JP3047549B2 - Serial printer and its home position setting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a home position setting device for a printer, and more particularly, to a home position setting device for a serial printer having a carriage reciprocatingly facing a recording medium.

[0002]

2. Description of the Related Art In general, a serial printer performs recording by reciprocating a carriage on which a recording head is mounted in a platen axis direction by a carriage driving motor via a timing belt or the like. Here, the carriage manages a distance from a reference position (a so-called home position) set at the time of the initialization operation of the printer by position detection means such as an encoder and the number of driving steps (in the case of a stepping motor), and moves to a predetermined position to print. I do.

In a conventional printer, a home position is generally set by detecting a movement of a carriage to a home position by providing a home position sensor such as a photo sensor or a micro switch. FIG. 8 shows a block diagram of a conventional example. FIG. 9 shows a structural diagram of a conventional example. Here, 12 is a home position sensor, and 13 is a shielding plate provided on the carriage. The home position sensor is composed of, for example, a photo interrupter as shown in FIG. 3 is a DC motor for driving the carriage, and 11 is a rotary encoder directly connected to the rotation shaft of the carriage motor. The output pulse of the rotary encoder 11 is connected to the position counter 5, and the addition and subtraction of the position counter 5 are performed according to the forward rotation and the reverse rotation of the DC motor, and the position of the carriage 6 is managed. CPU1 during the initialization operation of the printer
Drives the carriage motor 3 to move the carriage 6 in the home position direction. At the same time, monitoring of the output of the home position sensor 12 is started. When the shielding plate 13 on the carriage moves to a position where it blocks the home position sensor 12, a change in the output of the home position 12 is determined by the CPU.
1 is detected, the carriage motor 3 is stopped, and the position counter 5 is initialized. The home position has been set as described above, and the position management of the carriage at this transition is performed by the position counter 5.
When a stepping motor is used as a carriage driving motor, a position counter and a rotary encoder are generally unnecessary, and the position is controlled by the number of phase switching (the number of steps) using the excitation phase at the time when the change in the output of the home position 12 is detected as a reference position. Is performed.

As another method, there is a method of setting a position by causing a carriage to collide with a frame, a stopper or the like as disclosed in Japanese Patent Application Laid-Open No. 64-4377 and Japanese Patent Publication No. 2-26594. The former serves as a home position sensor by colliding the carriage to establish electrical continuity between the carriage and the frame, and eliminates the sensor. In the latter, the home position is set by using a stepping motor as a carriage driving motor, driving the motor for a specific time to collide with a frame, and then exciting to a specific phase.

[0005]

However, in the case of setting using various sensors, there are disadvantages that the structure becomes complicated and the cost becomes high, and that an error occurs in the detection position due to the structure and mounting accuracy of the printer. In other words, when the edge of the output of the home position sensor and the edge phase of the output pulse of the rotary encoder (or the timing of phase switching of the stepping motor) are very close to each other as shown in FIG. Due to the mechanical backlash described above, the home position is deviated every time the carriage is initialized.

In an apparatus for setting a position by colliding a carriage, when a stepping motor is used,
Since the phase is maintained after the step-out of the collision with the frame or the like, an error easily occurs in the detection position. Further, when a DC motor is used, the motor shaft vibrates due to the impact at the time of collision, and the encoder pulse is output irregularly, causing a malfunction of the position counter, thereby lowering the detection position accuracy. In addition, there are drawbacks such as generation of noise at the time of collision, deterioration of durability and reliability, and the like.

SUMMARY OF THE INVENTION An object of the present invention is to provide a home position setting device which solves the above-mentioned conventional disadvantages, eliminates the need for a home position sensor, is inexpensive, and has improved detection position accuracy.

