JPH0270471A - Positioning device for printer - Google Patents

Abstract

PURPOSE:To position a carriage at a predetermined position such as a home position by providing a positioning circuit for detecting the carriage by a first position sensor, then so controlling a motor as to decelerate the carriage and so controlling the motor as to stop the carriage in response to the detection of a second position sensor. CONSTITUTION:The moving region of a carriage is detected by zone slits 10a-10c formed at a slit plate 6 and a photosensor 7 to control a printing width and a printing position. A home position is detected by a signal based on the cooperation of a home position slit 11 formed on the plate 6 provided to position at the home position and the photosensor 7, and it is positioned at the home position. A home position sensor 8 generates a signal when a carriage 1 is moved to the vicinity of the home position. The sensor 8 includes, for example, a form of a microswitch which is energized by pressing down the carriage 1.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a printer positioning device for positioning a carriage on which a recording head is mounted to a predetermined position such as a home position.

[Conventional technology]

Conventionally, in order to position the print head in a predetermined position in a printer, for example, to position it at the home position, the home position is detected by a home position sensor, the carriage speed is reduced or the carriage is stopped at a certain time, and then the carriage is moved to the home position. This is done by energizing the motor that is the drive source of the carriage and pressing it against a stopper that locks the carriage at the home position.

(Problems to be Solved by the Invention) By the way, in the recording head used in an inkjet printer, the meniscus at the tip of the liquid flow path (nozzle) for ejecting liquid may recede and the nozzle tip may become dry.
Non-ejection may occur for several to several dozen lights. This tendency is particularly noticeable at low temperatures due to the increase in ink viscosity. This tendency is noticeable because full-color inkjet printers use multiple concentrations of ink for one color, and when printing large-sized computer graphics, the frequency of use of a particular nozzle decreases significantly. .

As a countermeasure against this, the recording head is set at a home position at regular intervals, and all nozzles are made to eject ink toward appropriate collection members.

Conventionally, the home position was determined by pressing against a stopper, so the position of the carriage and the platen, which was installed along the carriage's moving direction, was adjusted to regulate the recording surface of the recording medium by the impact force when pressing against the stopper. As a result of the misalignment, the relative position between the recording medium and the nozzle changes, and when recording is performed, recording gaps (white streaks) may occur along the direction of carriage movement.

The present invention aims to solve such problems.

By doing this, the carriage is positioned without contact, rather than being stopped mechanically.

[Means to solve the problem]

To this end, the present invention provides a carriage that is driven by a motor and is capable of reciprocating with a recording head mounted thereon; a first position sensor provided near a predetermined stop position of the carriage;
A second position sensor is provided at a predetermined stop position, and when positioning the carriage at a predetermined stop position, the motor is controlled to decelerate the carriage after detection by the first position sensor, and in response to detection by the second position sensor. and a positioning circuit that controls the motor to stop the carriage.

[For production]

According to the present invention, the motor is controlled to position a predetermined stop position, for example, a home position, using first and second position sensors and a positioning circuit (Example). An example will be explained in detail.

FIG. 1 shows a carriage section of an inkjet printer according to an embodiment/example of the present invention. Here 1 is carriage, 2
2A is an inkjet recording head mounted on a carriage, and 2A is its nozzle.

A timing belt 3 is hung around the pulleys 4a and 4b,
The pulley 4a is rotatably supported by a support shaft (not shown), and the pulley 4b is fixed to the shaft of the motor 5. The timing belt 3 is driven by a motor 5, and the carriage 1 fixed to the timing belt 3 can reciprocate.

A slit plate 6 is provided along the moving direction of the carriage 2, and functions as a signal generator in cooperation with a photosensor 7 provided on the carriage 2. That is, the timing slit portion 9 provided on the slit plate 6 and the photosensor 7
A timing sensor is configured by detecting the carriage position and determining the drive timing of the head. Also, by using this as a frequency generator,
A speed signal is taken from here, and constant speed control of the reciprocating movement of the carriage 1 is performed. Further, the eight movement areas of the carriage are detected by the zone slits 10a to 10c provided on the slit plate 6 and the photosensor 7, and are used to control the print width and print position.

Further, reference numeral 11 denotes a home position slit provided in the slit plate 6 used for positioning the home position, and the home position is detected by a signal based on the cooperation between this and the photo sensor 7. Positioning is done.

A home position sensor 8 generates a signal when the carriage 1 approaches the home position. This sensor 8 may be in the form of a microswitch, for example, and may be pressed down by the carriage 1 to become conductive.

FIG. 2 is an electrical configuration diagram of a positioning device according to an embodiment of the present invention, and FIG. 3 is a timing chart thereof. Here, 20 and 21 are command terminals for reciprocating the carriage.

When the carriage 1 is not near the home position, the home position sensor 8 (hereinafter not abbreviated as H, P) becomes H, and the output of the AND circuit 30.31 becomes the output of the AND circuit 28.2.
9 becomes the output of AND circuit 2 via inverter 22.
The output of 3.24 is L. Also, analog switch 1
4 becomes conductive, and analog switch 15 becomes non-conductive. When the terminal 20 is H and the terminal 21 is L, the AND circuit 28
is H, the AND circuit 29 is L, and H-P8 is H, so the AND circuit 30 is H, and the AND circuit 31 is L.
bawl. Since the AND circuit 30 is H, the transistors 18 and 41 become conductive through the OR circuit 32, and the inverter 3
Transistor 12 is turned on via transistor 5. Then, due to conduction of the transistors 12 and 41, a current flows through the motor 5 in the direction of A, and the carriage 1 moves toward the home position.

Similarly, terminal 20 is L and terminal 2! When is H,
Transistor 40.13 becomes conductive, energizing motor 5 in the direction opposite to A, and carriage 1 is driven in the opposite direction from the home position.

