JPH01247179A - Serial dot matrix printer - Google Patents

Abstract

PURPOSE:To improve printing quality by detecting magnetic flux variations by using an MR element which is provided on the lower end of a carriage with a magnetic pole section for head position detection arranged linearly in a shaft direction and transmitting the variation data to a control circuit. CONSTITUTION:If a printing head 3 moves in a shaft direction indicated by an arrow A, an MR element 2 generates a sinusoidal wave signal of two-phase resistance value variations by sensing magnetic flux variations from a magnetic flux section for head position detection 1. This sinusoidal wave signal is transmitted to a bridge circuit 12 through the interior of a carriage head and flexible cable 11. The sinusoidal wave signal of resistance value variations which is output from the MR element 2 is converted to a voltage signal by the bridge circuit 12, and further converted to a pulsed signal by a Schmit circuit 13. A reference point for the position of the printing head 3 is detected by a photosensor 6 and a trigger signal is sent to a counter 14. The counter 14 counts the number of pulses from the Schmit circuit 13 and transmits it to a microcomputer 15. The microcomputer 15 detects the position of the printing head 3 by a signal from the counter and controls a head driver circuit 16 and a motor driver circuit 17 based on a printing command.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a serial dot matrix printer;
In particular, the present invention relates to a serial dot matrix printer that uses a magnetoresistive element (hereinafter referred to as an MR element) to detect the speed and position of a print head.

[Conventional technology]

Conventionally, this type of printer has detected the position and speed of the print head by using a stepping motor as the carriage feed motor, or by using a DC servo motor and a rotary encoder and counting pulses from the rotary encoder. .

[Problem to be solved by the invention]

The conventional serial type dot matrix printer described above indirectly detects the position and speed of the print head from the rotation angle of the carriage feed motor, so it is affected by belt backlash, etc., and the actual printing This method has the disadvantage that an error occurs between the position and speed of the print head and the position and speed of the print head detected by counting pulse signals, which reduces the print quality when using reciprocating printing, 2-pass, or 3-pass methods. .

[Means to solve the problem]

The serial dot matrix printer of the present invention includes: a head position detection magnetic pole portion linearly arranged in the shaft direction that guides the movement of the print head; a photo sensor that detects a reference point of the print head; and a photo sensor that detects the reference point of the print head. a magnetoresistive element incorporated in the lower end of the carriage and disposed opposite to the head position detection magnetic pole part, and amplifies a magnetic flux change output according to the position of the magnetoresistive element with respect to the head position detection magnetic pole part. a bridge circuit that converts a signal from the bridge circuit into a pulse signal, and a Schmitt circuit that converts a signal from the bridge circuit into a pulse signal, and a Schmitt circuit that directly determines the position of the print head by counting the number of pulses from the Schmitt circuit using the signal from the photosensor as a reference point. The printer is equipped with a control circuit that detects and controls printing.

〔Example〕 Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a perspective view of one embodiment of the present invention, FIG. 2 is a configuration diagram of a position detection section in this embodiment, and FIG. 3 is a block diagram of this embodiment.

In this embodiment, a magnetic pole part 1 for head position detection is arranged parallel to a carriage feed shaft 7 that guides the movement of the print head 3, and a magnetic pole part 1 for head position detection is arranged at the lower end of the carriage of the print head 3 to face the magnetic pole part 1 for head position detection. A photo sensor 6 is provided at the right or left end of the movable range of the carriage, a DC servo motor 4 and belt 5 are used to drive the carriage, and the paper 10 to be printed is placed on the platen 9. The apparatus includes a paper feeding motor 8, a flexible cable 11, a bridge circuit 12, a Schmitt circuit 13, a counter 14, a microcomputer 15, a head driver circuit 16, and a motor driver circuit 17.

According to this embodiment having such a configuration, as shown in FIG. 2, when the print head 3 moves in the shaft direction indicated by the arrow A, the MR element 2 detects the change in magnetic flux from the head position detection magnetic pole part 1. It senses and generates a two-phase resistance change sine wave signal, which is transmitted to the inside of the carriage head and the flexible cable 11.
The signal is sent to the bridge circuit 12 via. As shown in the block diagram of FIG. 3, the sine wave signal of resistance change output from the MR element 2 is converted into a voltage signal by a bridge circuit 12, and further converted into a pulse signal by a Schmitt circuit 13. The reference point for the position of the print head 3 is detected by the photosensor 6, and a trigger signal is sent to the counter 14. The counter 14 counts the number of pulses from the Schmitt circuit 13 and sends it to the microcomputer 15. The microcomputer 15 detects the position of the print head 3 based on the signal from the counter 14, and controls the head driver circuit 16 and motor driver circuit 17 based on the print command.

〔Effect of the invention〕

As explained above, the present invention detects changes in magnetic flux using an MR element that is installed at the lower end of the carriage and moves with respect to a magnetic pole part for head position detection arranged linearly in the shaft direction, and sends the detected magnetic flux change to a control circuit. As a result, the position of the print head can be directly detected, which has the effect of preventing position detection errors due to backlash of the carriage feed belt, etc., and improving print quality.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of one embodiment of the present invention, FIG. 2 is a configuration diagram of a position detection section in this embodiment, and FIG. 3 is a block diagram of this embodiment. 1... Magnetic pole part for head position detection, 2... MR element,
3... Print head, 4... DC servo motor for carriage feed, 5... Belt for carriage feed, 6...
・Photo sensor, 7... Carriage feed shaft, 8
...paper feed motor, 9...platen, 10...
Paper, 11...Flexible cable, 12...Bridge circuit, 13...Schmitt circuit, 14...Counter, 15...Microcomputer, 16...Nodo Drino <circuit, 17... motor driver circuit.

Claims (1)

[Claims] a head position detection magnetic pole part linearly arranged in the shaft direction that guides the movement of the print head; a photosensor that detects a reference point of the print head; a magnetic resistance element disposed opposite to the head position detection magnetic pole part; a bridge circuit that amplifies a magnetic flux change output according to the position of the magnetic resistance element with respect to the head position detection magnetic pole part; A Schmitt circuit converts a signal into a pulse signal, and the position of the print head is directly detected by counting the number of pulses from the Schmitt circuit using the signal from the photosensor as a reference point to perform printing. A serial dot matrix printer characterized by comprising a control circuit for controlling the printer.