JPH0583390B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a print medium detection mechanism in a printer.

[Conventional technology]

Conventionally, microswitches, photo interrupters,
A mechanism composed of a reed switch or a Hall element and a detection lever is generally known.

FIG. 2 is a side sectional view showing a conventional example of the above-mentioned print medium detection mechanism in a serial printer. In the figure, 1 is a platen, 2 is a print medium,
a is the end of this print medium 2, 3 is this print medium 2
4 is the print medium 2
5 is a micro switch, 6 is a support bracket that holds this micro switch 5, 7 is a reset spring for the medium detection lever 4, 8 is a paper separator, and 9 is a continuous sprocket for feeding the medium. 10 is a printer control board, and 11 is a connector 12 for transmitting a medium detection signal from the microswitch 5, which is a print head.

The operation of the print medium detection mechanism with the above configuration will be explained.

When the printing medium 2 is inserted in the direction of arrow A, the printing medium 2 inserted between the platen 1 and the paper chute 3 holds the medium detection lever 4 in the state shown in FIG. 2 against the reset spring 7, and supports it. A medium detection signal from the microswitch 5 held by the bracket 6 is transmitted to the printer control board 10 through the connector 11, and the printer is ready for printing operation. Next, the print medium 2 is fed by the pin tractor unit 9, and the print medium 2
When the terminal end 2a of the paper separator 8 passes through the gap between the medium detection lever 4 and the paper separator 8, the medium detection lever 4
is the second due to the bias force of the reset spring 7.
Turn the micro switch 5 in the direction of arrow B in the figure.
is pressed, a print medium end detection signal is transmitted to the printer control board 10 through the connector 11, and the printer stops printing immediately or stops after printing several lines.

[Problem that the invention seeks to solve]

The print medium detection mechanism of a printer configured in this manner has a problem in that it is very complicated due to the large number of component parts, and furthermore, connectors and wiring are required, making assembly complicated.

Or, because the print medium is detected between the paper chute and the paper separator, it cannot be placed further away than the India position.
There have been problems in that it is not possible to print near the end of the print medium, or that complicated control is required to print multiple lines after detecting the end of the print medium.

Furthermore, when loading the print medium into the pin tractor unit, if you insert the print medium into an appropriate position along the axis of the platen and try to move it to the left or right, the medium detection lever gets stuck in the groove of the paper separator. There is a problem in that the side end hits the medium detection lever and it becomes impossible to shift it laterally.

In addition, although the above example uses a micro switch as a print medium detection sensor, similar problems occur when using a reed switch or a Hall element, and when using a photo interrupter or reflective photo sensor, paper There is also the problem that malfunctions may occur due to powder or dirt, or in the case of reflective photo sensors, malfunctions may occur due to dirt or print format patterns.

[Means for solving problems]

In order to solve these problems, the present invention provides a detection groove provided in the circumferential direction outside the print area of the platen in a print medium detection mechanism of a printer that detects the presence or absence of a print medium set on the platen. Then, the tip is inclined with respect to the axial direction of the platen, and the rear end is heavier than the tip,
When the printing medium contacts the leading edge, the trailing edge lifts up, and when the printing medium does not touch the leading edge, the weight of the trailing edge lifts the leading edge and loosely fits into the detection groove. a print medium detection lever rotatably arranged near the printing position; and a print medium detection lever provided on the printer control board so as to detect the rear end of the print medium detection lever without contacting the rear end; It is characterized by comprising a medium detection sensor that detects the presence or absence of a medium depending on whether or not it is detected.

[Effect]

In the present invention having such a configuration, when a print medium is set on the platen, this print medium contacts the tip of the print medium detection lever, which pushes the tip and lifts the rear end of the print medium detection lever. The medium detection sensor detects the printing medium by this movement of the trailing edge, and the printing medium is fed along with the printing operation, and the end of the printing medium passes the tip of the printing medium detection lever and no longer makes contact with it. and,
As the rear end of the print medium detection lever lowers due to its own weight, the front end lifts up. Due to the movement of the rear end at this time, the medium detection sensor no longer detects the print medium, and based on this, printing can be stopped.

Also, when setting the print medium on the platen as described above, if you insert the print medium into an appropriate place on the platen and shift it from side to side, if the tip of the print medium detection lever is pressed by the print medium, the Due to the tilted guide action and the weight of the rear end, the leading end is smoothly lowered, and it is possible to prevent the printing medium detection lever from interfering with the operation of shifting the printing medium left and right.

〔Example〕

A first embodiment will be described below with reference to the drawings.
FIG. 1 is a side sectional view, and FIG. 3 is a front view. In the following description, the same reference numerals are used for the same parts as in the above conventional example.

1 is a platen, 1a is a detection groove provided in a circumferential portion of the platen 1 other than the print area 13, 2 is a print medium, 2a is an end of this print medium, 3 is a paper chute, 9 is a pin tractor unit, 10 1 is a printer control board, and 12 is a print head.

Reference numeral 14 designates a printing medium detection lever, which is supported by a support bracket 15 and whose weight is distributed around a rotational fulcrum 16 so that the rear end 14b of the printing medium detection lever is slightly heavier than the tip 14a of the printing medium detection lever. The lever tip 14a is loosely fitted into the detection groove 1a.

17 is a medium detection sensor such as a photo interrupter that is directly arranged on the printer control board 10;
The medium detection sensor 17 can detect the rear end 14b of the print medium detection lever without contacting the rear end 14b of the print medium detection lever, and detects the presence or absence of a medium based on whether or not it has been detected.

