JPS63118284A - Serial printer - Google Patents

Abstract

PURPOSE:To accurately detect the position of a carriage, by stopping the carriage by utilizing stop pulses which are generated one for each predetermined number of dot pulses. CONSTITUTION:At the time of starting printing, a carriage 18 is moved to a home position on a carriage feed shaft 16 by rotating a DC motor 12 according to a home position pulse generated from a home position switch 44. The carriage 18 is then moved while printing on a printing paper 58 by controlling a head 22 according to printing data. A dot pulse signal is generated from a pulse-generating means 24 according to the rotation of the DC motor 12, and the printing timing of the head 22 is controlled by the dot pulse signal from the means 24. According to the rotation of the feed shaft 16, a stop pulse generating means 32 generates stop pulses, one for each 18 dot pulses. Consequently, it is made possible to perform secure bidirectional shortest-distance printing by accurately detecting the position of the carriage at the end of printing in each line.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a serial printer that prints by reciprocating a carriage equipped with a print head, and particularly to a serial printer that prints in the shortest possible time in both directions.

[Prior art] To perform shortest printing in both directions, it is necessary to detect the stop position of the carriage at the end of one line of printing, compare this with both ends of the next line of print data, and control the carriage to move closer. There is. For this purpose, it is important to accurately grasp the stop position of the carriage. Conventionally, a dedicated detection means was provided to detect the stop position of the carriage, or
Alternatively, dot pulses were used to control the timing of printing.

[Problems to be Solved by the Invention] However, the method of providing a dedicated detection means increases the cost of the apparatus accordingly. Furthermore, the method using dot pulses has the following problems.

Although dot pulses provide an accurate signal when the motor is rotating, they are not preferred as a means of detecting the stopped position of the motor or carriage. because,
Dot pulses usually involve rotating a disk on which slits are formed at narrow regular intervals, detecting the slits using optical means, and generating pulses.When the disk stops, the slits move back and forth in front of the detector. , because it stops at the detection boundary position, a counting error occurs.

[Means for Solving the Problems] In addition to dot pulses that control printing timing, the serial printer of the present invention sequentially generates one dot pulse for each predetermined plurality of dot pulses.

It has a top pulse, waits until the next stop pulse is detected when one line of printing is finished, issues a command to stop the carriage, stops the carriage between the next stop pulse, and then stops the carriage at that stop position. The movement of the DC motor is controlled so that the next line of print data is compared and the carriage is moved closer.

[Operation] When the DC motor is energized, the motor rotates and the carriage carrying the print head moves. Here, in response to the rotation of the motor, a dot pulse and a stop pulse are generated, one for each of the plurality of dot pulses. Then, while moving the carriage, the print head performs printing in response to commands from the dot pulse. When one line of printing is finished, the DC motor is controlled so that the carriage does not stop immediately, but waits for the detection of a stop pulse and is always stopped midway between the next stop pulse and the next stop pulse. Therefore, the stop position of the carriage can be accurately determined. This stop position is compared with the positions of both ends of the next line of print data, and the carriage is moved to the nearest position. Then, the next line is printed.

Here, the reciprocation of the carriage is performed by switching the DC motor between forward and reverse directions.

As a result, the position of the carriage can be accurately detected at the end of printing one line without providing a dedicated carriage position detection means, and by comparing with the print data of the next line, printing can be performed reliably in the shortest distance in both directions.

[Examples] Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing the main parts of a serial printer which is an embodiment of the present invention.

A DC motor 12 is installed on the frame 10. The DC motor 12 can be switched between normal and reverse rotation by switching the power supply. A transmission gear 14 is provided on one side of the output shaft of this DC motor 12,
The rotation of the DC motor 12 is transmitted to the carriage feed shaft 16. The transmission gear 14 consists of a gear 14a attached to an output shaft, and a gear 14d connected to this via a gear 14b1 and a gear 14c, and this gear 14d is fixed to a carriage feed shaft 16. A helical groove is formed in the carriage feed shaft 16, and the carriage 18 is engaged with and supported by the helical groove. A guide 20 is formed below the carriage feed shaft 16 by cutting and bending a part of the frame 10 so that the carriage 18 reciprocates without rotating. A dot print head 22, which is a thermal head, is mounted on the carriage 18.

