moreover, in scanners, since an original is scanned in the primary and secondary scanning directions on the cylinder on which it is mounted, the time-dependent control of back illumination is not applicable. Accordingly, it has been a practice in conventional reflective type scanners to illuminate the original from as many directions as possible.

The present invention has been made for the purpose of eliminating the aforesaid problems in the prior art. A first object of the invention is to provide a device enabling back illumination which is applicable to scanners. A second object is to provide a device which makes it possible to change the quantity of light for back illumination without changing the color temperature of the back illumination lamp. A third object is to provide a light quantity controlling device for back illumination applicable to conventional scanners.

Thus according to the invention there is provided a reflection type image scanning and recording system having a transparent, rotatable, cylindrical original mount, means for illuminating the front surface of the original, and means for illuminating the back of the original through said transparent cylindrical original mount provided with a light quantity control device comprising a light source, optical path means for directing the light from said source to the back of said original, adjustable shutter means having an inclined edge positioned in said optical path, and means for moving said shutter means relative to said optical path to thereby change the cross-sectional area of said optical path.

An embodiment of the invention will now be described by way of example only and with reference to Figs. 2 to 4 of the accompanying drawings in which: Figure 2 is a partially schematic, vertical cross-sectional view of the light quantity control device constructed in accordance of the present invention.

Figure 3 is a fragmentary plan view of the device shown in Fig. 2.

Figure 4a through 4c are schematic illustration of the operation of the device of Figs. 2 and 3.

In Figs. 2 and 3, the numeral 2 denotes a hollow original cylinder used in a conventional reflective scanning type color scanner schematically shown. Said original cylinder 2 is made of transparent plastic material, and disposed on an extension of the axis thereof are a lens 11 and a back illumination lamp 9 which is a halogen lamp. The numeral 10 denotes an attaching frame within which a mounting frame 12 for the lens 11 and a box 1 3 for the back illumination lamp 9 are juxtaposed.

The mounting frame 1 2 for the lens 11 has incorporated therein a lens barrel 14, a flarepreventing aperture 1 5 and an optical guide tube 16, and at the front end thereof a reflecting mirror 1 7 is provided, so that the light from the back illumination lamp 9 is passed through the lens 11 and reflected by the reflecting mirror 1 7 to illuminate the back surface of the original 6 from inside the cylinder 2.

The box 1 3 is provided at its bottom with a base 1 8 for mounting the back illumination lamp 9 and at its ceiling with an attaching member 20 for a shutter 1 9 to be interposed between the lamp 9 and the lens 11.

The shutter 19, as shown in Fig. 3, is formed of a curved plate and its lower end forms an inclined edge 21, as shown in Fig.

4. Thus, the shutter 1 9 has a varying shielding area. Further, the shutter 1 9 is fixed to one end of the attaching member 20 by a bolt 23 to extend downwardly. The other end of the attaching member 20 outside the box 1 3 is provided with a handle 24. Approximately the middle of said attaching member 20 is pivotally supported on a bracket 22 extending from the inner wali surface of the box 1 3.

That is, a bolt 26 is inserted through the bracket 22 and then through the attaching member 20, with a double nut 27 applied to said bolt 26. The numeral 28 denotes a guide plate contacted with the upper surface of the attaching member 20 and fixed to the box 1 3.

In addition, said lens 11 and said back illumination lamp 9 may advantageously be the lens and lamp used for illuminating light transmitting originals for the color scanner.

With the present invention arranged in the manner described above, the light from the back illumination lamp 9 illuminates the back surface of the original from inside the cylinder 2 via the lens 11, aperture 15, and reflecting mirror 17, and the quantity of this light can be adjusted as follows: By moving right and left a lever handle 24 in a horizontal plane by a pivotal motion about the bolt 26, the shutter 1 9 is moved along its arcuate path between the lens 11 and the back illumination lamp 9. With the movement of the shutter 19, because of the inclination of the edge 21 of the shutter 19, in its position shown in Fig.

4a, the quantity of light from the lamp 9 is at a maximum and the quantity of light is zero in the position as shown in Fig. 4c. The quantity of light can be continuously finely adjusted by the inclined edge 21 of the shutter 19 in between as shown in Fig. 4b.

In addition, the shutter in this embodiment has been described as being formed of the curved plate having the inclined edge 21 and as being moved between the lens and the lamp, but it may be a curved plate having a V-shaped notch in the middle and adapted to be vertically movable (not shown). In brief, the shutter is provided with an inclined edge adapted to finely adjust the quantity of light from the lamp; so long as this condition is satisfied, any mechanism may be used for the shutter.

Claims

1. A reflection type image scanning and recording system having a transparent, rotata ble, cylindrical original mount, means for illu minating the front surface of the original, and means for illuminating the back of the original through said transparent cylindrical original mount provided with a light quantity control device comprising a light source, optical path means for directing the light from said source to the back of said original, adjustable shutter means having an inclined edge positioned in said optical path, and means for moving said shutter means relative to said optical path to thereby change the cross-sectional area of said optical path.

2. A system as claimed in Claim 1, wherein said light source is a halogen lamp.

3. A system as claimed in Claim 1 or Claim 2 wherein said optical path means are aligned with the axis of said cylindrical original mount.

4. A system as claimed in any preceding claim, wherein said optical path means include a mirror disposed within said cylindrical original mount for redirecting the light from said source to the back of the original.

5. A system as claimed in any preceding claim, wherein a lens is positioned in alignment with said optical path, and said shutter means is disposed between said light source and said lens.

6. A system as claimed in any preceding claim wherein said shutter means are carried at one end of an elongate member having a handle at the other end, and said elongate member is pivotally attached between said ends behind the said light source for a pivotal movement about an axis intersecting said opti cai path.

7. A system as claimed in claim 6 wherein the edge is inclined with respect to the plane in which said elongate member moves.

8. A system as claimed in Claim 6, wherein said shutter means are curved along the path of the pivotal movement of said one end of said elongate member.

9. A system substantially as herein described and with reference to any of Figs. 2, 3 and 4 of the accompanying drawings.