KR20000034873A - Driving Method and Apparatus for Driven Body and Printer Using Thereof - Google Patents

Abstract

PURPOSE: A printer with an apparatus for driving a driven body is provided to reduce or eliminate the delay of return to the silent state caused by resonance by driving a stepping motor. CONSTITUTION: A ROM(read only memory,35) memorizes a pulse train per paper deliver step to escape resonance frequency of a driving system. A stepping motor(7) is driven to reduce or eliminate the resonance-induced delay of return to the silent state. An MPU(microprocessing unit,33) stops transferring recording paper within the set time even if there is no time to return the silent state with high-speed factors. Thus, the MPU prevents the factors from spreading or pitches from missing each other to keep good quality of factors.

Description

Driving method and driving device and printer using same {Driving Method and Apparatus for Driven Body and Printer Using Thereof}

The present invention relates to, for example, a driving method and a driving apparatus of a driven member for driving a driven member via an endless transmission means by a stepping motor, such as a paper conveying apparatus of a dot impact printer, and a printer using the same.

For example, there is a driving device for a driven body employed in a dot impact printer, which is configured to intermittently convey a continuous sheet as a driven body via an endless belt by a stepping motor as the printing progresses.

In the driving device of such a driven body, power is transmitted by an endless belt so that vibration in the vicinity of the resonant frequency is large, and even if the supply of the excitation pulse to the stepping motor is stopped, it takes time to recover to the quiet state due to the vibration. There was a flaw.

In particular, the dot impact printer capable of high speed printing alternately repeats printing and paper conveyance in a short time, so that the time allowed for restoring the quiet state of the driving device is extremely short. This results in paper being conveyed, resulting in deterioration of print quality.

In order to prevent such deterioration of the print quality, it is considered to perform a mechanical design of the drive device so that the drive frequency band of the stepping motor does not include near the resonant frequency of the drive system.

However, since the resonance frequency of the drive system is not a single frequency but also varies depending on the number of steps of paper conveyance, it is not practical to avoid the influence of resonance by the mechanical design of the drive device. In addition, even if the delay of the quiet state recovery due to resonance can be shortened to some extent by the mechanical design of the drive device, the resonance frequency can be changed only by changing the specification or position of one component of the drive device. Since it is necessary to perform a careful mechanical design and manufacture for every model of a drive device, it will be inferior to mass productivity and will become difficult to repair and adjust.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide a method and a driving device for a driven body which can satisfactorily reduce or eliminate the delay of the quiet state recovery due to resonance, and a printer using the same. .

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, the following technical means are calculated | required by this invention.

According to a first aspect of the present invention, there is provided a driving method for driving a driven body by means of a stepping motor via an endless transmission means, wherein the pulse train of the excitation pulse supplied to the stepping motor is transferred from the stepping motor to the driven body. The stepping motor is set for each drive step number for continuously driving to avoid the resonant frequency, the pulse trains are stored in the storage means, the pulse train is read out from the storage means according to the drive step number, and the excitation pulse is supplied to the stepping motor. There is provided a method of driving a driven member.

According to a second aspect of the present invention, there is provided a driving apparatus of a driven body including a stepping motor, a control device for controlling the stepping motor, and an endless transmission means, and a power transmission device for transmitting the power of the stepping motor to the driven body. For example, a memory means for storing the pulse train of the excitation pulse supplied to the stepping motor for each driving step number for continuously driving the stepping motor is provided, and the pulse train stored in the memory means comprises a stepping motor, a power transmission device, and a driven body. The drive device for the driven object is set so as to avoid the vicinity of the resonance frequency of the drive system, and the control device is configured to read the pulse train from the storage means and supply an excitation pulse to the stepping motor in accordance with the number of drive steps. Is provided.

As an endless transmission means, an endless belt or an endless chain can be used, but it is not limited to these.

As the driven member, recording paper, platen roller, and the like are considered, but are not limited to these.

The pulse train is information corresponding to the interval between adjacent excitation pulses, that is, the period of the excitation pulse, and the rotation speed of the stepping motor changes as the period of the excitation pulse changes. The excitation pulse is always constant in the on-period in each period, and the frequency of the excitation pulse is defined by the inverse of the period.