[0008]

SUMMARY OF THE INVENTION According to the present invention, there is provided a detecting means for outputting a signal by attaching a scale plate disposed on a main body along a moving direction of a carriage and allowing the relative movement with respect to the scale plate. Means, a position management means for changing a position counter according to an output signal from the detection means, and managing a carriage position with the position counter;
A carriage control unit that controls a carriage by a motor based on the position counter information of the position management unit; and a serial printer that performs printing by a recording head mounted on the carriage, wherein the scale plate has one end. The transparent part or the non-detection part of the shielding part alone, and the other part is configured as a detectable part that alternately repeats the transparent part and the shielding part, and the position management unit requests the carriage control unit when the power is turned on. And driving the carriage, and referring to a change mode of the output signal of the detection means, when detecting that the carriage has entered the non-detection portion area, initializing the position counter of the carriage. And Further, the present invention is arranged on the main body along the moving direction of the carriage, one end is a non-detection portion of only a transparent portion or a shielding portion, and the other is a detectable portion that alternately repeats a transparent portion and a shielding portion. A scale plate, detecting means attached to the carriage and detecting the transparent part and the shielding part by making it relatively movable with respect to the scale plate and outputting a signal, and changing a position counter by an output pulse from the detecting means. A position management unit that manages a carriage position with the position counter; and a carriage control unit that controls a carriage with a motor based on the position counter information of the position management unit. A serial printer for performing printing, wherein the position management unit requests the carriage control unit to move the carriage from the detectable unit direction to the non-detectable unit direction. The Tsu di is driven, the driving of the carriage motor is stopped when the output signal of said detecting means is no longer changed more than a predetermined time, the carriage motor
The position counter is initialized when the driving of the motor is stopped . Further, in the serial printer according to the present invention, the position management unit may request the carriage control unit to drive the carriage from the non-detection unit direction to the detectable unit direction and detect a change in an output signal of the detection unit. Ki
The driving of Yarijjimota is stopped, by driving the carriage in the opposite direction and further requests the carriage control means stops the driving of the carriage motor when the output signal of said detecting means is no longer changed more than a predetermined time, Kyarijjimo
When the driving of the motor is stopped , the position counter is initialized.

[0009]

When the carriage is moved in the direction of the home position while monitoring the output pulse of the encoder module during the initialization operation of the printer, the carriage is moved to a predetermined distance where the position detection portion at one end of the scale plate does not exist. , The output pulse of the encoder module is interrupted. When this is detected, the carriage driving motor is stopped, and the home position can be set by initializing the position counter.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments shown in the drawings will be described below.

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 is a block diagram showing one embodiment of the present invention.
1 is a CPU, 2 is a carriage motor drive circuit, and 3 is a carriage motor. 4 is an encoder module, and 5 is a position counter. 2 is a carriage, and 3 is a carriage motor. Reference numeral 7 denotes a scale plate constituting a linear encoder, and reference numeral 4 denotes an encoder module. 8 is a platen and 9 is a recording medium. Reference numeral 10 denotes a recording head, and a driving signal of the recording head 10 is an FPC (not shown).
Given through. The output pulse of the encoder module 4 is also transmitted to the control circuit and the CPU via the FPC. Here, the carriage motor 3 is a DC motor, and the encoder module 4 is a photo-interrupter that outputs A-phase and B-phase having an electrical phase difference of 90 °.
Carriage motor speed control is performed by encoder module 4
This is carried out by a carriage motor drive circuit by a linear encoder constituted by the scale plate 7 and the encoder. FIG. 3 shows a structure diagram of the scale plate. The scale plate 7 is processed so that a light transmitting portion and a shielding portion as a position detection portion appear alternately, and is obtained by etching a metal plate, printing a plastic film, or the like. The resolution of the position detection unit is appropriately determined by the printing density of the printer, the control characteristics of the carriage motor, and the like. The portion A is a portion where the position detection portion is not provided (either all the transmission portion or all the shielding portion), and the output pulse of the encoder module does not change in this portion.

The operation of one embodiment of the present invention will be described with reference to FIGS. At the time of the initialization operation of the printer (when the power of the printer is turned on and the reset signal is given), first, the carriage motor 3 is driven, and the carriage 6 starts to move toward the home position.
The encoder module 4 detects a transmitting part and a shielding part of the position detection part of the scale plate and outputs a pulse. The CPU 1 starts monitoring the output pulse. When the carriage 6 continues to move and reaches the portion of the scale plate 7 where the position detection portion is not provided (portion A in FIG. 3), the output pulse does not change. When detecting that the output pulse of the encoder module does not change even after the lapse of the predetermined time T1, the CPU 1 stops driving the carriage motor 3 and initializes the position counter 5. (That is, this position is set as the home position.) This state is shown in FIG. Here, it is needless to say that the predetermined time T1 must be longer than the period of the output pulse of the encoder module corresponding to the set moving speed of the carriage, but it is not erroneously detected at the time of rising of the carriage or at the time of speed fluctuation during constant speed running. The time is set so as to be able to detect and stop as early as possible in FIG. 3A. In this embodiment, the position counter 5 is a 4-bit
It consisted of UP / DOWN counter. Figure 5 for the circuit diagram
Shown in After stopping at the home position, the position counter is initialized by applying a signal to the reset terminal.

