JPH0289464A - Original reader - Google Patents

Abstract

PURPOSE:To attain read of an original efficiently at a rational speed by providing individually the 1st stepping motor for read scanning and the 2nd stepping motor for return scanning. CONSTITUTION:A read scanning stepping motor SM 108 and a return scanning SM 118 are provided separately and pullets 105, 106 are driven by belts 111, 121 respectively to move a carriage 102 having a light source 103 and a read sensor 104. Through the constitution above, even there is a large difference from the drive speed for the read and return scanning processing, it can be coped with. With the moving distance of the optical system per one step of the SM 108 selected to be a ratio of an integer, accurate positioning is easily attained, other SM is used for braking while one SM is being decelerated to attain quick stopping and the vibration of the reading SM is absorbed by exciting the return scanning SM to use the SM as a load at reading.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of application in fL business) The present invention relates to a document reading device, and more specifically, to a driving device m of the document reading device.
The present invention relates to a document reading device that uses two different steppings for reading scanning and return scanning.

[Conventional technology]

Conventionally known LIIP (laser beam printer)
In a copying machine in which a copying machine and an original reading device using a line sensor such as a CCD are directly connected, the continuous copying speed is influenced by the return scanning time of the original reading optical system. This is because printers are capable of continuous paper feeding, so the interval between each recording paper can theoretically be reduced to zero. However, in the case of continuous copying in a copying machine that does not have a page memory or the like, a return scan is required between each document reading scan to return the optical system to the reading start position.

Therefore, in order to increase the number of copies per unit time, it is necessary to shorten the time for this return scan, and the drive motor must be rotated at high speed.

On the other hand, in the case of copying machines, it goes without saying that lowering the process speed is effective in reducing costs.

Therefore, in order to obtain a copying machine that can produce a large number of copies per unit time at a low cost, the optical system drive motor should be rotated at a low speed during document reading scanning and at high speed during return scanning. Note that if a stepping motor is used as the driving device, it can be used in a wide frequency range.

FIG. 7 shows an example of an optical drive system in a conventional document reading device. Here, 101 is a document table on which a document is placed;
2 is a carriage that moves along the document table 101,! 03
and 104 are a light source and a contact type sensor for reading mounted on the carriage 102. The carriage 102 is connected to a wire 107 stretched between pulleys 105 and 106, and is driven by a driving stepping motor 108.

That is, 109 and 110 are respectively pulleys 108
and a pulley provided coaxially with the motor 108, and these motor pulley 110 and drive pulley 10.
The carriage 102 can be moved by a motor 1011 via a timing belt 111 stretched between the document plate 9 and the document table 101, and the sensor 104 can read the document on the document table 101 during this time.

Therefore, the motor pulley 110 and the drive pulley 109
The motor pulley 110 has a diameter ratio of l:3.
The drive pulley 109 rotates once in three rotations of
The diameter of the pulley 106 is set to 51.2 mm, the step angle of the stepping motor 108 is set to 0.72 deg, and the LTR size (
When copying a document with a paper width of 216 o+m at a rate of 20 sheets per minute at the same size, a pulse sequence as shown in FIG. 8 is obtained.

In the sequence shown in Fig. 8, A is an acceleration area during reading scanning, B is a run-up area for stabilizing the speed of the motor, and C is an acceleration area during reading scanning.
is a scanning constant speed area for reading a document, D is a deceleration area during reading scan, E is an acceleration area during return scanning, F is a constant speed return scanning area, and G is a deceleration area during return scanning.

(Problems to be Solved by the Invention) As shown in FIG. 8, in the conventional image reading device, when reading a document, that is, during scanning, the motor 108 operates at a driving frequency of 783 pps obtained from the following equation. It was configured to be driven at 10,000 pps during return scanning.

Therefore, if you try to make a 400% reduction copy using such a conventional document reading device, 1.
The motor must be driven at 96 pps (= 783 pps ÷ 4), and since the natural frequency of a stepping motor is around 200 Hz, vibrations often become a problem during driving.