As the storage means, a volatile memory in which power supply backup is performed on various nonvolatile memories or batteries is considered, but is not limited to these.

According to a preferred embodiment, the storage means stores a plurality of types of pulse trains for each number of drive steps, and the control device reads any one of a plurality of types of pulse trains having the same number of drive steps from the storage means according to an instruction from the outside. Supply an excitation pulse to the stepping motor.

According to a third aspect of the present invention, there is provided a driving method of a driven body for driving a driven body through an endless transmission means by a stepping motor, wherein a resonant frequency of a drive system from which the exciting current value supplied to the stepping motor reaches from the stepping motor to the driven body The stepping motor is set for each drive step number for continuously driving to avoid the vicinity, and stored in the storage means, the excitation current value is read out from the storage means in accordance with the drive step number, and the excitation current is supplied to the stepping motor accordingly. There is provided a method of driving a driven member.

According to a fourth aspect of the present invention, there is provided a driving device of a driven body including a stepping motor, a control device for controlling the stepping motor, and an endless transmission means, and a power transmission device for transmitting the power of the stepping motor to the driven body. As an example, an excitation current varying means for varying the excitation current supplied to the stepping motor and a storage means for storing the excitation current value supplied to the stepping motor for each number of drive steps for continuously driving the stepping motor are provided. The excitation current value is set so as to avoid near the resonant frequency of the drive system composed of the stepping motor, the power transmission device and the driven member, and the control device reads the excitation current value from the storage means in accordance with the number of driving steps, and accordingly the excitation current. The excitation current is supplied to the stepping motor by controlling the variable means. The drive device for a driven member, is provided.

According to a fifth aspect of the present invention, there is provided a driving device of a driven body including a stepping motor, a control device for controlling the stepping motor, and an endless transmission means, and a power transmission device for transmitting the power of the stepping motor to the driven body. For example, an arbitrary number of pulleys in contact with the stepless transmission means, a pulley control device for varying the tension of the stepless transmission means by displacing the position of the pulley, and a memory for storing the position of the pulley for each drive step number for continuously driving the stepping motor. The position of the pulley provided with the means and stored in the storage means is set so as to avoid the vicinity of the resonant frequency of the drive system composed of the stepping motor, the power transmission device, and the driven member, and the pulley control device is adapted from the storage means in accordance with the number of driving steps. Fig. 21 is a configuration in which the position of the pulley is read out and the position of the pulley is shifted accordingly. The drive system of the body is provided.

According to a preferred embodiment, the position of the pulley stored in the storage means is constant for each drive step number, and is set so that the vicinity of the resonance frequency deviates from the drive frequency band of the stepping motor.

According to a sixth aspect of the present invention, there is provided a driving device including a stepping motor, a control device for controlling the stepping motor, and an endless transmission means, and a power transmission device for transmitting the power of the stepping motor to the driven body. A damper detachable from the rotating shaft of the motor, a damper control device for varying the load of the stepping motor by attaching and detaching the damper to the rotating shaft of the stepping motor, and a storage means for storing the removal instruction of the damper for each number of driving steps for continuously driving the stepping motor. The damper removal instruction stored in the storage means is set so as to avoid the vicinity of the resonant frequency of the drive system composed of the stepping motor, the power transmission device, and the driven member, and the damper control device dampers from the storage means in accordance with the number of driving steps. Reads and removes the command to remove the damper from the rotary shaft of the stepping motor. The drive device for a driven member to the one characterized in, is provided.

According to a seventh aspect of the present invention, in a printer for intermittently conveying paper, using a stepping motor having a drive shaft for conveying paper as an endless transmission means as a drive source,

A printer comprising a control device configured to discontinuously change a frequency of a pulse train supplied at an acceleration and a deceleration of a stepping motor and to avoid a pulse supply near a resonance frequency of a power transmission system including a driving source. do.

According to the present invention, since the stepping motor is driven by avoiding the vicinity of the resonance frequency of the drive system, it is possible to satisfactorily reduce or eliminate the delay of the quiet state recovery caused by the resonance.

Therefore, when it is adopted in the paper conveying apparatus of the dot impact printer, for example, the paper conveyance can be stopped within the prescribed time even when the quiet recovery time is extremely small, such as when printing at high speed or when the paper thickness is thick. As a result, it is possible to eliminate bleeding and pitch shift of the printing, so that printing quality can be maintained well.