The above operation completes the setting of the home position of the printer, and thereafter the position is managed by the position counter. If the length of the portion of the scale plate where the position detection part is not provided is longer than the distance required for stopping the carriage motor after the stop command, the home position can be set without causing the carriage to collide with the frame or stopper. Become. If the distance cannot be made large structurally, a collision with the frame or the stopper will occur after the stop command. However, since the drive of the carriage motor is cut off and the collision is caused only by the inertial force, the impact force can be extremely small. In addition, since the encoder pulse does not change in a portion of the scale plate where the position detection portion is not provided, the position counter does not malfunction due to vibration of the carriage at the time of deceleration, stop, or collision. Furthermore, since the reference position is uniquely determined by the setting of the position detection portion of the scale plate, there is no deterioration in position accuracy due to the phase relationship as in a home position setting device using a rotary encoder and a home position sensor, and a printer with extremely high position accuracy. Can be realized.

When the carriage is located at a position where the position detection section is not provided (that is, within the home position) during the initialization operation, the output pulse of the encoder module cannot change, so that the carriage is pushed by the frame or the stopper. The carriage motor stops after a predetermined time has elapsed with the contact state kept, and the position counter is initialized. Therefore, the home position can be set by exactly the same control as when the carriage is outside the home position. However, if it is necessary to prevent collision or pressing of the carriage, first move the carriage in the direction opposite to the home position during the initialization operation, check the change in the output pulse of the encoder module, and then move in the direction of the home position. For example, the home position setting operation can always be performed under the same conditions, and collision and pressing of the carriage against the frame and the stopper can be avoided.

In this embodiment, an optical position detecting means using a photo interrupter and a scale plate provided with a light transmitting portion and a shielding portion is used. However, multi-polar magnetization is applied to the magnetoresistive element and the magnetic material. A similar device can be configured by a magnetic type position detecting means using the applied scale plate. At this time, the portion where the position detection portion is not provided may be non-magnetized or magnetized with only one of the N pole and the S pole.

[0016]

As described above, according to the present invention, it is possible to set the carriage home position with high position detection accuracy by simple control without providing a special sensor or the like, and it is inexpensive and highly reliable. It is possible to provide a printer with high reliability.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a structural view of a printer showing one embodiment of the present invention.

FIG. 3 is a structural view of a scale plate according to an embodiment of the present invention.

FIG. 4 is a view for explaining the timing of output pulses of the encoder module according to one embodiment of the present invention.

FIG. 5 is a circuit diagram showing a configuration example of a position counter according to one embodiment of the present invention.

FIG. 6 is a circuit diagram showing a configuration example of a conventional home position sensor.

FIG. 7 is a diagram illustrating output pulses of a conventional encoder and output pulses of a home position sensor.

FIG. 8 is a block diagram showing a conventional example.

FIG. 9 is a structural view of a printer showing a conventional example.

[Explanation of symbols]

 Reference Signs List 1 CPU 2 Carriage motor drive circuit 3 Carriage motor 4 Encoder module 5 Position counter 6 Carriage 7 Scale plate 8 Platen 9 Recording medium 10 Recording head 11 Rotary encoder 12 Home position 13 Shielding plate 14 Frame

Continuation of the front page (56) References JP-A-60-65308 (JP, A) JP-A-5-31990 (JP, A) JP-A-2-555 (JP, A) JP-A-1-221271 (JP) JP-A-59-26283 (JP, A) JP-A-58-7386 (JP, A) JP-A-54-48707 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB Name) B41J 19/18

Claims (6)

