JPH02294958A - Starting end and termination detector for cassette tape - Google Patents

Abstract

PURPOSE:To reduce the peak of a consuming current and to make a power supply filter compact by alternatively emitting a light emitting element, which detects the starting end side of a tape, and a light emitting element for detecting the termination side of the tape. CONSTITUTION:A tape X wound around a take-up side reel 51 and a supply side reel 52 is in contact with a cylinder 53 by a guide roller 54 and by this cylinder 53, magnetic recording or reading is executed. A signal from the cylinder 53 is sounded through a signal conversion part 55 and an amplification part 56. A first light emitting element 1 and a first light receiving element 2 are provided near the position of the take-up side reel 51 when a cassette 50 is mounted. By these elements, the starting end of the tape X is detected. A second light emitting element 3 and a second light receiving element 4 are provided in the side of the supply side reel 52 and the termination of the tape X is detected. The elements 1 and 3 alternatively turn on light with the frequency of several kHz by a light emitting element driving device 5. The elements 2 and 4 output a frequency equal with the above mentioned frequency. A starting end detector 6 and a termination detector 7 detect the output of this frequency and when the frequency is more than a level set in advance, the starting end or termination is judged.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a cassette tape start/end detection device.

<Prior Art> A detection device is used in a cassette tape recorder and the like to optically detect the beginning and end of a cassette tape. A cassette tape is formed with a light-transmitting part that transmits light at the beginning and end of the tape. Light is transmitted from a light-emitting element to this transparent part, and the transmitted light is received by a light-receiving element. It is structured to detect.

Normally, light-emitting elements are configured to emit light in pulses to eliminate the effects of ambient light, but in conventional detection devices, currents of the same phase were supplied to the light-emitting elements at the start and end ends, causing them to emit light at the same time. .

Problems to be Solved by the Invention> However, in the conventional configuration as described above, two light emitting elements are turned on at the same time, so power consumption fluctuates drastically between when the light is turned on and when the light is turned off. rs. There was a major drawback due to the impact on the source line. In addition, the power supply side is usually equipped with a power supply filter to prevent noise from entering the preamplifier section, etc., but the lighting currents of the two light emitting elements are superimposed, and the lighting frequency is several KH.
z, it was not possible to prevent the effect on the audio system small k section, etc., unless the capacitor capacity of the filter section was made large. However, large-capacity capacitors have a large shape, which is extremely disadvantageous for high-density packaging.

<Summary of the Invention> The present invention has been made to solve the problems of the conventional device described in "-", and includes a first light-emitting element for detecting a transparent part on the starting end side of the tape, and a second light-emitting element for detecting a light-transmitting part on the termination side; a power source including a power filter that commonly supplies power to the first and second light-emitting elements; The basic feature is that the device has a control means for causing the light emitting elements to emit light alternately.

Embodiments The present invention will be described in detail below based on embodiments shown in the drawings.

No. 'J-l:zl shows an example in which the present invention is applied to a DAT player, in which a take-up side reel 51 and a supply side reel 52 are provided inside the cassettes) to 50. The wound table X contacts the cylinder 53 by the guide roller 54 and the guide roller 54,
Magnetic recording or reading is performed.

The signal from the cylinder 53 is sent to the signal converter 55 and the amplifier 56.
It is transcribed into voice via .

A first light emitting element] and a first light receiving element 2 are provided near the position of the take-up reel 51 when the cassette 50 is installed, and are configured to detect the starting end of the tape X. . On the other hand, a second light emitting element 3 is provided on the supply side rill 52 side.
A second light receiving element 4 is installed so that the end of the tape X can be detected.

In this embodiment, the first light emitting element]-, the first light receiving element 2, and the second g! The optical element 3 and the second light receiving cable 4 are arranged on the same side, and the prisms 8 and 9 are arranged on the opposite side with the tape X in between.

The details are shown in FIG. The light emitted from the first light emitting element 1 and the second light emitting element; 3 is refracted by 180 degrees at the prisms 8 and 9, passes through the tape It has become. When the light-transmitting part of the table , are sent to the termination detector 7.

The first light emitting element 1 and the second light emitting element 3 are provided by a light emitting element driving device 5
The first light receiving element 2 and the second light receiving element 4 generate an output at a frequency equal to this frequency. The start end detector 6 and the end end detector 7 detect the output of this frequency, and when it reaches a preset level or higher, they determine that it is the beginning of the tape or the end of the tape, and send a signal to that effect to the control device 20. .