Other features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic side view of a main portion of an impact printer employing a drive device for a driven object of the present invention.

Fig. 2 is a schematic plan view of the main portion of the impact printer shown in Fig. 1;

Fig. 3 is a sectional view seen from the arrow direction A-A in Fig. 2;

4 is a schematic circuit block diagram of the impact printer shown in FIG.

Fig. 5 is an explanatory diagram for explaining the time variation of the frequency of the excitation pulse of the stepping motor for paper conveyance in the normal mode.

Fig. 6 is an explanatory diagram for explaining the time variation of the frequency of the excitation pulse of the stepping motor for paper conveyance in the detailed mode;

FIG. 7 is a flowchart for explaining the control processing procedure of the stepping motor by the MPU for paper transport motor control shown in FIG. 4; FIG.

8 is a schematic circuit block diagram of an impact printer in another embodiment.

Fig. 9 is a schematic circuit block diagram of an impact printer in still another embodiment.

10 is an enlarged plan view of the vicinity of a stepping motor for conveying paper in still another embodiment;

Fig. 11 is a partially cutaway perspective view of the main body portion of the damper shown in Fig. 10;

Fig. 12 is an enlarged plan view of the vicinity of the main body portion of the damper shown in Fig. 10;

<Explanation of symbols for main parts of the drawings>

3: recording paper

5: upper tractor

6: lower tractor

7: stepping motor

7b: axis of rotation

8: stepless belt

9: pulley

31: MPU for paper conveying motor control

35: ROM

41: excitation current supply circuit

42: motor

54: damper

54a: main body

54b: magnetic body part

EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment of this invention is described concretely with reference to drawings.

Fig. 1 is a schematic side view of the main portion of an impact printer employing a drive device for a driven object of the present invention, wherein a recording sheet 3 made of continuous paper as a conveyed body is provided in the gap between the recording head 1 and the platen roller 2; The conveyance path of and the conveyance path of the ink ribbon 4 are located. The recording sheet 3 is conveyed in the direction of the arrow by the upper tractor 5 and the lower tractor 6. The upper tractor 5 and the lower tractor 6 are rotationally driven by the stepping motor 7 via the pulley 7a and the endless belt 8 attached to the rotating shaft 7b of the stepping motor 7. The endless belt 8 is tensioned by the pulley 9.

Fig. 2 is a schematic plan view of the main portion of the impact printer shown in Fig. 1, and Fig. 3 is a sectional view seen from the direction of the arrow AA in Fig. 2, wherein the recording head 1 is linear to reciprocate along the supporting rod 11; It is attached to the shuttle 12. Although not shown in the recording head 1, 14 head blocks having 12 head pins in total in the main scanning direction, 24 in the sub scanning direction and 288 head pins in total are provided along the main scanning direction.

A pulley 14 is attached to one end of the rotation shaft 13 of the platen roller 2 and spans the pulley 14 and the pulley 17 fixed to the output shaft 16 of the stepping motor 15. The endless belt 18 is wound up. The endless belt 18 is tensioned by the tension roller 19.

The pair of upper tractors 5 are attached to the rotating shaft 21 and convey the recording paper 3 using the conveying holes 22 formed at predetermined intervals at both ends in the width direction of the recording paper 3. The pair of lower tractors 6 are attached to the rotating shaft 23 and convey the recording sheet 3 using the conveying holes 22 formed at predetermined intervals at both ends in the width direction of the recording sheet 3.

An electromagnetic clutch 24 is attached to one end of the rotation shaft 13 of the platen roller 2, and the electromagnetic clutch 24 mechanically rotates the rotation shaft 13 in a state in which the electromagnetic clutch 24 is not energized. In the state of locking and preventing rotation of the rotating shaft 13, and being energized by the built-in solenoid, the mechanical lock of the rotating shaft 13 is released and the rotation of the rotating shaft 13 is allowed.

