JPS63280235A - Original scanner - Google Patents

Abstract

PURPOSE:To smoothly and rapidly move an original scanning member forward or backward by driving the original scanning member by the 1st driving means only in one direction requiring the stable driving of the original scanning member, and in other cases, driving the original scanning member by the 2nd driving means. CONSTITUTION:A moving optical system 1 is constantly reciprocated at a speed determined by a constant speed motor M1, an original is scanned by the optical system 1, and during the period, the original is exposed and scanned by an illuminating lamp or a mirror fitted to the optical system 1. After ending the exposure scanning of the original, a reciprocating motor M2 switches its rotating direction, rotates at a high speed, inverts the optical system 1 to reciprocate and return the system 1, and then stops. Since the rotational speed of the reciprocating motor M2 is made lower than that of the constant speed motor M1, one-way clatch 5 is disconnected, the optical system 1 is inverted and reciprocated only by the motor M2 and the motor M1 is continuously rotated at the prescribed speed. At the time of continuous copying, said operation is repeated. Consequently, the original scanning member can be smoothly and rapidly driven.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a document scanning device used in cases where a moving optical system (document scanning member) of a copying machine or the like is driven back and forth at high speed.

(Prior Art) Conventionally, this type of document scanning device is equipped with one DC motor that drives a moving optical system back and forth, and this DC motor is controlled at a constant speed by phase-locked loop control only during reciprocation, and the DC Some motors drive optical systems and the like back and forth by reversing the polarity of the voltage applied to the motor.

(Problems to be Solved by the Invention) However, such prior art has the following problems when performing constant speed control using phase-locked loop control. In other words, factors such as variations in the frictional resistance of the guide rails, variations in the gear precision of the motor gearhead, or noise in the control circuit that tend to disturb the constant speed control may occur in the drive section of the moving optical system. When a so-called disturbance occurs, image blurring occurs due to irregular movement of the optical system despite phase-locked loop control. In other words, in phase-locked loop control, the control amount (voltage or current) is changed only when the influence of disturbance appears on the motor and a control deviation occurs, thereby performing control to cancel out the disturbance. However, in a high-speed copying machine with a process speed of about 445 cm/sec, the rotational speed of the motor changes before the control effect takes place. By the way, the drive mechanism of the optical system is set to have a small inertia in order to perform high-speed scanning, and there is a problem in that when the rotational speed of the motor changes, the moving speed of the optical system directly changes, causing image blurring. .

Therefore, in order to reduce the influence of disturbances, it is possible to attach a flywheel to the motor shaft to increase the moment of inertia and stabilize the rotation of the motor, but in this case, the moment of inertia of the motor is large. Therefore, a new problem arises in that it takes a long time to rise until a predetermined rotational speed is reached, and it is difficult to control the reciprocating drive, making it impossible to cope with higher speeds.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide an original document with a simple structure that allows the forward or backward movement of the original scanning member to be performed smoothly and at high speed. An object of the present invention is to provide a scanning device.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a flexible power transmission device that directly transmits a driving force to the document scanning member in an apparatus for controlling the drive of a document scanning member. The means includes a first pulley means connected to a first drive means having a large inertia for driving the document scanning member in only one direction, and a first pulley means coupled to a second drive means having a small inertia for reciprocating the document scanning member. At least the first drive means is configured to be able to come into contact with and separate from the transmission means.

In the present invention, the term "inertia" is used to mean that the inertia is small or large, depending on the state change of the document scanning member caused by the action of a certain disturbance.

(Function) In the present invention, the original scanning member is driven by the first driving means only in one direction in which it is necessary to stabilize the driving of the original scanning member, and the original scanning member is driven by the second driving means in other directions. to drive.

(Example) The present invention will be explained below based on illustrated embodiments.

FIG. 13 is a schematic diagram showing an electrophotographic copying machine to which a document scanning device according to the present invention is applied. The original 102 on the original placing table 101 is illuminated by an illumination lamp 103, and the first . Second and third mirrors 104, 105, 106 and fourth, fifth and sixth mirrors 107, 108, 10 for projection
9 onto the photoreceptor drum 110. Around the photosensitive drum 110, there are a primary charger 111, a developer 112, and a transfer/separation charger 11, which are known image forming means.
3,114, and a cleaning device 115 is arranged.