When terminal 20.21 is L, AND circuit 28.29 is L
So, AND circuit 30.31 and OR circuit 32.3
3, the transistors 12, 13, 40, and 41 become non-conductive, and therefore, energization of the motor 5 is prohibited.

The output of the timing sensor (hereinafter abbreviated as T and S) 7a is made into a speed signal via a frequency-voltage converter (hereinafter abbreviated as F and V) 16, and when H and P8 are H, the analog switch 1
4 to the differential amplifier 17, and the output of the differential amplifier 17 controls the base current of the transistors 13 and 13 through the transistors 18 and 19, thereby controlling the current of the motor 5. When the speed of motor 5 decreases, F, V16
The output of the differential amplifier circuit 17 decreases, the output of the differential amplifier circuit 17 increases, and the base current of the transistor 13 or 41 is increased to maintain constant speed.

When positioning the carriage l to the home position,
The terminal 20 is set to H, and the terminal 21 is set to L.

Therefore, current is applied to the motor 5 in the direction A, and the carriage 1 moves toward the home position. When reaching the vicinity of the home position, H and P8 become L, so the AND circuit 30.31 becomes L, and the direction in which the motor 5 is energized is determined by the AND circuit 23.24. At this time, the analog switch 14 becomes non-conductive, and conversely, the analog switch 15 becomes conductive.

Output cover Vr of zone sensor (hereinafter abbreviated as Z and S) 7b
Since the output of the comparator 36 becomes H, the analog switch 38 becomes conductive, and the OP amplifier 37 functions as an inverting circuit. Also, the output of the AND circuit 23 is H
Since the AND circuit 24 is at L, the OR circuit 32 is at H and the OR circuit 33 is at L. Therefore, the carriage is moving toward the home position.

When the photosensor 7 reaches the slit 11, the output of the zone sensor 7b decreases, and conversely, the output of the inverting circuit 37 increases, the output of the inverting circuit 17 decreases, and the current to the motor 5 decreases. When the output of the zone sensor becomes the same value as V raf, the output of the differential amplifier 17 becomes ;, and the power supply to the motor 5 is stopped.

When the carriage further moves toward the home position, the output of the comparator 36 becomes L, and the analog switch 3a
becomes non-conductive, and the OP amplifier 37 functions as a buffer circuit. Since the output of the comparator 36 is L, the AND circuit 23 and OR circuit 32 become L, and the AND circuit 24 and OR circuit 33 become H. Therefore, the transistors 13, 40 are made conductive by the OR circuits 32, 33, the motor 5 is energized in the direction opposite to A, and a force is applied to the carriage l in the direction opposite to the home position.

When the output of the zone sensor 7b decreases, the buffer circuit 37
The output of the differential amplifier 17 increases,
As a result, a current in the opposite direction to A increases in the motor 5. Therefore, negative feedback is applied by the zone sensor, and the carriage 1 comes to a stop in the vicinity where the output of the zone sensor becomes equal to V raf. Then, connect terminals 20 and 21 to L.
By doing so, the output of the OR circuit 27 becomes positive, and the outputs of the AND circuits 23 and 24 also become negative, so energization to the motor 5 can be prohibited.

For motor 5 and carriage 1 to be in the home position,
Set terminal 20 to H, terminal 21 to H, and terminal # to H for a predetermined time.
With this, the AND circuit 30 becomes L and the AND circuit 31 becomes H, and the motor 5 is energized in the opposite direction to A. Further, at this time, the analog switch 14 becomes conductive, and the analog switch 15 becomes non-conductive, so that constant speed control is performed.

In the above description, a photocoupler and a slit plate were used as the sensor used to define the carriage position, etc., but it goes without saying that the sensor may have various forms.

Furthermore, the present invention can be applied to any serial type printer that performs recording by moving the recording head, and is not limited to inkjet printers, and the stop position is not limited to the home position, but any printer that requires accurate positioning. It may also be a position.

[Effects of the Invention] As explained above, when positioning the carriage on which the recording head is mounted to a predetermined position,
Since the carriage is stopped mechanically without contact with the direction of rotation, the problem that occurs when a mechanical member such as a stopper butts against the carriage, that is, the white smearing of printed materials due to impact force, can be avoided. I was able to eliminate all of them. In addition, there were no new mechanical parts added, and the objective could be achieved by partially improving the sensor and adding a few circuits to the rest, so the effect was remarkable.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the carriage section of an inkjet printer according to an embodiment of the present invention, FIG. 2 is a positioning circuit diagram of this embodiment applicable to the configuration of FIG. 1, and FIG. 5 is a timing chart showing signal waveforms. DESCRIPTION OF SYMBOLS 1... Carriage, 2... Inkjet nozzle, 3... Timing belt, 4a, 4b... Pulley, 5... Motor, 6... Slit, 7... Photo sensor, 8...・Micro switch, 9... Timing slit, 10a, lOb, 10c, 10d --- Zone slit, 11... Home position slit, 12.13,
40,41,18.19...transistor, 7a...
- Timing sensor, 7b-...Zone sensor, 16...Frequency-voltage converter, 14.15.18...Analog switch. Diagram

Claims (1)

[Claims] 1) A motor capable of forward and reverse rotation, a carriage driven by the motor and capable of reciprocating movement with a recording head mounted thereon, and a first position sensor provided near a predetermined stop position of the carriage. a second position sensor provided at the predetermined stop position; controlling the motor to decelerate the carriage after detection by the first position sensor when positioning the carriage at the predetermined stop position; A positioning device for a printer, comprising: a positioning circuit that controls the motor to stop the carriage in response to detection by the second position sensor.