JPS63312770A - Picture reader - Google Patents

Abstract

PURPOSE:To execute the variable power of the longitudinal magnification of a picture throughout a wide range without generating the deterioration of a picture quality by providing a speed changing means for mechanically changing the scanning speed of an optical scanning system in a driving system for driving the optical scanning system. CONSTITUTION:A sub-scanning magnification is changed from 100% to 300%, for instance, and a copy button is depressed, and then, a CPU transmits a command for applying a power to a latching solenoid 61 so as to select a second gear train. Thereby, an iron core 61a receives an adsorbing force, an oscillating arm 58 is rocked in a direction as shown by an arrow (a) to energize second step gear pressers 56a, 56b in a direction shown by an arrow (b) through leaf springs 57a, 57b. Then, when a step motor 31 is rotated, a gear train group is rotated, a second gear 43 moves along a second gear shaft 42, is engaged with the gear part 45b of a third gear 45 and simultaneously disengaged of from a third gear part 45c. Then, the optical system is travelled at a travel speed 1/3 as fast as the travel speed at the time of constituting of a first gear train and the picture of 300% of the sub-scanning magnification is obtained.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is an image reading device that reads an original image by converting image light focused on a photoelectric conversion element such as a CCD into an electrical signal. The present invention relates to an image reading device.

(Prior Art) Conventionally, there are devices of this type that transmit images using a communication line such as a facsimile, and devices that are connected to a computer and record images on a storage medium such as a disk. In recent years, this type of image reading device and an image output terminal such as a laser beam printer are combined to form a so-called digital copying machine, making it possible to perform a variety of image processing.

Such digital copying machines are also equipped with a variable magnification mechanism for reducing or enlarging images, but this method uses an optical zoom mechanism to change the magnification, similar to that used in so-called analog copying machines. has not been adopted, i.e.
In this type of device, the image is scaled by thinning out or adding image signals in the reading direction of the line sensor (main scanning direction), and by scanning the optical system in the document scanning direction (sub-scanning direction). The magnification is changed by controlling the speed. Therefore, a digital copying machine has the advantage that it can change the magnification of an image at different magnifications in the vertical and horizontal directions, and the range in which the magnification can be changed is wider than that of an analog copying machine.

(Problems to be Solved by the Invention) Incidentally, in this type of digital copying machine, a step motor is usually used as a motor for driving an optical system that scans an original.

That is, a step motor is suitable for driving an optical system because it has better start-up or stopping performance during driving and superior positional accuracy than a servo motor or the like.

However, when changing the magnification of an image as described above using this step motor, there is a limit on the magnification ratio due to the drive characteristics of the step motor. That is, although the step motor is driven by pulsed signals and rotates by a predetermined angle per pulse, there is a limit to the number of pulse signals that can be input per second.

First, if the number of input pulses exceeds a predetermined value, the step motor cannot start even if there is no load.In this case, by increasing the number of input pulses step by step, it is possible to exceed this critical number of pulses Although it is possible to manually start the system, it is not appropriate for this type of device, which may suddenly stop during image reading.
On the other hand, if the number of input pulses falls below a predetermined value, the motor will resonate, causing the entire device to vibrate and generate intense noise.The ratio between the upper limit number of pulses and the lower limit number of pulses that can be input As a result, the scanning speed of the optical system driven by the motor is also limited to within about 5 times. Therefore, if the optical system is allowed to scan with some margin, there is a problem in that the possible magnification ratio will be limited to about 50% to 200%.

In order to solve this problem, it is conceivable to change the magnification of the image by electrical processing, but there is a problem that this cannot be used because the image quality deteriorates when the magnification is large.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems of the prior art, and its purpose is to provide an image reading device that can perform magnification over a wide range without deteriorating image quality. It's about doing.

