JPS6251468A - Automatic return mechanism of printing head - Google Patents

Abstract

PURPOSE:To prevent damage on a printing head by returning a printing head to a printing position through the operation of a release mechanism when a carrier is run with a head mounting plate set backward. CONSTITUTION:When a mounting plate 4 is pulled up with a head 5 retracted the upper end of a lever 18 is fitted to a fitting pawl 17, hold-the mounting plate 4 in a backward position. If printing operation is started under this condition, a shaft 9 is rotated in 'B' direction by the running of a carrier 3, and this rotation is transmitted to an intermediate shaft 26. Then a coil spring 29 is wound up to allow the rotation of the intermediate shaft 26 to be transmitted to a cam shaft 28 which is, in turn, rotated in 'C' direction, rocking the lever 18 clockwise. The mounting plate 4 is allowed to travel downward by a spring 16, thus returning the head 5 to a normal printing position. Further, under a condition where the mounting plate 4 has traveled downward the lever 18 rocks clockwise and a pin 21 is away from a seesaw lever 24 with the rotation of the shaft 9 not transmitted to the cam shaft 28 and a cam 31 left pendent whilst continuing printing operation. Thus it is possible to prevent damage on the printing head or an error in printing.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application - This invention relates to a print head mounting structure in a printer of an information processing device, and particularly relates to a print head that is evacuated for replacing an ink ribbon, etc. This relates to a mechanism that automatically returns the head to a predetermined printing position.

- Conventional technology and problems - The print head of a printer is installed with its tip close to a paper guide or internal material such as a platen or anvil, and the ink ribbon in wire dot printers etc. It is installed through a narrow gap between the guide member and the guide member. Therefore, a means (head escape mechanism) for retracting the print head is provided so that the distance between the print head and the paper guide member can be increased when replacing the ink ribbon or the like.

One means for retracting the print head is to mount the print head on a head mounting plate that is movably mounted on a carrier, and to retract the print head by manually retracting the head mounting plate. In such printers, when the print head is retracted, it is necessary to return the print head to its normal printing position before restarting printing operations, but conventionally this return operation was usually performed manually. Met. However, due to an operational error, printing operations are often restarted without restoring the print head, especially in printers with high printing speeds.
Accidents have occurred in which the print head is damaged due to the print head being forgotten to return.

1. Purpose of the Invention The present invention aims to prevent damage to the print head that occurs when printing is started with the print head retracted. The present invention aims to provide a technical means for automatically returning a print head that is in a retracted position to a normal printing position.

- Means for Achieving the Object - The automatic return mechanism for the print head of the present invention returns the print head by starting the rotation of the ribbon feed shaft when the printing operation is started, and will be explained by the reference numerals in the illustrated embodiments. For example, in a printer in which a head mounting plate 4 on which a print head 5 is mounted is mounted on a carrier 3 so as to be able to move forward and backward, the head mounting plate 4 is biased by a spring 16 in the advancing direction of the print head 5, and the head mounting plate 4 is mounted. A locking means 17.18 for holding the plate 4 in the retracted position is provided, and a release mechanism 31 of the locking means 17.18 is mounted in conjunction with the ribbon feed shaft 9 of the ink ribbon. When the carrier 3 is run with the head mounting plate 4 retracted, the opening mechanism 31 is activated by the rotation of the ribbon feed shaft 9 to return the print head 5 to the normal printing position. It is characterized by:

-Example- Next, the illustrated example will be further described. In the illustrated embodiment, the head mounting plate 4 is used as a locking means for the head mounting plate 4.
and an engaging lever 18 pivotally connected to the carrier 3, and when the printing operation is started in the head retracted state where the engaging claw 17 and the retaining lever 18 are engaged, Ribbon feed shaft 9 rotates due to the traveling movement of carrier 3
rotation is transmitted to the cam 31, and the cam 31 swings the engagement lever 18 to disengage the engagement claw 17 and the engagement lever 18, so that the head mounting plate 4 absorbs the biasing force of the spring 16. The printing head 5 mounted on the head mounting plate 4 returns to its normal printing position.

Figure 3 shows the relationship between the print head, platen, and ink ribbon in the printer, where 2 is a guide rod mounted on the printer frame (not shown), and 3 is a guide rod that runs along the guide rod 1.2. A carrier, 4 is a head mounting plate mounted on the carrier 3 so as to be slidable in the vertical direction in the figure, 5 is a print head mounted on the head mounting plate 4, 6
is an ink ribbon cartridge mounted on a carrier 3, and the print head 5 is retracted upward by pulling up the knob 7 provided on the head mounting plate 4, and in this state, the ribbon cartridge 6 is inserted from the front side in the figure or The ink ribbon 8 is replaced by pulling it out. The automatic return mechanism of the present invention is not shown in FIG.

FIG. 1 is a diagram showing the automatic return mechanism of the present invention, and the members explained in FIG. 3 are given the same reference numerals. 9 is a ribbon feed shaft supported by the carrier 3, and 10 and 11 are one-way clutches 12.1 connected to the ribbon feed shaft 9, respectively.
The pulleys 14 and 15 attached through the pulleys 3 are cables installed on the printer frame, and the cables 14 and 15 are each wound once or twice around the boot IJI0°11 and stretched.

The one-way clutch 12.13 is installed so as to transmit only the rotation of the pulley 10°11 in the direction of the arrow A in the figure to the ribbon feed shaft 9, and when the carrier 3 moves to the right in the figure, the stopped cable is The ribbon feed shaft 9 is driven by a pulley 11 driven by a strip 15 in the direction of arrow A in the figure, and conversely, when the pulley 11 moves to the left, the ribbon feed shaft 9 is driven in the same direction by the pulley 10.