The control device 20, which receives the start signal from the start end detector 6, performs necessary operations at the start end of the tape, such as stopping tape running. Further, the control device 20 which receives the termination signal from the termination detector 7 similarly performs necessary operations at the tape termination portion.

The details of the light emitting element driving device 5 will be explained with reference to FIG.

The power supply 10 is connected to the first light emitting element through the power supply filter]1.
, is configured to supply power to the second light emitting element 3.

The power supply filter 11 includes capacitors C1 and C2 in parallel with the power supply.
This eliminates the influence on the audio system due to fluctuations in power supply.

A switch 2 and a switch 13 are connected to the first light emitting element and the second light emitting element 3, respectively.
, the light is turned on at a predetermined frequency by turning the switch 13 on and off. switch 12, switch] 3 are each 1
~ It consists of transistors Q2 and Q3, and a number K H from a square wave generator 15 is connected to the base side of the transistor.
7. It is configured to supply a rectangular wave with a frequency of , and to be intermittent at this frequency. Switch 13 and square wave generator 15
An inharter 14 is interposed between the switch 12 and the switch 12, whereby a rectangular wave having an opposite phase to that of the switch 12 is supplied, and the switch 1-2 and the switch 13 are configured to be turned on alternately.

That is, when the rectangular wave from the rectangular wave generator 1-5 is {{), the switch 12 is turned on and current is applied to the first light emitting element 1 via the limiting resistor Rl, so that the first light emitting element 1 lights up. At this time,
The output of the inverter 14 is J, and the switch 13 is turned off and the second light emitting element 3 does not light up. "Square wave generator"
When the square wave from 5 or 1, the output of the inharter 14 is I
-I, switch 13 is turned on, and limiting resistor R2
Electricity is applied to the second light emitting element 3 via the second light emitting element 3, and the second light emitting element 3 lights up.

At this time, the first light emitting element does not light up.

In this way, the first light emitting element] and the second light emitting element 3 are configured to alternately light up. The overall current flowing at this time is almost constant, and the transient fluctuation when switching between the two remains. It is extremely small, and can be absorbed if the capacitor of the power filter 11 has a capacity of about several tens of μF.

In the second configuration, the light from the first light emitting element 1 and the second light emitting element 3 passes through the brisms 8 and 9, and then through the transparent part of the tape X, and is transmitted to the first light receiving element 2 and the second light receiving element. 4, and thereby the starting and ending ends of the table X are detected.

Since the first light emitting element 1 and the second light emitting element 3 are alternately and intermittently turned on by the light emitting element driving device 5, there is little variation in current. Therefore, the peak of current consumption can be reduced, and the capacitance of the capacitor of the power filter 11 can be made small.

As a result, the capacitor can be made smaller.

Effects of the Invention> As explained above, the cassette type tape start/end end detection device of the present invention includes a first light emitting element for detecting a light transmitting part on the start end side of the tape, and a light transmitting element for detecting a light transmitting part on the end side of the tape. a second light emitting element for detecting the light emitting element; a power source including a power filter that commonly supplies power to the first and second light emitting elements; Since the light emitting device has a control means for causing light to emit light, the current consumption is leveled and the peak current consumption can be reduced. Further, the capacity of the capacitor of the power supply filter can be reduced, and the device can be made smaller, which is advantageous in terms of implementation.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing an embodiment of the present invention, Figure 18-2 is a detailed diagram showing the mechanical structure of a light emitting element and a light receiving element.
FIG. 3 is a block diagram showing details of the light emitting element driving device. 1: First light-emitting element, 2: First light-receiving element, 3: Second light-emitting element, 4: Second light-receiving element, 5: Light-emitting element driving device, 6: Starting end detector, 7: Ending end detector, 8: Starting end Side prism, 9:
Terminal side prism, 10: Power supply, 11: Power supply filter, 1
2: Switch, 123: Switch, 14: Inverter,
15: Square wave generator, 20: Control device, 50: Cassette, 51: Take-up reel, 52: Supply reel, 53: Cylinder, 54: Guide roller, 55: Signal converter, 56
: Amplification section. Patent applicant Kiyoshi Takahashi, agent of Glarion Co., Ltd., patent attorney

Claims (1)

[Scope of Claims] A first light-emitting element for detecting a light-transmitting part on the starting end side of the tape; a second light-emitting element for detecting a light-transmitting part on the trailing end side of the tape; A cassette tape characterized by comprising: a power source including a power filter that commonly supplies power to the second light emitting elements; and a control means for causing the first and second light emitting elements to alternately emit light. Start/end detection device.