JPS644710B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an apparatus used in an image forming apparatus, etc., which scans an original image by relatively moving an original table and an optical system. It is related to.

[Background technology and its problems]

In the case of an image forming apparatus, for example, a copying machine with a moving document table, power from a drive source is transmitted to the document table using a single spring clutch through a power transmission member composed of a chain, a belt, etc. Scanning the document by moving this document table (also called exposure)
I try to do this.

However, although the spring clutch regulates the speed of movement of the document glass for exposure, it also restricts the speed of movement of the document glass during return, which does not contribute to exposure, and as a result, the return time increases. There was a problem that the speed of copying work could not be speeded up.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a document scanning device that can speed up image forming operations.

[Summary of the invention]

The present invention uses an endless moving body, and includes a first clutch that restricts movement in a direction that contributes to exposure scanning, and a second clutch that restricts movement in a direction that does not contribute to exposure scanning. The above object is achieved by individually controlling the clutches so that the moving speeds in the direction in which they contribute to exposure scanning and in the direction in which they do not contribute are made different.

[Embodiments of the invention]

The present invention will be specifically explained below using Examples.

FIG. 1 is a perspective view of a main part showing an embodiment in which the present invention is applied to a document table driving section of a copying machine, and FIG. 2 is a sectional view of a main part showing an example of a spring clutch portion thereof. Figures 3 and 4 are front views of the main parts thereof, Figure 5 is an explanatory diagram of the relationship between the ratchet wheel and pawl of the spring clutch, and Figure 6 shows an example of the sleeve used therein. FIGS. 7A and 7B are explanatory diagrams showing the state of connection between the stay and the chain; FIGS. 8A and 8B are explanatory diagrams showing an embodiment of the document table fixed position detection member; FIGS. FIGS. 9a to 9e are diagrams explaining the operation, and the first
FIG. 0 is a schematic explanatory diagram showing another example of the spring clutch.

Reference numeral 1 denotes an input gear, which is driven by a drive source (not shown) and is attached to a shaft 8 erected on a base 13 . Also, a first spring clutch (first spring clutch) is attached to the shaft 9.
A second spring clutch (second clutch) 37 is attached to the shaft 10.
is attached to the shaft 11, and an output gear 6 and a drive sprocket 7 are attached to the shaft 11. input gear 1, input gear 2 of the first spring clutch 36;
The input gears 3 of the second spring clutch 37 are in mesh with each other. The output gear 6, the output gear 4 of the first spring clutch 36, and the output gear 5 of the second spring clutch 37 are in mesh with each other. The first spring clutch 36 is connected to the shaft 9
A rib portion 15B for holding and fixing the brake pad 16 coaxially connected to the brake pad 16, a boss portion 15A for rotating the ratchet wheel 17, and a washer 18 for stopping the spring 21 that presses the ratchet wheel 17 against the brake pad 16. A sleeve 15 having a groove for a retaining ring 19 for stopping, a torsion spring 20, a brake pad 16, a ratchet wheel 17, and a spring 2.
1, a washer 18, a retaining ring 19, a pawl 24, a spring 27 for urging the pawl 24, and an electromagnetic solenoid 26 for moving the pawl 24. The torsion spring 20 surrounds the boss part of the input gear 2 and the boss part of the output gear 4, and has one end locked to the input gear 2 and the other end locked to the sleeve 15. ing. This torsion spring 20 is wound in such a direction as to tighten the boss portion of the input gear 2 and the boss portion of the output gear 4 when twisted in the direction of arrow A in FIG. The pawl 24 is supported on the base 13 by a pin 25 having an axis parallel to the shaft 9, and when the electromagnetic solenoid 26 is energized, the pawl wheel 1
The claw 7 and the tip of the claw 24 are angularly displaced about the pin 25 so as to engage with each other.
The sleeve 15 surrounds the torsion spring 20, and the brake pad 16 is locked to the rib portion thereof. It is in pressure contact with a ratchet wheel 17 that can rotate on the boss portion of the sleeve 15. The second spring clutch 37 is connected to the first spring clutch 3
The only difference is that this spring has a torsion spring 22 having a winding direction opposite to that of the torsion spring 20 of No. 6, and the other structure is almost the same as that of the first spring clutch 36. However, each spring clutch 3
The gear ratios of the input side gears and the output side gears 6 and 37 are set as follows. That is, the sum of the number of teeth of the input side gear 2 of the first spring clutch 36 and that of the input side gear 3 of the second spring clutch 37 is made equal to the sum of the output side gears 4 and 5 of each spring clutch, and the first spring clutch 36
The gear ratio of input side gear 2 and output side gear 4 is K,
If the gear ratio between the input side gear 3 and the output side gear 5 of the second spring clutch 37 is L, then the rotation between the input side gear 1 and the output side gear 6 when both spring clutches 36 and 37 are connected is The speed ratio is K and L
It will be expressed as the product of As a result, the first
The spring clutch 36 will be used for low speed power transmission, and the second spring clutch 37 will be used for high speed power transmission. Also, the ratchet wheels 17 and pawls 24 of the spring clutches 36 and 37
For example, the meshing (engagement) relationship between the two parts is as shown in FIG. In the figure, point E is the meshing point between the pawl 24 and the ratchet wheel 17, and F is the point where the ratchet wheel 1 at the point E.
7, G is the fulcrum of the pawl 24, H is the normal to the pawl of the pawl wheel 17 at point E, and if the angles αβ shown in the figure are made acute angles, the pawl 24 has a fulcrum. 1
A force I is applied to remove the brake pad 16 from the sleeve 15 or the ratchet wheel 17, and the rotation of the brake pad 16 is restricted by either the sleeve 15 or the ratchet wheel 17.
In addition, as shown in FIG. 6, the rib portion 1 of the sleeve 15
5B is provided with a projection 15a, which is fixed by engaging with a hole 16a provided in the brake pad 16. Furthermore, these two spring clutches 3
6 and 37 are connected to the base 13 via shafts 9 and 10.
It is reinforced while being sandwiched between the covers 14 and 14.