The transfer paper P, which is the final image carrier, has a paper feed force (cera) 116,
The paper is selectively fed out by rotating one of the paper feed rollers 118 and 119 from 117 to 117. Further, the transfer paper P is conveyed by a pair of registration rollers 120 in synchronization with the toner image formed on the photoreceptor drum 110, and after image transfer, the transfer paper P is transferred to a conveyor belt 121, a fixing device 122, and an ejection roller 1.
In the figure, 126 indicates a document pressing plate, and 127 indicates a fan for preventing temperature rise of the optical system.

This electrophotographic copying machine allows stepless magnification by changing the position and focal length of the zoom lens 125 without changing the optical path length.

FIG. 2 is a perspective view showing the driving mechanism of the moving optical system for scanning. In FIG.
A wire (or a belt may be used) 62 as a flexible power transmission means is wound around. This wire 62 is wound around fixed pulleys 63 and 64 that are rotatably supported on the main body of the copying machine, and is further wound around fixed pulleys 63 and 64 that are rotatably supported on the main body of the copying machine. It is wound so as to be folded back around a double pulley 66 rotatably supported by the support bodies 65 of the third mirrors 105 and 106, and both ends thereof are fixed to the main body. On the other hand, the first mirror 104 and the support body 67 of the illumination lamp 103 are fixed to the wire 62 with a mounting bracket 68. The supports 65, 67 are each slidably guided at one end by a guide rod 69, 70, and supported at the other end by a roller 72, 73 running on a guide rail 71. While the above configuration moves the first mirror 104 at a moving speed V,
The second and third mirrors 105 and 106 are moved at a moving speed of V/2. Note that one end 62a of the wire 62 is fixed under tension by a spring 74.

FIG. 1 is a configuration diagram showing an embodiment of a document scanning device according to the present invention. In this illustrated example, for convenience, a moving optical system 1 corresponding to one support 67 supporting the mirror 104 is used as a moving optical system. is shown, and the other support 65 is connected to a double pulley 66.

In this embodiment, a wire 62 serving as a transmission means for directly transmitting a driving force to the moving optical system l is provided with a first driving means 2 having a large inertia that drives the moving optical system l only in one direction, and A second drive means 3 having a smaller inertia than the first drive means 2 for reciprocating the optical system l, and a pulley 63 .
61, and at least the first drive means 2 can be brought into contact with and separated from the first boob 963.

The first and second driving means 2, 3 are equipped with DC motors Ml, M2, respectively, and the reciprocating motor M2 of the second driving means 3 is connected to a powder clutch, as shown in FIGS. A drive pulley (with a wire 62 wound around it through 4
(second pulley) 61, and the constant speed motor M! of the first drive element/stage 2! is connected via the one-way clutch 5 to a pulley (first pulley) 63 around which a wire 62 is wound. In this embodiment, as shown in FIG. 2, the first driving means 2 with large inertia is disposed on the moving optical system 1 side, so that the moving optical system 1 can be driven more smoothly. .

FIG. 3 is a partially cutaway front view specifically showing how the reciprocating motor and drive pulley are attached. The powder clutch 4 includes a drive member 7 having a gear 6 for deceleration on the input side.
, an output side driven member 8, and a coil 9, and the reduction gear 6 of the drive member 7 is
The output side driven member 8 is meshed with a gear 11 fixed to a drive shaft 10 of the reciprocating motor M2, while the output side driven member 8 is connected to a drive pulley 61 via an output shaft 12. Powder (magnetic powder) is interposed in the gap 13 between the driven member 8 and the drive member 7,
By energizing the coil 9, this powder transmits a predetermined torque. FIG. 4 shows the relationship between the excitation current of the powder clutch 4 and the transmitted torque, and FIG. 5 shows the relationship between the slip rotation speed of the powder clutch 4 and the transmitted torque. As can be seen from FIGS. 4 and 5, the powder clutch 4 can obtain the desired transmission torque by controlling the excitation current, and can obtain a constant transmission torque regardless of the rotational speed even when the rotation is slipping. I know that it will happen. Therefore, it is possible to drive the drive pulley 61 and drive the moving optical system 1 while synchronizing the rotation speed of the reciprocating motor M2,
On the other hand, the driving pulley 61 can be rotated with a constant torque without synchronization with the rotation speed of the reciprocating motor M2, and the moving optical system 1 can be driven.

