JPS62158070A - Position-detecting system for printing head - Google Patents

Abstract

PURPOSE:To shorten the period of time required for detecting the position of a printing head, by providing a detection plate provided alternately with shielding parts and non-shielding parts differing in length, and detecting the position of the printing head following a specified position-detecting procedure. CONSTITUTION:A detection plate 12 has a plurality of non-shielding parts 12a, 12c and the same number of shielding parts 12b, 12c, which are provided alternately, whereby a detector 11 is turned ON and OFF. The lengths of the non- shielding part 12a, the shielding part 2b, the non-shielding part 12c and the shielding part 12d are set to be a, b, c and d, respectively, which fulfill the relation a>b>c>d. When a command for detecting the position of a printing head 6 is supplied for initialization, it is judged whether or not the detector 11 is turned ON, then the head 6 is moved to a position at which an output from the detector 11 is inverted, and the head 6 is stopped there. Then, the head 6 is immediately moved in the opposite direction by a distance (y) to satisfy the relation b>y>c, is stopped, and it is judged whether or not the output of the detector 11 is ON.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for detecting the position of a print head in a serial printer in which a print head mounted on a carriage performs printing while moving in the width direction of a recording medium. be.

[Prior Art] Generally, in a known serial printer, a detector such as a photoswitch is fixedly installed at a position near the left end of the printer body (for example, a bottom plate that constitutes a mechanical support frame of the printer). The configuration was such that the home position was detected by a shielding plate provided on the side of the carriage carrying the print head that crossed the detector.

[Problems to be Solved by the Invention] For this reason, when it is necessary to detect the position of the print head at the time of initialization such as when turning on the power to the printer,
The print head must be moved to the home position. When the print head is at the home position at the time of initialization, the print head is first moved out of the home position and then returned to the home position. To move the print head to the home position, it is necessary to judge whether the detector has reversed each time the print head moves by one pulse, and therefore the print head movement speed cannot be increased any faster. That is the reality. Therefore, if the print head is located far away from the home position and closer to the right edge (this condition often occurs after normal printing has finished), there is a problem in that it takes time to detect the print head position. was there.

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel print head position detection method that can shorten the time required to detect the print head position.

[Means for Solving the Problems] The feature of the print head position detection method according to the present invention is that the print head mounted on a carriage performs printing while moving in the width direction of the recording medium. A detection plate in which a plurality of non-shielding portions are alternately formed and each of the shielding portions and the non-shielding portions have different lengths is fixedly arranged along the direction of movement of the print head to detect the detection plate. A detector whose on/off is controlled by the shielded and non-shielded parts of the plate is fixed to the carriage, and when a head position detection command is received, it is determined whether the output of the detector is on or off. and, based on the determination result, move the print head in a predetermined direction to a position where the output of the detector is reversed, and then move the print head in the predetermined direction by a predetermined distance, Thereafter, it is determined whether the output of the detector is on or off, and the position of the print head is detected based on the result of this determination.

[Embodiment] Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, two guide shafts 3.4 are fixed between the side plates 1 and 2 located parallel to each other.
The carriage 5 is slidably supported by. A print head 6 is mounted on the carriage 5, and a platen 7 rotatably supported by side plates 1 and 2 is provided in front of the print head 6. A recording medium 8 such as paper is passed between the print head 6 and the platen 7.
is arranged to be line-broken by the tractor device 9.10.

By the way, a detector 11 is attached to the back surface of the carriage 5. In this embodiment, the detector 11 is composed of a light emitting element and a light receiving element (both not shown). On the other hand, a detection plate 12 that cooperates with the detector 11 is fixedly installed on the bottom plate 13. 6. The detection plate 12 extends parallel to the moving direction of the carriage 5, and has a plurality of (two in this embodiment) non-shielding parts 12a, 12c and the same number of shielding parts 12b, 12d formed alternately. There is. When the detector 11 faces the non-shielding portion 12a or 12c, the light passes through and its output is on;
When facing the shielding portion 12b or 12d, the light is blocked and its output is turned off. Therefore, the detector 1'1 repeats turning on and off alternately along the movement area of the print head 6, and the sections in which it is on or off are the unshielded parts 12a and 12c of the detection plate 12 and the shielded part. 12
b, corresponding to the length of 12d. In this embodiment, the non-shielding part 12a and the shielding part 12b.

The non-shielding part 12c and the shielding part 12d each have a length a,
b, c, and d, each length is a>b>c
>d relationship.