A sprocket 7 is coaxially attached to the output gear 6 via a shaft 11, and a sprocket 38 is installed at a position apart from the sprocket 7.
is rotatably fixed, and a chain (or timing belt) 28 as an endless moving body is stretched between both sprockets 7 and 38.
A protruding portion 29 and a detected object (for example, a shielding plate) 30 used to stop the document table at a fixed position are attached to appropriate locations on the chain 28. The protrusion 29 protrudes outward through a long hole 31a of a stay 31 extending downward from a document table 32 serving as a scanning means, and is secured by a flange 29a. The protruding portion 29 and the stay 31 constitute a connecting member. That is, as shown in FIG. 7, for example, the long hole 31 of the stay 31
If the width of a is A, the diameter of the protrusion 29 is B, and the vertical length of the flange 29a is C, then A>B
By setting the condition ≧C, the protruding portion 29 will not come off the stay 31 even if the chain 28 oscillates laterally. or,
With such a dimensional relationship, the flange 29a or the stay 31 can be easily removed or assembled by rotating the stay 31 by 90 degrees. still,
D in the figure is a pitch of the chain, and the flange portion 29 is connected via a locking piece 39 connected between the pitches.
a is installed. Further, the chain 2 is attached to the base side of the copying machine main body 12 below the document table 32.
Fixed position detection member 3 located above the moving area of 8
4 is fixed, and when a shielding plate 30 provided on the chain 28 passes, it outputs an electric signal to turn off, for example, the electromagnetic solenoid 26 of the second spring clutch 37. That is,
The fixed position detection member 34 consists of a magnet 34a and a reed switch 34b as shown in FIGS. 8a and 8b, and is used for detecting the home position of the document table 32. Further, a detection switch 35 is provided on the upper part of the base of the copying machine main body 12, on the right side in the figure, and furthermore, a detection switch 35 is provided at the bottom of the document table 32 with a gap in the area passing above the detection switch 35. Magnets 33A, 33 as position detection members
B is installed. Of this magnet,
The magnet 33A on the left side of the first figure is used to detect the limit position of the document table. For example, when the document platen reaches the limit position as shown in FIG.
The electromagnetic solenoid of the spring clutch 36 is deenergized to produce a signal for energizing the second spring clutch 37, and the other magnet 33B is used for detecting the paper start position.

Next, the operation of the device will be explained with reference to FIGS. 9a to 9e.

When the original platen 32 is in the normal position, the original platen 32
The protrusion 29 from the chain 28 that is engaged with the stay 31 attached to the chain 28 is located on the lower right side of the sprocket 38, and the shielding plate 30 attached to the chain 28 is located at a fixed position provided on the frame. Since the detection device 34 is shielded, the first and second
The electromagnetic solenoids 26 of the spring clutches 36, 37 are not energized. Therefore, the first and second
The pawls 24 of the spring clutches 36, 37 are not engaged with the ratchet wheel 17, and in this state, the inner diameters of the torsion springs 20, 22 are close to the boss portions of the input gears 2, 3 and the output gears 4, 3. 5, the power is not transmitted from the input side gears 2 and 3 to the output side gears 4 and 5, and the document table 32
maintains a fixed position (state a in the figure). At this time,
Input side gears 2 and 3, torsion springs 20 and 22, sleeve 15 and brake pad 1 attached to it
6, ratchet wheel 17, springs 21, 23, washer 1
8. Both retaining rings 19 are rotatable.

