Device for fitting and adjusting an encoder

A device for fitting and adjusting an encoder comprising a first inclined plate and a second inclined plate joined together rotatably between an encoder fitting surface and a fitting flange, a joined surface between the two inclined plates being slightly inclined to a surface orthomic to the axis of a rotation shaft while remaining surfaces on the opposite side of each plate being orthogonal to the axis, so that the rotation shaft of a rotatable body is in parallel to a rotations shaft of the encoder by adjustment of either plate or both.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a device for fitting and adjusting an encoder in 
which, when a rotation shaft of a scanning drum in a drum type image 
scanning and recording apparatus is joined to a rotation shaft of an 
encoder through a diaphragm type coupling or the like so that a rotating 
angular speed of the former may be exactly transmitted to the latter, 
error in transmission of the rotating angular speed due to deviation of 
squareness between a flange and a rotation shaft of an encoder itself can 
be corrected. 
2. Prior Art 
In a drum type image scanning and recording apparatus, when, for example, a 
scanning drum on the peripheral surface of which an original picture is 
mounted and a recording drum on the peripheral surface of which a 
photosensitive material such as film is mounted, are respectively rotated 
at a specified angular speed, a reproduced image of said original picture 
is supposed to be recorded either at full or magnified size on said 
photosensitive material. For that purpose, the apparatus is usually 
equipped with a timing signal generating means to control various timings 
at the time of recording such reproduced image. As one of such means a 
rotary encoder is connected with each rotation shaft of the scanning drum 
on the original picture reading side and the recording drum on the 
recording side thereof through a coupling adapted to the encoder. 
Accordingly, it is required for such coupling to accurately transmit 
rotation of the rotation shaft of said drums to a shaft of the encoder. 
Generally, when joining a drive shaft such as a rotation shaft of the 
scanning drum to the rotation shaft of the encoder through a coupling, it 
is very difficult to connect both rotation shafts coaxially for reasons of 
machining accuracy of a supporting bracket, flanges, bearings, etc. Hence, 
as a coupling satisfying the aforementioned requirement even when both 
rotation shafts are not coaxial (i.e., a coupling enabling transmission of 
equal angular speed), a so-called diaphram type coupling is widely used. 
According to such diaphram coupling, even though the rotation shafts of 
the drum and the encoder are not coaxial, transmission of an equal angular 
speed is supposed to be possible, so far as it is established that angles 
.theta..sub.1 and .theta..sub.2 made among axes of the coupling shaft (1), 
drum rotation shaft (2) and encoder rotation shaft (3) on the same plane 
(on a paper in this case) are equal to each other as shown in FIG. 4. In 
such arrangement, however, if the encoder rotation shaft (3) moves a 
slight distance in the same plane, for example, as shown in two dot chain 
lines in FIG. 4 .theta..sub.1 ' is not equal to .theta..sub.2 ' 
(.theta..sub.1 '.noteq..theta..sub.2 ') and the angular speed cannot be 
transmitted from the drum rotation shaft (2) to the encoder rotation shaft 
(3). 
On the other hand, as shown in FIG. 5, if the drum rotation shaft (2) and 
the encoder rotation shaft (3) are parallel to each other in the same 
plane (a paper in this case), the angles made among the axes of the 
coupling shaft (1), drum rotation shaft (2) and encoder rotation shaft (3) 
must be .theta..sub.1 =.theta..sub.2, .theta..sub.1 '=.theta..sub.2 ' as 
shown by the two dot chain lines in FIG. 5 even when aforementioned 
parallel movement occurs in the same plane, and the equal angle speed can 
be transmitted from the drum rotation shaft (2) to the encoder rotation 
shaft (3). 
Heretofore, a fitting device of such encoder comprises a bracket (6) fixed 
to a base (4) and by which an encoder (E) is coaxially fitted to the 
rotation shaft (2) of a drum (D) at its flange portion (5). This fitting 
bracket (6) is fixed to the base (4) so that a surface to which the flange 
portion (5) is fitted is orthogonal to the drum rotation shaft (2). Then, 
a diaphram coupling (C) is coaxially connected to the drum rotation shaft 
(2) and fitted to a shaft end portion of an extended shaft (2') having the 
same diameter as the rotation shaft (3) of the encoder (E) and a shaft end 
portion of the encoder rotation shaft (3). 
Accordingly, unless there is no error at all in the squareness between the 
fitting surface of the flange portion (5) of the encoder (E) and the 
rotation shaft (3) thereof, the aforementioned parallel relation is 
established between the drum rotation shaft (2), i.e., the extended shaft 
(2') and the encoder rotation shaft (3), and even when there is slight 
offset between both shafts (2'), (3), transmission of equal angular speed 
is supposed to be carried out from the drum rotation shaft (2) to the 
encoder rotation shaft (3). 
3. Problem to be Solved 
It is true that an equal angular speed is sometimes not transmitted as 
designed from the drum rotation shaft (2) to the rotation shaft (3) of the 
encoder (E) fitted on the conventional encoder fitting device. As a result 
of investigations, it is found that such problem is caused by a slight 
angle error in the squareness between the fitting surface of the flange 
portion (5) of the encoder (E) and the rotation shaft (3) thereof. Such 
error can be corrected by machining the fitting surface of the flange 
portion (5) on the basis of the rotation shaft (3), but such correction is 
rather troublesome requiring much labor and time. 