Further, while a flywheel F is attached to the constant speed motor M1 of the first drive means 2, a flywheel is not attached to the reciprocating motor M2 of the second drive means 3, and the flywheel F is attached to the constant speed motor M1 of the first drive means 2. The driving means 2 has a large moment of inertia,
The second drive means 3 is set to have a small moment of inertia.

The control circuit that controls the rotation of the constant speed, reciprocating motors Ml and M2 using a phase lock loop (PLL) is the same for both the first and second driving means 2.3, but the driving speed is different from that of the second driving means. Motor M2 is set higher. 03Ci
, osc2 are reference Xi X2 X2 X1 oscillators that generate reference pulse signals s, s (s>s), and El, B2 are motors M1. Pulse SM1. with a period corresponding to the rotation of M2. is a pulse encoder that generates SM2 - AI + A2 is the reference oscillator os
Reference pulse signal Sx output from c1 and osc2
1. The phase error between Sx2 and the motor rotation pulse signals S and S obtained from the pulse encoder E1*B2 is detected and 1 is added to the adder.

Phase detectors input phase error signals PL and P2 to MI M2, and Bl and B2 perform frequency-voltage conversion (F/V conversion) on the motor rotation pulse signals SN□ and SM2 obtained from the pulse encoders E1 and B2, respectively. ), the pulse signal S
M1. DC voltage v1 according to the frequency of SM2. v2 to the adder 1. This is a frequency detector that inputs into 2. Note that the rotation error detector including the phase detector and frequency detector may be integrated as an IC*
Ll*L2 is a low pass filter, PAL.

PA2 is a power amplifier, and Di and D2 are drivers.

Then, the phase error between the reference pulse signals SXi, SX2 and the motor rotation pulse signals S, S is detected by the phase detectors At, A2, and the phase error MI M2 signals PL, P2 are sent to the adder Kl, as a voltage by 2. In addition to the motor rotation pulse signals SM1 and SM2 converted into , this voltage causes a low-pass filter LL.

L2. Power amplifier PAL, PA2 and dry/< p
1. By driving constant speed motor M1 and reciprocating motor M2 through
2 are driven at a constant speed of XI and X2 at predetermined rotational speeds designated by reference pulse signals S and S, respectively.

In the above configuration, the document scanning device according to this embodiment has 1
The driving of the moving optical system is controlled as follows.

First, when a copy key (not shown) is pressed, as shown in FIG. The constant speed motor M1 of the driving means also starts rotating at a speed according to the designated copying magnification. The previous rotation has ended (0,
After 5 to 3 seconds have elapsed), the reciprocating motor M2 of the second driving means starts and the scanning (forward movement) of the moving optical system l begins (section ■), but at this time the constant speed motor M1 moves at the specified speed. has already been reached. The forward speed ■1 of the reciprocating motor M2 is the sixth
As shown in the figure and FIG. 7, Δ
vm/sec (Δv = 0.01~0.5 vo
) is set just faster. Therefore, the reciprocating motor M
2 increases its speed to catch up with and try to overtake the speed of constant speed motor M1, but when the speed of reciprocating motor M2 becomes equal to the speed of constant speed motor M1, one-way clutch 1
The reciprocating motor M2 is integrated with the constant speed motor M1 to drive the moving optical system 1, but the flywheel F is attached to the constant speed motor M1, and the moment of inertia of the reciprocating motor M2 is Since the powder clutch 4 has a sufficiently larger inertia than the sum of the inertia of the moving optical system 1 and the powder clutch 4 starts constant torque slip rotation, the circumferential speed of the output pulley 61 is reduced by rotation by the constant speed motor M1. The moving optical system l is constantly driven back and forth at a speed determined by the constant speed motor M1, and the document is scanned (section ■).
During this time, the original is exposed and scanned by the illumination lamp and mirror attached to the moving optical system 1.

When the exposure scanning of the original is completed, the reciprocating motor M2 switches the rotation direction, rotates at high speed (1.2 m/sea), reverses the moving optical system 1, moves backward, returns to the home position, and then stops. (Interval■.

(2), (2) At that time, the rotational speed of the reciprocating motor M2 becomes lower than that of the constant speed motor M1, so the one-way clutch 5 is disengaged, and the moving optical system 1 is reversed and moved back only by the reciprocating motor M2. Constant speed motor M1 continues to rotate at a predetermined speed. Note that one or more operations are repeated during continuous copying.

