JPH0510235B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for driving a pulse motor that drives a printer's carriage, paper feed mechanism, platen, etc. This invention relates to a method of driving a pulse motor that is difficult to operate.

[Background of the invention]

As a conventionally known printer, there is a thermal printer as shown in FIG. 3, for example. In this figure, 1 is a frame forming the main body, 2 is a platen around which recording paper is wound, and 3 is a platen rubber attached to the front surface of the platen 2 at a printing position. Reference numeral 4 designates a thermal head disposed to face the platen 2, 5 a tape cassette, and 6 a cassette holder that holds the tape cassette 5 and constitutes a cassette shift mechanism to be described later. The entire cassette shift mechanism is constructed using a carriage 7, which will be described below, located below the tape cassette 5.
Supported by 7a is a rotatable shaft extending along the platen 2 and passing through a carriage 7, which will be described later. Although not shown, a cam and a worm wheel are integrally provided at the left end of the shaft 7a, and the pulse motor 8 rotates a worm (not shown) that engages with the worm wheel. The shaft 7a is designed to rotate.

Further, reference numeral 9 denotes a lever having one end that engages with a cam integrally provided on the shaft 7a, which is connected to the support shaft 1.
0, and the other end engages with the body of a slider 11 that is movable in the horizontal direction in the drawing. Note that this slider 11 is rotatably provided integrally with the output shaft of a pulse motor 12, and gears are formed on both sides. The gears on both sides of the slider 11 are connected to the pulse motor 12.
The drive gears 13 and 14 can be selectively engaged with the drive gears 13 and 14 which are loosely fitted to the output shaft of the motor.

Further, 15 is a driven gear that engages with the drive gear 13 and rotates integrally with the drive gear 13, and has a bevel gear 16 on its side. 17 is bevel gear 16
It is a bevel gear that engages with the pulley 19 and is integrally provided with a pulley 19 having a protrusion 18 on the circumferential side. 20 is a metal belt whose both ends are connected to the carriage 7, which will be described later.
It has a square hole 21 that engages with the protrusion 18 of the pulley 19. 22 is placed on the opposite side of the pulley 19,
This is a pulley around which the metal belt 20 is wound.

The metal belt 20 and pulleys 19, 2 described above
2. The bevel gear 17, the driven gear 15 having the bevel gear 16, and the slider 11 are connected to the carriage 7 that holds the thermal head 4, tape cassette 5, etc.
A carriage transfer mechanism 33 is configured to move the cartridge along the platen 2, that is, in the left-right direction in the drawing, via a drive gear 13 connected to the pulse motor 12.

Further, 23 is a driven gear that engages with the drive gear 14, has a small diameter gear 24 on the side, and is loosely fitted to the paper feed shaft 25 so as to be rotatable. A gear 26 engages with the gear 24, and has a small diameter gear 27 on the side. 28 is a gear that engages with gear 27;
It is rotatably mounted integrally with the paper feed shaft 25. A sprocket 29 is provided integrally with the paper feed shaft 25, and has protrusions 30 on the same surface that are fitted into holes formed at both edges of the recording paper, for example.

The sprocket 29, the paper feed shaft 25, the gear 28, the gear 26 having the gear 27, the driven gear 23 having the gear 24, and the slider 11 move the recording paper 31 shown by the two-dot chain line wound around the platen 2 to the carriage 7. A paper feeding mechanism 34 is configured to feed the paper via a drive gear 14 connected to the pulse motor 12 in a direction perpendicular to the feeding direction, that is, in the direction of an arrow 32.

Although not particularly shown, the thermal head 4
As the shaft 7a rotates, the platen 2 is pressed against or released from the platen 2 via a cam (not shown) or the like.

Next, the carriage transfer operation and paper feeding operation of this thermal printer will be described.

(1) [Carriage transfer operation] As the pulse motor 8 shown in FIG. 3 rotates, a worm, a worm wheel,
The lever 9 rotates counterclockwise in FIG. 1 about the support shaft 10 via the cam. Therefore, the slider 11 engaged with the lever 9 moves to the left in FIG. 1, and the gear formed on the left side of the slider 11 engages with the drive gear 13. Here, when the pulse motor 12 rotates, the slider 11 rotates, and as the drive gear 13 rotates, the driven gear 15, that is, the bevel gear 16 rotates, and as the bevel gear 16 rotates, the bevel gear 1
7, that is, the pulley 19 rotates. Then, when the pulley 19 rotates, the metal belt 20 moves, and thereby the cartridge 7 on which the tape cassette 5, thermal head 4, cassette shift mechanism, etc. are mounted moves in the left-right direction in FIG. 3, that is, along the platen 2. do.

