JPS6350124Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printing paper detection device for detecting the presence or absence of printing paper between a thermal printing head and a platen in printing on printing paper using a thermal printing head.

This kind of printing using a thermal printing head can produce better printing if the platen is made softer, but a softer platen becomes more susceptible to heat. In other words, when no printing paper is set on the platen, the heat generating part of the print head is in direct contact with the platen, so when a printing pulse is applied to the print head in this state to perform so-called blank printing, the surface of the platen will not be printed. Deformation may occur due to heat from the heat generating part of the head. Therefore, in the past, a paper detection device was placed at the insertion section of the printing paper to detect the presence or absence of printing paper. However, it is difficult to perform printing until then, and there are limitations on the width of the printing paper used or the position in which the printing paper can be set.

The present invention was developed in view of the above circumstances, and its purpose is to reliably detect the absence of printing paper between the thermal printing head and the platen to prevent blank printing, and to set the printing paper on the platen. There are no restrictions on the paper width or setting position of printing paper,
To provide a printing paper detecting device capable of printing not only roll paper but also cut paper to the lowest end of the paper and maximally printing without wasting the printing paper.

An embodiment of the present invention will be described below with reference to the drawings. 1 is the metal frame of the printing device,
Conductive metal bearings 3, 3 are fitted into shaft holes 2, 2 provided at opposing positions, and these bearings 3,
Both ends of a platen shaft 4 made of steel, for example, are rotatably supported at 3 . Reference numeral 5 denotes a platen made of a relatively soft conductive rubber material, into which the platen shaft 4 described above is fitted, so that the surface of the platen 5 and the machine frame 1 are electrically conductive. ing. Reference numeral 6 denotes a thermal printing head which is provided so as to be able to reciprocate from side to side along the front surface of the platen 5, and will be described in detail below. That is, 7 is a ceramic plate as a substrate, and a glass glaze layer 8 is formed on the surface of this ceramic plate.
For example, seven resistor films 9 as heating elements are formed on the surface of the glass glaze layer 8 in the vertical direction.
1 to 15 are formed. Reference numerals 16 to 23 denote conductor layers formed on the surface of the glass gray layer 8, and one end of each of these conductor layers forms connector portions 16a to 23a. The conductor layers 16 are commonly connected to one end of each of the resistor films 9 to 15, and the conductor layers 17 to 23 have their other ends connected to the resistor films 9 to 15, respectively.
It is connected to the other end of 5. 24 and 25 are detection electrodes located above the resistor film 9 and below the resistor film 15, and these are the conductor layers 26 and 27, respectively.
It is formed on the surface of the glass glaze layer 8 formed on the surface of the ceramic plate 7 via the glass glaze layer 8 . At the other end of each of these conductor layers 26 and 27, a connector portion 26 similar to the connector portions 16a to 23a is provided.
a and 27a are formed. 28 is an oxidation-resistant layer, 29 is an abrasion-resistant layer, and these are the resistor film 9.
to 15 and the conductor layers 16 to 23, 26, 27, and the detection electrodes 24, 25
surface is directly exposed to the outside. On the other hand, a female connector 30 is connected to the thermal printing head 6, and printing signals are applied to the connector portions 16a to 23a via a flexible cable 31. 32 is a detection circuit, which includes a connector part 26 of the flexible cable 31.
Lead wires 31a, 31b connected to a, 27a
is connected as an input line, and the ground terminal of this detection circuit 32 is connected to the machine frame 1 via a ground wire 33. This detection circuit 32 detects that the potential of at least one of the lead wires 31a and 31b is at the machine frame 1.
It is designed to generate an output signal when the potential becomes the same as that of . 34 is an alarm circuit connected to the detection circuit 32, and is provided with a buzzer 35 as an alarm device. Although not shown, the detection circuit 3
The output signal from the detection circuit 32 is also supplied to a print signal generator that supplies a print signal to the thermal print head 6, and when the output signal from the detection circuit 32 is given, the output of the print signal is stopped. It's summery.

Next, the operation of this embodiment configured as above will be explained. When the printing paper 36 is present between the thermal printing head 6 and the platen 5, the printing paper 36 electrically insulates between the detection electrodes 24, 25 provided on the thermal printing head 6 and the platen 5. (see FIG. 5), the detection circuit 32 does not generate an output signal, and the printing pulse from the printing signal generator is transmitted to the flexible cable 3.
1 to the resistor films 9 to 15 of the thermal printing head 6.
is selectively applied to the printing paper 36, and a printing operation is performed on the printing paper 36 in a well-known manner.

