JPH02258385A - Cassette ribbon detection circuit - Google Patents

Abstract

PURPOSE:To provide the title circuit having long life and generating no erroneous operation by mounting a switch means detecting the presence/absence of the mounting of a ribbon cassette to close/open a feeder line and a photointerruptor means wherein a light emitting circuit is provided to the feeder line. CONSTITUTION:When a cassette is mounted, a switch means S is closed to supply a current to a light emitting diode D. The emitted light EL from the light emitting diode D is absorbed and scattered by the surface of a ribbon in a ribbon present state. Therefore, the base circuit of a phototransistor Q is not driven and the collector circuit of the phototransistor Q is cut off and the output OT of a CMP becomes almost 0V to output the effect that the ribbon is not finished. In a ribbon finish state, the reflected light RL from the surface of the ribbon is inputted to the base circuit of the phototransistor Q and the collector circuit of the phototransistor Q is brought to a continuity state and the output OT of the CMP shows the finish of the ribbon. When the cassette is detached, the switch means S is opened to cut off the supply of a current to the light emitting diode D and, by this mechanism, the output OT of the CMP senses the detachment of the cassette.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is directed to detecting and circuiting the end of a ribbon (tape) provided within a cassette.

[Prior Art] Conventionally, this type of detection circuit always detects the ribbon end regardless of whether a cassette is loaded or not.

[Problems to be Solved by the Invention] As a result, the photointerrupter element gradually deteriorated and its lifespan was shortened.

Additionally, there was a risk of false detection due to the intrusion of external light when the cassette was not loaded.

The present invention eliminates the above-mentioned drawbacks of the prior art, and its purpose is to provide a cassette ribbon detection circuit that has a long life and is free from malfunctions.

[Means for Solving the Problems] In order to achieve the above object, the cassette ribbon detection circuit of the present invention includes a switch means for closing/opening a power supply path by detecting whether or not a ribbon cassette is loaded; The outline thereof is to include a photointerrupter means in which at least a light emitting circuit is provided in the power supply path.

[Function] In this configuration, the switch means closes/opens the power supply path by detecting whether or not a ribbon cassette is loaded. Since the photointerrupter means has at least its light emitting circuit provided in the power supply path, it does not operate while the cassette is not loaded.

[Description of Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a circuit diagram of a cassette ribbon detection circuit according to an embodiment. In FIG. 0, S is a switch means, the contact of which is turned on/off in conjunction with whether or not a ribbon cassette (not shown) is loaded. PHI is a font interrupter element and includes a light emitting diode D and a phototransistor Q inside.

In addition, T indicates a part of the ribbon (tape) in the ribbon cassette, and the surface of the ribbon is dark in the middle of the ribbon (with ribbon), and at the end of the ribbon (without ribbon), the surface of the ribbon is dark. It has a silver color (reflective treatment).

As described above, when the cassette is loaded, the switch means S closes and power is supplied to the light emitting diode D.

When the ribbon is present (in the middle of the ribbon), the emitted light EL from the light emitting diode D is absorbed and scattered without being reflected on the ribbon surface. Therefore, the base circuit of phototransistor Q is not driven and the collector circuit of Q is cut off.

In other words, one terminal of the comparator circuit (CMP) is approximately +5V
is maintained. On the other hand, the child terminals of CMP are resistors R4 and R1
The voltage is always maintained at +2.5V by the partial voltage.

Therefore, the output OT of CMP becomes approximately Ov, which indicates that the ribbon is not finished.

Furthermore, in the state where the ribbon is finished, the reflected light RL reflected on the ribbon surface is input to the base circuit of the phototransistor Q, so that the collector circuit of Q is conductive. That is, one terminal of CMP is held at approximately O■. Therefore, the CMP output O
T becomes approximately +5v, and a message to the effect of "ribbon end" is output.

On the other hand, when the cassette is removed, the switch means S opens to cut off the power supply to the light emitting diode D, since there is no longer any practical benefit in detecting whether or not the ribbon is finished. This allows CM
The output OT of P is approximately Ov, but since the control software has already sensed "cassette removal", there is no need to be concerned with the presence or absence of the ribbon.

Note that another switch means that operates in the same manner as the switch means S may be provided at the portion of the collector circuit of the phototransistor Q indicated by the arrow P.

In this way, when the ribbon cassette is removed, the power supply to the phototransistor Q is also cut off, so one terminal of the CMP is unconditionally maintained at approximately +5V, which is disturbed by the collector of Q that receives outside light. Never.

Further, the cassette ribbon according to the present invention includes ink ribbon cassettes used in thermal printers, as well as magnetic tape cassettes (magnetic tape reels) used for audio, video, information processing, etc.

Furthermore, although a reflective photointerrupter element is used in the above-described embodiment, the present invention is not limited thereto; for example, if the end of the ribbon is treated to be transparent, a transmissive photointerrupter element may be used.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide a cassette ribbon detection circuit that has a long life and does not malfunction.

In addition, the control software has been simplified, allowing you to receive highly reliable detection information at all times.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a cassette ribbon detection circuit according to an embodiment of the present invention. In the figure, S: switch, PHI: photointerrupter element, D: light emitting diode, Q: phototransistor, CMP: comparator. Patent applicant Canon Co., Ltd.

Claims (1)

[Claims] A cassette ribbon detection circuit comprising a switch means for closing/opening a power supply path by detecting whether or not a ribbon cassette is loaded, and a photointerrupter means having at least a light emitting circuit provided in the power supply path.