Next, the excitation current of the powder clutch will be explained in more detail. One purpose of this powder clutch is to stably scan the moving optical system 1 during constant speed scanning (■). That is, in the present embodiment, although the reciprocating motor M2 accelerates with a constant force, the speed is suppressed by the constant speed motor M1, and the constant speed motor Mr (speed 0... 445 m/see)
and reciprocating motor M2 (speed (1+0.01~0.5)Xo
, 445 m/sec) was resolved by increasing the inertia of the constant speed motor M1 system, and further stabilization was achieved by slip-rotating the powder clutch 4 with a constant transmission torque. has been realized. The other purpose of the powder clutch is to use the reciprocating motor M2 for purposes other than constant speed scanning (■, ■, ■, ■).
The objective is to cause the moving optical system l to scan in synchronization with the . Therefore, the intervals ■, ■.

In (2) and (2), the moving optical system 1 is scanned in correspondence with the drive of the reciprocating motor M1 and l to l without causing the powder clutch 4 to slip. Therefore, in this example, as shown in FIG. ), the excitation current is relatively lowered, that is, the transmitted torque is lowered to facilitate slip rotation and to reduce energy loss. By the way, the rated output torque of the reciprocating motor M2 is about 10 to 12 kgc■, and the sections ■, ■,
In (1) and (2), the excitation current of the powder clutch 4 is set to 0.8 A and the transmitted torque is set to 10 kgc (2) so that the output torque of the reciprocating motor M2 is directly transmitted to the moving optical system 1. In addition, since the driving torque of the moving optical system l during steady scanning is usually 2 to 3 kgcm, the driving torque is reliably transmitted to the moving optical system l, and the powder clutch 4 is likely to slip, and the constant speed, reciprocating motor M1 ．． The excitation current is set to 0.32A so that the PLL control of M2 is not disturbed, that is, so that the slip rotation of the powder clutch 4 occurs at an increase of 4 kgc.
is controlled.

On the other hand, since the powder clutch 4 provides a constant transmission torque even if it slips, the excitation current may be kept constant without being changed as described above.

FIG. 8 shows a second embodiment of the document scanning device according to the present invention, and the same parts as in the first embodiment are given the same reference numerals. The reciprocating motor M2 of the driving means 3 is simply driven with a constant voltage 14 without phase-locked loop control, and by switching the constant voltage, forward and reverse rotation is performed, and the reciprocating motor M2 is driven without using a powder clutch. The drive pulley 61 is directly connected to the drive pulley 61. In this case, the configuration of the control circuit and drive system can be simplified, and if the moment of inertia of the constant speed motor M1 is increased to a certain extent, the reciprocating motor M2
There is no problem even if speed variations occur.In this case, of course, the speed of the reciprocating motor M2 is always set to a higher value than the constant speed motor M1.The other configuration and operation are the same as in the first embodiment. Therefore, its explanation will be omitted.

FIG. 9 shows a third embodiment of the document scanning device according to the present invention, and the same parts as in the first embodiment are denoted by the same reference numerals. In this embodiment, a one-way clutch is used. An electromagnetic clutch 15 is provided in place of this, and a speed difference detector 16 compares the rotational speeds of the constant speed motor M1 and the reciprocating motor M2, and when the rotational speed of the reciprocating motor M2 becomes equal to that of the constant speed motor M1, a flip-flop circuit 17 is provided.
The electromagnetic clutch 15 is actuated via the reciprocating motor M2, and the electromagnetic clutch 15 is disconnected by the reversal signal of the reciprocating motor M2. In such a case, as shown in FIG.
When the rotational speed of the motor M2 matches that of the constant speed motor M1, the first and second drive means 2.3 are operated integrally by the action of the electromagnetic clutch 15, so that the moment of inertia of the first drive means 2 is accelerated. It acts on both speed and deceleration, allowing for more stable control than when using a one-way clutch. The other configurations and functions are the same as those of the first embodiment, so their explanation will be omitted.

FIG. 11 shows a fourth embodiment of the document scanning device according to the present invention, and the same parts as in the third embodiment are denoted by the same reference numerals. In this embodiment, a speed difference detector 16
One of the signals input to the.

Not the rotational speed of constant speed motor M1, but the reference oscillator os
The third embodiment is the same as the third embodiment except that the target speed is specified by c1. In such a case, the moving optical system l can be controlled to match the target speed.