(Means for Solving the Problems) In order to achieve the above object, the present invention scans an image of a document with a scanning optical system driven by a pulse motor and reads it with a linear reading means, and An image reading device that changes the vertical magnification of an image by controlling the scanning speed of the optical system by the pulse motor, further comprising a control means for controlling a drive pulse to the pulse motor, and driving the scanning optical system. The present invention is characterized in that the drive system is provided with a speed change means for mechanically changing the scanning speed of the scanning optical system.

(Function) In the present invention, the scanning speed of the scanning optical system relative to the driving force of the pulse motor is mechanically changed and set by the speed changing means provided in the drive system, and the driving force of the pulse motor is further controlled by the control means. The vertical magnification of the image is changed by electrical control using drive pulses from the image sensor.

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

FIG. 3 is a perspective view showing the configuration of an embodiment of an image reading device according to the present invention. In the figure, a document is placed face down on a document glass (not shown) held by glass placement plates 1a and 1b, and is brought into close contact with the document glass by a document pressure bonding plate (not shown). The original P is illuminated by the illumination member 2, and its reflected light image is reflected by the first mirror 3. 2nd mirror 4. It is deflected by the third mirror 5 and imaged onto the CCD 7 by the lens 6. One first mirror that holds the illumination member 2 and the first mirror 38. A second mirror 9 holding the second mirror 4 and the third mirror 5 is held on rail stands 10a and 10b. Reference numeral 11 denotes a speed change gear R, which changes the speed and transmits the torque of a step motor 31, which will be described later, to the drive shaft 12.
Increase the rotation to 11. Drive pulleys 1 are provided at both ends of the drive shaft 12.
3a.

13b is fixed, and the drive pulley 13a.

A wire (not shown) wound around 13b is engaged with a first mirror 8 and a second mirror 9, and both ends are fixed to the main body.

According to the rotation of the drive pulleys 13a and 13b, the first mirror 8
．． The second mirror 9 has a speed ratio of 1.34 and the rail stand 10a
, 10b, ): to scan the entire screen of the document. 14 is a power input unit; 15 is a DC power source for obtaining a required DC voltage from AC voltage; 16 is a CPU circuit board as a first stage of control for controlling the sequence of the entire device;
7 is a COD circuit (board) that controls the CCD 7; 18 is a lighting circuit board that controls the lighting member 2, from which power is supplied to the lighting member 2 via a cable (not shown); 19 is a board that is read by the CCD 7; This is an interface connector that outputs the captured image to the outside.

Figures 4(a) and 4(b) show the first mirror 8. Only the side near the transmission means 11 is shown in the plan view and front view of the drive system A in which the second mirror 9 is run at a speed ratio of 1:y2. The optical wire 20 has a threaded rod 20a fixed to its tip, and is fixed by a nut 22 to a wire fixing plate 21 attached to the rail stand 10a. The optical wire 2o is first hooked onto the second mirror pulley 23 rotatably held by the second mirror unit 9, reversed, fixed to the first mirror unit 8, and wound several times around the drive boob 913a.

Thereafter, it is reversed, hung on a wire pulley 24 rotatably held by the main body, and then reversed, and further hung on a second mirror pulley 23 and reversed, so that the round terminal-shaped end is fixed to the main body.

20b is a coil spring that applies tension to the optical wire 2o;
0c and 20d are sleeves for forming loops at the ends of the wires in order to hook the coil springs 20b onto the optical wires 20. 25 is a wire stopper fixed to the main body; 2nd Mira 8.9 Stops running while it is running F
The first error occurs due to a detection failure of a sensor (not shown) that detects the position. This prevents the optical wire 20 from coming off the drive pulley 13a when one second mirror passes a predetermined stop position I: and the two collide to create a locked state. That is, the wire stopper 25 is positioned so that the sleeve 20c hits the wire stopper 25 before the first mirror 8 and the second mirror 9 collide.

