JPH0720997Y2 - Reading roller for contact image sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a reading roller for a contact image sensor such as a facsimile.

(Prior Art) As a document reading device for a facsimile, a device shown in FIG. 2 is known. In FIG. 2, the reading roller 1 is a rotatable rubber roller composed of a core metal 1a and a rubber layer 1b. The surface of the glass plate 3 of the contact-type image sensor 2 pushed up by the lower spring 4 is in contact with the lower surface of the reading roller 1 at a constant pressure. A feed roller 5, a swingable document separating piece 6 and a document table 7 are provided on the document supply side of the reading roller 1, and the feeding roller 5 is a driving motor common to the reading roller 1. It is driven by (not shown) and rotated at a predetermined speed, and a large number of originals 8 placed on an original table 7 are separated one by one by an original separating piece 6 and imaged with the above-mentioned reading roller 1. It is sent to the contact portion of the sensor 2. In this case, manuscript 8
Is fed forward by a frictional force with the reading roller 1, so that a slip occurs between the reading roller 1 and the original 8 and the image obtained on the receiving side is greatly expanded, or the left and right sides of the original 8 are increased. Conventionally, the rubber layer 1b of the reading roller 1 is formed of silicone rubber having a relatively large friction coefficient so that the original 8 is not skewed due to a difference in the feeding speed of the sheets. It was maintained at the standard.

(Problems to be Solved by the Invention) The above-mentioned reading roller 1 is idle while the glass plate 3 of the sensor 2 is in contact with the lower surface of the original 8 at a constant pressure until the leading edge of the document 8 reaches the reading roller 1. In contrast to rotation, conventionally, the rubber layer 1b of the reading roller 1 was formed of silicone rubber having a relatively large friction coefficient, so that the reading roller 1 was made of a smooth glass. The torque required to rotate the reading roller 1 in pressure contact with the surface of the plate 3 (hereinafter referred to as the axial torque), that is, the loss torque of the drive motor generated during the idle rotation becomes large, and the reading roller 1 and the feeding roller are fed. A large motor is required to drive the roller 5, which makes it difficult to downsize the entire device.

The present invention provides a reading roller capable of reducing the driving torque during idling rotation without deteriorating the transportability of the reading roller 1, and thereby the driving motor,
As a result, the size of the entire device can be reduced.

(Means for Solving the Problem) A contact image sensor reading roller 10 (see FIG. 1) of the present invention is for a contact image sensor including a cored bar 11 and a rubber layer covering the surface of the cored bar 11. Reading roller
10, the above rubber layer is a central rubber layer 12 that covers the central portion in the width direction of the cored bar 11 and end rubber layers 1 that cover both sides in the width direction.
The central rubber layer 12 is made of silicone rubber having a relatively large hardness and friction coefficient, and the end rubber layer
13 is formed of a silicone rubber having a relatively small hardness and friction coefficient.

The silicone rubber forming the central rubber layer 12 is JIS-
A rubber has a hardness of 50 to 70 degrees and a friction coefficient of 0.8 to 1.2 on a smooth glass surface. In addition, the end rubber layer 13 is a JI
SA rubber hardness 30-45 degrees, friction coefficient to glass 0.3
Formed from ~ 0.7 silicone rubber. Then, the reading roller 10 is pressed against the glass surface 3 of the contact image sensor 2.
The axial torque required to rotate the reading roller 10 when contacted at 68 g / cm (original paper size A4 with a load of 1.5 kg) is 1.0 to 1.6 kgcm for paper size A4 (total rubber layer width 220 mm). , The width d of the central rubber layer 12 is 1.2 to 1.9 kg · cm for paper size B4 (total rubber layer width 260 mm) and 1.4 to 2.3 kg · cm for paper size A3 (total rubber layer width 310 mm). It is preferable to set it in the range of 10 to 50% of the total width D. The end surface of the central rubber layer 12 is preferably formed into a conical surface or a flat surface having an inclination angle α of 60 to 90 degrees with respect to the axis so that the central rubber layer 12 does not cover the end rubber layer 13. .

(Function) The central rubber layer 12 is made of a conventional relatively hard silicone rubber,
Further, since the end rubber layers 13 are each formed of a relatively soft silicone rubber, the original 8 is mainly fed forward by the central rubber layer 12, so that the straightness of the original 8 is improved and skewing is less likely to occur. Moreover, since the end rubber layers 13 having the same diameter as the center rubber layer 12 and the hardness and the coefficient of friction being low are provided on both sides of the center rubber layer 12, the end rubber layers 13 are formed as
The shaft torque is reduced as compared with the case where the diameter of the end rubber layer 13 is smaller than 12 so that the end rubber layer 13 does not contact the original document 8, and the transportability is maintained at substantially the same level as that of the conventional silicone rubber.
Further, when the reading roller 10 is directly contacted with the glass surface 3 of the contact type image sensor 2 and rotated, the unevenness of the glass surface 3 is absorbed by the edge rubber layer 13 having low hardness and the edge portion is Since the friction coefficient of the rubber layer 13 is low, the axial torque of the reading roller 10 is smaller than that of the conventional silicone rubber, and therefore, the loss torque of the drive motor when the reading roller 10 idles is reduced, and the drive motor is accordingly reduced. Can be downsized. Also, the central rubber layer
Since both 12 and the end rubber 13 are silicone rubber, the bonding force at the boundary is improved and peeling is less likely to occur as compared with the case where the rubber type of both rubber layers 12 and 13 is changed.