Fig. 4 is a schematic circuit block diagram of the impact printer shown in Fig. 1, wherein the stepping motor 7 for paper conveyance is driven by a motor control signal from the MPU (Micro Processing Unit) 31 for controlling the paper conveying motor, that is, an excitation pulse. The platen stepping motor 15 is controlled by the motor control signal from the platen motor control MPU 32. The electromagnetic clutch 24 is controlled by a control signal from the platen motor control MPU 32. The sheet conveying motor control MPU 31 and the platen motor control MPU 32 are controlled by the upper MPU 33, and the upper MPU 33 has an operator panel 34 having a key switch group operated by a user. The operation signal from is input. The encoder signal is input from the stepping motor 7 to the sheet conveying motor control MPU 31, and the encoder signal is input from the stepping motor 15 into the platen motor control MPU 32. A ROM (Read Only Memory) 35, a RAM (Random Access Memory; Random Access Memory) 36, and a timer circuit 37 are bus-connected to the MPU 31 for controlling the sheet conveying motor. The platen motor control MPU 32 also has a bus, a ROM, a RAM, and a timer circuit.

Next, an outline of the operation will be described. During recording, the head pin of the recording head 1 is selectively projected and driven in accordance with the image data, and the tip of the head pin contacts the recording surface of the recording sheet 3 via the ink ribbon 4. As a result, the ink of the ink ribbon 4 is transferred to the recording surface of the recording sheet 3 in the form of dots, and an image corresponding to the image data is recorded. At this time, since the movement of the recording paper 3 in the paper thickness direction is restricted by the platen roller 2, the recording paper 3 is not pushed out by the impact of the head pin. This operation is repeated with the movement along the support rod 11 of the linear shuttle 12, and an image of one band is recorded on the recording surface of the recording sheet 3.

When one band of images is recorded by one advance or return of the linear shuttle 12, the paper conveying operation is commanded from the upper MPU 33 to the paper conveying motor control MPU 31, whereby the sheet conveying motor control is performed. The MPU 31 outputs a motor control signal to the stepping motor 7. As a result, the output shaft of the stepping motor 7 rotates, and the rotational force is transmitted to the rotation shafts 21 and 23 via the pulley 7a and the endless belt 8, and the upper tractor 5 and the lower tractor 6 Is rotated, and the recording sheet 3 is conveyed in the direction of the arrow in FIG. The amount of conveyance at this time is determined by the distance between the area already recorded and the area to be recorded next, and the stepping motor 7 is driven by the number of steps corresponding to the amount of conveyance. That is, the recording paper 3 is conveyed by the recording width in the sub-scanning direction by the recording head 1 in the region where images such as letters and graphics to be recorded are continuous in the conveying direction of the recording paper 3, The recording sheet 3 is conveyed by a distance longer than the recording width in the sub-scanning direction by the recording head 1 in a blank region or page boundary where no image exists. In addition, for example, in the case of polymerized printing, an operation of conveying the recording sheet 3 in the reverse direction is applied as in the case of completing the modification table by separately recording numerals and ruled lines.

When conveying the recording sheet 3 in this manner, the sheet conveying motor control MPU 31 reads the pulse train from the ROM 35 in accordance with the mode designation information and the sheet conveying step number information supplied from the upper MPU 33. Therefore, the excitation pulse as a motor control signal is supplied to the stepping motor 7 accordingly.

That is, in the ROM 35, two types of pulse trains are stored in advance for each paper conveying step number corresponding to the conveying amount of the recording sheet 3. The two types of pulse trains are pulse trains used in normal mode and pulse trains used in detailed mode. For each paper conveying step number, for example, a pulse train is stored in the ROM 35 for every one step up to 100 steps, and the number of paper conveying steps exceeds 100 steps and pulses every five steps up to 1000 steps. This means that the train is stored in the ROM 35, and that the pulse train is not necessarily stored in the ROM 35 for each step for all the number of paper conveying steps. These pulse trains avoid the resonant frequency of the drive system from the stepping motor 7 to the recording sheet 3, and also the movement of the recording sheet 3 actually stops from the stop of supply of the excitation pulse to the stepping motor 7. It is determined for each sheet conveying step number by experiment or the like so that the quiet state recovery time up to is included within a predetermined time.