1(a) and 1(b) are a top view and a front view showing the configuration of the main parts of the drive system A. In this embodiment, the transmission means 11 has two
A case will be explained in which there are two gear trains. 31 is a step motor as a pulse motor, and a linear body 32.
33 to the mounting plate 34. A Hertobouri 35 is fixed to the rotating shaft of the step motor 31.

11, and has the following configuration. That is,
36 is a gear 1 holding plate, on which four wooden gear shafts are fixedly installed. 37 is a first stage gear shaft, and a first stage gear 38 rotates around this shaft 37.

The first stage gear 38 has a belt straight portion 38a and a gear portion 38b, and a timing belt 39 is placed between the belt a shape portion 38a and the belt pulley 35. 40 is the second
This is a stage gear shaft, and a second stage gear 41 rotates around this car 40. Reference numeral 42 designates a second stage gear shaft, around which the second retractable gear 43 rotates. 44 is a third stage gear shaft, and a third stage gear 45 rotates around this sleeve 44. The third stage gear 45 has three gear parts 45a and 45b with different internal gear engagement.
, 45c. 46 is an optical drive gear fixed to the drive shaft 12, and the gear portion 45 of the third stage gear 45
One dove matches with a. 47 is the third stage gear shaft 4 at both ends.
This inter-gear positioning member has a portion that fits into the drive shaft 12 and the third-stage gear 45, and guarantees the distance between the shafts of the gear portion 45a of the third stage gear 45 and the optical drive gear 46. 48.
A coil spring 49 is attached to the second stage gear shaft 40.42 and urges the second stage gear 41.43 upward in the drawing. The second stage gear 41 meshes with the gear part 38b of the first stage gear 38 and the gear part 45c of the third stage gear 45, and the second stage gear 43 meshes with the gear part 38b of the first stage gear 32 and the third stage gear. 45 gears 45b, respectively. 50 is a tension pulley that applies tension to the timing belt 39; 51 is a tension pulley 1;
This is a tension arm that supports a tension pulley 52 that rotatably holds the motor 50, and is fixed at a predetermined position on the motor mounting plate 34 to maintain a predetermined tension. The motor mounting plate 34 is connected to the gear train holding plate 36 and the motor unit mounting plate 54 via several 91 steel bodies 33.
The gear train holding plate 36 and the motor unit mounting plate 54 are fixed to the main body. In this way, by holding the step motor 31 via the elastic bodies 32 and 33 and using the timing belt 39 to transmit the drive, vibrations generated when the motor 31 rotates are prevented from being transmitted to other parts. .

FIGS. 1(a) and 1(b) show a state in which the second stage gear 41.43 forms a second gear train against the pressing force of the coil pad J48.49. At this time, the driving force of the motor 31 is transmitted in the order of the first gear 38 → the second gear 43 → the gear portion 45b of the third gear 45 → the gear portion 45a → the optical drive gear 46. Furthermore, the second stage gear 41.43 is connected to the coil spring 48.
．． By moving in the axial direction with the pressing force of 49, the first
A gear train is constructed. The driving force of the motor 31 at this time is transmitted in the order of the first stage gear 38 → second stage gear 41 + gear part 45c of the third stage gear 45 → gear part 45a → optical drive gear 46.

Comparing the first gear train and the second gear train, since the second stage gear 41, 43 works as an idler gear, the ratio of the number of peaks of the gear portions 45b and 45c of the third stage gear is equal to the torque of the motor 31. In this embodiment, the gear section 4 determines the ratio of the reduction ratio.
Since the number of ridges 5c is set to the tail of the number of ridges in the gear portion 45b, the ratio of the reduction ratio of the first gear train and the second gear train is l:
It becomes 3.

