JPH0211374A - Automatic corrector for platen gap - Google Patents

Abstract

PURPOSE:To enable fixed printing quality to be maintained by providing means for measuring the gap between a printing head and for moving the head so as to adjust the gap to a desired value. CONSTITUTION:A main controlling part 3 causes a reflection-type sensor 2 to output an output signal from an emitting part so that the signal is reflected by a platen 4. A signal returned by reflection is received by a receiving part of the sensor 2, and is fed back to the main controlling part 3. The main controlling part 3 detects the distance between a printing head 1 and the platen 4 based on the emitted signal and the feedback signal, and operates a motor 5 to move the head upward or downward until the distance becomes equal to a desired platen gap. By this, the gap between the head 1 and the platen 4 is corrected, and the spacing therebetween can be maintained at a constantly fixed value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is suitable for use in a dot impact printer in which the print head moves up and down, and relates to an automatic platen gap correction device therefor.

[Conventional technology]

Conventionally, the platen gap of this type of print head vertical movement method was corrected by measuring the gap between the print head and the platen with a measuring instrument and manually moving the initial position of the print head until the desired platen gap was achieved.

[Problem to be solved by the invention]

However, with the conventional platen gap correction method described above, the gap between the print head and the platen cannot always be kept constant due to factors such as the installation method of the measuring instrument, the accuracy of the measuring instrument, and the measurement error of the measurer. This has caused a problem of deterioration in print quality. Another disadvantage is that even if the platen gap is adjusted by -degrees, the platen gap changes during use.

The object of the present invention has been made in view of the above-mentioned drawbacks.
To provide a platen gap automatic correction device of a vertical movement type of a print head, which can always keep the gap between the print head and the platen constant and maintain constant printing quality.

[Means to solve the problem]

To achieve the above object, the present invention comprises means for measuring the gap between the print head and the platen, and drive means for moving the print head to bring this gap to a desired value. .

[Effect]

In this way, in the automatic platen gap correction device according to the present invention, the driving means is actuated by the signal from the measuring means, and the gap between the print head and the platen is always kept constant, so that a constant print quality can be achieved. It becomes possible to maintain

〔Example〕

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

FIG. 1 is a schematic diagram showing an embodiment of an automatic platen gap correction device according to the present invention.

The print head 1 of the dot impact printer has a head bin (not shown) for printing and is DC driven. In addition, the reflective sensor 2 is attached to the print head 1, and although not shown, the reflective sensor 2 is equipped with a signal (light,
It has a structure that includes a transmitter that emits sound (such as sound) and a receiver that receives reflected signals.

The main control unit 3 causes the reflective sensor 2 to output a signal,
The reflected signal is fed back, thereby calculating the gap between the print head 1 and the platen 4, and outputting an output signal to the motor 5 to determine the excess or deficiency. This motor 5 receives a signal from the main controller 3, and the print head 1
It is designed to move up and down.

Next, the operation of the platen gap correction device of the present invention will be explained.

First, the main controller 3 causes the reflective sensor 2 to output an output signal from the transmitter, and causes the signal to be reflected by the platen 4.

Then, the reflected signal is received by the receiving section of the reflective sensor 2, and this signal is fed back to the main control section 3. Here, the main controller 3 determines the distance between the print head 1 and the platen 4 from the transmitted signal and the feedback signal, operates the motor 5 until a desired platen gap is reached, and thereby moves the print head 1 up and down. As a result, the gap between the print head 1 and the platen 4 can be corrected, and the gap between them can always be kept constant.

〔Effect of the invention〕

As explained above, according to the automatic platen gap correction device of the print head vertical movement type according to the present invention, there is provided a means for measuring the gap between the print head and the platen, and a means for moving the print head to adjust the platen gap to a desired value. The driving means moves the print head in response to a signal from the measuring means, and the gap between the print head and the platen can be kept constant at all times, so that constant printing can be achieved. It has an excellent effect of maintaining quality.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of an automatic platen gap correction device using a print head vertical movement type according to the present invention. DESCRIPTION OF SYMBOLS 1... Print head, 2... Reflective sensor, 3... Main control section, 4... Platen, 5... Motor. Applicant NEC Corporation Representative Patent Attorney Umeo Yamauchi

Claims (1)

[Claims] An automatic platen gap correction apparatus comprising: means for measuring a gap between a print head and a platen; and means for moving the print head to adjust the gap to a desired value.