For example, in the normal mode, when the number of paper conveying steps is 1000 steps, when the frequency of the excitation pulse supplied to the stepping motor 7 is changed as shown by the solid line A in FIG. 5, and the number of paper conveying steps is 200 steps As shown by the solid line B in FIG. 5, the frequency of the excitation pulse supplied to the stepping motor 7 is changed. Such a frequency change of the excitation pulse is realized by the sheet conveying motor control MPU 31 supplying the excitation pulse to the stepping motor 7 in accordance with the pulse train read out from the ROM 35. The excitation pulse is always constant regardless of the period, and the frequency changes with the change of the period. Like the a ₁ , a ₂ part of the solid line A and the b ₁ , b ₂ part of the solid line B, the frequency of the excitation pulse is set to avoid the vicinity of the resonance frequency of the drive system.

In the detail mode, when the number of paper conveying steps is 1000 steps, as shown by the solid line C in FIG. 6, the frequency of the excitation pulse supplied to the stepping motor 7 is changed. As shown by the solid line D, the frequency of the excitation pulse supplied to the stepping motor 7 is changed. Like the c ₁ , c ₂ portion of the solid line C and the d ₁ , d ₂ portion of the solid line D, the frequency of the excitation pulse is set around the resonance frequency of the drive system. In the detailed mode, the deceleration period of the stepping motor 7 is considerably longer than in the normal mode. This is to prevent the deterioration of the print quality by making the quiet time recovery time extremely short. That is, in the normal state, the quiet state recovery time is included within a predetermined time even in the normal mode. For example, when the paper thickness of the recording paper 3 is thick or the influence of humidity or the like, the specific gravity of the recording paper 3 becomes heavy. In this case, since the inertia force of the recording paper 3 is increased, the quiet state recovery time may be long. Therefore, even in such a case, the detailed mode is set so as to reliably prevent deterioration in printing quality. Switching between the normal mode and the detailed mode is realized as a result of the operator performing the predetermined operation with the key switch of the operator panel 34 and recognizing it by the upper MPU 33.

In addition, the platen roller 2 and the electromagnetic clutch 24 are appropriately controlled by the platen motor control MPU 32.

In this way, the recording by the recording head 1 and the sheet conveyance by the sheet conveyance drive source 7 are repeated every time the linear shuttle 12 advances and returns, and the image is recorded on the recording sheet 3.

FIG. 7 is a flowchart for explaining the control processing procedure of the stepping motor 7 by the sheet conveying motor control MPU 31 shown in FIG. 4, and the behavior of the recording paper 3 will be described with reference to this flowchart.

First, the sheet conveying motor control MPU 31 judges whether or not a sheet conveying operation command is input from the upper MPU 33 (S1).

When the sheet conveying operation command is input from the upper MPU 33 (S1: Yes), it is determined whether the sheet conveying motor control MPU 31 is in the normal mode (S2). That is, since the sheet conveying operation instruction from the upper MPU 33 includes the sheet conveying step number and the operation mode information of the recording sheet 3, it is checked whether the operation mode is the normal mode or the detailed mode.

If the operation mode is the normal mode (S2: YES), the MPU 31 for controlling the paper conveying motor may perform the pulse train for the normal mode corresponding to the number of paper conveying steps included in the paper conveying operation instruction from the upper MPU 33. Read out (S3). Then, the sheet conveying motor control MPU 31 generates an excitation pulse based on the pulse train read out from the ROM 35 and supplies it to the stepping motor 7 (S4). The frequency of this excitation pulse changes as shown by the solid line A in FIG. 5 when the number of sheet conveying steps is 1000 steps, for example. As a result, the recording sheet 3 is conveyed at a speed corresponding to the frequency of the excitation pulse of the stepping motor 7.

Next, the sheet conveying motor control MPU 31 judges whether or not the driving of the stepping motor 7 is finished (S5). In other words, it is checked whether all the predetermined pulse trains are read from the ROM 35 to generate an excitation pulse.

When the driving of the stepping motor 7 ends (S5: YES), this process ends.

In step S5, if the drive of the stepping motor 7 is not complete | finished (S5: No), it will return to step S3 and drive of the stepping motor 7 will continue.