A dot pulse generating means 24 is provided at the other end of the output shaft of the DC motor 12. This dot pulse generating means 24 consists of a dot pulse disk 26 fixed to an output shaft and a photocoupler 30 that detects a slit 28 formed therein, and generates a dot pulse signal corresponding to the rotation of the DC motor 12. A stop pulse generating means 32 is provided on the other end side of the carriage feed shaft 16.

This stop pulse generating means 32 is connected to the carriage feed shaft 1.
It consists of a stop pulse disk 34 fixed to 6, and a photocoupler 38 that detects a slit 36 formed therein. Further, a reed switch 40 is provided at the left end of the guide 20, and a home position switch 44 is provided together with a permanent magnet 42 provided at the lower end of the carriage 18.
is formed. A clutch mechanism 50 is connected to a gear 14d fixed to the carriage feed shaft 16 via a switching gear 46. The switching gear 46 includes a swingable gear switching plate 46a, a gear 46b, and a gear 46c attached thereto.
It consists of The switching gear 46 is connected to a gear 52 via a rotatable gear 48 and a clutch mechanism 50. Here, clutch machine +1llf50 is gear 50a
The paper feed trigger lever 54a of the paper feed trigger mechanism 54 is engaged with the clutch cam 50b. The paper feed trigger mechanism 54 includes a paper feed trigger lever 54a that is intermittently driven by a trigger signal, a spring 54b for returning the trigger lever 54a, and a paper feed trigger solenoid 54c.

The gear 52 is fixed to the shaft of the platen 56, and supports the printing paper 58 and rotates the printing paper 58.
send.

The operation of the apparatus of the embodiment shown in FIG. 1 will be explained with reference to FIG. 2 which shows the relationship between stop pulses and dot pulses and FIG. 3 which is a flow sheet diagram.

When starting printing, first, the carriage 18 is moved on the carriage feed shaft 16 by the rotation of the DC motor 12 in response to a home position pulse generated from the home position switch 44, and moved to the location of the reed switch 40, that is, the home position. be done. Then, the dot print head 22 is controlled based on the print data, and the carriage 18 is moved while printing on the print paper 58. Here, a dot pulse signal is generated by the dot pulse generating means 24 in response to the rotation of the DC motor 12, and the timing of printing by the dot print head 22 is controlled by the dot pulse signal from the dot pulse generating means 24. The stop pulse generating means 32 generates one stop pulse for every 18 dot pulse signals in response to the rotation of the carriage feed shaft 16.

As shown in FIG. 2, in this example, the carriage 18 starts moving from the position of the home position pulse (HP), and after detecting the first stop pulse (SP) Nol,
Printing starts from the next dot pulse #1. In the case of full-digit printing, 520 sections from dot pulses #1 to #521 are printed. When the No. 30 stop pulse is detected, the PF trigger is energized and the PF operates.
That is, after the paper is fed, the carriage 18 is moved to the print start position of the next line, normally to the rightmost end of the print data of the next line.

FIG. 3 shows a flow sheet for controlling the operation of the carriage in a normal case, and will be explained using this flow sheet. 1
The process starts from a state where printing of a line is completed and the carriage 18 is stopped. First, this stop position Nn is compared with the leftmost end Nnl and rightmost end Nn2 of the next line of print data to determine which is closer. If the leftmost end Nnl is close, proceed to the left; if the rightmost end Nn2 is close, proceed to the right. Here, the flowsheets on the right and left side are logically the same, so the flowsheet on the left side will be explained. When the carriage 18 is moved to the left and a stop pulse on the left side of the leftmost end Nnl of the print data is detected, the DC motor control means applies a brake to the DC motor 12 to stop the carriage 18 before the next stop pulse. . Next, the DC motor 12 is reversely rotated by the carriage movement direction control means to move the carriage 18 to the right. When a stop pulse on the left side of the leftmost Nnl is detected, counting of dot pulses is started from here, and the dot print head 2 is started from a predetermined position.
2 starts printing. When the carriage 18 moves to Nn2, printing of that line is completed, but the carriage 18 is not stopped immediately, and the DC motor control means starts the DC motor 12 after detecting the next stop pulse.
The brake is applied to stop the carriage 18 between the next stop pulse and the next stop pulse. Usually 8 after detection of stop pulse
It stops at the position after ~9 dot pulses have elapsed. Note that the paper is fed before or after the carriage 18 stops, and the process returns to the start.

