JPH07266656A - Serial printer - Google Patents

Abstract

PURPOSE:To drive a pulse motor with a speed suitable to printing without necessitating any clock having a frequency coinciding with a constant speed running. CONSTITUTION:This serial printer is provided with a pulse motor 5, connected to a carriage through a timing belt 7, a counting means 23, outputting timing signals, whose period is longer than a phase switching time, and another timing signal, having a time shorter than the phase switching time, upon effecting constant speed running with a predetermined speed of the carriage 1, and a signal generating means 25, generating a phase switching signal based on two kinds of timing signals, while the pulse motor 5 is driven by a motor driving circuit 25 by switching said two kinds of timing signals alternately.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial printer which prints by reciprocating a carriage having a print head in parallel with a platen by a pulse motor, and more specifically, a technique for controlling the speed of a pulse motor for driving the carriage. Regarding

[0002]

2. Description of the Related Art In a printer in which a recording head reciprocates in parallel to a platen for printing, a carriage is connected to a pulse motor via a transmission mechanism such as a timing belt, and a pulse is generated by a driving pulse from a controller. The motor is operated at a predetermined speed to move the print head at a speed suitable for printing. Since the pulse motor normally rotates in synchronization with the drive pulse, as long as the data of the repetition frequency of the drive pulse is stored in the storage means, the means for detecting the print position or the like of the carriage is not required. There is an advantage that the position and speed can be controlled accurately and the mechanism can be simplified as compared with the case of using a DC motor. By the way, when performing control based on such digitized data, since a clock pulse signal that defines the basic timing is required, a clock signal generation means is usually provided and the signal from this is divided. A clock pulse signal having a predetermined frequency is obtained to set the timing of phase switching.

On the other hand, the printer defines the control means constituted by a microcomputer for converting the data inputted from the host into the bitmap data and controlling the operation of the recording head, and for defining the operation thereof. The clock pulse generating means is provided. Of course, if the frequency of the clock pulse required by the microcomputer for controlling the overall operation of the printer and the clock frequency of the pulse driving the pulse motor driving the carriage have an integral multiple relationship, they can be shared. It will be possible. However, even if there are a plurality of clock frequencies for driving the microcomputer, it does not necessarily mean that a frequency suitable for the carriage drive motor exists, and it is necessary to separately prepare a clock suitable for driving the carriage drive motor. There is.

[0004]

However, providing another clock generating means only for the carriage drive motor causes a problem of cost increase.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a carriage at a target speed even when a clock pulse having a frequency suitable for running the carriage at a constant speed does not exist. Is to provide a new serial printer capable of driving the.

[0005]

In order to solve such a problem, according to the present invention, a pulse motor connected to a carriage via a transmission means and a phase in which the carriage is driven at a constant speed at a predetermined speed. A drive pulse to the pulse motor while performing phase switching based on the plurality of timing signals, at least one kind of timing signal having a longer cycle than the switching time, at least one kind of timing signal outputting a timing signal having a shorter time, and a plurality of timing signals. And a motor drive means for outputting

[0006]

The pulse motor driven by the phase switching timing determined by each clock signal becomes faster and slower than the constant speed running suitable for printing, but the inertia of the carriage does not affect the print quality. It runs with a certain fluctuation range.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the illustrated embodiments. FIG. 1 shows an embodiment of the present invention, in which reference numeral 1 is a carriage on which a recording head 2 is mounted, and a guide member 4 provided in parallel with a platen 3 is indicated by an arrow D in the drawing. It is reciprocally movable. Reference numeral 5 denotes a pulse motor for driving the carriage 1. In this embodiment, a pulse motor capable of 1-2 phase excitation and 2-2 phase excitation is used, and it is provided between the motor rotation shaft 5a and the idler 6. The recording head 2 is reciprocally moved in the paper width direction of the recording paper by being connected to the carriage 1 via a timing belt 7 which is stretched over the paper.

Numeral 10 is a print control means composed of a microcomputer or the like, which has a frequency f, and in this embodiment, 14.
A plurality of frequencies F1, F2 from the clock generation circuit 11 for dividing the 7 MHz original oscillation signal into 1/12 and 1/384,
In this embodiment, a clock signal having a period of 0.8 μsec and a period of 26 μsec is received to control the entire operation required for printing.
The print data is input from a host (not shown), and a control signal is output to a carriage motor control unit 20 and a print head drive circuit 13, which will be described later.