In step S2, if it is not a normal mode (S2: NO), it is a detailed mode, so that the paper conveying motor control MPU 31 corresponds to the number of paper conveying steps contained in the sheet conveying operation instruction from the upper MPU 33. The pulse train for the mode is read out (S6). Then, the sheet conveying motor control MPU 31 generates an excitation pulse based on the pulse train read out from the ROM 35 and supplies it to the stepping motor 7 (S7). The frequency of this excitation pulse changes as shown by the solid line C in FIG. 6 when the number of sheet conveying steps is 1000 steps, for example. As a result, the recording sheet 3 is conveyed at a speed corresponding to the frequency of the excitation pulse of the stepping motor 7.

Next, the sheet conveying motor control MPU 31 determines whether or not the driving of the stepping motor 7 is finished (S8). In other words, it is checked whether all the predetermined pulse trains are read from the ROM 35 to generate an excitation pulse.

When the driving of the stepping motor 7 ends (S8: YES), this process ends.

In step S8, if the drive of the stepping motor 7 is not complete | finished (S8: No), it will return to step S6 and drive of the stepping motor 7 will continue.

In step S1, if the paper conveying operation command is not input from the upper MPU 33 (S1: No), the process returns to step S1 and waits for the paper conveying operation command to be input from the upper MPU 33.

In this way, by storing the pulse train in the ROM 35 for each paper conveying step number, the stepping motor 7 is driven by avoiding the vicinity of the resonance frequency of the drive system. Thus, the delay of the quiet state recovery due to the resonance can be satisfactorily reduced or I can eliminate it. Therefore, even if the quiet printing recovery time is extremely small by performing high speed printing, the movement of the recording paper 3 can be stopped within the prescribed time, and the bleeding of the printing and the deviation of the pitch can be eliminated, so that the printing quality can be improved. I can keep it.

In addition, since the pulse train in the normal mode and the pulse train in the detailed mode are stored in the ROM 35 for each number of paper conveyance steps, the recording is performed under the influence of a thick paper thickness or the humidity, for example. Even when there is a concern that the quiet state recovery time of the paper conveyance becomes longer in a situation different from the normal state, such as when the specific gravity of the paper 3 becomes heavy, the movement of the recording paper 3 is changed by switching the operation mode to the detailed mode. The printing can be stopped within a prescribed time, and the printing quality can be maintained well by preventing the spread of the printing and the deviation of the pitch.

Moreover, in the said embodiment, although it was comprised so that either a normal mode and a detailed mode can be selected as an operation mode, you may comprise so that it may operate in a single operation mode.

In addition, in the said embodiment, although the frequency of the excitation pulse of the stepping motor 7 was set so that the resonance frequency of a drive system may be avoided, you may comprise so that the resonance frequency of a drive system may be avoided by changing the excitation current of the stepping motor 7.

That is, as shown in Fig. 8, the excitation current supply circuit 41 is controlled by the MPU 31 for controlling the paper conveying motor, and the excitation pulse is supplied from the excitation current supply circuit 41 to the stepping motor 7. You can configure it. As the excitation current supply circuit 41, for example, a constant voltage circuit capable of varying the output voltage, a constant current circuit capable of varying the output current, a power supply circuit capable of selectively switching a resistor connected in series to the output terminal, or the like. Can be used. The sheet conveying motor control MPU 31 may control the exciting current supply circuit 41 to change the exciting current of the stepping motor 7 for each sheet conveying step number, or the frequency of the excitation pulse is near the resonance frequency of the drive system. The excitation current may only be changed when it is reached. Information for changing the excitation current is stored in the ROM 35 in advance.

When the exciting current of the stepping motor 7 is changed in this way, the output torque of the stepping motor 7 changes, so that the resonance frequency of the drive system can be changed. Therefore, by appropriately changing the exciting current of the stepping motor 7, resonance can be avoided, and as a result, the delay of the quiet state recovery caused by the resonance can be eliminated.

As shown in Fig. 9, the motor 42 is controlled to be driven by the paper conveying motor control MPU 31, and the motor 42 is configured to change the position of the pulley 9 in Fig. 1. good. The sheet conveying motor control MPU 31 may control the motor 42 to change the position of the pulley 9 for each sheet conveying step number, or the frequency of the excitation pulse of the stepping motor 7 is near the resonance frequency of the drive system. You may change the position of the stepping motor 7 only when it arrives. The information for changing the position of the pulley 9 by controlling the motor 42 is stored in advance in the ROM 35.