Note that in FIG. 1, R, R2, R3, and R4 are regions corresponding to the non-shielding portion 12a, the shielding portion 12b, the non-shielding portion 12c, and the shielding portion 12d.

By arranging the detector 11 and the detection plate 12 as described above, the position detection of the print head 6 during initialization can be completed in a short time by the position detection method of the present invention according to FIG. I can do it.

When receiving a command to detect the position of the print head 6 for initialization, it is first determined whether the detector 11 is on or not, regardless of the position where the print head 6 is stopped (
Step I). If the detector 11 is in the on state at this time, that is, the print head 6 is in the area R in FIG.
, or R3, the print head 6 is moved rightward to a position where the output of the detector 11 is reversed to OFF, and is stopped (step 2). Thereafter, the radar 6 is immediately moved to the opposite direction, that is, to the left, by a predetermined distance y and stopped, and it is then determined whether the output of the detector 11 is on (step 2).

Here, the moving distance y of the print head 6 is b>y>c
・・・・・・■The relationship is set as follows.

If the detector 11 is in the on state, this means that the print head 6 was initially located in the region R1. Therefore, after moving a distance y, the print head 6
is stopped at a position (a - y) from the left end of its movement area.

Also, assuming that the detector 11 is in the OFF state, this means that the print head 6 was initially located in the region R3. Therefore, after moving a distance y, the print head 6 moves from the left end of its moving area (a+b+c-y).
This means that it is stopped at a certain position.

Assuming that the detector 11 was in the OFF state in the above-mentioned step (3), that is, that the print head 6 was stopped in the area R2 or R4 in FIG. to a position where the output of is inverted to ON (step n-). and detector 1
From the position where the output 1 is turned on, the print head 6 is further moved in the same direction by a distance 2 and stopped, and the detector 11
It is determined whether the output of is on (step m-).

Here, the moving distance 2 of the print head 6 is b>z>c
・・・・・・■The relationship is set as follows.

If the detector 11 is in the OFF state, this means that the print head 6 was initially located in the region R4. After moving a distance of 2, the print head 6
is stopped at a position (a+b+C-z) from the left end of its movement area. Further, if the detector 11 is in the on state, this means that the print head 6 was initially located in the region R2. Therefore, after moving a distance of 2, the print head 6 has stopped at a position (a-z) from the left end of its movement area.

Note that although the above embodiment is an example in which the movement area of the print head 6 is divided into four areas, it is also possible to divide it further into smaller areas. In this case, the detection operation in step (2) or (2) described above will be performed multiple times.

Further, the detector 11 may use a magnetically sensitive switch instead of a photoswitch. In this case, the detection plate 12 or 112 needs to be made of a magnetic material.

[Effects of the Invention] According to the print head position detection method according to the present invention described in detail above, the maximum movement distance of the print head required for initialization is shortened, and the average distance required for print head position detection is accordingly shortened. The time can be reduced compared to known methods.

In addition, since it can be handled with a combination of one detector and one detection plate, the cost is almost the same as that of known ones (therefore, there is no increase in cost.
Since this position detection method does not require the print head to be moved to the leftmost home position, it is suitable for position detection for printers with cut feeders whose set position and printing width are different from those using continuous paper. Optimal.

[Brief explanation of drawings]

The drawings show preferred embodiments of the present invention.
The figure is a perspective view of a serial blink to which the present invention is applied, and FIG. 2 is a flowchart of a print head position detection method according to the present invention. 5...Carriage 6...Print head 8...Recording medium 11...Detector 12...Detection plates 12a, 12c... ...Non-shielding parts 12b, 12d...Amount of shielding part upper

Claims (1)

[Claims] In a serial printer in which a print head mounted on a carriage prints while moving in the width direction of a recording medium, a plurality of shielding portions and non-shielding portions are alternately formed, and the shielding portions are adjacent to each other. and a detection plate in which the non-shielding parts have different lengths from each other is fixedly arranged along the moving direction of the print head, and the detection plate is turned on and off by the shielding part and the non-shielding part of the detection plate. A detector that is controlled is fixed to the carriage, and when a head position detection command is received, it is determined whether the output of the detector is on or off, and based on the result of this determination, the print head is is moved in a predetermined direction to a position where the output of the detector is reversed, and then the print head is moved in a predetermined direction by a predetermined distance, after which the output of the detector is reversed. A print head position detection method characterized in that it determines whether the print head is on or off, and detects the position of the print head based on the result of this determination.