JPS59227653A - Ribbon terminal edge detecting apparatus - Google Patents

Abstract

PURPOSE:To certainly detect the terminal edge of a ribbon even if a little amount of ink is fallen-off from the ribbon by constituting the captioned apparatus so that the light transmitted from a luminous element installed at the position opposed to the ribbon contact surface on a guide member is reflected by the ribbon and lead to a light receiving element. CONSTITUTION:During the time when the ink-applied part of a ribbon travels on a guide member 20, the reflected light which reaches a light receiving element 17 does not exceed the threshold value of the element, since the ink-applied part has a low reflectance, and detection is not carried-out. When a reflection body at the ribbon terminal edge part reaches the guide member 20, the reflected light at a sufficient level reaches the light receiving element 17, and the terminal edge of the ribbon is detected, and the revolution of a ratchet-equipped driving pole 12 is suspended by an electrical circuit, and the traveling of the ribbon is suspended, and printing is suspended, and replacement of ribbon is instructed. Further, since the light transmitted from a luminous element 15 is reflected by the ribbon having convex curved form, and the light whose intensity is reduced by a certain degree reaches the light receiving element 17, the intensity of the reflected light is not varied and erroneous detection is not generated, even if a little amount of ink is fallen-off from the ribbon at the terminal edge part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a ribbon end detection device using optical means. Note that the ribbon in the present invention includes not only ink ribbons of typewriters or thermal transfer printers, but also all band-shaped bodies that are made to run along a predetermined path when used, such as magnetic tapes for audio or video.

[Prior Art] The above-mentioned ribbon, for example, an ink ribbon for a thermal transfer printer, is usually wound into a roll, and when used, the roll is used as a supply side, and the ribbon is unwound from the outer periphery and fed out to the ribbon use position. A running path is formed in which the used ribbon is run through the print head and is wound up as a take-up roll. This feeding and running of the ribbon is automatically performed in synchronization with normal printing. Therefore, when the supply roll runs out of ribbon, it is necessary to stop printing and replace the ribbon, and for this reason, a device for detecting the end of the running ribbon is included.

Conventionally, as such a ribbon end detection device, a device as shown in FIGS. 1 and 2 has been used. FIG. 1 is a schematic plan view of the ribbon cassette housing with the upper cover removed in a state in which the detection device is in use, and FIG. 2 is a sectional view taken along line II-II'. ■ is the housing of the ribbon cassette, in which the unused ribbon 3 wound around the core 2 is unwound and fed out, and the rollers 4, 5
The ribbon is then run in the vicinity of the print head 6 (outside the cassette housing), and further along a path passing through the rollers 7, and is wound around the core 8 as a used ribbon 9. Here, the core 2 and the wound ribbon 3 are collectively referred to as a supply roll, and the core 8 and the wound ribbon 9 are collectively referred to as a winding roll. The core 2 is supported so as to be freely rotatable around a center pole 11 which is a fixed positioning member on a carriage (not shown) on which the cassette housing 1 is mounted. - On the other hand, the core 8 is supported around a ratcheted ball 12 provided on the carriage so as to be rotatable and forcibly rotated in the direction of the arrow. The print head 6 is installed on a carriage, and when printing, it is a chain tl! The ribbon is moved to position a6', which causes the ribbon to move to the platen (not shown).
Printing is performed according to the characters and patterns formed on the print head 6 when pressed against the paper above. Therefore, from the supply roll to the print head 6, the ribbon is unused, and from the print head 6 to the take-up roll, the ribbon is used.

The ribbon end detection device is provided in an unused ribbon portion of the ribbon travel path. That is, as shown in FIG. 1, a detection device 14 is inserted from below between the rollers 4 and 5 through an opening 13 formed at the bottom of the cassette housing 1. The detection device 14 is fixed to the carriage, and as shown in FIG.
is located on the other side, and a light receiving element 17 is located on the other side. For example, a light emitting diode (LED) is used as the light emitting element 15, and a phototransistor is used as the light receiving element 17, for example. Terminals of the light emitting element 15 and the light receiving element 17 are soldered to a printed circuit board 18 and connected to a predetermined electric circuit. Of course, the light from the light emitting element 15 is emitted toward the light receiving element 17. The used part of the ribbon is opaque because ink is applied to the transparent base film 1-.
By forming a transparent portion on which ink is not applied over an appropriate length at the end of the ribbon, light from the light emitting element 15 is transmitted to the ribbon 3 during normal ribbon running.
' (opaque part) and does not reach the light-receiving element 17, but when the transparent part at the end of the ribbon reaches the detection device 14, the light from the light-emitting element 15 reaches the light-receiving element 17. An electrical signal is generated to detect the end of the ribbon.

Such conventional ribbon end detection devices have the disadvantage that if there is any ink drop on an unused ribbon, it may be mistakenly detected as the end of the ribbon.

[Object of the present invention] In view of the prior art as described in ``-'', an object of the present invention is to provide an improved ribbon end detection device that does not cause false detection.

[Example of the present invention] Hereinafter, the present invention will be described in detail based on the drawings.

In the following drawings f, the same components as in the conventional apparatus shown in FIGS. 1 and 2 are denoted by the same numbers.

FIG. 3 is a plan view of the ribbon end detection device in use, with the cassette housing 1 and the detection device housing 14' shown with their lids removed.

