Original image focusing apparatus having positionally adjustable focus lens

The present invention provides an original image focusing apparatus having a lens for focusing image light from an original on the photosensitive member, a first guide member for guiding a movement of the lens, a carriage on which the lens and the first guide member are mounted, and a second guide member for guiding movement of the carriage. The second guide member can be adjusted in a plurality of positions.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an original image focusing apparatus used 
in a copying machine and the like, and adapted to focus image light from 
an original on a photosensitive member. More particularly, it relates to 
an original image focusing apparatus wherein a focusing lens can be 
shifted in a first direction and a second direction independently. 
2. Related Background Art 
In the past, in order to copy an original image while properly registering 
an original with a recording sheet regardless of a resting reference 
position for the original and a stacking reference position for the 
recording sheets, a technique in which a lens is shifted in a direction 
perpendicular to an optical axis thereof, as well as a direction along the 
optical axis has been adopted to an analogue copying machine, as disclosed 
in U.S. Pat. No. 4,639,121 (Japanese Patent Appln. Laid-Open No. 
61-295544). 
However, in the above conventional apparatus, since the lens was shifted in 
both the optical axis direction and the direction perpendicular to the 
optical axis independently, it was difficult to properly position the 
posture of the lens with respect to the optical axis of the lens by merely 
incorporating the lens into the apparatus. Further, even when the lens was 
initially aligned with the optical axis, since the lens was widely shifted 
in two-dimensional directions, the lens was apt to be deviated from the 
optical axis, thus causing a problem regarding poor-alignment of the 
copied image, the fog in the image caused due to the beams of the image 
light reflected by elements in the apparatus, which results in the 
deterioration of the image. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide an original image focusing 
apparatus having a lens shifted in a first direction and a second 
direction independently, which can solve a problem regarding the 
deterioration of an image. 
Another object of the present invention is to provide an original image 
focusing apparatus having a lens shifted in a first direction and a second 
direction independently, wherein the posture or position lens with respect 
to an optical axis of the lens can be adjusted in a simple manner. 
The other object of the present invention will be apparent from the 
following descriptions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention will now be explained in connection with embodiments 
thereof with reference to the accompanying drawings. 
FIG. 1 is an elevational sectional view of a copying machine into which an 
original image focusing apparatus according to a preferred embodiment is 
incorporated. In FIG. 1, the reference numeral 1 denotes an elongated 
original illuminating halogen lamp; 2 denotes a reflection hood for 
reflecting light from the lamp 1 toward an original illumination portion; 
3 denotes an original glass support on which an original 4 is rested; 5 
denotes a slit member for regulating image light from the original; 6 
denotes a first scanning mirror for scanning the original at a speed V 
together with the lamp 1 and the slit member 5 and for reflecting the 
image light from the original; 7 and 8 denote second and third mirrors 
moved at a speed of 1/2 V and adapted to reflect the image light from the 
first scanning mirror successively; and 9 denotes a zoom lens for focusing 
the image light from the original on a photosensitive member 11. The 
reference numeral 16 denotes a correction plate for correcting a light 
amount of the image light passed through the zoom lens 9; 10 denotes a 
fixed mirror for reflecting the image light passed through the zoom lens 9 
onto the photosensitive member 11; 12 denotes an electrophotographic 
process means for performing the charging, developing, transferring and 
cleaning; 13a, 13b and 14 denote sheet supply cassettes; 15 denotes an 
automatic sheet original feeding device; 17 denotes a fixing device; and 
18 denotes an ejecting portion. 
In the illustrated embodiment, the zoom lens 9 is so designed that it can 
be shifted in a direction along an optical axis (i.e. optical axis 
direction) and a direction perpendicular to the optical axis 
independently, as will be fully described later. 
Accordingly, in the illustrated embodiment, it is possible to copy the 
original image on a recording sheet while maintaining the proper 
registration therebetween even when the original is set at a "side 
reference" and the recording sheet is set at a "central reference". 