FIG. 2 is a perspective view showing the configuration of the gear train switching means. In the same figure, 56a and 56b are: 2nd stage gear retainers that hold three 52-stage gear retainers 55a and 55b in a concentric equidistant space, and are swingably supported by leaf springs 57a and 57b. . The second stage gear holding pawls 55a and 55b pass through holes provided in the gear train holding plate 36 and protrude toward the gear train side. The two leaf springs 57a and 57b are the swing arm 5.
The two arm portions 58a and 58b of No.8 are joined to each other. The swinging arm 58 is fixed to the gear train holding plate 36 and held by the solenoid holding plate 60 so as to be able to swing around a shaft 59 . The other end of the swing arm 58 is connected to the iron core 6 of a latching solenoid 61 fixed to a solenoid holding plate 60.
1a. Here, the rafting tolenoid is similar to a general solenoid in that it obtains suction force by applying electricity, but because it has a built-in permanent magnet, it maintains the suction force at a certain level even if the power is cut off. That's a big deal. Therefore, it is an OT function to perform a suction operation using pulsed power, hold the operation, and release the holding operation again using pulsed power of the opposite polarity.

When the swinging arm 58 rotates fully in the direction of arrow a, the second stage gear pressers 56a and 56b move in the direction of the arrow until they abut against the gear train holding plate 36, and at this time, the second stage gear presser claws 55a, 55b is the second stage gear 41.43! The pressing force exerted by the coil springs 48 and 49 is set to be greater than the spring pressure when the coil springs 48 and 49 are tightly wound. In addition, the swing arm 58
The tips of the second-stage gear retaining pawls 55a and 55b are set so that they do not protrude beyond the surface of the gear train holding plate 36 on the side where the gear train is located when the gear is fully rotated in the direction opposite to the arrow a. .

In this embodiment having the above configuration, an image is read with variable magnification in the following manner.

First, when the device is powered on, 100% (equal magnification) is selected as the initial setting. When a copy button (not shown) is pressed in this state, the CPU (not shown) issues a command to increase the pulse power of the opposite polarity to the rafting tolenoid 61 to select the first gear train. The following table shows typical values of the gear train and the number of input pulses to the step motor 31 corresponding to the magnification ratio in the vertical direction, that is, the sub-scanning direction.

Information corresponding to the magnification change rate in 1% increments, including the above-mentioned representative value, is stored in the CPU, and the CPU issues an appropriate command according to the specified magnification change rate. In other words, the magnification ratio in the sub-scanning direction is 33%.
When selected between 132% and 132%, the first gear train for high speed mode is selected, and when selected between 133% and 400%, the second gear train for low speed mode is selected. Now, the equipment is number one.
If the device is in the state of forming the second gear train, no change will occur even if pulsed power of opposite polarity is applied to the latching solenoid 61, but if the device is in the state of forming the second gear train, no change will occur. If so, change the gear train to the first gear example as follows. That is, the iron core 61a, which had been attracted to the main body of the rafting solenoid l"61, is pushed out of the main body by the repulsive force that exceeds the attractive force of the built-in permanent magnet due to the pulsed power of the opposite polarity, and is pushed out from the main body by the built-in permanent magnet (not shown). The position is maintained by the restoring spring. As a result of this operation, the swing arm 58 swings in the direction opposite to the arrow a, and the second stage gear pressers 56a and 56b move in the direction opposite to the arrow a. direction, the urging force on the second stage gears 41 and 43 is increased and removed.Next, when the step motor 31 starts rotating, the gear train group rotates, and the second stage gear 41 and the third stage gear The second stage gear 41 is connected to the coil spring 4 when the south side engages with the gear portion 45c.
8 along the second stage gear shaft 4o,
At the same time as the gear portion 45c of the third stage gear is engaged, the second stage gear 43 is also moved along the second stage gear shaft 42 by the biasing force of the coil spring 49, and the engagement of the gear portion 45b of the third stage gear is released. be done. This operation realizes switching from the second gear train to the first gear train. The transmission means 11, which constitutes the first gear train in this way, rotates the optical drive pulleys 13a and 13b, so that the first mirror 8 and the second
When scanning a document image by running one mirror 9, the number of input pulses to the step motor 31 is set to 800.
By using pps, an image with a sub-scanning magnification of 100% can be obtained.