When the position of the pulley 9 is changed in this way, the tension of the endless belt 8 changes, so that the resonance frequency of the drive system can be changed. Therefore, by appropriately changing the position of the pulley 9, the resonance can be avoided, and as a result, the delay of the quiet state recovery due to the resonance can be eliminated.

Of course, the pulley 9 for adjusting the tension of the endless belt 8 is not limited to one, The number of installations is arbitrary.

Such a change of the position of the pulley 9 may be performed alone or in combination with the change of the pulse train or the change of the excitation current described above.

As shown in Fig. 10, the resonance may be avoided by changing the load of the stepping motor 7. That is, the shaft 53 is rotatably supported by the bearing 52 attached to the frame 51. The main body portion 54a of the electromagnetic damper 54 is attached to this shaft 53. The stepping motor 7 for paper conveyance is attached to the frame 55, and the magnetic body of the damper 54 is provided at the end opposite to the end to which the pulley 7a is attached to the rotation shaft 7b of the stepping motor 7. 54b is attached. The magnetic body portion 54b has a disk shape. The distance between the main body portion 54a and the magnetic body portion 54b of the damper 54 is shown relatively large in FIG. 10, but is actually very small. As shown in Fig. 11, the main body portion 54a of the damper 54 has a substantially disk-shaped case 56, an iron inertial member 57 and a resin ring member housed inside the case 56. (58), and the silicone gel (59) is filled between the inertial member (57) and the ring member (58).

Although not shown, an electromagnet is incorporated in the main body portion 54a of the damper 54, and one end of the coil of the electromagnet is disposed at the center of the shaft 53 of the hollow shaft 53 as shown in FIG. Is connected to one end of the The other end of the coil of the electromagnet is connected to one end of the cylindrical conductor 62 whose inner circumferential surface opposes the outer circumferential surface of the conductor 61 with a slight gap. One end of the leaf spring 63 is in contact with the other end of the conductor 61, and one end of the leaf spring 64 is in contact with the other end of the conductor 62. The leaf spring 63 is electrically connected to the cable 66 via the connector 65, and the leaf spring 64 is electrically connected to the cable 67 via the connector 65. The connector 65 is attached to the frame 51 by the fixing anvil 68.

In a state in which the coil of the electromagnet embedded in the main body portion 54a of the damper 54 is not energized, the main body portion 54a and the magnetic body portion 54b are completely separated from each other, and the rotating shaft 7b of the stepping motor 7 is provided. ) Rotates, the body portion 54a of the damper 54 does not rotate. When energized by the coil of the electromagnet of the damper 54, the magnetic body part 54b is attracted to the main body part 54a, and both are coupled by magnetic force, and when the rotating shaft 7b of the stepping motor 7 rotates, the rotating shaft 7b And the damper 54 rotates.

The MPU 31 for controlling the paper conveying motor gives a removal instruction to the coil of the electromagnet of the damper 54 via the cables 66 and 67, the connector 65, the leaf springs 63 and 64, and the conductors 61 and 62. Output Specifically, it switches to the state which energizes the coil of the electromagnet of the damper 54, and the state which does not. The MPU 31 for controlling the sheet conveying motor may switch the energized state of the damper 54 to the coil of the electromagnet for each sheet conveying step number, or the frequency of the excitation pulse of the stepping motor 7 has reached the resonance frequency of the drive system. Only when it is performed, the energized state of the damper 54 to the coil of the electromagnet may be switched. The information for switching the energization state of the damper 54 to the coil of the electromagnet is stored in advance in the ROM 35.

As described above, when the main body portion 54a and the magnetic body portion 54b of the damper 54 are coupled or separated, the load of the stepping motor 7 changes, so that the resonance frequency of the drive system can be changed. Therefore, resonance can be avoided by appropriately switching the coupled state and the disengaged state, and as a result, the delay of the quiet state recovery due to the resonance can be eliminated.

Such a load change by the damper 54 may be performed alone or in combination with the above-described change of the pulse train or change of the excitation current.

As described above, according to the present invention, since the stepping motor is driven by avoiding the vicinity of the resonance frequency of the drive system, it is possible to satisfactorily reduce or eliminate the delay of the quiet state recovery caused by the resonance.