Incidentally, the "side reference" for the original indicates the fact 
that the original is set in such a manner as to coincide with one end of 
the original glass support in a direction perpendicular to a scanning 
direction of the original with a same position on the original glass 
support, and the "central reference" for the recording sheet indicates the 
fact that the recording sheet is set in such a manner that a central 
portion of the recording sheet in a direction perpendicular to a sheet 
feeding direction is always positioned at a same position. 
Further, as mentioned above, since the zoom lens 9 can be shifted in the 
optical axis direction and the direction perpendicular to the optical axis 
independently, it is possible to shift the original image (to a direction 
perpendicular to the scanning direction) regardless of the change in the 
magnification rate of the image, thereby permitting the image treatment 
for forming an image at any position on the recording sheet even when the 
analogue copying machine is used. 
Next, a copying sequence and operation steps of the copying machine 
according to the illustrated embodiment will be briefly described. 
First of all, the original is set on the original glass support 3 or in the 
original feeding device 15, and the size of the recording sheet and, if 
necessary, the magnification rate of the image are selected. Then, a copy 
switch (not shown) is depressed. 
When the copying operation is started, the zoom lens 9 is shifted to a 
position depending upon the size of the recording sheet and the 
magnification rate of the image, and is stopped there. At the same time 
when the lamp 1 is turned ON, the first, second and third scanning mirrors 
6, 7, 8 are shifted from the left (in FIG. 1) toward a direction shown by 
the arrow B (i.e. to the right) below the original glass support 3, thus 
scanning the original successively. Light beams from the lamp 1 are 
reflected effectively by the reflection hood 2, thus illuminating the 
original 4 rested on the original glass support 3. 
The reflected light from the illuminated surface of the original 4 passes 
through the original glass support 3 again and passes through an open 
portion of the slit member 5 to reach the first, second and third scanning 
mirrors 6, 7, 8 successively. Then, the light is reflected by these 
mirrors successively to reach the photosensitive member 11 through the 
focusing zoom lens 9 and the fixed mirror 10. When the lamp 1, reflection 
hood 2, slit member 5 and first scanning mirror 6 reach a final original 
reading end position (where these elements are denoted by the same 
reference numerals, but adding dash (')), the lamp, reflection hood, slit 
member and first to third scanning mirrors start to be shifted to a 
direction shown by the arrow C, thus returning to a position for the next 
copying operation. 
The image information obtained on the photosensitive member 11 by scanning 
the under surface of the original glass support in the direction B is 
treated by the electrophotographic process means 12, thereby transferring 
a toner image corresponding to the image light onto a surface of the 
recording sheet. In this case, the recording sheet starts to be supplied 
in response to the scanning timing of the scanning mirrors, thereby being 
fed in registration with the electrophotographic process means. After, the 
transferring operation, the recording sheet is passed through the fixing 
device having a rotating fixing roller 17, where the transferred toner 
image is permanently fixed to the recording sheet. Thereafter, the 
recording sheet is ejected in the ejecting portion 18. In this way, the 
copying operation is finished. 
Next, an optical system through which the image light from the original 
reaches the photosensitive member will be explained. 
1. Original Illumination System 
FIG. 2 is an enlarged schematic view of an original illumination system. A 
portion 41 from the front to the rear on the original glass support 3 and 
therearound are illuminated by the lamp 1 and the reflection hood 2. The 
light reflected from the original passes through an open portion 51 of the 
slit member 5 disposed substantially in a confronting relation to the 
original glass support 3 to be directed to the first scanning mirror 6 
(FIG. 1). The distribution of an light amount on the original glass 
support is shown in FIG. 3. In FIG. 3, the abscissa indicates a dimension 
of a surface of the original from the front to the rear, and the ordinate 
indicates the light amount. An effective illumination area indicates a 
range to be copied. Even in such an effective illumination area, the 
distribution of the light amount on the original surface has the 
unevenness as shown, due to the dispersion and error in the manufacture of 
the lamp and the reflection hood. Thus, in the illustrated embodiment, a 
slit member 52 including an open portion having a variable width as shown 
in FIG. 4 is arranged below the original illumination portion so that the 
unevenness of light beams directing from a lower portion of the slit 
member to the first scanning mirror 6 can be corrected by changing the 
width of the open portion in correspondence to the unevenness of the light 
amount on the original surface. For example, the slit width at a position 
b in FIG. 4 corresponding to a position b in FIG. 3 where the light amount 
is great is decreased; whereas, the slit portion at a position a in FIG. 4 
corresponding to a position a in FIG. 3 where the light amount is small is 
increased. This can be fully accomplished by providing appropriate means 
such as light amount sensors below the slit member. 