(57) [Claims] 1. A scale plate disposed on a main body along a moving direction of a carriage, a detecting unit attached to the carriage and outputting a signal by enabling relative movement with respect to the scale plate, A position management unit that changes a position counter by an output signal and manages a carriage position with the position counter; anda carriage control unit that controls a carriage by a motor based on position counter information of the position management unit. A serial printer that performs printing by a recording head on a carriage, wherein the scale plate has one end as a non-detection unit having only a transparent portion or a shielding portion, and the other portion as a detectable portion that alternately repeats a transparent portion and a shielding portion. With this configuration, the position management unit requests the carriage control unit to drive the carriage when power is turned on. Referring to change aspects of the output signal of the detecting means, wherein when detecting that it has entered the carriage to the non-detection unit area, a serial printer for initializing said position counter of the carriage. 2. A scale provided on a main body along a moving direction of a carriage, one end of which is a non-detection portion having only a transparent portion or a shielding portion, and the other is a detectable portion which alternately alternates a transparent portion and a shielding portion. A detecting means for detecting the transparent part and the shielding part and outputting a signal by being attached to a carriage and being movable relative to the scale plate; and changing a position counter according to an output signal from the detecting means. A position management unit that manages a carriage position with the position counter; and a carriage control unit that controls a carriage with a motor based on the position counter information of the position management unit. Wherein the position management unit requests the carriage control unit to move the carriage from the detectable unit direction to the non-detectable unit direction. It is moving, the driving of the carriage motor is stopped when the output signal of said detecting means is no longer changed more than a predetermined time, calibration
A serial printer that initializes the position counter when the ridge motor stops driving . 3. A scale disposed on the main body along the moving direction of the carriage, one end of the scale being a non-detection portion having only a transparent portion or a shielding portion, and the other being a detectable portion which alternately alternates a transparent portion and a shielding portion. Plate, detection means attached to the carriage, and detecting the transparent part and the shielding part by making it relatively movable with respect to the scale plate, and outputting a signal; and referring to an output signal from the detection means, the carriage Position management means for calculating the position of the carriage and managing the carriage position with a position counter; and carriage control means for controlling the carriage with a motor based on the position counter information of the position management means. A serial printer for performing printing by a head, wherein the position management unit requests the carriage control unit to carry from the non-detection unit direction to the detectable unit direction. Drives the di-, carry after detecting a change in the output signal of said detecting means
The drive of the carriage motor is stopped, and the carriage is driven in the reverse direction in response to a request from the carriage control means.When the output signal of the detection means does not change for a predetermined time or more,
Stop the drive of the carriage motor,
A serial printer that initializes the position counter at the time of stopping the operation of the printer. 4. The motor according to claim 1, wherein said motor is a DC motor, and said detecting means is an encoder module comprising a photointerrupter for outputting an A phase and a B phase having a phase difference of 90 degrees electrically. A serial printer according to any one of the preceding claims. 5. A scale disposed on the main body along the direction of movement of the carriage, one end of which is a non-detection portion having only a transparent portion or a shielding portion, and the other portion is a detectable portion which alternately alternates between a transparent portion and a shielding portion. Plate, a detecting means attached to the carriage, which detects the transparent part and the shielding part by enabling relative movement with respect to the scale plate and outputs a signal, and changes a position counter by an output signal from the detecting means. and location management means for managing the carriage position at said position counter,
A carriage control means for controlling a carriage by a motor based on position counter information of the position management means; and a home position setting method in a serial printer for performing printing by a recording head mounted on the carriage, wherein the position a step of driving the carriage and management means request the carriage control means from the detectability unit direction to the non-detection unit direction, stops the driving of the carriage motor when the output signal of said detecting means is no longer changed more than a predetermined time And a step of initializing the position counter when the carriage motor stops driving . 6. A scale disposed on the main body along the direction of movement of the carriage, one end of which is a non-detection portion having only a transparent portion or a shielding portion, and the other is a detectable portion which alternately alternates between a transparent portion and a shielding portion. Plate, a detecting means attached to the carriage, and detecting the transparent part and the shielding part by making it relatively movable with respect to the scale plate and outputting a signal, and the carriage referring to an output signal from the detecting means. Position management means for calculating the position of the carriage and managing the carriage position with a position counter, and carriage control means for controlling the carriage by a motor based on the position counter information of the position management means, mounted on the carriage. A serial printer for performing printing by a recording head, wherein the position management unit requests the carriage control unit to move the carriage from the non-detection unit direction to the detectable unit direction. Driving the carriage, stopping the carriage after detecting a change in the output signal of the detection means, driving the carriage in the reverse direction, and the output signal of the detection means does not change for a predetermined time or more. a step of stopping the driving of the carriage motor at the home position setting method configured and process by initializing the position counter in the driving stop time of the carriage motor.