JPH0732069Y2 - Line printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a line printer capable of detecting the position of a head carriage of a print head.

(Prior Art) A conventional general line printer is configured as shown in FIG.

In FIG. 3, reference numeral 1 denotes a head carriage in which a plurality of print heads are juxtaposed, and the head carriage 1 is movably held in the horizontal direction by two guide shafts 2 provided in a main body (not shown). Further, the protrusion 3 provided on one of the bottom portions of the head carriage 1 and the protrusion 5 of the follower arm 4 mounted on the main body face each other, and the follower arm 4 and the other portion of the head carriage 1 are A compression spring 6 is stretched between them, and an eccentric cam 7 is arranged between the protrusion 3 of the head carriage 1 and the protrusion 5 of the follower arm 4. The eccentric cam 7 is connected to the motor 8 and is positioned. A detection device 9 is provided.

Then, when the motor 8 is rotated in one direction to rotate the eccentric cam 7, the head carriage 1 is driven via the protrusion 3 in the half rotation of the eccentric cam 7, and the head carriage 1 moves leftward. . Further, when the eccentric cam 7 makes a half rotation, the follower arm 4 in which the protrusion 5 is in contact with the eccentric cam 7 is rotated, and the rotation of the follower arm 4 causes the protrusion 3 of the head carriage 1 via the compression spring 6. Eccentric cam 7
Follows and abuts and moves to the right. That is, the eccentric cam 7
The rotation of the eccentric cam 7 converts the eccentric amount of the eccentric cam 7 into the displacement amount of the linear movement of the head carriage 1.

And the dot printer is 5 x per character
Using the dot matrix of 7, the dots are combined in a mosaic manner to create characters. The printing is performed by moving the printing head back and forth by a fixed distance, for example, 120 dots, and on the forward and backward paths of the head. The dots are printed at the position to which the print signal is added, out of the predetermined print positions determined in step 1. At this time, the position detection device 9 detects the position of the head carriage 1 to prevent the print positions from deviating to the left and right in the forward and backward passes.

By the way, as the position detecting device 9 of the head carriage 1, for example, the structure described in Japanese Patent Laid-Open No. 60-189456 is known, and an eccentric cam 7 is provided with an optical encoder plate coaxially with the eccentric cam 7. The digital display of the encoder plate is read by the rotation of the optical sensor, and the position of the head carriage 1 is detected by this optical sensor.

(Problems to be Solved by the Invention) However, the conventional position detection device 9 for the head carriage 1 does not directly detect the position of the head carriage 1, but detects the rotational position of the eccentric cam 7 to detect the head position. Since the position of the carriage 1 is detected, the accurate position cannot be detected unless the protrusions 3 and 5 for the eccentric cam 7 are set with extremely high accuracy. Therefore, even if printing is performed at the same position on the forward and backward passes of the print head, the actual position of the head carriage 1 and the position indicated by the position detection device 9 are likely to deviate, resulting in the forward print position. Then, the positions for the backward printing will not be aligned.

Also, since the eccentric cam 7 and the protrusions 3 and 5 are worn,
It is difficult to maintain high accuracy between the position of the head carriage 1 and the position detected by the position detection device 9.

The present invention has been made in view of the above problems, and provides a line printer that accurately detects the position of the head carriage and can easily and reliably prevent printing deviation between the forward path and the backward path. The purpose is to

[Constitution of device]

(Means for Solving the Problems) The present invention relates to a line printer for printing characters by operating a plurality of print heads juxtaposed on the head carriage in synchronization with the reciprocating movement of the head carriage. Both ends of the belt attached to the head carriage along the moving direction of the head carriage,
The intermediate portion of this belt is fixed and wound around the pulley, and the pulley is pivotally supported in the vicinity of the movable range of the head carriage and rotates according to the movement of the head carriage. The rotating plate is provided with regular optical digital information along the portion, and a detecting means for optically detecting the optical digital information of the rotating plate.

(Operation) The present invention moves the belt in accordance with the linear reciprocating motion of the head carriage, rotates the pulley by the movement of the belt, and rotates the rotating plate provided coaxially with the pulley. The position of the head carriage is detected by reading the optical digital information of the. Also, since the belt is wound around the pulley and the middle part is fixed, the movement of the belt accompanying the movement of the head carriage is ensured. Since it can be converted into rotation of the pulley, the movement of the head carriage can be accurately detected.

(Embodiment) An embodiment of the line printer of the present invention will be described below with reference to FIGS. 1 and 2.

Since the basic structure is the same as that shown in FIG. 3 of the conventional example, the corresponding parts will be denoted by the same reference numerals.

A head carriage in which a plurality of print heads are juxtaposed is held movably in the horizontal direction by two guide shafts 2 provided in a main body (not shown). Further, the protrusion 3 provided on one side of the bottom portion of the head carriage 1 and the protrusion 5 of the follower arm 4 mounted on the main body are opposed to each other, and
A compression spring 6 is stretched between the follower arm 4 and the other part of the head carriage 1, and an eccentric cam 7 is arranged between the protrusion 3 of the head carriage 1 and the protrusion 5 of the follower arm 4. A motor 8 is connected to the eccentric cam 7 and a print position detecting device 11 is provided.

When the eccentric cam 7 is rotated by rotating the motor 8 in one direction, the head carriage 1 is driven via the protrusion 3 in the half rotation of the eccentric cam 7, and the head carriage 1 moves leftward. Further, when the eccentric cam 7 makes a half rotation, the follower arm 4 in which the protrusion 5 is in contact with the eccentric cam 7 is rotated, and the rotation of the follower arm 4 causes the protrusion 3 of the head carriage 1 via the compression spring 6. Follows the eccentric cam 7 and moves to the right. That is, as the eccentric cam 7 rotates, the eccentric amount of the eccentric cam 7 is converted into the displacement amount of the linear movement of the head carriage 1.