(2) [Paper feeding operation] When the pulse motor 8 shown in Fig. 3 rotates,
The lever 9 is rotated clockwise about the support shaft 10 via a worm, a worm wheel, and a cam (not shown) from the state shown in FIG. 3, that is, the state in the carriage drive operation described above. Therefore, the slider 11 engaged with the lever 9
moves to the right in FIG. 3, and the slider 11
The gear formed on the right side of is the drive gear 14.
engage with. Here, when the pulse motor 12 rotates, the slider 11 rotates, and this slider 1
As gear 1 rotates, gears 14, 23, 24, 2
6, 27, and 28 rotate, the paper feed shaft 25 rotates, and as the paper feed shaft 25 rotates, the sprocket 29 rotates, whereby the recording paper 31 wound around the platen 2 is rotated by a predetermined amount. , for example, one line in the direction of arrow 32 perpendicular to the direction of movement of the carriage 7.

Although not specifically mentioned here, the pulse motor 8 is also used to rotate the shaft 7a and shift the tape cassette 5.

Incidentally, in this conventional printer, the pulse motor 12 is used to transfer the carriage 7 and drive the paper feeding mechanism as described above. A pulse motor is also called a stepping motor, and is configured so that when one pulse is sent to the pulse motor drive device, the motor rotates by a certain angle (step angle). It is compatible with digital control and is suitable as an incremental drive motor.

(2) Since it rotates in synchronization with an external input signal, it can also be used as a variable speed synchronous motor.

(3) The generated torque is large relative to the moment of inertia of the rotor, and the start-up ability is far superior to that of ordinary synchronous motors. Also, the resistance torque against external forces that try to maintain a certain position is large.

(4) Unlike DC motor brushes, there is no need to worry about mechanical wear and maintenance.

Due to these advantages, it has been increasingly applied to printers, X-Y plotters, etc. in recent years. The above conventional example also uses a pulse motor for this reason, but there is one problem with using this pulse motor. As shown in Figure 4, the conventional pulse motor drive method is to always rotate a predetermined number of pulses in one direction to transport the carriage 7 or feed paper, and then print while stopping at that position. This occurs because the cycle of rotating in the same direction again by a predetermined pulse and then stopping is repeated. That is, in this driving method, as shown in FIG. 5, the drive gears 13 and 14 connected to the pulse motor and the driven gears 15 and 23 connected to the carriage transfer mechanism 34 and the paper feed mechanism 33 are always in pressure contact, and during this pressure contact, The pressure of these drive gears 1 becomes large due to the fact that the pulse motor has a large resistance torque against external force as mentioned above.
Stress is applied to the teeth of gears 3 and 14 and driven gears 15 and 23 that mesh with each other, and this stressed state is maintained while the motor is stopped.
Usually, these driving gears 13, 14 and driven gear 1
Since 5 and 23 are molded from synthetic resin material, stress cracking and stress deformation are likely to occur if the stress state is maintained, and these cracks and deformation result in malfunction. Therefore, in the conventional method of driving a pulse motor, which repeatedly rotates and stops only in the same direction to transfer the carriage 7 or drive the paper feed mechanism 33, there is always a risk of malfunction and a short period. maintenance was required.

[Purpose of the invention]

The present invention has been made in view of the actual situation in the prior art, and its purpose is to propose a method for driving a pulse motor in a printer that eliminates printer malfunctions and eliminates the need for maintenance related to the drive mechanism. It is in.

[Summary of the invention]

In order to achieve this object, the present invention includes a frame forming a main body, a platen on which the recording paper comes into contact, a carriage that can be transported along the platen, and a frame that is attached to the carriage and arranged so as to face the platen. a paper feed mechanism that feeds recording paper between the print head and the platen, working together with the platen or independently of the platen;
In a printer equipped with a pulse motor that transports the carriage and drives the paper feed mechanism, and a drive means that transmits the driving force of the pulse motor to the carriage transport mechanism and paper feed mechanism, In order to eliminate such stress on the drive mechanism, the pulse motor is configured to be stopped after the pulse motor has been sent to the target position by at least one step more than the number of feed steps, and then returned by this extra step.

[Embodiments of the invention]

Hereinafter, a method for driving a pulse motor according to the present invention will be explained based on the drawings. FIG. 1 is an explanatory diagram showing the relationship between input pulses and driving steps of a pulse motor, showing the driving method of the present invention.

The pulse motor used in the present invention is equivalent to the pulse motors 8 and 12 used in the conventional printer shown in FIG. 3, and only the driving method is different. The explanation of other parts of the printer will be omitted.