Next, when a copy button (not shown) is pressed, the electromagnetic solenoid 26 of the first spring clutch 36 is energized, the tip of the pawl 24 engages with the pawl of the ratchet wheel 17, and the ratchet wheel 17 stops rotating. Then, the brake pad 1 connected to the flange portion of the sleeve 15
6 and the ratchet wheel 17, the torsion spring 20
is tightened, thereby transmitting power to the output gear 4. As a result, the rotation of the output gear 4 is transmitted to the output gear 6 via the output gear 5 of the second spring clutch 37, and the chain 28 moves in the direction of arrow X in FIG. 9a. At this time, the original platen 3
A protrusion 29 (fixed to the chain 28) that moves up and down within the long hole of the stay 31 attached to
was initially located on the lower right side of the sprocket 38, so when the chain 28 starts to move in the do. Then, when the protrusion 29 has completely rotated around the sprocket 38, the original table 32 changes direction and moves (forward) in the right direction in the figure (state b in the figure). The forward speed of the document table 32 is kept at a low speed regulated by the first spring clutch 36, and at this stage an optical system (not shown) is driven to perform exposure scanning. That is, the moving speed of the document table 32 at this time is the exposure speed.

Next, when the paper start position detection magnet 33B attached to the document table 32 turns on the detection switch 35 while the document table 32 is moving forward (during exposure scanning), a paper start signal is output to a control section (not shown). , the copy paper is restarted (state c in the same figure).

Next, the original platen 32 continues to move forward, and the limit position detection magnet 33B closes the detection switch 3.
5 is turned on. In this position, the protrusion 2 is engaged with the stay 31 attached to the document table 32.
9 (attached to the chain 28) is located at the right end of the sprocket 7 in the drawing. At this timing, the second spring clutch 3
The electromagnetic solenoid 26 No. 7 is energized, and the document table 32 shifts to the returning operation. That is, the electromagnetic solenoid 26 of the second spring clutch 37 is energized by the signal from the detection switch 35 at this time, and from then on, power is transmitted in the same manner as the operation of the first spring clutch 36, and the document table 32 is moved. move it. At this time, immediately after the second spring clutch 37 starts operating, the electromagnetic solenoid 26 of the first spring clutch 36 is deenergized with a slight delay.
This is to ensure that the transition from the operation of the first spring clutch 36 to the operation of the second spring clutch 37 is smooth in consideration of the transient state of the operation of the clutch spring, and that the document table 32 does not stop. . The process of stopping the operation of the first spring clutch 36 at this time will be explained. When the electromagnetic solenoid 26 is de-energized, the pawl 24 that was attached to the ratchet wheel 17 of the first spring clutch 36 is pulled by the spring 27 and removed from the ratchet wheel.
The ratchet wheel 17 becomes rotatable, and the frictional force acting between the brake pad 16 and the ratchet wheel 17 disappears, and the torsion spring 20 returns to its original state.
Power transmission to the output gear 6 and sprocket 7 is stopped. Due to the operation of the spring clutch 37, the document table 32 moves to the left (reverse) in the drawing along the rotational direction of the sprocket 7. The speed at this time is higher than in the case of the above-mentioned movement (state d in the figure).

Then, while the document table 32 is returning at high speed, the shielding plate 30 attached to the chain 28 passes through the sprocket 38, its direction is changed, and it moves toward the position of the fixed position detection device 34 (see e in the figure). condition).

Then, the document table 32 returns to the normal position, and the shielding plate 30 attached to the chain 28 moves to the normal position detection device 34.
When the detection device 34 outputs an electric signal, the electromagnetic solenoid 26 of the second spring clutch 37 is cut off, and the transmission of power is cut off in the same way as the operation of the first spring clutch 36, and the document table 32 is kept at a fixed position. It will stop at that position.