SUMMARY OF THE INVENTION 
Accordingly, an object of the invention is to provide an improved encoder 
fitting and adjusting device in which troublesome correction is replaced 
with a simple adjusting operation at the time of fitting an encoder, 
whereby a drum rotation shaft and an encoder rotation shaft are kept in a 
parallel relation therebetween. 
In order to accomplish the foregoing object, a device for fitting and 
adjusting an encoder according to the invention is arranged as follows. 
That is, the technique of the invention involves a device for fitting and 
adjusting an encoder connected to a rotation shaft of a rotatable body 
through a diaphram type coupling or the like, and wherein a fitting 
surface on which an encoder for transmitting rotation of equal angular 
speed of said rotation shaft is fitted is formed orthogonal to an axis 
(X--X) of the rotation shaft of said rotatable body, and a fitting, 
bracket having a through hole around said axis (X--X) is fixed to a base, 
said device being characterized in that 
A first inclined plate having a through hole is joined to a fitting surface 
of said bracket so that the through hole and that of said bracket may be 
coaxial, 
a second inclined plate having a through hole is held on the opposite side 
of said joined surface of the first inclined surface so that the through 
hole and that of said first inclined plate may be coaxial, 
the joined surface between said first and second inclined surfaces are not 
orthogonal to said axis (X--X) but formed into a gentle inclined surface 
with a slight inclination, 
in normal condition, respective opposite sides to the joined surface 
between said first and second inclined plates (the opposite side of the 
second inclined plate is used as the encoder fitting surface) are kept 
parallel to each other so as to be orthogonal to said axis (X--X), and 
both first and second inclined plates are rotatable. 
Since the encoder fitting adjusting device according to the invention is 
arranged as above, when the second and first inclined plates are fixed by 
appropriately rotating them so that an angle made between the axis (X--X) 
and a normal line in the encoder fitting surface may be equal to an 
inclination which is an error in a preliminarily measured squareness 
between the fitting surface on the encoder and the rotation shaft thereof 
and that said inclination is offset as such position as said angle becomes 
equal to the inclination, the rotation shaft of the encoder is kept in 
parallel to the rotation shaft of the rotatable body, and accordingly by 
joining each rotation shaft together at their shaft end portions through a 
diaphram type coupling, rotation can be exactly transmitted from the 
rotation shaft of the rotatable body to the rotation shaft of the encoder. 
Thus, in the device for fitting and adjusting an encoder according to the 
invention, a slight deviation in the squareness between the flange surface 
for fitting the encoder and the rotation shaft thereof is substantially 
cancelled by rotating the annular inclined plates at a large angle. This 
means an adjustment for keeping the rotation shaft of the rotatable body 
and that of the encoder in parallel to each other can be quite easily 
performed, and hence an equal angular speed can be exactly transmitted 
from the rotation shaft of the body to that of the encoder by using a 
diaphragm type coupling, for example.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Described hereinafter is a embodiment of the present invention in which a 
rotation shaft of a scanning drum and a rotation shaft of an encoder in a 
drum type image scanning and recording apparatus are joined together 
through a diaphragm type coupling with reference to the accompanying 
drawings. 
The device of FIG. 1 comprises a conventional bracket (6) shown in FIG. 6 
to which a first annular inclined plate (11) and a second annular inclined 
plate (12) are added. A joined surface between the first and second 
annular inclined plates (11), (12) is not orthogonal to the axis (X--X) of 
said drum rotation shaft (2) but formed into a gentle inclined surface 
making a slight angle .theta.(.theta.=0.5.degree. approx. for example) to 
an arthotomic surface with the axis (X--X) as shown in FIG. 3. 
Accordingly, in the normal condition illustrated, a joined surface between 
the first annular inclined plate (11) and the bracket (6) is kept in 
parallel to a joined surface between the second annular inclined plate 
(12) and a flange portion (5) of said encoder, and both of these joined 
surfaces are orthogonal to the axis (X--X) of the drum rotation shaft (2). 
The first annular inclined plate (11) has projecting engaging portions, a 
left one engaging with an inner peripheral surface of the bracket (6) 
while a right one engages with the second annular inclined plate (12). As 
shown in FIG. 2, a plurality of or arcuate slots (13) for set bolts are 
formed (for example, 4 slots) on the second annular inclined plate (12) to 
connect it rotatably with the first annular inclined plate (11), and 
tapped holes (14) are formed in the intermediate points between each two 
slots (13) for fitting the encoder (E). Further, although not illustrated 
in the form of a plan view, a plurality of or arcuate slots (15) (4 slots, 
for example) are formed correspondingly on the first annular inclined 
plate (11) for the set bolts to connect it rotatably with to the bracket 
(6), and a plurality of tapped holes (16) (12 holes, for example) for said 
set bolts are formed on a circumference of the first plate (11) having the 
same diameter as the circumference of the second annular inclined plate 
(12) on which the arcwise slots (13) are formed. A plurality of tapped 
holes (17) for said set bolts are formed on a circumference of the bracket 
(6) having the same diameter as the circumference of the first annular 
inclined plate (11) on which the arcwise slots (15) are formed. 
