US3673414A

US3673414A - Automatic tape feed controlling means

Info

Publication number: US3673414A
Application number: US70035A
Authority: US
Inventors: Hiroshi Taniguchi; Takahiro Nakamura; Hideki Sakumoto
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 1969-09-18
Filing date: 1970-09-08
Publication date: 1972-06-27
Anticipated expiration: 1989-06-27
Also published as: FR2062272A5; NL7013753A; DE2045844A1; JPS4925883B1; CA947419A; NL148172B; GB1327262A

Abstract

The prescribed position along the running direction of the tape is detected and taken out as an electric signal. The unidirectional component of the differentiated output of the detected electric signal is taken out for controlling the tape driving system to feed or stop the tape in a steady condition.

Description

United States Patent Taniguchi et al. 5] June 27, 1972 [54] AUTOMATIC TAPE FEED CONTROLLING MEANS [56] References Cited [72] lnventors: Hiroshi Taniguchi, Hirakata; Takahiro UNITED STATES PATENTS Nakamura, Neyagawa; Hideki Sakumoto, Moriguchi, n fj 3,290,509 12/1966 Meng ..250/219 D 3,526,776 9/1970 Mizukoshi ..250/231 R [731 Assignw Elmric lndusrial 3,566,132 2/1971 Walker ..307 311 [22] Filed: Sept. 8, 1970 Primary Examiner-James W. Lawrence [2!] Appl' 70035 Assistant Examiner-D. C. Nelms Attorney-Stevens, Davis, Miller & Mosher [30] Foreign Application Priority Data Sept. 18, 1969 Japan ..44/75589 [57] ABSTRACT The prescribed position along the running direction of the [52] U.S.Cl. ..250/206, 226/45, 250/219 D, tape is detected and taken out as an electric signal. The 7/ 317/124 unidirectional component of the differentiated output of the Int. Cl detected electric signal is taken out for controlling the tape Field of Search 219 219 219 DD, driving system to feed or stop the tape in a steady condition.

4 Clairm, 14 Drawing Figures AUTOMATIC TAPE FEED CONTROLLING MEANS This invention relates to means for automatically controlling the tape feed, and more particularly to means for automatically operating a tape feed controlling mechanism by detecting the prescribed position of a running tape by means of mechanical, optical or electrical means and taking out the position detected as an electrical signal.

In the conventional magnetic tape feeding system and the like it has been known and put into practice that the tape feed is controlled according to an optical, electrical or mechanical signal made by a transparent tape, a reflective tape or a conductive tape attached to the tape at the starting end, closing end or intermediate portion thereof. However, various kinds of conventional means for controlling the feed of the running tape have not been operated in a stable manner for various conditions of the tape feed such as normal feed, quick feed, rewinding and others. Otherwise, a very complicated device has been needed for making the operation of the controlling device stable.

Accordingly, the primary object of the present invention is to provide means for operating the controlling means of the tape' feeding system which with certainty operates the tape feed under any condition of the tape through a signal taken out mechanically, electromagnetically or photoelectrically from the running tape.

Another object of the present invention is to provide means for automatically controlling the tape feed which is operated with a small amount of electric power and without any complicated mechanism or circuit'in the tape feeding system as described above.

Other objects, features, and advantages of the present invention will be made apparent from the following description taken in conjunction with the accompanying drawing in which:

FIG. I is an explanatory side cross-sectional view of the conventional tape feed controlling means,

FIG. 2 is a block diagrammatic view of one embodiment of the present invention,

FIGS. 3A to 3G show the relation of the electric signals with the tape,

FIG. 4 is a view of the electric circuit in anembodiment of the present invention,

FIGS is a view of the electric circuit in another embodiment of the present invention,

FIG. 6 is a view of the electric circuit in still another embodiment of the present invention, and

FIGS. 7A and 7B are schematic views of the VTR cassette to which the present invention is applied.

' One of the conventional means for controlling the tape feed automatically is shown in FIG. 1. An opaque magnetic tape 1 is provided with a transparent tape 2 connected therewith for indicating the prescribed position of the tape for operating the tape feeding means. A light source 3 is disposed in one side of the tape 1 and a photoresponsive element 4 such as a phototransistor is disposed in the opposite side of the tape at the symmetrical position with respect to the light source 3, so that the light from the light source 3 is received by the photoresponsive element 4 when the tape running therebetween is transparent. When the photoresponsive element 4 receives the light from the light source 3, the signal generated from the element 4 is transmitted to a relay plunger 6 to operate the tape feeding mechanism. The device as shown in FIG. 1, however, has the following disadvantage. That is, if the tape 1 is stopped at a position where the transparent tape 2 is between the light source 3 and the photoresponsive element 4, the photosensitive element 4 keeps on working and transmitting the signal to the relay plunger 6 whichresults in an excessive consumption of the electric power. And further, in order to start the tape feed again, the tape feeding mechanism should be operated manually or another separate automatic tape feeding means should be provided. Especially, in the case that the tape feeding system is operated by a battery, the battery is discharged in a short time due to the excessive current through the relay and plunger. In view of the above fact, it has been necessary to design the conventional means as described above so that the consumed electric power may be reduced to a minimum when the tape is stopped where the transparent portion thereof is held between the light source and the photoresponsive element.