Reference numeral 20 denotes the above-mentioned motor control means, which includes command signals from the print control means 10 and clock signals of a plurality of frequencies F1 and F2 necessary for driving the microcomputer constituting the print control means. , A phase switching time Δt0 suitable for causing the carriage 1 to run at a constant speed at a specified speed V0 suitable for printing, and in this embodiment, 505 μsec, 75
A control signal is output to the phase switching signal generating means 25 by receiving a clock signal of a frequency F2 having a period capable of obtaining 4 μsec, 1014 μsec or generating a time closest thereto. Has been done.

Reference numeral 21 is an acceleration / deceleration control means, which is provided with data relating to a plurality of speed modes 1, 2, 3, 4, 5 in order to realize various printing modes, and corresponds to each printing mode. Store the speed data that defines the speed of constant speed traveling required in the mode as the drive frequency (PPS), the excitation method, the maximum current value during acceleration, and the maximum current value during constant speed traveling and deceleration. Therefore, the excitation time of each phase corresponding to the speed mode selected by the print control means 10 is read out from the timing data storage means 22, which will be described later, and the timing means 23 controls the phase switching means 25.

Reference numeral 22 is the timing data storage means described above, and as shown in Table 2, the phase switching time corresponding to the phase switching order from the stopped state to the constant speed running and the phase switching when the constant speed running is started. Time and unit time ΔT defined by the clock signal of frequency F2 input to the time measuring means 23.
= 26 μsec.

[0012]

[Table 2]

Of these speed modes, mode 2 has an ideal value of 505 μsec as the phase switching time during constant speed running, and this time 505 μsec is the clock frequency F.
Since there is no integer multiple relationship with the basic time 26 μs that can be generated by 2, two types of t1 = ΔT × 20 that are closest to this time 505 μs and have an integer multiple relationship with the unit time ΔT.
= 520 μsec and t2 = ΔT × 19 = 494 μsec are stored.

FIG. 2 schematically shows the above-mentioned motor drive circuit. The A phase wound around the rotor 5b,
Excitation windings 5c, 5d, 5 for A-bar phase, B-phase and B-phase bars
e and 5f are switching means S1, S2 and S, respectively.
It is connected to the drive power source E via S3 and S4, and is configured to be able to selectively excite each of the excitation windings 5c, 5d, 5e and 5f.

FIG. 3 shows an embodiment of the above-mentioned motor drive circuit, which is a switching transistor 30 which constitutes a switching means for selectively connecting each of the excitation windings 5c, 5d, 5e, 5f to the drive power supply Vcc. , 31, 3
2, 33 and the terminal 34 from the phase switching signal generating means 25,
A resistor 4 for receiving a control signal from 35, 36, 37 to selectively turn on / off the switching transistors 30, 31, 32, 33 and detecting a current flowing through the excitation winding.
The drivers 38 and 39 are provided with a chopping function for chopping the current based on the signals 0 and 41 to maintain the effective value of the exciting current at a predetermined value.

Reference numeral 42 denotes a drive current adjusting means for driving the carriage in a printer of a system in which the motor for driving the carriage obtains the circling power of the ink ribbon, such as a monochrome ink ribbon and a color ink ribbon having different ribbon widths. Since the amount of load acting on the motor is different, it is for setting the limiting current value of the drive pulse, that is, the peak value of the drive pulse to be large in the case of color printing.

That is, in Table 1, when the monochrome ink ribbon is used, the speed mode 3 is selected,
The peak value of the pulse at the time of acceleration, constant speed, and deceleration, that is, the maximum current is limited to 330 mA, while the speed mode 4 is selected when using the color ink ribbon. , And the limiting current value during deceleration is 370 mA
To increase the torque of the motor 5.

[0018]

[Table 1]

Next, the operation of the apparatus thus configured will be described with reference to FIGS. 4 and 5. When the print control means 10 selects the speed mode 1, the speed mode 3, the speed mode 4, and the speed mode 5 by the input of the print signal from the host, these modes are subjected to phase switching during constant speed running. The time is an integral multiple of the unit time ΔT generated by the clock signal of the frequency F2, that is, 29 times, and 3
Since it matches with any of 9 times, 75
Each time either 4 μsec or 1014 μsec is measured, only the phase switching time (FIG. 4 (a),
In (b)), the pulse motor 5 can be driven at a constant speed.

