JPS6331973Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a dot printer, and more particularly to a printer reset detection mechanism that utilizes the cooperative action of a reed switch and a magnet.

Examples will be shown while generally explaining the parts related to the printer of the present invention.

FIG. 1 is a schematic diagram of the printer, and a general explanation of its operation will be given below.

1 is the frame of the printer, 2 is a motor that is the drive source of the printer, and 3 is a bracket fixed to the motor 2. A reduction gear 41 (shown in Figure 5) is incorporated inside the bracket 3, and the rotation of the motor 3 is to apply driving force to the cylindrical cam 4. A cam groove 5 is formed in the cylindrical cam 4 for swinging the head 12 from side to side via a head swinging pin 8 (shown in FIG. 2). Further, a magnet is provided on the cylindrical cam 4 as a means for generating a reset signal for the printer. This magnet 6
The reed switch (shown in FIG. 6), which is in a cooperative relationship, is closed by the magnetic flux of the magnet 6, and a reset signal R is obtained. On the other hand, the timing signal T for energizing the head is supplied to the tachogenerator 1.
It is obtained from 0. For example, if a character is to be composed of 5.times.7 dots, the dot head 12, which has four printing levers, must move back and forth seven times from side to side. That is, the cylindrical cam 4 rotates seven times.
Naturally, the reset signal R will also be generated seven times.
Paper feed drive gear 16 supported on a cylindrical camshaft 17
rotates simultaneously with the cylindrical cam 4, and rotates the paper feed roller 11 via the paper feed transmission lever 14 for each dot line. Reference numeral 13 denotes a platen, and the printing lever of the dot head hits the ribbon and the recording paper to form dots on the recording paper. 9 is a flat cable for connecting the dot head coil and the driver.

Furthermore, FIGS. 2a and 2b are detailed views of the dot head 12, and FIG. 2a is a diagram showing the configuration of the dot head 12 as viewed from the platen 13 side of the printer.

In a, 21 is a print lever, 22 is a push rod that applies driving energy to the print lever 21, and is fixed integrally with the plunger 28.
Reference numeral 23 denotes a print lever return spring, which returns the print lever 21 to its original standby position after the head coil 25 is energized. 24 is a print lever shaft, which includes a print lever 21 and a print lever return spring 2.
3 are each supported by a shaft. 25 is a head coil, and in FIG. 2a, four head coils are installed.

b is a configuration diagram seen from the side of the cylindrical cam 4, and 2
8 is a plunger, and 8 is a head swing pin.

FIGS. 3 and 4 are timing diagrams when printing two digits using one printing lever in a 5×7 character structure. From the first timing pulse _T1 when the reset pulse R rises, the electromagnets _M1 , _M2 , _M3 , _M4
This figure shows an example of 7 dot lines forming a 5×7 character by sequentially energizing the dots to form dots.

Conventionally, as shown in FIG. 5, the reset detection magnet 6 has been made by cutting out a concave shape on the surface of the cylindrical cam 4, inserting the magnet 6 into the notch, and gluing the magnet 6 to prevent it from coming off due to the rotation of the cam 4. Generally, it was fixed with adhesive. However, according to the conventional method, when using a two-component adhesive to fix the magnet 6 to the cylindrical cam 4, it has disadvantages in terms of workability and man-hours, such as leaving it in a high temperature bath for a certain period of time. There is. Also, reed switch 7
However, in order to maintain an accurate gap between the magnets 6, the dimensions of the concave bottom had to be strictly controlled, such as by aligning the surface of the magnet 6 with the surface of the cylindrical cam. .

The present invention was devised in view of these shortcomings, and its purpose is to absorb the dimensional variations between the cavity of the cylindrical cam and the magnet, and to move the magnet into the cavity for other parts. The purpose is to fix it in a completely tight state without using it.

Another purpose is to make parts quality control rough and to improve reliability.

Examples will be described in detail below.

6a, b, and c show embodiments of the present invention, in which a magnet 6 is embedded in an axially opening-shaped cavity provided in a cylindrical cam 4 by being pushed from the axial direction. Furthermore, several tapered protrusions 51 are provided on the inner surface in the axial direction of the mouth-shaped cavity,
The magnet 6 is regulated by the tapered protrusion 51 and is completely fixed to two surfaces, the top surface and one side surface of the mouth-shaped cavity. If a sufficient caulking allowance is provided for the taper, there is no need to fix the magnet 6 with adhesive later, and the magnet 6 can be held sufficiently.

As described above, according to the present invention, at least two of the cavities
In order to fix the magnet in close contact with one surface, a plurality of tapered ridges with a crimping margin are provided in advance along the axial direction on the surface of the cavity opposite to the aforementioned surface, so that the magnet can be inserted into the cavity while gradually crushing the tapered ridges without applying any load to the magnet, and the magnet can be completely fixed in the cavity. Furthermore, since the magnet is positioned by the ridges so as to be pressed against the two surfaces of the cavity, the magnet is completely fixed to the cavity even if there is a dimensional variation between the cavity and the magnet. Therefore, since the magnet is fixed to the cylindrical cam that is continuously rotating without loosening, the rotational position of the cylindrical cam can be accurately detected together with the reed switch.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a printer, with reference numeral 1 a frame, 2 a motor serving as a driving source, and 3 a motor bracket, from which driving force is transmitted to a cylindrical cam 4 via an internal reduction gear. 4 is a cylindrical cam, 5
1 is a cam groove, 7 is a reed switch, 9 is a bracket cable, 10 is a tachometer generator, 11 is a paper feed roller, 12 is a dot head, 13 is a platen, 14 is a paper feed transmission lever, and 15 is a paper feed one-way clutch gear. 16 is a paper feed drive gear, and 17 is a camshaft. 2A and 2B are detailed views of the dot head 12, in which 21 is a print lever, 22 is a push rod, and 23 is a print lever return spring. 24 is a printing lever shaft, on which the printing lever 21 and the return spring 23 are respectively supported. 25 is a head coil. 27 is a head carriage, 8 is a head swing pin, and 28 is a plunger, which are fixed integrally with the push rod 22. 9 is a flat cable. Third
The figure shows the dot head shown in Figure 2 a and b.
This is an example of digit printing. FIG. 4 shows the timing relationship for printing the characters shown in FIG. 3 and the timing of energizing the electromagnet. FIG. 5 is a diagram showing a conventional method of fixing the magnet 6 and the cylindrical cam 4 according to the present invention, and 41 is a reduction gear. 6a, b, and c show embodiments of the present invention, and 51 is a tapered protrusion.

Claims (1)

[Scope of Claim for Utility Model Registration] In a reset detection mechanism of a printer that prints on the recording paper by reciprocating the print head along the recording paper using a cylindrical cam, the printing head prints dots on the recording paper; a cylindrical cam having a cam groove that engages with the print head to reciprocate the print head along the recording paper, and a cavity formed along the axial direction; a reed switch arranged opposite to the magnet press-fitted into the cylindrical cam and for detecting the rotational position of the cylindrical cam; In order to bring the magnet into close contact with at least two side surfaces, a tapered protrusion having a caulking margin in advance is provided on a surface of the cavity opposite to the side surface along the axial direction. Features printer reset detection mechanism.