Claims (9)

As a method of driving a driven body for driving a driven body through an endless transmission means by a stepping motor, The pulse train of the excitation pulse supplied to the stepping motor is set for each drive step number for continuously driving the stepping motor so as to avoid near the resonant frequency of the drive system from the stepping motor to the driven body, and the pulse train is stored in the storage means. Remember, And the excitation pulse is read out from the storage means and supplied to the stepping motor in accordance with the driving step number. With a stepping motor, A control device for controlling the stepping motor; A drive device for a driven body including an endless transmission means and having a power transmission device for transmitting power of the stepping motor to the driven body, A storage means for storing the pulse train of the excitation pulse supplied to the stepping motor for each driving step number for continuously driving the stepping motor, The pulse train stored in the storage means is set so as to avoid near the resonant frequency of a drive system composed of the stepping motor, the power transmission device, and the driven member, And the control device is configured to read the pulse train from the storage means and supply an excitation pulse to the stepping motor in accordance with the number of driving steps. The said memory means memorize | stores a plurality of types of said pulse trains for every said drive step number, And the control device reads any one of a plurality of types of pulse trains having the same number of drive steps from the storage means in accordance with an instruction from the outside, and supplies an excitation pulse to the stepping motor. As a method of driving a driven body for driving a driven body through an endless transmission means by a stepping motor, The excitation current value supplied to the stepping motor is set for each number of drive steps for continuously driving the stepping motor so as to avoid near the resonance frequency of the drive system from the stepping motor to the driven body, and stored in the storage means, And the excitation current value is read from the storage means in accordance with the number of driving steps, and an excitation current is supplied to the stepping motor accordingly. With a stepping motor, A control device for controlling the stepping motor; A drive device for a driven body including an endless transmission means and having a power transmission device for transmitting power of the stepping motor to the driven body, An excitation current varying means for varying an excitation current supplied to the stepping motor; A storage means for storing the excitation current value supplied to the stepping motor for each driving step number for continuously driving the stepping motor, The excitation current value stored in the storage means is set to avoid the vicinity of the resonance frequency of the drive system composed of the stepping motor, the power transmission device, and the driven member, The control device is configured to read the excitation current value from the storage means in accordance with the driving step number, and to supply the excitation current to the stepping motor by controlling the excitation current varying means accordingly. Driving device. With a stepping motor, A control device for controlling the stepping motor; A drive device for a driven body including an endless transmission means and having a power transmission device for transmitting power of the stepping motor to the driven body, An arbitrary number of pulleys in contact with the endless transmission means, A pulley control device for varying the tension of the stepless transmission means by displacing the position of the pulley; Storage means for storing the position of the pulley for each drive step number for continuously driving the stepping motor; The position of the pulley stored in the storage means is set so as to avoid near the resonant frequency of the drive system composed of the stepping motor, the power transmission device, and the driven member, And the pulley control device reads the position of the pulley from the storage means in accordance with the number of driving steps, and shifts the position of the pulley accordingly. 7. The drive of the driven body according to claim 6, wherein the position of the pulley stored in the storage means is constant for each of the drive step numbers, and the vicinity of the resonance frequency is set so as to deviate from the drive frequency band of the stepping motor. Device. With a stepping motor, A control device for controlling the stepping motor; A drive device comprising an endless transmission means and provided with a power transmission device for transmitting power of the stepping motor to a driven body, A damper detachable from a rotating shaft of the stepping motor, A damper control device for varying the load of the stepping motor by attaching and detaching the damper to a rotating shaft of the stepping motor; A storage means for storing the removal instruction of the damper for each drive step number for continuously driving the stepping motor; The removal instruction of the damper stored in the storage means is set so as to avoid near the resonant frequency of the drive system composed of the stepping motor, the power transmission device, and the driven member, The damper control device is configured to read a removal instruction of the damper from the storage means in accordance with the number of driving steps, and to attach and detach the damper to the rotation shaft of the stepping motor according to the driving step. In a printer for intermittently conveying paper, using a stepping motor having a drive shaft for conveying paper as an endless transmission means as a drive source, And a control device configured to discontinue the frequency change of the pulse train supplied at the time of acceleration and deceleration of the stepping motor, and to avoid the pulse supply in the vicinity of the resonance frequency of the power transmission system including the drive source. .