The head mounting plate 4 is urged downward by a spring 16, and its lower moving end position is regulated by a stopper (not shown). An engaging pawl 17 is formed on the shoulder of the head mounting plate 4, and a retaining lever 18 whose upper end engages with the engaging pawl 17 is pivotally attached to a pin 19 planted on the carrier 3. and is biased in the engagement direction by a compression spring 20. A pin 21 is installed in the engagement lever 18, and this pin 21 is connected to a clutch shoe 23 of a spring clutch 22, which will be described later.
It is engaged with the seesaw lever 24 equipped with.

A gear 25 is fixed to the ribbon feed shaft 9, and a gear 27 is meshed with the gear 25, which is fixed to an intermediate shaft 26 rotatably mounted on the carrier 3.

The tip of the intermediate shaft 26 faces the rear end of a camshaft 28 rotatably attached to the carrier 3, and as shown in FIG. 2, a coil spring 29 is loosely fitted between the shafts 26 and 28. ,
A clutch shoe 23 is in contact with the circumferential surface of the coil spring 29 to form a spring clutch 22. The clutch shoe 23 is attached to the tip of a seesaw lever 24 that is pivotally supported on the carrier 3 by a pin 30. A cam 31 is fixed to the camshaft 28, and the cam 31 faces the tip of the engagement lever 18.

Next, the operation of the illustrated embodiment will be explained.

When the print head 5 is retracted by pulling up the head mounting plate 4, the upper end of the retaining lever 18 engages with the engagement claw 17 to hold the head mounting plate 4 in the retracted position (upward position in the figure). There is. Then, the tip of the engagement lever 18 falls below the engagement claw 17 and swings counterclockwise in the figure, so the pin 21 pushes up the rear part of the seesaw lever 24 and presses the clutch shoe 23 against the coil spring 29. I'm letting you do it. When the printing operation is started in this state, the carrier 3 starts running to the right or left, and as the carrier 3 runs, the ribbon feed shaft 9 rotates in the direction of arrow B in the figure. This rotation is transmitted to the intermediate shaft 26 via gears 25 and 27, and since the clutch shoe 23 is pressed against the coil spring 29
The rotation of the intermediate shaft 26 is transmitted to the camshaft 28, and the cam 31 rotates in the direction of arrow C in the figure. This rotation of the cam 31 causes the engagement lever 18 to swing clockwise in the figure, disengaging the engagement claw 17 and the engagement lever 18, and the head mounting plate 4 is moved downward by the spring 16. The print head 5 is returned to the normal printing position. When the head mounting plate 4 is moved downward, the back of the engagement lever 18 comes into contact with the tip of the engagement claw 17, and the engagement lever 18 swings clockwise in the figure. Since the clutch shoe 23 is separated from the clutch shoe 24 and does not press against the coil spring 29, the connection between the intermediate shaft 26 and the camshaft 28 is released. Therefore, the rotation of the ribbon feed shaft 9 is not transmitted to the cam shaft 28, and the cam 3
1 continues the printing operation while hanging down due to its own weight.

It should be noted that the spring clutch 22 interposed between the intermediate shaft 26 and the camshaft 28 can of course be replaced with a clutch of other structure that is opened and closed by the swinging action of the engagement lever 18. The swinging lever 18 and the cam 3 are arranged so that the cam 31 can rotate 180 degrees when the lever 18 swings clockwise in FIG.
1, the intermediate shaft 26 and the cam shaft 28
It is also possible to have a structure in which the two are directly connected without intervening a clutch. In addition to the rotation of the ribbon feed shaft 19 in the illustrated embodiment, the operating source for the opening mechanism is the rotation of the ribbon feed shaft 19 in the illustrated embodiment.
It is also possible to use the rotation of a print head cooling fan driven by the running of the carrier 3, the rotation of the running wheels or guide rollers of the carrier 3, etc.

Effects of the Invention As described above, when the automatic return device of the present invention starts the printing operation with the print head retracted, the printing operation can be started regardless of the traveling direction of the carrier at the time of starting printing. Since the release mechanism immediately operates to return the print head to the specified printing position, there is no risk of damage to the print head or printing errors even if the operator forgets to return the print head after it has been evacuated. (This has the effect of reducing the burden on the operator and ensuring stable operation of the printer.

[Brief explanation of the drawing]

The figures show an embodiment of the present invention, in which Fig. 1 is a perspective view of the device, Fig. 2 is a sectional view showing details of the spring clutch, and Fig. 3 is a printer in which the device of the present invention is used. FIG. 2 is a front view schematically showing a portion of the print head. In the figure, 3: Carrier 4: Head mounting plate 5: Print head 8: Ink ribbon 9: Ribbon feed shaft 1
6: Spring 17: Engagement pawl 18: Engagement lever 20: Compression spring 22: Spring clutch 23: Clutch shoe

Claims (1)

[Claims] 1. In a printer in which a print head is mounted on a head mounting plate that is attached to a carrier so as to be movable forward and backward, and the print head is retracted by retracting the head mounting plate, the head mounting plate is moved in the direction in which the head advances. A locking means is provided that is biased and installed and holds the head mounting plate in the retracted position, and a release mechanism for the locking means, so that when the carrier is run with the head mounting plate retracted, An automatic return mechanism for a print head in a printer, wherein the release mechanism operates to return the print head to a printing position. 2. In a printer having an ink ribbon, the opening mechanism is attached in conjunction with the ribbon feed shaft of the ink ribbon, and the opening mechanism is activated by rotation of the ribbon feed shaft when the carrier is run. The automatic return mechanism of the print head according to scope 1.