In this way the light beams directing from the slit member to the mirrors 
and the lens can be made even or uniform (without any unevenness) from the 
front to the rear, as shown in FIG. 5. 
2. Optical System having Variable Magnification by Zoom Lens 
In the embodiment shown in FIG. 1, the magnification rate can be varied by 
shifting the position of the zoom lens in the optical axis direction and 
by changing the focal length of the zoom lens. That is to say, the 
magnification rate is varied by shifting the position of the whole zoom 
lens and by shifting an inner lens in the zoom lens, while maintaining a 
distance from the original surface to the surface of the photosensitive 
member constant. In this way, according to the illustrated embodiment, 
since the length of the optical path including the zoom lens is not 
changed, when the magnification rate is desired to be varied, the mirrors 
such as the scanning mirrors disposed in the optical path are not required 
to be shifted, thus avoiding an additional complex mechanism and a large 
space. Incidentally, the unevenness in the light amount generated by the 
zoom lens can be corrected by a correction plate 16 (FIG. 1) fixed to the 
zoom lens 9. 
3. Position Adjustment Means for Zoom Lens 
FIG. 6 is an enlarged schematic view of the original image focusing 
apparatus according to this embodiment, showing the zoom lens and 
therearound. The zoom lens 9 is housed in a lens mount 91 on which the 
correction plate 16 is secured. A lower end portion of the lens mount 91 
is provided with an aperture through which a first guide rail 21 for 
guiding the zoom lens in the optical axis direction passes. The first rail 
21 comprises a shaft having a circular cross-section and extending to a 
guiding direction straightly. A zoom belt 30 extends between a shaft of a 
zoom pulse motor 28 and a roller 31 (not visible in FIG. 6) in parallel 
with the first rail 21. Further, a portion of the belt 30 is secured to 
the lens mount by a belt holder 32. When the magnification rate is 
changed, the shaft of the zoom pulse motor 28 is rotated to shift the zoom 
belt 30, thereby shifting the lens mount 91 including the zoom lens 9 
along the first rail 21 in directions shown by the arrow e. A shifting 
amount of the lens mount is controlled by the number of steps of the pulse 
motor detected by a photo-sensor 33. 
The above-mentioned zoom lens 9, lens mount 91, first rail 21, pulse motor 
28, zoom belt 30 and photo-sensor 33 are mounted on a lens carrier 22. The 
lens carrier 22 can be slid by a bearing 105 and a second rail 24 
extending to a direction perpendicular to the optical axis (i.e., 
direction perpendicular to a length of the first rail 21) so that the 
carrier can be shifted and guided along the second rail 24. The second 
rail 24 comprises a shaft having a circular cross-section and extending to 
a guiding direction straightly. The lens carrier 22 can be pivoted around 
the second rail 24. 
The lens carrier 22 and the second rail 24 are arranged on a lens support 
27. Further, a pulse motor 26 is secured and positioned in front of the 
lens support 27. A belt 25 extends from a shaft of the pulse motor 26 to a 
pulley mounted on the lens support at a rear portion thereof. A portion 
(not visible in FIG. 6) of the belt 25 is secured to the lens carrier 22 
so that the lens carrier can be shifted along the second rail 24 in a 
directions shown by the arrow d. A shifting amount of the lens carrier is 
controlled by the number of steps of the pulse motor detected by the 
photo-sensor. When the light beams from the original enters into the 
focusing apparatus from the direction f, if the zoom lens is in the left 
position in FIG. 6, the enlarged copy will be obtained. On the other hand, 
if the zoom lens is in the right position, the contracted copy will be 
obtained. 