However, if the hardness of the silicone rubber forming the central rubber layer 12 is less than 50 degrees of JIS-A rubber hardness, or if the friction coefficient is less than 0.8, the transportability is reduced and the image stretches. And the skew becomes excessive. On the contrary, the hardness is
If it exceeds 70 degrees, the flexibility becomes poor, and it becomes difficult to press the document at the reading position of the sensor accurately. If the friction coefficient exceeds 1.2, the shaft torque becomes excessive. Also,
When the JIS-A rubber hardness of the end rubber layer 13 is less than 30 degrees, the deformation becomes large, so that the shaft torque is excessively absorbed by the sensor surface, and conversely, when the hardness exceeds 45 degrees. Has a small amount of deformation, so that the central rubber layer 12 is insufficiently pressed against the document, and the transportability is degraded. Further, when the friction coefficient of the end rubber layer 13 is less than 0.3, the transportability is reduced, and when it exceeds 0.7, the axial torque becomes excessive. Further, if the width d of the central rubber layer 12 is less than 10% of the total width D, the transportability becomes insufficient, and conversely, if the width d exceeds 50% of the total width D, the axial torque loss becomes excessive. At the boundary between the central rubber layer 12 and the end rubber layer 13,
When the central rubber layer 12 covers the end rubber layer 13, the outer peripheral boundary line is disturbed.

(Embodiment) In FIG. 1, the rubber type and hardness of the central rubber layer 12 and the end rubber layer 13 in the reading roller 10 having an overall width D of 220 mm,
The coefficient of friction and the width d of the central rubber layer 12 were variously changed, and the elongation, skew amount and axial torque of the images were compared. In addition,
The hardness, the coefficient of friction, the image elongation, the amount of skew and the axial torque of the rubber layer were measured by the following methods.

Hardness: According to JIS-A rubber hardness tester.

Coefficient of friction μ: A reading roller made of the same rubber with a width of 220 mm and having a diameter of 20 mm is pressed against the surface of the glass plate with a load W of 805 g (including the weight of the reading roller), and the reading roller is parallel to the surface of the glass plate. Moreover, the tensile load w was measured when sliding at right angles to the axis and moving at a speed of 100 mm / min, and calculated by the formula μ = w / W.

Image stretch: The length of 268 m drawn on the test chart No. 2 where the image stretches easily using a facsimile in copy mode.
The difference (mm) between the length L obtained by copying a straight line of m and the length l obtained by copying a straight line of the same length drawn on plain paper is taken as the elongation of the image.

Skew amount: When feeding an A4 size document, the edge was introduced along the guide, and the amount (mm) in which the trailing edge was displaced from the guide was defined as the skew amount.

Axial torque: The glass surface of the image sensor is pressed against the surface of the reading roller with a force of 1.5 kg to stabilize the axial torque through 100 originals, and then a torque gauge is fixed to the axis end of the reading roller to rotate. Then, the highest torque reading is used as the shaft torque.

The measurement results are shown in Tables 1 and 2 below. However, A1 in the table is a commonly used silicone-modified hard ethylene propylene rubber (SEP), A2 is a silicone rubber with a general orientation and a relatively high hardness and friction coefficient, and B1 is a polymeric material as a lubricant. Soft ethylene propylene rubber (EPDM) blended with fine powder, B3 to B6 soft rubber blended with the above lubricant, and C a hard chloroprene rubber of a general blend. In addition, Sample No. 3 is made entirely of the above SEP (A1),
This means that the part with a width of 60 mm in the center is made thicker than other parts to form a step.