In addition, to increase the drive frequency when reading the original, pulley 1
It would be better to increase the ratio of the diameters of pulley 10 and pulley 109, that is, the reduction ratio, but in that case, 1O90θQpp
Since it is driven at a frequency even higher than s, a normal stepping motor cannot respond to such a high frequency, and it is also difficult to control it with an inexpensive microcomputer. I had no choice but to limit my speed.

The purpose of the present invention is to focus on the above-mentioned conventional problems, and in order to solve them, it is possible to avoid low-speed ranges where vibration is a problem and high-speed ranges where control is difficult, and to read efficiently and at a reasonable speed. An object of the present invention is to provide a document reading device that can be implemented.

[Means to solve the problem]

In order to achieve such an object, the present invention provides a document reading device that performs a reading scan in which an optical system is scanned to read a document, and a return scan in which the optical system is returned to the initial position of the reading scan. The present invention is characterized in that it separately includes a first stepping motor that performs scanning and a second stepping motor that performs return scanning.

[Effect]

According to the present invention, two stepping motors are used as a driving device for a document reading device, one for low-speed driving and one for high-speed driving,
By using them separately during read scanning and return scanning, and by changing the reduction ratio of the motor drive during read scanning and return scanning, it is possible to reduce the low speed range where vibration is a problem and the high speed range where control is difficult. It is possible to drive the motor by avoiding it.

In addition, at this time, by making the distance traveled by the optical system in one step of the stepping motor (hereinafter referred to as SM) in an integer ratio between the reading scan and the return scan, the positioning when moving the optical system is made more accurate. It can be carried out.

〔Example〕

Embodiments of the present invention will be described in detail and specifically below based on the drawings.

FIG. 1 shows an example in which the present invention is applied to a copying machine, in which the same reference numerals as shown in FIG. 7 are used for the drive device and optical system used for reading and scanning. Note that 108 is a stepping motor for reading scanning, 118 is a stepping motor for return scanning, and 119 is a motor pulley coaxial with motor 1]8.
120 is a drive pulley coaxial with the wire drive pulley 105, and 121 is a timing belt stretched between the motor pulley 119 and the drive pulley 120.

However, in this example, the diameter ratio of the motor pulley 110 for reading scanning and the drive pulley 109 is set to 1.8,
While driving the wire 107 at a reduced speed, the diameter ratio of the motor pulley 119 for return scanning and the drive pulley 120 is set to 1=
2, and when returning, the driving speed of the wire 107 is reduced. Now, set the diameter of pulleys 105 and 106 to 5
1.2ntn+ binding, process speed 84mm/s
If the rotation angle in one step of 5M108 and 118 is set to ec and is set to 0.72 degrees, the moving distance of the carriage in one step of 5M108 during reading scanning is given by the following equation.

For four columns, the z3 moving distance of the carriage in one step of the SMI 18 during return scanning is given by the following equation.

Therefore, in this example, the distance traveled by the carriage per step by 5M10B during read scanning and 5M11 during return scanning.
The ratio of 8 to the carrier radio hyperactivity distance per step is 1:4.

Furthermore, in FIG. 1, 130 is a paper selection key 131, a copy magnification display section 132, and a copy magnification setting key! 33, an operation section including copying condition input keys such as a copy number display section 134, a copy number setting key 135, a copy key 136, etc., and a display means; Control unit, which controls others! 508 and 150B are Drino for 5M108 (and 5M11B
This is a driver for use.

In addition, 8 and CLK[l are 5MIO3 and S
Clock pulse I words for step driving Ml 18, 110F8 and ll0FB are 5M10
These are control signals for driving 8 and 5Mll8, respectively, and CL8 and 110F8 are co-supplied to the driver 1508, and CLKB and II OF B are co-supplied to the driver 150B, according to timings described later. Therefore, driver 1508 and 150B send out summation 611 signals 1608 and 160B according to the timing to drive 5M108 and 118, respectively.

Next, the copying procedure in this example will be explained based on the control sequence flow shown in FIG.

