JPH05169708A - Broken character detecting system - Google Patents

Abstract

PURPOSE:To provide a system which reflects an error at positioning of print caused by open loop control and makes specifying of a factor of occurrence of broken character easy and alarms it. CONSTITUTION:The title system has a mark sensor part 4 detecting position of a paper and a logical control part 2 performing print control. A motor driving part 3 inputs a motor driving pulse output from the logical control part 2 and drives a step motor. A broken character alarming part 7 outputting an alarm based on detection of a broken character detecting part 6 is also provided. A rotary encoder 5 is mounted on a printer unit 1 and an information from the rotary encoder 5 is given to the logical control part 2 to perform a closed loop control.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a white spot detection system, and more particularly to a white spot detection system that warns a dot drop in print control of a thermal printer.

[0002]

2. Description of the Related Art A conventional thermal printer will be described with reference to FIG. Referring to FIG. 2, a conventional thermal printer includes a printer unit 1 for printing on paper, a motor drive unit 3 for driving a motor of the printer unit 1, a mark sensor unit 4 for detecting the position of the paper, and this mark sensor unit. 4 includes a logic control unit 2 which receives a detection signal from the control unit 4 and supplies a control signal to the printer unit 1 and the motor drive unit 3.

A conventional thermal printer operates as follows. First, the mark sensor 4 detects the position of the paper.
Next, the sheet is conveyed to the first printing position. After this sheet is conveyed, thermal history control for one line is performed. Printing is performed by performing the control for each line.

In such a conventional thermal printer control system, open loop control causes a mechanical error such as a back crash of a motor to be directly reflected in printing when the paper is positioned. There is a drawback that white spots are likely to occur.
Further, there is a drawback that it is difficult to identify the cause of occurrence even when so-called white spots occur.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a white spot detection system which eliminates the above-mentioned drawbacks, detects white spots, and facilitates identification of a cause.

[0006]

A system according to the present invention comprises a print controller for supplying a signal from a rotary encoder mounted on a thermal printer unit to a logic controller for driving a step motor to perform a closed loop control of the step motor.
Printing at a proper position on a sheet based on a heat application pulse for thermal history control given from the logic control unit, a motor drive pulse to be given to the motor drive unit from the logic control unit, and a signal from the rotary encoder And a white spot detection unit that reports an error to the white spot warning unit when an error is determined.

[0007]

An embodiment of the present invention will now be described in detail with reference to the drawings.

Referring to FIG. 1, one embodiment of the present invention is
A printer unit 1 for printing on paper, a motor drive unit 3 for driving a paper conveying step motor in the printer unit 1, a mark sensor unit 4 for detecting the position of the conveyed paper, and a logical control for performing print control. Part 2 is provided.

In addition to these conventional elements, one embodiment of the present invention has the following features. The rotary encoder 5 is used for performing closed loop control, and outputs a signal to the logic control unit 2 while the motor is being driven.

The white spot detection unit 6 applies a heat application pulse for heat history control supplied from the logic control unit 2, a motor drive pulse to be given from the logic control unit 2 to the motor drive unit 3, and the rotary encoder 5. When the heat is applied to the proper position of the paper, that is, whether or not the heat is printed, is analyzed based on the signal from the sheet, and it is determined that the error indicates that the heat is not printed at the proper position of the paper after the analysis.
An alarm signal is output via the logic control unit 2. The whiteout warning unit 7 gives a warning in response to this alarm signal.

By combining these features of one embodiment of the present invention, it is possible to detect white spots in one format printing unit. If the deviation of the print timing is excessive, the print operation is interrupted. At the time of this interruption, the stop position is stored in the storage unit, and if the blank area is within the allowable range, the paper is set again, and the mark sensor unit 4 conveys the paper to the interruption position. This can be achieved by mounting the rotary encoder 5 on the printer unit 1 and giving information from the rotary encoder 5 to the logic control unit 2 to perform closed loop control.

If a white spot actually occurs at the time of white spot warning, it can be set that there is a cause factor in the motor or control. If there is no white spot, it is specified that there is a factor in mechanical things such as pressing of the head. it can.

[0013]

According to the present invention, a rotary encoder is mounted to realize closed loop control, and the output of the rotary encoder 5, the pulse from the motor drive unit 3 and the heat application pulse are input to the white spot detection unit 6 and analyzed. By warning the occurrence of white spots, white spots are detected in units of one format, and the cause of the white spots can be easily identified.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a conventional technique.

[Explanation of symbols]

 1 Printer unit 2 Logic control unit 3 Motor drive unit 4 Mark sensor unit 5 Rotary encoder 6 White spot detection unit 7 White spot warning unit

Claims (1)

[Claims] 1. A means for performing a closed loop control of a step motor by supplying a signal from a rotary encoder mounted on a thermal printer unit to a step motor driving logic control section, and a heat history control provided from the logic control section. Based on the heat application pulse for, the motor drive pulse to be given to the motor drive section from the logic control section and the signal from the rotary encoder, it is compared whether or not printing is performed at an appropriate position on the paper, and white spots are removed. A white spot detection system including a white spot detection unit for detecting the white spot.