As can be seen in Tables 1 and 2 above, the hardness is 60
Sample Nos. 9 and 10 provided with a central rubber tank 12 made of a hard silicone rubber A2 having a degree of friction of 0.9 and an end rubber layer made of a soft silicone rubber B3 having a hardness of 35 degrees and a friction coefficient of 0.6. , 11, 12, 13 and the above-mentioned central rubber layer 12 and hardness 35 degrees, the coefficient of friction is 0.5, the end rubber layer made of a soft silicone rubber B4 sample number 14, 15, 16, 17,
In No. 18, the axial torque increases as the width of the central rubber layer increases, and if the material of the end rubber layer is changed from rubber B3 with a large friction coefficient to small rubber B4 without changing the material of the central rubber layer, the axial torque will change. Becomes smaller. Then, in the sample numbers 9 to 13 using the rubber B3 having a large friction coefficient as the end rubber layer, there is no large change in the elongation and the skew amount of the image, and the axial torque is large when the width of the central rubber layer is large. Become. Further, in Sample Nos. 14 to 18 in which the rubber B4 having a small friction coefficient is used as the end rubber layer, the elongation and the skew amount of the image are large when the width of the central rubber layer is small. In these sample numbers 9, 10, 11, 14, 15, 16, 17, 18, the shaft torque is small and falls within the range of 1.0 to 1.6 kg · cm.
In case of 10, 11, 16, 17, 18, the image elongation is 7 mm or less,
The skew amount is 5 mm or less, and the transportability is good.

On the other hand, in the combinations other than the above, even if the axial torque becomes a preferable value, the elongation or the skew amount increases and the transportability decreases. On the contrary, when the transportability becomes good, the axial torque increases. Be oversized. That is, sample numbers 1, 5, 6, 8
Is EPDM (B1) and silicone rubber (B3, B4, B), which have smaller hardness and friction coefficient than hard silicone rubber A2.
Since the entire rubber layer is formed in 6), the shaft torque is small, but the elongation and skew are large. However, since sample No. 7 is made of silicone rubber (B5) having a low hardness and a relatively high friction coefficient, it has good transportability, but has a large axial torque. Further, in Sample No. 4, since the entire rubber layer is made of silicone rubber, the transportability is good, but the axial torque is excessive. In the sample No. 3, since the widthwise central portion has a larger diameter than both sides to form a step, the skew amount is particularly small, but the axial torque is excessive. Also, sample numbers 5 and 6 are EP
Although the friction coefficient and axial torque are smaller than those of sample No. 1 made of DM (B1), since it is made of silicone rubber B3 and B4, the amount of elongation and skew does not become larger than that of sample No. 1, and is slightly While getting smaller. Also, the end rubber layer of sample number 15 was changed from silicone rubber with a friction coefficient of 0.5 (B4) to silicone rubber with a friction coefficient of 0.8 (B5).
No. 9 has improved transportability but has excessive axial torque.
On the other hand, Sample No. 20, which has been changed to silicone rubber (B6) with a friction coefficient of 0.2, has a small axial torque, but the transportability is significantly reduced. Also, sample No. 21 uses the same amount of hard silicone rubber A2 and soft silicone rubber (B4) as sample No. 15, so the shaft torque is the same, but hard silicone rubber A2 is used at the end. Since the soft silicone rubber B4 is used in the center, the edge rubber layer made of hard silicone rubber does not work for narrow documents, and the rubber layer made of soft silicone rubber (B4) only Produces the same result as. Further, in the sample No. 22, since the entire rubber layer is formed of chloroprene rubber having a friction coefficient larger than that of silicone rubber, the axial torque becomes excessive.
Sample No. 2 in which the central rubber layer was formed from this chloroprene rubber and the end rubber layer was formed from hard silicone rubber
The shaft torques of 3 and 24 are too large.

(Effect of the Invention) As described above, according to the present invention, the rubber layer of the reading roller for the contact type image sensor is composed of the central rubber layer at the center in the width direction and the end rubber layers at both sides in the width direction. Made of silicone rubber with relatively high hardness and friction coefficient,
Since the edge rubber layer is formed of silicone rubber having a relatively small hardness and friction coefficient, the width of the central rubber layer is set according to the paper size and the elongation and skew amount of the image are set by the conventional silicone rubber. The shaft torque can be made smaller than that of the above-mentioned silicone rubber while maintaining the same level as that of the product, so that the drive motor and thus the entire device can be downsized. Since both the central rubber layer and the end rubber layer are made of silicone rubber, the bonding force at the boundary between both rubber layers is large, and peeling hardly occurs.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view of a facsimile reader. 1, 10: reading roller, 2: contact image sensor, 3: glass plate, 11: core metal, 12: central rubber layer, 13: end rubber layer.

Claims (1)

[Scope of utility model registration request] 1. A reading roller for a contact type image sensor comprising a cored bar and a rubber layer covering the surface of the cored bar, wherein the rubber layer covers a central rubber layer covering the central part in the width direction of the cored bar and the width. End rubber layer covering both sides in the direction, the central rubber layer is formed of JIS-A rubber hardness 50 to 70 degrees, the friction coefficient to glass is 0.8 to 1.2 and the silicone rubber having a relatively large friction coefficient. A reading roller for a contact type image sensor, characterized in that the rubber layer is formed of a silicone rubber having a JIS-A rubber hardness of 30 to 45 degrees, a friction coefficient of 0.3 to 0.7 with respect to glass and a relatively small friction coefficient.