JPH0321480A - Printing head position detector in serial printer - Google Patents

Abstract

PURPOSE:To obviate the position detection sensor, facilitate assembling, and reduce the cost by a method wherein drive coils incorporated in a printing head and a magnet generating an induced current in said drive coils are used, the induced current generated in the drive coils is detected by a detection circuit, and the position of the printing head is detected. CONSTITUTION:A printing head 4 is reciprocated along a guide shaft 3. When the printing head 4 reaches, for example, a home position, at least one of drive coils 5 crosses the magnetic flux of a magnet 6. Then, an induced current generated in the drive coil 5 is detected by a detection circuit 8, and a detection signal is outputted. At this time, the printing head 4 is disposed out of a printable range and, therefore, a drive signal is not supplied from a drive circuit 7 to the drive coil 5. In this manner, the detection circuit 8 can properly detect only the induced current. A microcomputer controlling a printer recognizes that the printing head comes to the home position by the detection signal and conducts a required home sensing action.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a position detection device for a print head of a serial printer.

[Prior Art] A serial printer performs a so-called home sense operation in order to know the position of the print head when the power is turned on. Optical sensors, microswitches, and the like are used as position detection sensors for this purpose.

[Problem to be solved] Conventionally, when optical sensors and microswitches are used to detect the position of the print head, not only these parts are required, but also cables connecting the optical sensors and the circuit board, etc. It also requires.

This complicates the structure of the printer and complicates the assembly process, which is one of the causes of high printer costs.

An object of the present invention is to make it possible to detect the position of a print head with a simple configuration without requiring a conventional position detection sensor that causes high costs, to facilitate assembly, and to reduce the cost of a printer. There is a particular thing.

[Means for Solving the Problems] In order to achieve the above object, the print head position detection device for a serial printer of the present invention incorporates a drive coil for printing, and the print head position detection device of the present invention has a drive coil for printing, which is moved back and forth in parallel with the platen. a magnet that is fixedly disposed on the printer frame side and that exerts a magnetic flux on at least one of the drive coils when the print head moves; The sensor is equipped with a detection circuit that detects the induced current.

[Function] When the print head moves back and forth and crosses the magnetic flux of the magnet provided on the printer frame side, an induced current is generated in the drive coil built into the print head.

This current is detected by a detection circuit to detect the position of the print head.

[Example] An example of the present invention will be described below with reference to the drawings.

As shown in Figure 1, the platen 2 is attached to the printer frame 1.
A guide shaft 3 is provided parallel to the platen 2, and a print head 4 is mounted on a carriage that reciprocates along this guide shaft.

As shown in the second diagram, the print head 4 is equipped with drive coils 5 for driving a plurality of printing elements.

A permanent magnet 6 is fixedly arranged on the printer frame 1 side at a position where it applies magnetic flux to at least one of the drive coils 5.

As shown in FIG. 2, the drive coil 5 of the print head 4...
A drive signal is supplied from the drive circuit 7 to drive each printing element. Further, a detection circuit 8 is connected to at least one of the drive coils 5 in order to detect the induced current generated when the drive coils 5 cross the magnetic flux of the magnet 6.

Next, the operation will be explained.

The print head 4 is reciprocated along the guide shaft 3, and the first
At least one of the drive coils 5 crosses the magnetic flux of the magnet 6 when it comes to the illustrated home position, for example. Therefore, an induced current is generated in this drive coil 5. This induced current is detected by the detection circuit 8 and outputs a detection signal.

At this time, since the print head 4 is not in a position for printing, no drive signal is supplied from the drive circuit 7 to the drive coil 5. Therefore, the detection circuit 8 can accurately detect only the induced current.

Microcomputer that controls the printer (not shown)
The printer learns from this detection signal that the print head has reached the home position, and performs the necessary home sensing operation.

Further, when the print head 4 prints, the print head 4 is in a position not facing the magnet 6. For this reason, the print head 4
will not malfunction due to the magnet 6.

Note that the mounting position of the magnet 6 is not limited to the rear of the print head, but may be in the front or below as long as it is a position where magnetic flux can be exerted on the drive coils 5 .

[Effect] The present invention configured as described above uses a drive coil built into the print head and a magnet that generates an induced current in the drive coil, and a detection circuit detects the induced current generated in the drive coil. Since the position of the print head is detected by using the printer, there is no need for home sensors or connection cables as in the past, reducing costs, and the simple structure makes assembly easier. .

[Brief explanation of drawings]

FIG. 1 is a plan view of essential parts showing an embodiment of the present invention, and FIG. 2 is a circuit block diagram. 1●●●Printer frame, 2...Platen, 4...Print head, 5-...Drive coil, 6...Magnet, 8...Detection circuit. that's all

Claims (1)

[Claims] A print head that includes a built-in drive coil for printing and that moves back and forth parallel to the platen, and a print head that is fixedly disposed on the printer frame side so that when the print head moves, the drive coil is moved. A position detection device for a print head of a serial printer, comprising: a magnet that exerts a magnetic flux on at least one; and a detection circuit that detects an induced current generated in the at least one drive coil when the at least one drive coil crosses the magnetic flux.