Pulse motor 12 used in this printer
is set to stop at 4-pulse input positions A, C, E, and G, for example. In the conventional driving method, as shown in Figure 4, when 4 pulses are input, the pulse motor 12 advances 4 steps in the same direction from stop position A to stop position C, and if 4 more pulses are input, it moves from stop position C to stop position E.
Then, when 4 more pulses are input, the cycle goes from stop position E to stop position G. However, in the method of the present invention, 5 pulses are input from stop position A, and the cycle goes from stop position A to position D in 5 steps. It moves forward, receives one pulse input in the backward direction, moves backward one step, and stops at position C. After printing, etc. is performed at this stop position C, it receives another five pulses input and moves forward to position F. Furthermore, 1 pulse is input in the backward direction, it moves backward by 1 step and stops at the E position, and in the same way, 5 pulses are input from the E position, moves forward to the H position, receives a 1 pulse backward signal, and returns to the stop position G. The pulse motor 12 is driven in a cycle of returning and stopping.

When driven in this way, a total of 6 pulses are required to drive from stop position A to stop position C, but the last pulse is the input to pulse motor 1.
As shown in FIG. 2, the drive gears 13 and 14 on the pulse motor 12 side
and the driven gears 15, 23 on the drive mechanism side do not mesh with each other during operation of the printing mechanism, etc., and no stress is generated on the teeth of both gears 13, 14, 15, 23 when stopped. In this way, drive gear 1
When the pulse motor 12 is stopped for the longest period of pressure contact between the driven gears 15 and 15 and 23, the members do not come into contact with each other and stress is not generated on the members forming the teeth of the gears 13, 14, 15 and 23. teeth,
This effectively suppresses stress cracking, stress deformation, etc. that occur in these members. That is, since stress is generated in the member only when the carriage 7 is transferred and when the paper is fed, the stress state does not persist for a long time, and the occurrence of the above-mentioned deformation etc. is extremely reduced.

Although this embodiment and the conventional example use a thermal printer, the method of the present invention can be applied to, for example, an electrostatic printer, a discharge breakdown printer,
It can be applied not only to non-impact printers such as energized printers, but also to impact printers such as wire dot printers and type selection type printers.
It can be applied not only to paper feed and carriage transfer, but also to type selection mechanisms, as well as to ribbon cassette shift mechanisms, ribbon feed mechanisms, etc.

〔Effect of the invention〕

As is clear from the above description, when a pulse motor for driving used in a printer is stopped at a predetermined stop position, the present invention is provided after the motor has been fed to the target position by at least one step more than the number of feed steps. By configuring the pulse motor to stop after returning by this extra step, it is possible to effectively suppress the generation of stress between the members of the drive gear connected to the pulse motor and the driven gear connected to the drive mechanism. 1) Stress cracking and stress deformation of both gear members can be minimized.

(2) Since the occurrence of stress cracking and stress deformation in the members of both gears is minimized, printer malfunctions can be effectively prevented.

(3) For the same reason as (2), maintenance related to the drive mechanism can be minimized and maintenance costs can be reduced.

There are other effects.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the relationship between input pulses and drive steps in the pulse motor driving method according to the present invention, and FIG. 2 is an explanatory diagram showing the relationship between the driving gear and the driven gear when the present invention is applied. Figure 3 shows
FIG. 4 is an explanatory diagram showing the relationship between input pulses and drive steps in the conventional pulse motor driving method, and FIG. 5 is a diagram showing the relationship between the conventional driving gear and driven gear. It is an explanatory diagram showing a relationship. DESCRIPTION OF SYMBOLS 1... Frame, 2... Platen, 4... Thermal head, 7... Carriage, 8, 12... Pulse motor, 33... Carriage transfer mechanism, 34
...Paper feeding mechanism.

Claims (1)

[Claims] 1 A frame forming the main body, a platen on which the recording paper comes into contact, a carriage movable along the platen, a print head attached to the carriage and arranged to face the platen, and a print head that works together with the platen. Alternatively, a paper feeding mechanism that feeds the recording paper between the print head and the platen independently of the platen, a pulse motor that moves the carriage and drives the paper feeding mechanism, and a pulse motor that transfers the driving force of the pulse motor to the carriage feeding mechanism and the paper feeding mechanism. In order to eliminate the stress on the drive mechanism due to carriage transfer and paper feed drive, in printers equipped with a drive means for transmitting the paper to the target position, this extra 1. A method for driving a pulse motor in a printer, characterized in that the pulse motor is stopped after the pulse motor is returned by a step of .