A roller 23 (rotary member) arranged at an end of the lens carrier 22 in 
the optical axis direction serves to regulate the height of the lens 
carrier 22 and can roll on the lens support when the lens carrier 22 is 
shifted in the directions d. The roller 23 has a rotation center varying 
in an up-and-down direction so that the deviation of the lens carrier 22 
in the up-and-down direction can be adjusted by pivoting the lens carrier 
22 around the second rail 24. 
Now, a mechanism for moving the roller 23 in the up-and-down direction will 
be fully explained. Incidentally, FIG. 7 is a schematic elevational view 
of the carrier (looked at from the direction f ). 
The roller 23 can roll around an eccentric shaft 106 which is rotatably 
mounted on the lens carrier by a stepped screw 107. Since the eccentric 
shaft 106 is eccentric around the stepped screw 107, when the eccentric 
shaft 106 is rotated, the roller 23 is rotated together with the eccentric 
shaft 106 around the stepped shaft 107, so that the height of the roller 
23 is varied in accordance with the eccentric amount of the eccentric 
shaft 106 and the rotating amount of the eccentric shaft 106. 
Consequently, in the illustrated embodiment, it is possible to correct the 
deviation of he lens carrier 22 in the up-and-down direction, thus 
preventing deterioration of the image such as the poor alignment of the 
focused image and the unclear image. 
Next, an attachment of ends (shown in FIG. 6 as m and n) of the second rail 
or shaft 24 will be explained. FIG. 8 is an enlarged view of a portion m 
shown in FIG. 6, FIG. 9 is an exploded perspective view of the portion of 
FIG. 8 before assembling, and FIG. 10 is an enlarged view of a portion n 
shown in FIG. 6. 
In FIG. 8, one end of the shaft 24 is supported on a first support plate 
101 provided on the lens support 27 via a height adjusting plate 102. This 
arrangement is further explained with reference to FIG. 9. 
In FIG. 9, a stepped end 24a of the shaft 24 is fitted into a hole 102a 
formed in the height adjusting plate 102 to be positioned with respect to 
the height adjusting plate 102. The adjusting plate 102 is provided with 
positioning holes 102c and a support plate 101 is provided with 
corresponding positioning slots 101c. By inserting positioning pins into 
the positioning holes 102c and slots 101c of the adjusting plate 102 and 
support plate 101, the adjusting plate 102 is positioned with respect to 
the support plate 101. After such positioning, the adjusting plate 102 is 
secured to the support plate 101 by set screws 104 passing through holes 
102b in the adjusting plate, and the shaft 24 is secured to the support 
plate 101 by a screw 203 via the adjusting plate 102. Incidentally, in 
this case, the stepped end 24a of the shaft 24 is fitted into an elongated 
slot 204 formed in the support plate 101. 
Now, the elongated slot 204 of the support plate 101 extends in the 
up-and-down direction, and the holes 102b are so called baggy holes each 
having a diameter greater than a diameter of the set screw 104. 
Accordingly, by loosing the screws 203, 104, the end 24a of the shaft 24 
can be shifted along the elongated slot 204 together with the adjusting 
plate 102, so that the position of the shaft 24 can be adjusted in the 
up-and-down direction. After the adjustment, by tightening the screws 203, 
104 again, the end of the shaft 24 is fixed to the support plate 101 at 
the adjusted position. Incidentally, during the adjustment, the 
positioning pins are removed from the positioning holes 102c and slots 
101c. 
In this way, the end 24a of the shaft 24 can be adjusted in the up-and-down 
direction (directions shown by the arrow k in FIG. 6), so that the 
discrepancy of the zoom lens 9 around the first rail or shaft 21 can be 
corrected. 
Next, a supporting mechanism for supporting the other end of the shaft 24, 
i.e., an end portion n shown in FIG. 6 will be explained with reference to 
FIG. 10. 