FIG. 12 shows a fifth embodiment of the document scanning device according to the present invention, and the same parts as in the third embodiment are designated by the same reference numerals. In this embodiment, the reciprocating motor M2
is also connected to the drive pulley 61 via the electromagnetic clutch 17, and the speed of the constant speed motor M1 and the reciprocating motor M2 is detected by the speed difference detector 16, and the electromagnetic signal is connected to the drive pulley 61 via the signal switch 18 depending on the magnitude of both. One of the clutches 15, 17 is selectively activated. Therefore, there is no mutual interference between the reciprocating and constant-speed drive means, and control can be easily performed.Other configurations and operations are the same as those of the first embodiment, so a description thereof will be omitted.

In the above embodiment, a case has been described in which the flywheel F is attached to the constant speed motor M1 in order to increase the inertia of the first drive means, but the invention is not limited to this. The inertia may be increased by increasing the angular momentum by rotating at a high speed, and the rotation of the constant speed motor may be transmitted to the moving optical system via a reduction gear.

Furthermore, in the above embodiment, a case has been described in which the second drive means is connected to the transmission means via a powder clutch, but the invention is not limited to this, and a hysteresis clutch or the like having the same characteristics as a powder clutch may be used. May be used.

(Effects of the Invention) The present invention has the above-described structure and operation, and only in one direction (original scanning direction) in which it is necessary to stabilize the drive of the original scanning member, the original scanning member is moved at least in the first direction having a large inertia. Since the original scanning member is driven by the driving means and the other driving means is driven by the second driving means having small inertia, it is possible to drive the original scanning member smoothly and at high speed. Since the first driving means and the second driving means are connected to flexible power transmission means that transmits driving force to the document scanning member via the first and second pulleys, the apparatus can be made smaller. At the same time, transmission loss of driving force can be minimized.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing a first embodiment of a document scanning device according to the present invention, Fig. 2 is an oblique/main view showing the drive mechanism of the moving optical system of the device, and Fig. 3 is a reciprocating motor and powder clutch. 4 and 5 are diagrams showing the characteristics of the powder clutch, and Figures 6 and 7 are diagrams and graphs showing the control state of the device. 8 is a block diagram showing a second embodiment of the present invention, FIG. 9 is a block diagram showing a third embodiment of the present invention, FIG. 10 is a graph diagram showing the operation of the same embodiment, and FIG. FIG. 12 is a block diagram showing a fourth embodiment of the present invention, FIG. 12 is a block diagram showing a fifth embodiment of the present invention, and FIG. 13 is a schematic diagram showing an image forming apparatus to which the present invention can be applied. Explanation of symbols 1... Moving optical system 6... First driving means 7
...Second driving means 4...Powder clutch 5
...One-way clutch diagram 3

Claims (10)

[Claims] (1) In a device for controlling the drive of a document scanning member, a flexible power transmission means for transmitting a driving force to the document scanning member includes a first drive having a large inertia that drives the document scanning member only in one direction. a first pulley means connected to the first pulley means and a second pulley means connected to a second drive means having small inertia for reciprocating the document scanning member, and at least the first drive means is connected to the first pulley means. A document scanning device characterized in that it can come into contact with and separate from a means. (2) The document scanning device according to claim 1, wherein the first and second drive means are connected to the first and second pulley means via clutches, respectively. (3) The document scanning device according to claim 1 or 2, wherein the first driving means includes a flywheel. (4) The document scanning device according to any one of claims 1 to 3, wherein the first driving means includes a motor that is controlled in a phase-locked loop. (5) The document scanning device according to claim 2, wherein the first drive means is connected to the first pulley means via a one-way clutch. (6) The document scanning device according to claim 2, wherein the first drive means is connected to the first pulley means via an electromagnetic clutch. (7) The document scanning device according to claim 2, wherein the second driving means is connected to the second pulley means via a powder clutch. (8) The document scanning device according to claim 2, wherein the second drive means is connected to the second pulley means via a hysteresis clutch. (9) Claim 7 or 8, characterized in that the second driving means is controlled in a phase-locked loop at least when the speed is constant, and the clutch is controlled to perform constant torque slip rotation. The document scanning device described in . (10) The document scanning device according to claim 7 or 8, wherein the excitation current of the clutch is set such that a value at a constant speed is relatively smaller than a value other than that. .