Since the stop pulse is thus used as a signal to stop the movement of the carriage 18, the carriage 18 is always stopped during the stop pulse, and the stop position can be reliably detected. Therefore, reliable shortest printing in both directions can be performed without providing a dedicated carriage position detection means.

In addition, in the flow sheet of FIG. 3, when moving the carriage 18 to the leftmost end of the next line of print data, move the carriage 18 to the left,
When moving to the rightmost end, it is set to the right, but depending on the comparison with the stop position, the moving direction may not necessarily be this direction, and the moving direction may be opposite.

FIGS. 4 and 5 show a paper feeding mechanism suitable for the serial printer of the present invention. When this paper feeding mechanism is used, whether the DC motor 12 rotates forward or reverse when one line of printing is completed, or during paper feeding, the DC motor 12
Paper can be fed normally even if the direction of rotation of 2 changes. As shown in FIG. 4A, when the gear 14d is rotating normally (clockwise), only the gear 46b transmits rotation to the gear 48.
The gear 48 also rotates clockwise, allowing normal paper feeding. and,
DC motor 12 reverses and gear 14b reverses (counterclockwise)
When this happens, the swingable gear switching plate 46A automatically swings by the force of the gear 14d as shown in FIG.
8 will be communicated.

Therefore, in this case as well, the gear 48 rotates normally (clockwise), and normal paper feeding is performed.

The paper feeding operation (PF operation) will be explained.

When printing of one line is completed and the first stop pulse NoN is detected, the paper feed trigger solenoid 54c of the intermittent paper feed trigger mechanism 54 for 5 to 6 pulses is energized. Then, the paper feed trigger lever 54a is driven, and the clutch cam 50b engaged with it is rotated. Since the clutch mechanism 50 is a known spring clutch, the gear 50a is thereby
The rotation of gear 48 is transmitted to gear 50c, and the rotation of gear 48 is transmitted to gear 50c.
2, and the paper is fed. If the moving direction of the carriage 18 for shortest bidirectional printing does not change from that during printing, see Figure 5 A. If the moving direction changes, see Figure 5 B.
Although the rotation of the DC motor 12 changes as shown in FIG. 2, paper feeding is performed normally in either case.

If such a paper feeding mechanism is provided, printing and paper feeding can be performed in the shortest distance in both directions using one DC motor, and cost reduction and size reduction can be achieved.

Although one embodiment has been described above, it goes without saying that the various members may be modified in the usual manner. ′
For example, the print head may be of a type other than the thermal type, such as an impact type, a magnetic sensor may be used instead of a photocoupler, or a claw clutch may be used instead of a spring clutch as the clutch mechanism. .

[Effects of the Invention] As explained above, this invention has a structure in which the carriage is stopped using a stop pulse that is generated for every number of dot pulses, so that the position of the carriage can be accurately grasped. The effect is that printing in the shortest distance in both directions is possible without providing a dedicated position detection means.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the main parts of a serial printer which is an embodiment of the present invention, Fig. 2 is an explanatory diagram showing the relationship between stop pulses and dot pulses, and Fig. 3 is a flowchart for explaining the operation of the carriage. FIG. 4 is a diagram for explaining the paper feeding mechanism, and FIG. 5 is a diagram for explaining the paper feeding operation. 12... DC motor 18... Carriage 22... Dot print head 24... Dot pulse generating means 32... Stop pulse generating means 50...
Clutch mechanism 54...Paper feed trigger mechanism'.

Claims (1)

[Scope of Claims] A DC motor capable of forward and reverse rotation, a carriage equipped with a dot print head and reciprocated by the forward and reverse rotation of the DC motor, and a carriage capable of printing by the print head in correspondence with the rotation of the DC motor. a dot pulse generating means for generating a dot pulse to control the timing of the dot pulse;
a stop pulse generating means that sequentially generates stop pulses, and a DC motor is driven to move the carriage back and forth, and at the end of printing one line, detects the next stop pulse, and then detects the next stop pulse. a DC motor control means for controlling a DC motor so that the carriage stops; a print position detection means for detecting the leftmost and rightmost ends of the next line of print data; A serial printer comprising: carriage movement direction control means for controlling the forward and reverse rotation of the DC motor so as to compare the left end and the rightmost end and move the carriage toward the closest end.