Accordingly, by fixing the first annular inclined plate (11) to the fitting 
bracket (6) by said set bolts, the second annular inclined plate (12) can 
be turned to get a required position by a turning rod inserted in a 
through hole (18) radially formed on the second annular inclined plate 
(12) under the state that the set bolts between the first and second 
annular inclined plates (11), (12) are removed. Then the second annular 
inclined plate (12) can be fixed to the first annular inclined plate (11) 
by said set bolts. Such fixation can be applied in almost the same manner 
when fixing the first annular inclined plate (11) to the fitting bracket 
(6). 
Operation of this device is described hereunder. 
First, an angle made between the rotation shaft (3) of the encoder (E) and 
the fitting surface of the flange portion (5), i.e., an inclination 
(.phi.) between the axis of the rotation shaft (3) and the normal line of 
said fitting surface is measured. 
Then, under the state that the set of bolts for fixing the first annular 
inclined plate (11) to the bracket (6) is taken off, the first annular 
inclined plate (11) is rotated so as to be in an angle range possible to 
be corrected by the rotation of the second annular inclined plate (12) 
alone, and then by turning the second annular inclined plate (12), the 
second annular inclined plate (12) is fixed to the first plate (11) by 
said set bolts at a rotation angle position where the angle made between 
the normal line on the surface for fitting the flange portion (5) of the 
encoder (E) and the axis (X--X) of said drum rotation shaft (2) is equal 
to said inclination (.phi.). 
When the encoder (E) is fixed to the second annular inclined plate (12) 
arranged as above at the flange portion (5), since the rotation shaft (3) 
of the encoder (E) is in parallel to the rotation shaft (2) of the drum 
(D), rotation of an equal angular speed is exactly transmitted from the 
drum rotation shaft (2) to the encoder rotation shaft (3) by connecting of 
a shaft end surface of the extended shaft (2') of the rotation shaft (2) 
with that of the rotation shaft (3) under said parallel state. 
In the case of rotating the second annular inclined plate (12) alone of the 
two inclined plates (11) (12) under the normal state shown in FIG. 1, a 
relation between the inclination (.phi.) made between the axis (X--X) and 
the normal line of the encoder fitting surface of the second annular 
inclined plate (12) and a rotation angle (.beta.) can be calculated by the 
underdescribed process. By graduating such relation on the joined surface 
area of the first and second annular inclined surfaces as shown in FIG. 3, 
the encoder fitting operation can be carried out more easily using the 
graduations, i.e., scales. 
Described hereunder is a process for calculating the relation between the 
inclination (.phi.) and the rotation angle (.beta.). 
Referring to FIG. 3, a normal line OP is drawn from the center (0) of the 
first annular inclined plate (11). An angle made between the axis (X--X) 
of the drum rotation shaft (2) and the normal line OP is equal to an 
inclination (.theta.) made by the joined surface between the first and 
second annular inclined plates (11) (12). Then a point (A) is established 
on the normal line OP which is distant from the point (0) by an unit 
length 1, and a point (B) is further established at an intersection point 
of a line perpendicular to the normal line OP with the axis (X--X). 
The second annular inclined plate (12) is turned clockwise through 
(.beta..degree.) on the normal line OP as indicated by the arrow. 
Considering that the point (B) moves to a point (B.sub.1) by such turning 
and establishing this point (B) as the origin (0,0,) in the shown 
coordinates (x, y), the coordinates (x.sub.1, y.sub.1) of the point 
(B.sub.1) can be expressed as follows: 
x.sub.1 =tan .theta..multidot.sin .beta. 
y.sub.1 =sin .theta.-sin .theta..multidot.cos .beta.=sin .theta.(1-cos 
.beta.) 
And B B.sub.1 =(x.sub.1.sup.2 +y.sub.1.sup.2).sup.1/2 is obtained. 
Further, establishing the inclination (.phi.) made between the line 
OB.sub.1 and the axis (X--X), the following expression is obtained: 
##EQU1## 
Since the inclination (.theta.) of the joined surface between the first and 
second annular inclined surfaces (11) (12) is known (0.5.degree., for 
example), it is possible to obtain the inclination (.phi.) made between 
the normal line on the second annular inclined plate (12) and the axis 
(X--X) when the second plate (12) is turned by (.beta..degree.) with 
respect to the first annular inclined plate (11). 
In this manner, the inclination (.phi.) produced when turning the (.beta.) 
every 2.degree. or 5.degree. is calculated to be graduated on the joined 
area of the inclined plates (11) (12). 
It is also possible to make a table of the relation between (.phi.) and 
(.beta.) to use for the adjustment. 
In addition, a diaphram type coupling is used as a joint in the above 
described embodiment, but the invention includes an arrangement using two 
universal joints (hook joint) through an intermediate shaft or ejual speed 
ball pjoints, which is the same as the embodiment form the view point of 
principle.