When making a copy, first in step 201, copy conditions such as paper size, copy magnification, number of copies, etc. are set. That is, the paper size is set with the paper selection key 131 of the operation unit 130, the copy magnification is set with the copy magnification setting key 133, and the number of copies is set with the copy number setting key 135.

1. Assuming that the number of copies is set to 20 at a magnification of 100% of the TR size, the set copy conditions are sent to the control unit 140, and step 2 is performed based on the copy conditions.
In step 02, the scanning distance and scanning speed are calculated. LT
When the R size is 100%, the scanning punch 11 is 21 [imm]
(LTR size paper length) and the scanning speed is 84 mm/sec, which is the process speed. Therefore, in 5M108,
Clock pulse signal CL manually input to driver 150A
Rotation is performed in synchronization with KΔ. In other words, 5M108 is 0.72 times the number of pulses supplied to driver 150A.
degree and rotates at a speed corresponding to the pulse frequency.

Note that the pulse frequency of CLKA in this case is calculated as shown in the following equation and becomes 2089 (pps).

× Copy magnification 84 (mm/5ec) X 8 51.2 (mm)
60deg) x 1=12089(+)ps) So, under these conditions, for example, what is the copy speed? a minute 20
When trying to realize a total of 100 pixels, the pulse sequence becomes as shown in FIG. In other words, the time required from the leading edge of the first sheet to the leading edge of the next sheet, that is, the time used to copy one LTR size sheet is 2990 (msec).
Therefore, 20 copies can be made per minute. Also, since the carriage movement distance per SMI step during reading scan (forward) and return scan (backward) is in the ratio l:4, the total number of pulses during forward and backward movement is By controlling the ratio to be 4:l, the carriage can be accurately returned to the document reading start position.

In addition, such accurate positioning is particularly important when it is necessary to read the exact same position many times, such as in a full-color copying machine.In this example, the total number of pulses during forward drive is Since there are 5540 pulses and 385 pulses per month in total during backward drive, and the ratio is 4:I, accurate relative positioning can be maintained at all times during repeated scanning.

In addition, in FIG. 3, areas A, B, C, D, E, F, J
3 and G are the same as in FIG. 8 described in the conventional example. Note that the region H is a buffer time for switching between driving the other after either one of the forward driving 5M 108 and the backward driving SM 118 has stopped reliably.

Returning to FIG. 2 again, when the copy key 136 is pressed in step 203, the signal 110FA from the control unit 140 becomes 5V% low] or Ov in step 204, and the forward drive is started, and a predetermined pulse signal CL is applied. 28 is manually powered by 5M driver 1508. Note that the signals 110FΔ and HOFII are signals that control whether or not to supply current to the 5Ms 108 and 118; respectively, when Ov, no current flows through the SM, and when 5V, no current flows through the SM.
A current flows through the clock pulse signal CLKA or CL.
The SM is driven in synchronization with KB.

Thus, in step 205, for example, it is determined whether the predetermined number of pulses shown in FIG.
OF 8 becomes Ov, signal CLKA is stopped, 5
Driving of M10B is stopped.

When the forward drive is finished, the next step 206 is to start the reverse drive, and the signal from the control section 140 is sent to HOFBh.
) 5V, CLK[143 is input to the driver 150A, and in the next step 207, when it is confirmed that the predetermined number of pulses have been completed, the drive signal 11, old 2B or O
When the signal reaches v, the LKB signal is stopped.

In this way, the process moves to the next step 208, and if it is determined that the predetermined number of copies has not been completed, the process returns to step 204, where II Q F A becomes 5V, the forward drive is started again, and the process is completed. If so, the copying ends.

Next, a second embodiment will be described.

In the previous embodiment, the polarities of the control signals 110F8 and 110FB were opposite to each other during forward drive and backward drive. This was to eliminate the load by not supplying current to the other SM while one SM is being driven.

However, when switching between forward and backward movement of the SM, it is desirable to stop the driven SM in as short a time as possible. Therefore, for example, as shown in Figure 4,
After issuing the final pulse to the clock pulse signal CLK for forward drive and before entering reverse drive, the control signal II OF B
If the voltage is set to 5V and a current is supplied to the reverse drive 5M118, the SML 18 acts as a brake, and the forward drive 5M108 can be stopped in a short time.