Next, select the sub-scanning magnification between 133% and 400%,
When the copy button is pressed, the CPU issues a command to apply forward polarity pulse power to the rafting gear 1/noid 61 so as to select the second gear train. As a result, the iron core 61a of the latching solenoid 61 receives the attraction force and is drawn into the main body, and after the attraction 11, the attraction force is maintained by the built-in permanent magnet. Due to this operation, the swinging arm 58 swings in the direction of arrow a about the shaft 59, and the leaf spring 57a is released.

The second stage gear pressers 56a and 56b are urged in the direction indicated by the arrow via the second gear presser 57b. Next, when the step motor 31 starts rotating, the gear train group rotates, and when the second gear 43 and the gear portion 45b of the third gear 45 are engaged, the second
The stage gear 43 moves along the second stage gear shaft 42 due to the biasing force of the second stage gear holding pawl 55b that exceeds the pressing force of the coil spring 49, and simultaneously engages with the gear portion 45b of the third stage gear 45, and simultaneously moves into the second stage gear 43. The stage gear 41 also moves along the second stage gear shaft 4o by the urging force of the second stage gear holding pawl 55a, and: f
The engagement of the S3 gear 45 with the gear portion 45c is released. This operation realizes switching from the first gear train to the second gear train. In this configuration, if the number of high-power pulses to the pump motor 31 is driven at 800 pps, the optical system will travel at the same speed as when configured with the first gear train, resulting in an image with a sub-scanning magnification of 300%. is obtained.

As described above, "T fFs" means that the traveling speed of the scanning optical system can be changed from a minimum of 1 to a maximum of 12 by using both the gear train switching and the selection of the number of high-power pulses to the step motor 31. Therefore, the magnification ratio in the sub-scanning direction is 1
This allows you to enjoy a wide range of magnification, with 33% on the reduced side and 400% on the enlarged side.

In this embodiment, a method of moving an optical system was adopted as a method of reading an image, but the method is not limited to this. It is also possible to apply configurations.

Further, in this embodiment, the deceleration it of the R-speed gear 11, which is composed of the first gear train and the second gear train, is set to 1:3, but it is not limited to this. Depending on the space and layout, you can do whatever you want. Furthermore, although the VJ46 points of the first gear train and the second gear train were set to 132,133%, this can also be set arbitrarily.

(Effects of the Invention) As described above, the present invention includes a control means for controlling the drive pulses to the Noculus motor, and also allows the drive system for driving the scanning optical system to mechanically control the scanning speed of the scanning optical system. By providing a speed change means for changing the speed, the vertical magnification of the image can be varied over a wide range without deteriorating the image quality, and there is an effect that a variety of images can be read in a rotational manner.

[Brief explanation of the drawing]

FIG. 1(a) is a cross-sectional view showing the main parts of the drive system in an embodiment of the image reading device according to the present invention, and FIG.
a) is a front view, FIG. 2 is a perspective view showing the gear train switching means,
FIG. 3 is a perspective view showing an embodiment of an image reading device according to the present invention, FIG. 4(a) is a plan view showing a drive system of the embodiment,
Figure (b) is a front view of figure (a). Explanation of symbols 7... COD (reading means) 8... One first mirror 9... One second mirror 11
... Speed change means 16 ... CPU circuit board (control means) 31 ... Step motor (pulse motor) A ... Drive system patent applicant Canon Corporation.

Claims (1)

[Claims] The image of the original is scanned by a scanning optical system driven by a pulse motor and read by a line-shaped reading means, and the scanning speed of the scanning optical system is controlled by the pulse motor to read the image. An image reading device that changes the vertical magnification, further comprising a control means for controlling a drive pulse to the pulse motor, and a drive system for driving the scanning optical system to mechanically change the scanning speed of the scanning optical system. An image reading device characterized by being provided with a speed change means.