JPH0136613Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a printing device having a paper feeding function.

In a printing device that automatically feeds paper, when printing on one sheet of paper is completed and the sheet of paper is ejected, the next sheet of paper is automatically fed.

Generally, the trailing edge of the paper that is sent out by the platen after printing is completed operates a micro switch installed at the ejection position away from the platen to confirm the ejection of the paper, and the subsequent stop signal of the platen drive motor is used to supply the next paper. It is conceivable to perform a start.

The object of the present invention is to enable a printing device to detect paper optically without using a mechanical microswitch, and to provide a printing device with improved detection accuracy.

The details of the invention will be explained with reference to embodiments shown in the figures.

In FIG. 1, the paper 1 passes through the first pressure roller 2 with the pressure roller 2 separated from the platen 4 and is fed to a position where it is stopped by a stopper claw or the like. During this time, the previous paper is ejected from the platen and the paper pressing roller 3 is released from the platen 4.
Next, the pressure roller 2 is pressed against the platen, the platen 4 rotates, the paper is fed to a predetermined position, and the platen 4 stops, stopping the paper, and the paper pressing roller 3 is moved to the position where it presses the paper, and paper feeding is completed, that is, preparation for printing is completed. becomes.

According to the printing operation by the printing member, the paper 1 is printed and sent out one line by the platen 4.

A detection member 5, such as a reflective photo sensor, is arranged between the pressure roller 2 and the paper press roller 3. Although it is better to place it as close to the paper pressing roller 3 as possible, it is easier to arrange it between the two pressure rollers 2 due to its structure.

In order to reliably detect the passage of paper, the surface of the platen 4 is made black so that it is easy to distinguish the difference in the light reflection state from the almost white paper.

When the trailing edge of the paper 1 sent out by the rotation of the platen 4 passes the detection member 5 after printing, the amount of light reflected changes. As shown in FIG. 2, this change in the amount of reflection is detected by a detection member 5, amplified as an electrical signal by an amplifier circuit 6, and inputted to a rear end detection circuit 7. The trailing edge detection circuit 7 detects passage of the trailing edge from the reflection amount change signal. A trailing edge detection signal from the trailing edge detection circuit 7 is input to an AND circuit 8 as, for example, a high level signal. On the other hand, a drive signal for the paper feed pulse motor is sent as a pulse signal to the control section of the paper feed section feed roller driving pulse motor 10, where it is amplified by an amplifier circuit 9.

After the signal that detects the rear end from the rear end detection circuit is input to the AND circuit 8, the pulses of the drive signal input to the AND circuit 8 are counted. That is, for each pulse of the pulse signal, a count signal is inputted to the counter 11 as a signal to add +1 from the AND circuit 8 and is counted.

Considering the number of counts until the trailing edge of the paper 1 passes the detection member 5 and is separated from the platen and the platen is stopped, and the distance that the subsequent paper can be fed by that time, that is, the number of pulses. The number of pulses from when the detection member 5 detects the trailing edge until a paper feed start signal is given to the subsequent paper feed member is calculated in advance and inputted into the comparator 13 as the fixed feed amount 12. The comparator 13 compares the fixed feed amount with the signal from the counter 11, and when they match, the comparator 13 outputs a signal as a paper feeding start signal to operate the paper feeding member.

By detecting the trailing edge of paper as it is being fed by the platen and then counting the number of pulses, it is possible to start feeding the subsequent paper after a certain period of time. It can be made narrower.

By positioning the detection member 5 as close as possible to the paper pressing roller 3, the counting time after the trailing edge is detected can be shortened, and the reliability of the control can be increased accordingly. Since the detection member 5 is disposed between a pair of pressure rollers 2 arranged at a constant interval in the paper feeding direction, the detection member 5 can detect the paper held between the pressure roller 2 and the platen 4. This stabilizes the paper position, improving detection accuracy. The reflective photo sensor as a detection member is provided facing the bottom surface of the platen between a pair of pressure rollers, so the reflective photo sensor is surrounded by the platen and the pair of pressure rollers. Therefore, unnecessary light from the outside can be prevented from entering the reflective photo sensor, and detection accuracy can be improved. Also,
Since the platen is generally black, there is a large difference in the amount of light reflected from the platen, which is almost white. Therefore, by arranging the reflective photo sensor facing the platen, it is possible to improve the detection accuracy. Furthermore, since it is a reflective photo sensor rather than a mechanical micro-switch, it can be placed very close to the platen as a reflective surface, eliminating the need for extra space and eliminating the need for paper passage beneath the platen. This is advantageous in terms of design since it is only necessary to consider the minimum space available.

Since the passage of the trailing edge of the paper is detected at a position close to the platen, stable detection is possible.

The detection member that is the basis for generating the next paper feeding start signal is connected to a circuit device that not only detects the trailing edge of paper but also generates a signal that detects the presence or absence of paper, and the detection member is connected to a circuit device that generates a signal that detects the presence or absence of paper, and the detection member is connected to a circuit device that generates a signal that not only detects the trailing edge of paper but also detects the presence or absence of paper. Jam detection can also be performed by generating a jam signal when the paper feeding end signal that has reached the position and the signal indicating that no paper is present are input to an AND circuit. That is, it is also possible to perform paper feeding start control for the subsequent paper and jam detection control using one detection member.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating the arrangement of detection members of a printing device according to the present invention, and FIG. 2 is a block diagram of a control device according to the present invention. 1... Paper, 2... Pressure roller, 3... Paper pressing roller, 4... Platen, 5... Sensing member, 7...
Trailing edge detection circuit, 8...AND circuit, 11...Counter, 12...Fixed feed amount, 13...Comparator.

Claims (1)

[Scope of utility model registration request] A printing member for printing, a platen, a pair of pressure rollers disposed opposite to the bottom surface of the platen and having a constant interval in the paper feeding direction, and a position between the pair of pressure rollers. A printing device comprising: a reflective photo sensor disposed opposite to the lower surface of the platen; and paper feeding is controlled by the reflective photo sensor.