In FIG. 10, a stepped end 24b of the shaft 24 is supported on a second 
support plate 34 constituting a rib on the lens support 27, via a height 
adjusting plate 103. The end 24b is fitted into a hole 205 formed in the 
height adjusting plate 103 to be positioned with respect to the height 
adjusting plate 103. Similar to the adjusting plate 102, by inserting 
positioning pins into positioning holes and slots of the adjusting plate 
103 and support plate 34, the adjusting plate 103 is positioned with 
respect to the support plate 34. After such positioning, the adjusting 
plate 103 is secured to the support plate 34 by set screws 206. 
Incidentally, in this case, the stepped end 24b of the shaft 24 is fitted 
into an elongated slot 110 formed in the support plate 34. Now, the 
elongated slot 110 of the support plate 34 extends in the up-and-down 
direction, so that, similar to the adjusting plate 102, the adjusting 
plate 103 can be shifted in the up-and-down direction along the elongated 
slot 110 by loosing the screws 206. 
In this way, the end 24b of the shaft 24 can be adjusted in the up-and-down 
direction (directions shown by the arrow l in FIG. 6), so that the 
discrepancy of the zoom lens 9 around the first rail or shaft 21 can also 
be corrected. 
As mentioned above, since the both ends of the shaft 24 can be adjustingly 
shifted in the up-and-down direction, by shifting the both ends of the 
shaft by the same amounts, the height of the zoom lens 9 can be adjusted, 
and, by shifting the both ends of the shaft by different amounts, the 
inclined angle of the zoom lens can be adjusted. 
Incidentally, the shaft 24 is secured to the support plate 101 by the screw 
203 while being pulled toward the support plate 101 in the longitudinal 
direction of the shaft, and the other end of the shaft 24 near the support 
plate 34 is not secured to the support plate but is merely positioned by 
the adjusting plate 103. Further, the shaft 24 can be adjustingly shifted 
to directions shown by the arrow j in FIGS. 6 and 8. Such adjustment will 
be explained with reference to FIGS. 8 and 9. 
As shown in FIGS. 8 and 9, the support plate 101 is secured to the lens 
support 27 by a screw 202. In this case, a hole 207 of the support plate 
101 through which the screw 202 extends is a so-called baggy hole, and 
positioning slots 201 formed in the support plate 101 on both sides of the 
hole 207 extend in the optical axis direction. 
That is to say, after the support plate 101 is positioned with respect to 
the lens support 27 by inserting positioning pins (not shown) into the 
positioning slots 201 of the support plate 101, the support plate 101 is 
secured to the lens support by tightening the screw 202. In this case, in 
a condition that the positioning pins are inserted into the positioning 
slots, when the screw 202 is loosened, the support plate 101 can be 
shifted in the direction j along the slots 201. After the support plate 
has been shifted to any position, it is secured to the lens support again 
by tightening the screw 202 again. 
Accordingly, the end 24a of the shaft 24 can be adjustingly shifted with 
respect to a third axis perpendicular to both the shaft (first rail) 21 
and the shaft (second rail) 24 to correct the discrepancy of the zoom lens 
9. 
In this way, the posture of the zoom lens 9 can be determined at three 
points, i.,e, roller 23 provided on the end of the lens carrier 22 and 
both ends 24a, 24b of the second rail 24, so that, by adjusting these 
points in the up-and-down direction, the height and the angular position 
of the zoom lens 9 can easily be adjusted. 
Incidentally, in the illustrated embodiment, while the first rail mounted 
on the lens carrier was positioned in parallel with the optical axis and 
the second rail for guiding the lens carrier was positioned perpendicular 
to the optical axis, the rail mounted on the lens carrier may extend in 
the direction perpendicular to the optical axis and the rail for guiding 
the lens carrier may extend along the optical axis. 
Further, in the illustrated embodiment, while the focusing lens was the 
zoom lens, a single-focus lens may be used as a focusing lens. 
As mentioned above, although the present invention has been explained in 
connection with particular embodiments, the present invention is not 
limited to such embodiments, but various alterations and modifications can 
be effected within the scope of the present invention.