Further, a print position detecting device 11 for detecting the position of the head carriage 1 is attached to the head carriage 1. In the print position detecting device 11, a support plate 12 is fixed to the lower surface of the head carriage 1, and the support plate 12 is provided. A side plate 13 is bent and formed in the vicinity of one side portion. Then, the auxiliary plate 15 having the two long holes 14 in the side plate 13 is screwed through the long holes 14.
A spring 18 as a belt tension member is mounted between the one end of the auxiliary plate 15 and the projecting piece 17 of the support plate 12 so that it can be displaced.
Is stretched, and the auxiliary plate 15 is biased to the left.

Further, a pulley 19 is axially attached to a main body (not shown) at one side of the support plate 12, and a fan-shaped rotating plate 21 having a diameter larger than that of the pulley 19 is integrally fixed to a shaft 20 of the pulley 19, and Moving board
A regular slit group 22 as optical digital information is radially formed on the circumference 21 of the circumference 21. A belt 23 made of steel, for example, is wound around the outer periphery of the pulley 19 in an α shape. The intermediate portion of the belt 23 is the pulley 19, one end is the side plate 13 of the support plate 12, and the other end is the auxiliary plate 15.
Each of them is fixed with a stopper 24.

Further, a photo sensor 25 as a U-shaped detecting means is disposed so that the light emitting portion and the light receiving portion face each other with a gap so as to sandwich the slit group 22 of the rotating plate 21.

Next, the operation of the above embodiment will be described.

First, when the motor 8 rotates in one direction to rotate the eccentric cam 7, the head carriage 1 reciprocates left and right via the protrusion 3 of the head carriage 1 and the protrusion 5 of the follower arm 4.
At the same time, when the head carriage 1 is driven to one side in the outward path, the belt 23 is pulled to one side. Therefore, the pulley 19 and the rotating plate 21 rotate in one direction, and the photo sensor
At 25, the rotation amount of the pulley 19 is read by the crossing amount of the slits of the slit group 22.

On the contrary, in the case of the return path, the rotation direction of the motor 8 is the same, but when the head carriage 1 is driven to the other side, the belt 23 is pulled to the other side. Therefore, the pulley 19 and the rotating plate 21 rotate in the other direction, and the photosensor 25 similarly reads the amount of rotation of the pulley 19 by the amount of crossing the slits of the slit group 22.

The output from the photo sensor 25 is the slit group 22.
It becomes a pulse digital signal corresponding to the number of slits traversed. The position of the head carriage 1 is detected by counting the number of pulses. Then, the dot is driven at a predetermined position by the position detection signal, and a dot matrix type character having no positional deviation is created.

As a measure for preventing the deviation between the print positions on the forward path and the return path caused by the mechanical delay, the number of pulses corresponding to the print delay may be increased or decreased from the obtained count value.

Further, the belt 23 need not be a steel belt as long as it does not extend.

According to the above-described embodiment, the photo sensor 25 detects the number of the slit groups 22 of the rotary plate 21 that is directly connected to the head carriage 1. Therefore, the position can be detected by the head carriage 1 with extremely high accuracy and high resolution. . Further, since the position of the head carriage 1 is directly detected by using the pulley 19 and the belt 23 independently of the motor 8 and the eccentric cam 7 to detect the position of the head carriage 1, the detected value due to wear or the like is There is no change in printing performance due to changes over time.

Further, the optical digital information is not limited to the slit group 22, but may be, for example, a digital reflection symbol that is regularly expressed in a radial pattern. In this case, the photosensor 25 is not limited to the slit group 22.
Instead of the transmission detection type when using, the reflection detection type in which the light emitting portion and the light receiving portion are provided on the upper surface of the digital reflection symbol is used.

[Effect of device]

According to the line printer of the present invention, the belt is moved in accordance with the linear reciprocating motion of the head carriage, the pulley is rotated by the movement of the belt, and the rotating plate provided coaxially with the pulley is rotated. By reading the optical digital information of the moving plate, the position of the head carriage is detected,
Further, since the belt is wound around the pulley and the intermediate portion is fixed, the movement of the belt accompanying the movement of the head carriage can be reliably converted into the rotation of the pulley, so that the movement of the head carriage can be accurately detected, The position of the head carriage can be detected with extremely high precision and high resolution, and further, the deterioration of the printing performance due to the change of the detected value with time due to wear or the like is small.

[Brief description of drawings]

FIG. 1 is a partially cutaway plan view of a line printer according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of the same as above, and FIG. 3 is a partially cutaway plan view of a conventional line printer. 1 ... Head carriage, 18 ... Spring as tension member, 19 ... Pulley, 21 ... Rotating plate, 22 ... Slit group as optical digital information, 23 ... Belt, 25 ... Detection means As a photo sensor.

Claims (2)

[Scope of utility model registration request] 1. A line printer for printing characters by operating a plurality of print heads juxtaposed on the head carriage in synchronism with the reciprocating movement of the head carriage, wherein both ends in the longitudinal direction are formed on the head carriage. A belt attached along the moving direction of the head carriage, and an intermediate portion of the belt is fixed and wound around the belt, and is pivotally supported near the movable range of the head carriage and rotates according to the movement of the head carriage. A pulley, a rotary plate provided coaxially with the pulley and provided with regular optical digital information along the circumference thereof, and a detection means for optically detecting the optical digital information of the rotary plate. Line printer characterized by having and. 2. A utility model registration claim comprising a tension member for tensioning and holding the head carriage in a moving direction of the head carriage.
Item line printer.