Similarly, when shifting from reverse drive to forward drive, after issuing the final pulse of the clock pulse signal CLKB for reverse drive and before starting forward drive, set the control signal 10F8 to 5V and apply current to 5M108. For example, SMI 18 can be stopped in a short period of time. In this way, the vibration can be suppressed by stopping the vibration immediately after the reverse drive and stopping immediately after the reverse drive, which will affect the forward drive, that is, when reading the document, by stopping the vibration after a short time after the reverse drive.
That alone will bring you great benefits.

Next, the third embodiment will be explained.

In SM, vibration caused by drive pulses is often a problem, and in response to this, it is necessary to apply an appropriate load during drive.C)
An effective measure is to absorb vibrations.

Therefore, in the wooden embodiment, in order to suppress the vibration of the 5M 108 during document reading, that is, during forward drive, a current of an amount that provides an appropriate load is also supplied to the 5M 118 for backward movement.

FIG. 5 shows the configuration of the third embodiment. This example is a reverse SM
In order to use 118 as an appropriate load during forward drive, a current of a lower value is passed through 5M118 than during normal reverse drive.

Such a current value can be easily controlled by applying a known control signal CDB to the S and M drivers 118 at the timing shown in FIG. In other words, the current value flowing through 5M118 decreases when CDB is OV, and the rated value current flows when CDB is 5V.
By keeping the signal HOFB continuously at 5V even during forward drive, and allowing a current lower than the rated value to flow through 5Ml1ll when COB is set to Ov, the 5M
118 can be used as a suitable load for vibration countermeasures for 5M108.

(Effects of the Invention) As described above, according to the present invention, (1) separate SMs are provided for reading scanning and return scanning as optical system drive devices of the document reading device, so that; Even if there is a large difference in driving speed between the read scan and the return scan, it can be handled appropriately without causing any strain on each SM.

(2) By using an integer ratio of 8 distances of the optical system per step of the SM during read scanning and return scanning,
Even if separate SMs are used for read scanning and return scanning,
Accurate positioning can be easily maintained.

(3) When decelerating one of the two SMs, the other SM can be used as a brake to quickly reduce the speed of one SM.
M can be stopped.

(a) It is possible to absorb the vibration of the read scanning SM by exciting the return scanning SM when reading a document and using it as a load on the reading scanning SM.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a first embodiment in which the present invention is applied to a copying machine, Fig. 2 is a flowchart of an SM drive sequence according to the first embodiment of the present invention, and Fig. 3 is a diagram showing the SM drive sequence of the first embodiment. An explanatory diagram of a pulse sequence, FIG. 4 is a timing chart of control signals according to a second embodiment of the present invention, FIG. 5 is a configuration diagram of a copying machine document reading device according to a third embodiment of the present invention, and FIG. A timing chart of control signals according to a third embodiment of the present invention; FIG. 7 is a configuration diagram showing an overview of a conventional document reading device; FIG. 8 is an explanatory diagram of an SM pulse sequence in a conventional document reading device. . 101... Original table, 102... Carriage, 103... Light Z source, 104... Reading sensor, 105106... Pulley, 107... Wire, 108... Stepping motor for reading scanning , 109.
120...Drive pulley, 110.119...L motor pulley, 111.12
DESCRIPTION OF SYMBOLS 1...Timing belt, 118...Stepping motor for return scanning, 13θ...Operation unit, 131...Paper selection key 133...Copy magnification setting key 135...Copy number setting key +36...・Copy key 1+0...control unit, 1508, 150B...5M driver, CL to 8, C
LKB...Clock pulse fa, +10FA, l
l0FB...4. (J control signal, ■... control signal.

Claims (1)

[Scope of Claims] 1) In a document reading device that performs a reading scan in which an optical system is scanned to read a document, and a return scan in which the optical system is returned to an initial position of the reading scan, the reading scan is performed. A document reading device comprising a first stepping motor and a second stepping motor that performs the return scanning.