Next, the operation of the embodiment with the above configuration will be explained.
First, when the print medium 2 is inserted in the direction of arrow A in the drawing, the print medium detection lever tip 14a that is in contact with the bottom of the detection groove 1a of the platen 1 rises up to the surface of the platen 1 due to the rigidity of the print medium 2. , the rear end 14b of the print medium detection lever is connected to the medium detection sensor 1.
7 and is maintained in the state shown in FIG. 1, making the printer ready for printing.

Next, the print medium 2 is fed by the pin tractor unit 9, and when the terminal end 2a of the print medium 2 passes the print medium detection lever tip 14a, the print medium detection lever 14 is rotated by the weight of the print medium detection lever rear end 14b. It rotates about the fulcrum 16 in the direction of arrow B in FIG. Accompanying this, the rear end 14b of the print medium detection lever crosses the medium detection sensor 17 disposed on the printer control board 10, and the printer immediately stops the printing operation.

Next, a second embodiment will be explained with reference to FIG.
The drawing is a front view of the main part, and the following explanation is based on the above-mentioned Part 1.
Only the parts that are different from the embodiment will be explained.

1 is a platen, 1b is a platen end, 18 is a collar, which is fixed facing the platen end 1b and the platen 1 on the same axis, and a printing medium detection lever 1.
4 is configured to loosely fit into the detection groove 19.

In this way, unlike the first embodiment, no groove is provided on the surface of the platen 1, but the collar 18 fixed on the same axis of the platen 1 at the platen end 1b, a sprocket wheel (not shown), etc. are used in the first embodiment. A detection groove 19 having the same function as the detection groove 1a may be configured.

FIG. 5 shows a third embodiment, and is a front sectional view of a portion showing the shape of the tip of the medium detection lever 14.
When the print medium detection lever tip 14a is inclined with respect to the 1-axis direction of the platen as shown in the figure, when the print medium 2 is set and moved in the direction of arrow A in FIG. 5, the print medium side end 2c and the print medium are moved. The inclined portion of the detection lever tip 14a causes the printing medium detection lever 14 to rotate about the rotational fulcrum 16, and the printing medium detection lever tip 14a moves in the direction of arrow B in FIG. 5 to enter the printing medium detection state.

〔Effect of the invention〕

As explained above, the print medium detection mechanism of the present invention includes a detection groove provided in the circumferential direction so as to be located outside the printing area of the platen, a tip inclined with respect to the axial direction of the platen, and The trailing edge is made heavier than the above, and when the printing medium contacts the leading edge, the trailing edge lifts up, and when the printing medium does not contact the leading edge, the weight of the trailing edge causes the leading edge to lift up. a print medium detection lever rotatably disposed near the printing position so as to loosely fit into the detection groove; and a printer control board configured to detect the rear end of the print medium detection lever without contacting the rear end thereof. Since it is constructed with a medium detection sensor installed on the top of the device that detects the presence or absence of a medium depending on whether the rear end is detected, there is no need for reset springs, connectors, etc. used in conventional mechanisms. , the structure becomes simpler and the number of wiring etc. can be reduced.

In addition, since the print medium detection lever is placed near the printing position, even if printing is stopped when the end of the print medium passes over this print medium detection lever, printing will continue until near the end of the print medium. This also has the effect of eliminating the need for complex control.

In addition, the rear end of the print media detection lever is made heavier than the front end, and the weight of this rear end causes the front end to rise and loosely fit into the detection groove, so the print media detection lever can be moved in a specific direction. There is no need for a biasing means such as a spring to bias the print media, and the media detection sensor is a non-contact sensor that detects the rear end of the print media detection lever without contacting it. Compared to the sensor, the action force of the print medium detection lever is small, and the effect of high reliability of operation can also be obtained.

Furthermore, when the tip of the print medium detection lever is pressed by the print medium, the tip smoothly lowers due to the guiding effect of the slope attached to the tip and the weight of the rear end, so that the print medium detection lever can move the print medium from side to side. Another advantage is that the printing medium can be easily shifted left and right without interfering with the shifting operation.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of the first embodiment of the present invention;
The figure is a side sectional view of the conventional example, FIG. 3 is a front view of the first embodiment, FIG. 4 is a front view of main parts of the second embodiment, and FIG. 5 is a front view of main parts of the third embodiment. . DESCRIPTION OF SYMBOLS 1...Platen, 2...Print medium, 2a...Terminal end of print medium, 10...Printer control board, 12
...Print head, 14...Print medium detection lever,
14a...Print medium detection lever tip, 14b...
Rear end of printing medium detection lever, 17...medium detection sensor.

Claims (1)

[Claims] 1. A print medium detection mechanism of a printer that detects the presence or absence of a print medium set on a platen, comprising: a detection groove provided in the circumferential direction so as to be located outside the print area of the platen; The platen is inclined with respect to the axial direction, and the rear end is heavier than the front end, so that when the print medium contacts the front end, the rear end lifts up, and when the print medium does not contact the front end, the rear end lifts up. A print medium detection lever is rotatably arranged near the printing position so that the tip lifts up due to the weight of the rear end and loosely fits into the detection groove, and comes into contact with the rear end of the print medium detection lever. A print medium detection sensor for a printer, characterized in that the medium detection sensor is provided on a printer control board so as to detect the trailing edge without detecting the trailing edge, and detects the presence or absence of the medium depending on whether or not the trailing edge is detected. mechanism.