As is clear from the above description, since the document table can be moved at low speed during exposure and at high speed when returning, copying operations can be speeded up.
In addition, the spring clutch uses the friction force of the brake pad caused by the spring body, and by using only one surface of the brake pad, the friction force becomes constant and a constant torsion force can be applied to the torsion spring. As a result, overload of the torsion spring is prevented, and operation can be stabilized. In addition, since the engagement state between the pawl and the ratchet wheel was set as shown in Fig. 5,
The pawl and ratchet wheel are smoothly separated, and as a result, a spring clutch with good responsiveness can be provided. Furthermore, since the two spring clutches are supported by being sandwiched between the two plates of the base and cover via the shaft, there is no need to provide a conventional E-ring or a groove for it, and it is possible to use an E-ring etc. In addition to eliminating dimensional errors that occur in the shaft, the shaft is supported on both sides, increasing its strength. In addition, the protruding portion serving as a connecting member between the chain and the stay is a flange portion having a width included in the width in the short direction of the long hole of the stay, and a length that is also longer than the width in the short direction of the long hole of the stay. Since the chain is connected via the chain, it is prevented from falling off due to horizontal sway of the chain, and when the chain is rotated 90 degrees, it comes out of the elongated hole of the stay, making it easy to disassemble and reassemble.

The invention is not limited to the above embodiments. For example, in the above embodiment, the first spring clutch and the second
The input and output gears of the spring clutch are shown engaged in series, but the input and output gears may also be arranged in parallel as shown in Figure 10. This allows the spring clutches to rotate in the same direction.

Note that the present invention is not limited to an apparatus using the document table moving method;
Needless to say, the present invention can also be applied to devices using a moving optical system.

〔Effect of the invention〕

According to the present invention described in detail above, it is possible to provide a document scanning device that can speed up image forming operations.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a main part showing an embodiment in which the present invention is applied to a document table driving section of a copying machine, and FIG. 2 is a sectional view of a main part showing an example of a spring clutch portion thereof. Figures 3 and 4 are front views of the main parts thereof, Figure 5 is an explanatory diagram of the relationship between the ratchet wheel and pawl of the spring clutch, and Figure 6 shows an example of the sleeve used therein. FIGS. 7A and 7B are explanatory diagrams showing the state of connection between the stay and the chain; FIGS. 8A and 8B are explanatory diagrams showing an embodiment of the document table fixed position detection member; FIGS. FIGS. 9a to 9e are diagrams explaining the operation, and the first
FIG. 0 is a schematic explanatory diagram showing another example of the spring clutch. 28... Endless moving body, 30... Position detection member (shielding plate), 32... Scanning means (document table), 36,
37...first and second clutches, 33A, 33B
... position detection member (magnet), 34 ... position detection member (fixed position detection device), 35 ... position detection member (detection switch).

Claims (1)

[Scope of Claims] 1. In a device that exposes and scans an image of a document using a reciprocating scanning means, an endless moving body that moves in one direction, and this endless moving body and the scanning means are connected. a connecting member that transmits movement of the endless moving body in one direction to reciprocate the scanning means; and a first connecting member that transmits power for moving the endless moving body in the one direction at a first speed. a clutch, a detection means for detecting the position of the scanning means, and moving the endless moving body in the one direction at a second speed different from the first speed in response to an output signal of the detection means. A second clutch for transmitting power for scanning an original document. 2 Make the second speed faster than the first speed, and
The document according to claim 1, wherein the scanning means is moved forward by an endless moving body that moves at a speed of , and the document is scanned by the forward movement of the scanning means. scanning device. 3. The document scanning device according to claim 1 or 2, wherein the first and second clutches are spring clutches. 4. The connecting member is connected by a stay attached to the scanning means and a protruding member that enters a long hole provided in the stay, has a flange at one end, and has the other end attached to the endless moving body. 3. The document scanning device according to claim 1, wherein the flange portion is configured such that it does not come out of the elongated hole of the stay. 5 The spring clutch consists of an input gear, an output gear, a torsion spring surrounding these bosses, a sleeve surrounding the torsion spring, a brake pad attached to the sleeve, and a ratchet wheel that makes surface contact with the brake pad. A spring that presses a ratchet wheel against a brake pad, a pawl that engages with the ratchet wheel, and an electromagnetic solenoid that displaces this pawl around a fulcrum parallel to the axis of the spring clutch. A document scanning device according to claim 3. 6 A spring clutch has a pawl that stops the ratchet wheel and rotates around a fulcrum. Claims 3 or 5, characterized in that the angle formed by the angle connecting the two and the normal line of the point where the ratchet wheel and the pawl engage with each other from the top of the ratchet wheel and the pawl of the ratchet wheel are acute angles, respectively. Original scanning device. 7. The document scanning device according to any one of claims 3, 5, and 6, wherein the spring clutch is reinforced by two plates sandwiching the shaft. .