JPS5922262A - Device for detecting cassette in cassette tape recorder or the like - Google Patents

Abstract

PURPOSE:To detect the existence of a loaded cassette tape precisely, by using an output signal from a rotation detecting means of a tape winding driving part fitted to detect the final end of the tape. CONSTITUTION:A rotation detecting circuit 26 outputs a pulse signal A proportional to the turning speed of a reel motor 20. The output signal A is inputted to an integrating circuit 32 and an electric signal C to be changed in proportion to the turning speed of the reel motor 20 is outputted. The output voltage C is inputted to a comparator 34 and compared with reference voltage B outputted from a reference voltage generating circuit 36 and the compared result D is outputted. When the cassette tape is not loaded, the reel motor 20 is reduced at its load and turned at a speed considerably higher than that of the loaded status of the tape. In accordance with the difference of the period of the output signal A, the output voltage C is high at the load of the tape and low at the unloaded time. The reference voltage B is set up to the intermediate value of the difference of the voltage C which is generated by the existence of the cassette. When the cassette tape is not loaded, the output D is turned to the ''H'' level and the unloaded status is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cassette detection device for detecting whether or not a cassette tape is loaded in a cassette tape recorder or the like.

Conventionally, cassette tape recorders, etc. (recording/playback devices i'
The cassette detection device in the cassette tape loading section (including the cassette tape loading section) consists of a detection lever provided facing the cassette tape loading section and a mechanical switch that is linked to this lever.When the cassette tape is loaded, The lever moves when pushed by the case, and the switch operates.

Conventional cassette detection devices using this type of mechanical switch have a relatively short contact life and low reliability.
In order to cope with the increase in contact resistance due to contact oxidation caused by the surrounding atmosphere, it is necessary to send sufficient current to the contacts, which tends to generate contact opening/closing noise, which can enter the tuner etc. That was a problem. Furthermore, it is difficult to automate the processing of lead wires from the switch and the assembly of the lever and its interlocking drawings, which increases assembly time, which increases costs.

This invention was made in view of the above-mentioned conventional problems, and its purpose is to improve the tape winding drive provided in general cassette tape recorders etc. for detecting the end of the tape, without using a mechanical switch. It is an object of the present invention to provide a cassette/detection device for a cassette tape recorder or the like, which can reliably detect whether or not a cassette tape is attached by using an output signal of a rotation detection means of a cassette tape recorder.

In order to achieve the above object, the present invention provides a cassette tape recorder or the like having a rotation detecting means for outputting a ξ noise signal with a frequency proportional to the rotational speed of a tape winding drive section, the output of the rotation detecting means is There is an integrating circuit that integrates the signal and outputs a voltage signal that changes proportionally to the rotational speed, a comparator that compares the output voltage of this integrating circuit with a preset reference voltage, and an operating mode of the tape running drive system. An operation permission circuit is provided that allows the above-mentioned connominator to perform comparison and output operations normally only when the constant speed running mode is set during playback or recording. The present invention is characterized in that it is detected that the winding drive section is under a light load and rotates at a cylinder speed in the ``-'' mode.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 1 shows a first embodiment of the invention. As is well known,
Tape running drive system includes capstan 10° and pinch roller 1.
2. It has two reel stands 14 and 16. Reel stand 16
is rotationally driven by an IJ-le motor 20 via a pulley 18. The reel motor 20 is driven by the output of a power supply circuit 22 that is controlled by a command signal E from a control circuit (not shown), and its rotation direction is switched by a switching circuit 24. Reel stand 1 driven by reel motor 20
6 is the tape winding side in the constant speed tape running mode during playback or recording.

The rotation detection circuit 26 is configured to detect the rotation of the reel motor 2o from changes in current caused by the brushes of the motor 20. In other words, there is a resistor 2 in the current-carrying path of the motor 2°.
8 is inserted, and the current change that occurs each time the brush passes the electrode when the motor 20 rotates is converted into a voltage signal by the resistor 28.

The rotation detection circuit 26 converts this voltage signal into a connominator 30.
The reel motor 2 is amplified and waveform shaped by a circuit centered on
It is configured to output a pulse signal A proportional to 00 rotation speed.

The output signal A of the rotation detection circuit 26 is input to an integrating circuit 32 composed of a resistor and a capacitor, and the voltage signal 07! changes proportionally to the rotation speed of the reel motor 20! l'-obtained. The rotation detection circuit 26 and the integration circuit 32 are configured to detect, by the cessation of the pulse of the output signal A, that the reel motor 20 has been forcibly stopped after the tape has been wound to the end. The present invention uses the output signal C of this integrating circuit 32 to detect whether or not a cassette is attached as described below.