1 is a housing of a ribbon cassette, in which the unused ribbon 3 wound around the core 2 is unwound and fed out, and is placed near the roller 4.5 and the printing end 6 (outside the cassette housing), and further is caused to travel along a path passing through rollers 7, and used ribbon 9 is wound around core 8. The core 2 is supported so as to freely rotate around a center ball 11 fixed to the carriage, while the core 8 is forcibly rotated around a ratcheted pawl 12 provided so as to be driven and rotated by the carriage. It is supported as much as possible. When the ball 12 is rotated by an appropriate driving means, the take-up roll is rotated in the direction of the arrow by the ratchet mechanism, and the ribbon runs in the direction of the arrow inside the cassette housing (outside the cassette housing in the vicinity of the print head 6). The supply roll is rotated in the direction of the arrow, and unused ribbons 3 are sequentially fed out. During printing, the print head 6 moves to the position 6'.

The ribbon end detection device of this embodiment has a guide member 20 provided so as to be in constant contact with one side of the running unused ribbon 3' on the ribbon running path.

The guide member 20 has rollers 4 in the cassette housing l.
and the roller 5.

The ribbon contacting surface of the guide member 20 has an appropriate curvature, and is configured so that the ribbon traveling path forms a curved surface on the guide member 20. A light emitting element 15 is provided at a position facing the ribbon contact surface of the guide member 20. Polarizing filter 1
6 and a light receiving element 17 are arranged. Light emitting element 1
5 and the terminals of the light receiving element 17 are punched and fixed to the printed circuit board 18, and these are connected to the housing 14.
' and is fixed to the carriage. A transparent window 21 is formed on the wall surface of the cassette housing 1 at a position between the guide member 20 and the light emitting element 15 and light receiving element 17. Here, 1 light emitting element 15, light receiving element 17
And the guide member 20 allows the light emitted from the light emitting element 15 to pass through the polarizing filter 16 and the window 21.
It is reflected by the running unused ribbon 3' of 1- and returns to the window 2.
1 and a transparent window 22 provided in the detector housing 14' to be guided to the light receiving element 17. Here, if the radius of curvature of the ribbon contact surface of the guide member 20 is too small, the ribbon 3' will reach the light receiving element 17.
Since the reflected light from the mirror becomes too weak, an appropriate curvature is selected to receive the proper reflected light. Further, the reason why the guide member 20 is provided in the unembodied detection device is to prevent the ribbon 3' from sagging at the detection position.

The end of the ribbon whose end is detected by the unexamined detection device is a ribbon whose used part is a low reflectance material coated with ink, and whose end is formed into a reflector having a high reflectance. The reflector is, for example, a ribbon base film 1 coated with aluminum vapor-deposited instead of coated with ink.

Therefore, the ink applied part of the ribbon is the guide member 20-f.
When the vehicle is traveling in the second direction, since the ink portion has a low reflectance, the reflected light reaching the light receiving element 17 does not exceed the threshold of the element, and no detection is performed. When the reflector at the end of the ribbon reaches the guide member 20, a sufficient level of reflected light reaches the light receiving element 17, whereby the end of the ribbon is detected, and an electric circuit moves the drive ball 1 with a ratchet.
2 is stopped, ribbon running is stopped, printing is stopped, and ribbon replacement is supported by appropriate display means.

As described above, according to the ribbon end detection device on the Kinotsu side, the running unused ribbon 3' always comes into contact with the guide member 20 at the end detection position and runs at a predetermined curvature. Therefore, no slack occurs at the end detection position, and therefore the detection condition can always be kept constant.

In the ribbon end detection device of this embodiment, the light from the light emitting element 15 is reflected by the ribbon having a convex curved surface, and the light reaches the light receiving element 17 with its intensity reduced to some extent. Therefore, even if ink falls on the ribbon, the reflected light from that part will not exceed the threshold of the element, and no false detection will occur.

Also, when detecting the end of an ink ribbon using color ink (for example, red, blue, brown, etc.) that has a higher reflectance than normal black ink, the reflected light from the ink application area exceeds the threshold of the element. There is no possibility of false detection.

Furthermore, in the ribbon end detection device of this embodiment, since the light emitting element 15 and the light receiving element 17 are not located on both sides of the ribbon 3', there is no need to provide an opening for inserting the element in the cassette housing 1, and therefore, there is no need to provide an opening for inserting the element into the cassette housing 1, thus preventing dust from entering the housing 1. It does not get stuck in the ribbon cassette and stick to unused ribbons, and when the ribbon cassette is installed in the carrying case, the ribbons are not caught and damaged.

Note that the present invention is not limited to -1;
For example, although the embodiment has been described with respect to a thermal transfer printer, a magnetic tape for audio is almost the same except that a recording, erasing, and reproducing head is provided in place of a print head at the use position, and a carriage is not required. Terminal detection can be performed in the same way.

[Effects of the Present Invention] As described above, according to the present invention, the end of the ribbon can be reliably detected, and even if there is ink dripping on the ribbon, there will be no false detection.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a conventional ribbon end detection device in use with the top cover of the cassette housing removed, and FIG. 2 is a sectional view taken along line II-II'.
FIG. 3 is a plan view of the cassette housing and the detection device housing with the lids removed in the operating state of the ribbon end detection device of the present invention, and FIG.
'It is a sectional view. Cassette housing 2, 8: Core 3.3': Unused ribbon 4.5, 7: Roller 6, 6': Print head 9: Used ribbon 1]: Center ball 12: Ball with ratchet 13: Opening 14: Detection device 14': detection device housing

Claims (1)

[Claims] (1) In a device for detecting the end of a ribbon that is fed out from a supply roll and travels to a take-up roll via a ribbon use position, a guide member is arranged so as to be in constant contact with one side of an unused ribbon, The ribbon contact surface of the guide member has an appropriate curvature, and a light emitting element and a light receiving element are provided at positions facing the ribbon contact surface of the guide member so that light from the light emitting element is reflected by the ribbon on the guide member. 1. A ribbon end detection device, characterized in that the ribbon end is arranged so as to be guided to a light receiving element.