On the other hand, when the print control means 10 selects the drive mode of the speed mode 2, the acceleration / deceleration control means 21
The data stored as the mode 2 data in the timing storage means 22 is read out, and the timing means 23 outputs a phase switching signal for each phase switching order.

That is, when the speed mode 2 is selected by the print control means 10, the acceleration / deceleration control means 21 reads the data defined as the speed mode 2 of the timing storage means 22 for each phase order, and 3042 μsec. 2392
.mu.sec, 494 .mu.sec, etc., up to a speed suitable for printing with an acceleration time that is an integral multiple of the unit time .DELTA.T, the excitation method defined in this speed mode, in this embodiment, the carriage 1 by 1-2 phase excitation. The motor 5 is driven so as to accelerate.

In this way, when entering the final stage of the acceleration process, the acceleration / deceleration control means 21 has two kinds of phase switching times defined as the switching time for constant speed running in the timing storage means 22, t1 = 520 μsec. , And t2 = 494 μsec are read out, and these time data are alternately measured by the time measuring means 23.
To the cycles t1 and t2 as shown in FIG.
Output a series of timing signals that alternately change.

As a result, the excitation time t1 = 520
When μsec is selected, the pulse motor 5 rises to a prescribed velocity V0, that is, a velocity V1 that exceeds the velocity when driven at an excitation time of 505 μsec. When the excitation time in this phase reaches 520 μsec, the next excitation time is t2 = 4.
94 μs is selected. This excitation time is the specified speed V
Since it is too short time to obtain 0, the speed gradually decreases to the speed V2 below the specified speed V0. Hereinafter, two kinds of long and short data, that is, 520 μsec and 494 μsec are alternately selected as the excitation time, and the motor 5 has a high speed V with the specified speed V0 as a boundary.
Rotate while switching between 1 and low speed V2.

Since a timing belt and a carriage are connected to the pulse motor and inertia is present, the pulse motor 5 does not step out and the speed of the carriage 1 can be adjusted within a range that does not hinder printing. The target speed V1 is maintained as much as possible.

In the above embodiment, two types of timing signals, long and short, are used for the phase switching timing driven at the target speed, but three or more types of timing signals are used. However, it is clear that the same effect is obtained. Further, in the above-described embodiment, the case where the carriage and the pulse motor are connected by the timing belt has been described as an example, but the present invention may be applied to the case where the both are connected through another transmission means such as a ball screw. It is clear that the same effect is achieved.

[0026]

As described above, according to the present invention, the pulse motor connected to the carriage via the transmission means and at least one type of phase switching time when the carriage is driven at a constant speed at a constant speed are provided. And a timing means for outputting at least one kind of short-time timing signal, and a motor drive means for outputting a drive pulse to the pulse motor while performing phase switching based on the plurality of timing signals. Since the printer is equipped with, the carriage can be driven at a speed suitable for printing even if the apparatus does not have a clock signal of an optimum frequency for running the carriage at a constant speed. Not only can it be simplified, but the noise spectrum generated during driving can be divided into two frequencies. It is possible to mitigate the degree of harshness by.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an apparatus showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a simplified motor drive circuit in the same apparatus.

FIG. 3 is a circuit diagram showing an embodiment of a motor drive circuit suitable for the above apparatus.

4 (a), (b), and (c) are diagrams showing phase switching timing signals used in each speed mode by the same device.

FIG. 5 is a diagram showing a carriage speed when two types of phase switching times are alternately selected and a pulse motor is driven in the same apparatus, and a phase switching timing when a constant speed running is started. .

[Explanation of symbols]

 1 Carriage 2 Recording Head 3 Platen 5 Pulse Motor 20 Motor Control Means

Claims (2)

[Claims] 1. A pulse motor connected to a carriage via a transmission means, a timing signal having a period longer than at least one kind of phase switching time when the carriage is run at a constant speed, and at least one kind. And a motor driving means for outputting a driving pulse to the pulse motor while performing phase switching based on the plurality of timing signals. 2. The serial printer according to claim 1, wherein the crest value of the drive pulse is changed according to the type of the ink ribbon.