After the printing operation is performed continuously in this manner and printing is completed to the bottom of the printing paper 35, the paper feed operation is performed by rotating the platen 5, and the resistor film 9 of the platen 5 and the thermal printing head 6 is rotated. to 15
However, when the printing paper 36 is not facing at least a part of the resistor films 9 to 15, one of the detection electrodes 24 and 25 It is in direct contact with the surface of the platen 5. That is, the surfaces of the machine frame 1 and the platen 5 are electrically connected because the platen 5 is made of conductive rubber and the platen shaft 4 and bearing 3 are also made of metal and are conductive.
Therefore, since the surface of the platen 5 is maintained at the ground potential of the detection circuit 32 via the machine frame 1 and the ground wire 33, the detection electrodes 24,
25 and the surface of the platen 5, the lead wires 31a and 31b, which are the input wires of the detection circuit 32,
One of the potentials becomes the ground potential of the detection circuit 32, and the detection circuit 32 generates an output signal. When the output signal is given from the detection circuit 32 in this way, the alarm circuit 34 is activated and the buzzer 35 is activated.
sounds, and at the same time, the output signal causes the print signal generator to stop outputting the print signal.
In addition, all of the resistor films 9 to 15 are printed on the printing paper 35.
If the sensing electrodes 24 and 25 are not facing each other, both of the sensing electrodes 24 and 25 come into contact with the surface of the platen 5, so the output of the print signal is stopped by the output from the sensing circuit 32, and the buzzer 35 sounds in the same way as described above. This means that the upper end of the printing paper 35 is located between the resistor films 9 and 1.
The same is true even if it does not face a part of 5.

According to this embodiment configured in this way, when there is no printing paper 36 between the thermal printing head 6 and the platen 5, the buzzer 35 is activated and the output of the printing signal is also stopped, so that blank printing can be avoided. It is possible to reliably prevent the surface of the platen 5 from being damaged. Since the entire platen 5 is made of conductive material, the printing paper 3 is narrower than the width of the platen 5.
6, even if the thermal printing head 6 comes off the left and right ends of the printing paper 36, the detection electrode 2
4 and 25 come into contact with the surface of the platen 5 and can detect the absence of the printing paper 35 between the resistor films 9 to 15 of the thermal printing head 6 and the platen 5, so the paper width can be freely selected. In addition, the printing paper 36
The resistor films 9 to 15 of the thermal printing head 6 are aligned with the printing paper 3, not only when it is set in the center of the platen 5, but also when it is set offset to the left and right from the center.
6, print paper 3 in the same way as above.
By being able to detect the absence of the printing paper 36
There are no restrictions on the set position.

Furthermore, since the presence or absence of the printing paper 36 is determined near the printing position on the platen 5, printing can be performed to the lowest end of the printing paper 36, and therefore, it is possible to print on continuous roll paper as well as cut paper. There is no unprintable portion at the bottom edge, and the maximum amount of printing can be done on the printing paper without wasting it.

In the above embodiment, since the detection electrodes 24 and 25 are attached directly to the ceramic plate 7 of the thermal printing head 6, it is possible to place the detection electrodes 24 and 25 as close to the resistor films 9 to 15 as heating elements as possible. Since the absence of the printing paper can be detected at a position extremely close to the resistor films 9 to 15, the detection accuracy is high. The absence of printing paper is detected and the printing signal is stopped, thereby reliably preventing blank printing on the platen 5 and preventing even the slightest damage to the surface of the platen 5. In addition, by forming the resistor films 9 to 15 and the detection electrodes 24, 25 on the ceramic plate 7 as in this embodiment, the manufacturing becomes easier and the cost is lower than when the detector is provided separately. It can also be kept cheap.

Further, an alarm device such as a lamp may be provided in place of the buzzer 35 described above, and a configuration may be adopted in which only the alarm device is activated when the detection circuit 32 detects the absence of the printing paper 36, or The present invention may be implemented by simply outputting a printing stop signal to the apparatus and omitting the alarm circuit.

As is clear from the embodiments described above, the present invention is capable of detecting the absence of printing paper between the thermal printing head and the platen to prevent blank printing, as well as adjusting the paper width and setting of the printing paper set on the platen. It is possible to provide a printing paper detecting device that has various practical effects such as being able to print to the lowest edge of even cut paper without any restrictions on position, and maximizing printing without wasting paper. .

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a schematic perspective view showing the overall structure, and FIG. 2 is a plan view of the thermal printing head.
5 and 6 are side views showing different operating states. In the drawing, 1 is a machine frame, 5 is a platen, 6 is a thermal printing head, 9 to 15 are resistor films, 24 and 25 are detection electrodes, 32 is a detection circuit, 34 is a buzzer (alarm device), and 36 is printing paper. It is.

Claims (1)

[Claims for Utility Model Registration] 1. A thermal printing head in which a plurality of heating elements are arranged on a substrate in a line along the printing paper feeding direction is installed along a platen at right angles to the printing paper feeding direction. In a thermal printing device that prints on printing paper placed on a platen while moving the platen in a direction, the platen is rotatably supported on a metal machine frame via a conductive bearing. The platen is made of a conductive material, and one of the plurality of heating elements arranged in a line along the printing paper feeding direction on the substrate of the thermal printing head is located at both ends. Two detection electrodes are provided on the substrate so as to be located near the outside and on the same line as the heating element, and when there is no printing paper between at least one of the two detection electrodes and the platen, the machine a detection circuit that detects the absence of printing paper between the printing head and the platen when the frame and at least one of the detection electrodes is electrically connected; 1. A printing paper detection device characterized in that when it is detected that there is no printing paper between the thermal printing head and the platen, power to the heating element is cut off. 2. A utility model registration request characterized in that the detection circuit is connected to an alarm device and operates the alarm device when the absence of printing paper between the platen and at least one of the two detection electrodes is detected. The printing paper detection device according to item 1.