JPS6129277B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printing device in which a carriage carrying a printing head moves along a guide means to print.

With the recent development of digital technology and servo technology,
Detecting the rotational position of a motor and controlling its speed and position are widely used. In order to perform speed control and position control with higher precision, it is necessary to increase the number of slits in one circumference of the disk as much as possible. Furthermore, there has been a recent trend toward downsizing devices by using photoencoders, and slit disks that are small and have a large number of slits have come to be used. In this case, the major factor that determines the shape and number of slits is the light source of the photoencoder, and it is impossible to increase the number of miniaturized slits unless a completely parallel light source with high intensity is used. For this purpose, a light source with high light intensity, such as an incandescent bulb, an infrared bulb, or an LED, was used, and an optical system using lenses etc. was used to create parallel rays of light. Therefore, these light source devices are considerably larger than the slit disk and its peripheral equipment. Therefore, when a light source device and a photoencoder are incorporated into a carriage, not only does the drive source such as a motor that drives the carriage become large, but the carriage itself becomes heavy, making high-speed printing impossible.

Further, when a light source is provided on the carriage, it is necessary to connect a cord for the light source device to the carriage, which increases the running load on the carriage.

SUMMARY OF THE INVENTION An object of the present invention is to provide a printing device suitable for high-speed printing by reducing the weight of the carriage and reducing the running load on the carriage.

This will be explained below based on the drawings.

FIG. 1 shows a typewriter printhead using a conventional photoencoder incorporated within a carriage (not shown). A type wheel 1 and a slit disk 3 are engaged with a shaft 2a of a motor 2 mounted on a carriage. Further, a light emitting member 4 and a light receiving member 7 are fixed to the carriage. The light emitting member 4 incorporates a light source 5 such as an incandescent bulb or LED, and a lens 6 for converting the light into parallel rays. The light-receiving member 7 houses a light-receiving element 8 such as a phototransistor and an index slit 9 that focuses light in order to obtain an output that is approximately the same as the pitch of the slit disk 3.

In the above example, in order to increase the number of slits in the slit disk 3, the light intensity of the light source must not be further increased, but a larger light source must be used. Also, in order to obtain more perfectly parallel light rays, a lens with a long focal length must be used. Therefore, the photoencoder portion within the carriage has a considerably large shape and mass, and the motor (not shown) for driving the carriage must also be large.

The present invention provides a printing device using a photoencoder that improves the above-mentioned problems.

This will be explained below based on the figures.

FIG. 2 shows an embodiment of a typewriter which is a printing device incorporating a photoencoder using a laser as a light source of the present invention.

A motor 2 is attached to a carriage 12 that moves parallel to a platen (not shown) along a guide rod 11, and a type wheel 1 and a slit disk 3 are engaged with the shaft 2a of the motor 2 as controlled disks. There is. A light receiving element 8 and an index slit 9 necessary for controlling the position and speed of the type wheel 1 in order to determine the drive timing of the type wheel 1, and a mirror 13 for reflecting laser light in the direction of the light receiving element 8. is attached to the carriage 12. 1
4 is a laser device whose optical axis is parallel to the moving direction of the carriage 12, and the laser beam is reflected by a mirror 13 and projected onto the light receiving element 8 through the slit disk 3 and the index slit 9. The figure shows a state in which a laser device 14 as a light source is installed outside the carriage.

In this embodiment, unlike the conventional large light source,
Since a lens is not required, the device can be made smaller, and by using a laser beam, the number of slits in one circumference of the disk can be increased to improve accuracy. Furthermore, providing the laser device outside the carriage is effective in making the carriage smaller and lighter.

As described above, in the present invention, a light source is provided outside the carriage, and the carriage is provided with a means for determining the drive timing of the print head using the light from the light source, so that the weight of the carriage is reduced and the running load of the carriage is reduced. It is suitable for speeding up printing.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the main parts of a conventional typewriter using a photoencoder, and FIG. 2 is a partial perspective view of an embodiment of a typewriter which is a printing device to which the present invention is applied. 1 is a type wheel, 2 is a motor, 3 is a slit disk, 8 is a light receiving element, 9 is an index slit, 13 is a reflecting mirror, and 14 is a laser device.

Claims (1)

[Claims] 1. In a printing device that performs printing by moving a carriage equipped with a printing head along a guide means, a light source with an optical axis parallel to the moving direction of the carriage is provided outside the carriage, and the light from the light source is used. A printing device characterized in that the carriage is provided with a light receiving element, a slit member, and a reflecting member for determining the driving timing of the printing head.