JPH0140760B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for holding and tightening type in conjunction with the sliding of a type bar piece in the printing mechanism of a typewriter. By preventing the printed characters from falling off during return, high-speed printing is possible. Still another object of the present invention is to prevent printing blur by strongly pressing the type with a weak force just before printing, and to accurately regulate the rows and columns of the print on the recording paper, as well as to control the entire printing mechanism. It is an object of the present invention to provide a printing device that has little printing torque fluctuation and that allows easy adjustment of printing pressure.

Conventionally, in this type of printing device, as shown in FIG. 1, a type bar piece 2 is supported on a type bar 1 so as to be slidable in the direction of arrow x, and tightly engages type 3. Reference numeral 4 denotes an input cam, which is rotatable around a cam support pin and is integrally constructed with a type bar support shaft, a base, etc. (not shown). In this printing device, the input cam 4 is rotated in the direction of arrow Y by a drive device to print on the recording paper on the platen, and the input cam 4 is returned to its original position by the reaction force and the bar return spring. For this reason, when the driving force of the drive device is released just before printing or after printing, the input cam 4 becomes free, and the type bar piece 2 loses the force to press the type 3, causing vibrations, poor adjustment, etc. Printed characters may fall off due to various factors. Naturally, the return drive device for high-speed printing also cannot drive the input cam 4 in the direction opposite to the direction of arrow Y. Furthermore, unless the input cam 4 is urged in the direction of the arrow Y until the moment of printing, the type 3 cannot be tightly engaged (if the type 3 is not tightly engaged, printing misalignment, irregularities in rows and columns, etc. will occur on the recording paper). For this reason, printing pressure adjustment has become complicated.

In order to solve the above-mentioned drawbacks, a type holding and clamping device as shown in FIG. 2 has been proposed. The fall prevention cam 6 is integrally constructed with a cam support pin 5, a type bar support shaft (not shown), a base, etc., and the swing cam 7 uses the swing cam support pin 9 on the fall prevention cam 6 as a fulcrum of rotation. and spring hook pin 1
A pressure spring 8 provided between 1 and 11 biases the cam until it comes into contact with the swing cam guide pin.
On the other hand, a protrusion 2' is provided on the type bar piece 2,
This protrusion 2' has a slight gap S with respect to the outer periphery of the drop-off prevention cam 6 when the type 3 is held.
Therefore, the printed characters 3 during printing and during return after printing do not fall off because the protrusions 2' are regulated by the fall prevention cam 6. Further, just before printing, the protrusion 2' is urged by the swing cam 7 and tightly engages the type 3. However, in such a printing device, when the pressure spring 8 is strengthened to strengthen the tightness of the type 3, a large rotational load is applied by the swing cam 7 in the direction opposite to the arrow Y direction just before printing. On the other hand, such a printing device uses the kinetic energy (product of mass and angular velocity squared) of the movable parts (type bar 1, type bar piece 2, type 3, etc.), so it is necessary to adjust the printing pressure. is synonymous with controlling the angular velocity of the type bar 1. Therefore, since the generation of rotational load slows down the type bar 1, printing pressure adjustment errors are likely to occur, and in some cases, printing pressure adjustment has become difficult.

The present invention is intended to improve the above-mentioned drawbacks, and will be explained below with reference to FIGS. 3 to 7.

Note that parts with the same functions as those in the conventional example are given the same numbers.

As shown in FIG. 7, the cam support pin 5 includes a type bar support shaft 12, a type bar holder 13, and a base 1.
4. Constructed integrally with the falling-off prevention cam 6. On the other hand, the type bar 1 is rotatable on the type bar support shaft 12,
An input cam 4 and a swing cam 7 are provided, and a pressure arm 16 is provided that swings around a pressure arm fulcrum pin 15 provided on the type bar 1. The protrusion 2' on the bar 2 is inserted. A pressure roller shaft 17 is further provided on the pressure arm 16, and a pressure roller 18 is rotatably inserted around the shaft, and when the type is held, the outer peripheral surface of the pressure roller 18 forms a drop-off prevention cam. 6. It is configured to have a slight gap S between the outer circumferential surface and the outer circumferential surface. On the other hand, the swing cam 7 which is rotatably provided around the cam support pin 5 is provided to swing within a range regulated by the swing cam guide pin 10, and is further provided with a pin fixed to the fall prevention cam 6. A pressure spring 8 provided between the swing cam 11 and the swing cam 7 is biased in the direction opposite to the arrow Y. Note that 19 is a return spring for the type bar piece 2, and 20 is a bearing, in particular, an angular bearing was used. 21 is a bar return spring, 22 is a ball receiver, and 23 is a lock screw for adjusting backlash in the thrust direction.