The output voltage C of the integrating circuit 32 is input to the converter 34, and the reference voltage B output from the reference voltage generating circuit 36 is input to the converter 34.
The output of the comparison result becomes a detection signal indicating the presence or absence of a cassette. The reference voltage generation circuit 36 applies a reference voltage B obtained by dividing the power supply voltage by the resistors 38 and 40 to the comparator 34, but the regular reference voltage B is used when running at a constant speed during playback or recording. Occurs only in mode.

In other words, this circuit 36 includes the transistor 42 as the above-mentioned operation permitting circuit, and this transistor 42
is the above command signal E that is at L level only in constant speed driving mode.
and in other modes the signal E IJ: I
- the transistor 42 is turned on at the voltage level, and the reference voltage B is reduced to approximately zero volts. In addition, the capacitor 44
is for ripple filter.

FIGS. 2 and 3 show waveforms at various parts of FIG. 1, with FIG. 2 showing the case where a cassette tape is installed, and FIG. 3 showing the case where it is not installed.

If a cassette tape is installed, capstan 1
A reel stand 16 is driven by a reel motor 20, and the tape is fed out at a constant speed after being pinched by a pinch roller 12.
It is wound up by. At this time, the tape places a large load on the reel motor 20, and the tape is wound up while being pulled.

When a cassette tape is not attached and the constant speed running mode is entered, there is no load of tape to be wound, and the reel motor 20 has a light load and rotates at a considerably faster speed than when a tape is attached.

This situation is shown in FIGS. 2A and 3A.

When no tape is attached, the period TN to the output signal of the rotation detection circuit 26 is approximately 10.3 mS as an actual measurement, and when the tape is attached, the rotational speed of the motor 200 changes depending on the winding diameter of the tape. However, the period TA to the output signal of the rotation detection circuit 26 is actually measured to be 3 to 100 m5, and TN and IrA can be clearly distinguished.

Due to the difference in the period of the output signal A in the constant speed running mode depending on the presence or absence of the cassette, there is a clear difference in the output voltage C of the integrating circuit 32, and as shown in FIGS. 2 and 3, when the tape is loaded, The voltage C is high, and the voltage C when not attached is low. The reference voltage B stably generated by the circuit 36 in constant speed running mode is:
It is set to an intermediate value of the difference in voltage C depending on whether a cassette is present or not. As a result, as shown in FIG. 3, when the constant speed running mode is entered with no cassette tape installed, the output J) of the comparator 34 becomes H level, and it is detected that no cassette tape is installed. Based on this detection, a predetermined control such as stopping the tape running drive system is performed.

FIG. 4 shows a second embodiment of the invention.

In this embodiment, the rotation of the reel stand 16 is transmitted to the rotating magnet 50 via the belt 48.
Zero rotation is detected by the hole l052 in the rotation detection circuit 26.

As explained in detail above, according to the present invention, the rotation detection means provided for detecting the tape end in general tape recorders etc. can be used without newly installing a cassette detection mechanism in the tape loading mechanism. The cassette detection device can be realized at a low cost with a very small number of shared electronic components, and is highly reliable and has no fear of noise generation.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the first embodiment of this invention, FIG. 2, and FIG.
The figure is a waveform diagram showing the operation of each part in FIG. 1 with and without a cassette, and FIG. 4 is a configuration diagram of a second embodiment of the present invention. The same reference numerals are given to the sections in each figure, and 16 is a reel stand;
20 is a reel motor, 26 is a rotation detection circuit, 32 is an integration circuit, 34 is a connominator, 36 is a reference voltage generation circuit, 42 is a transistor as an operation permission circuit, 50 is a rotating magnet, and 52 is a Hall IO. Agent - Patent attorney Jo Kuzuno - (1 other person) 313 Figure 2 ■8 Figure 3 N

Claims (1)

[Claims] (1) In a cassette tape recorder or the like having a rotation detection means that outputs a pulse signal with a frequency proportional to the rotational speed of the tape winding drive unit, the output signal of the rotation detection means is integrated and the pulse signal is proportional to the rotational speed. an integrating circuit that outputs a voltage signal that changes to , a comparator that compares the output voltage of this integrating circuit with a preset reference 1L pressure, and a tape running drive system whose operating mode is set to constant speed running during playback or recording. A cassette detection device for a cassette tape recorder or the like, comprising an operational πf circuit that allows the comparator to perform normal comparison and output operations only when