The order of printing will be explained below. FIG. 3 shows the input cam 4 in a non-energized state. When the type 3 enters the predetermined position on the type bar 1, the drive device causes the
When the input cam 4 rotates in the direction of arrow Y, the type bar piece 2 enters the threaded portion 3' of the type 3 along the guide groove 1' provided in the type bar 1. Along with type bar piece 2
The pressure arm 16 moves by the protrusion 2' provided on the holder, and becomes the state shown in FIG. When the input cam 4 continues to be biased in the direction of the arrow Y by the drive device, the type bar 1, type bar piece 2, and type 3 begin to rotate about the type bar support shaft 12 while maintaining the same relationship. The state shown in Figure 5 will be reached. At this time, the outer peripheral surface of the pressure roller 18 and the falling-off prevention cam 7
There is a slight gap S on the outer peripheral surface. Naturally, this gap S is made smaller than the stroke of the type bar piece 2 entering the type binding portion 3', thereby preventing the type 3 from falling off. When the input cam 4 further rotates, the swing cam 7 protrudes from the drop-off prevention cam 6, so that the pressure roller 18 hits the protrusion of the swing cam 7 just before printing. Therefore, the swing cam 7 also rotates together with the pressure roller 18, that is, together with the type bar 1, type bar piece 2, type 3, etc., as shown in FIG. At this time, the weaker the force of the pressure spring 8 is, the smaller the fluctuation of the load torque applied to the input cam 4 becomes. Since the wedge effect of the pressure roller 18 is amplified several times and the type bar piece is pressed by the lever principle, sufficient type clamping force can be obtained.

As explained above, the present invention has a simple configuration and there is no dropout of printed characters during printing or during recovery after printing, and a return load is applied to the input cam, making high-speed printing possible. Furthermore, since there is little variation in the load torque applied to the input cam, it is possible to finely adjust the printing pressure, and the printing pressure adjustment method can also be adjusted by, for example, controlling the input cam drive device over time. This is extremely effective in practical terms, such as preventing irregularities in printing in the row and column directions.

[Brief explanation of drawings]

1 and 2 are front views of a conventional example, and FIG. 3 is a front view of an embodiment of the present invention in a non-energized state of the input cam.
FIG. 4 is a front view of the printed characters in the holding state, FIG. 5 is a front view of the printing state in the middle of printing or return, FIG. 6 is a front view of the same printing state, and FIG. 7 is an exploded perspective view of the same. 1...Type bar, 2...Type bar piece,
3...Print, 4...Input cam, 5...Cam support pin, 6...Drop-off prevention cam, 7...Rocking cam, 8...
...Pressure spring, 12...Type bar support shaft, 13...
Type bar holder, 14... Base, 16... Pressure arm, 18... Pressure roller, 19... Piece return spring, 20... Bearing, 21... Bar return spring.

Claims (1)

[Claims] 1. A type bar that is swingable around a cam support pin and is provided with removable type; a type bar piece that is slidable within the type bar and is provided with pressable type; a pressure arm having a pressure roller that has one point of the bar as a fulcrum and swings as a type bar piece slides;
When the type bar is swung while the type bar is pressed, there is a fall-prevention cam fixed to the pressure roller with a gap, and a cam support pin that comes into contact with the pressure roller and moves to the printing position just before printing. A typewriter type clamping device consisting of a swinging cam that is swingable around a type bar independently of the type bar, and a pressure spring that returns the swinging cam to its original position.