In the conventional tape feed controlling means as shown in FIG. 1, an opaque tape 5 is further connected with the end of the transparent tape 2 for turning off the relay and plunger or the light source 3 after the tape feeding is stopped for reducing the power consumption. Such methods for saving the power employed in the conventionaltape feed system as described above have defects as follows. The length of the tape which runs after the signal for stop is detected until the tape actually stops greatly difiers where the tape feeding speed is slow as in the case of reproducing and recording and the tape feeding speed is fast as in the case of quick feeding and rewinding, which results in an increase in the number of misoperations. And it is required that the device will normally operate regardless of the time interval after the tape is stopped and until the tape is again started to run. Under the above disposition of the conventional tape feed controlling system, a complicated mechanism and circuit is needed for performing a steady operation without fail because a plurality of circuits are required to be combined in the system.

Another disadvantage inherent in the use of the above described prior art as shown in FIG. 1 is that a large force is needed to operate the manual lever for bringing the tape feed mechanism out of the neutral situation. That is, the tape feed mechanism is set to recover its neutral situation when the tape stopping signal is detected (since the tape feed mechanism should be started from its neutral position), the tape feed mechanism is always set in its neutral situation when the tape is stopped at the position as shown in FIG. 1. Therefore, an extremely large force is needed to manually operate the mechanism to bring it out of the neutral situation since the photoresponsive element, relay and plunger are working to keep the mechanism in its neutral situation. Further, if the manual lever is released before the transparent area of the tape moves out of the detecting portion between the light source and the photosensitive element, the tape feed mechanism is again set in its neutral situation.

Especially in the case where a considerably large torque is exerted when quick feeding and rewinding due to the large torque of the motor for taking up the tape as in'the case of a cassette type Video Tape Recorder, it is necessary to automatically control, at least stop, the tape feed. If the tape feed is not stopped automatically by means of a detecting means for detecting the end of the tape in the cassette type VTR, there are often troubles of breaking of tape, damaging the magnetic head and so forth.

The present invention eliminates the disadvantages of the conventional automatic tape feed controlling means as described hereinabove and provides an automatic tape feed controlling means of simple construction which steadily operates under any condition of the tape feed and works with a small electric power. And the automatic tape feed controlling means in accordance with the present invention is particularly suitable and useful for a battery powered tape deck.

FIG. 2 is a block diagram showing an embodiment of the present invention. In FIG. 2, the reference numeral 7 denotes an opaque magnetic tape and 8 denotes a transparent tape connected thereto at the end. In the opposite sides of the tape 7 are disposed symmetrically a light source 9 and a photoresponsive element 10. The reference numeral 11 denotes a differentiation circuit for differentiating the signal from the photoresponsive element 10. A pulse amplifier 12 connected with the differentiation circuit 11 operates, in the described embodiment, on that portion of the differentiated signal wave which is above a predetermined positive voltage level. The reference numeral 13 denotes a relay connected to a tape feed controlling mechanism 15 through a plunger 14.

Operation of the device as shown in FIG. 2 will now be described with reference to FIG. 3. In FIG. 3A an opaque tape indicated with hatching having a transparent tape connected therewith runs in the direction of the arrow at the speed of v,

At a time Fl the boundary of an opaque tape and the transparent tape crosses the light path of the light from the light source to the photoresponsive element 10. In this case, the photoresponsive element is turned on at the time of t=t and as shown in FIG. 3B the electric current through the photoresponsive element 10 is represented by a low level OFF during the time of t t,, and a high level ON during the time of t t,. The signal as shown in FIG. 3B is converted into a pulse signal as shown in FIG. 3C through differentiation by the differentiation circuit 11. The differentiated pulse as shown in FIG. 3C is converted into a pulse as shown in FIG. 3D through the pulse amplifier 12 which amplifies the pulse shown in FIG. 3C only at the position where the pulse has a value above a definite positive value. Accordingly, the working of the relay 13 is represented by the pulse wave as shown in FIG. 3E and the working duration of the relay 13 is indicated by the top plan portion of the pulse having a length corresponding to the time duration At. This working duration At can be controlled to a proper length by properly selecting the value of the capacitor C and the value of the resistor R determining the time constant of the differentiation circuit which will be described in detail hereinafter referring to FIG. 4.

In the case where the running direction of the tape is opposite the case shown in FIG. 1 as shown in FIG. 3F wherein the photoresponsive element 10 is turned on during t t and turned off during t t,, the differentiated pulse has a negative value as shown in FIG. 36. Since the pulse amplifier 12 shown in FIG. 2 has a unidirectional property, there is no output from the pulse amplifier 12. Accordingly, the relay and the plunger do not operate and there is no operation of the tape feed controlling means in this case.

As apparent from the above description, in accordance with the device constructed as described above the tape feed controlling mechanism is operated to stop the tape feed by the relay and plunger at the instant when the tape stopping signal is detected and after a time of At the relay and plunger are turned off. Therefore, the consumed power is very small since the electric current flows only instantaneously through the electrical element requiring a large amount current such as for a relay and plunger.

Further, it is advantageous in the tape feed controlling means in accordance with the present invention as shown in FIG. 2 that the tape feed controlling means is automatically set in its neutral situation always when the tape feed situation is changed and the consumed power is held small even if the controlling means is left in its neutral situation until it is manually operated. This is particularly advantageous in the case that this tape feed controlling means is applied to a battery powered tape deck.

Another advantage of the tape feed controlling means in accordance with the present invention is that the tape controlling means is never misoperated when the transparent tape is changed to the opaque tape since a unidirectional pulse amplifier is employed to give a pulse output in only one direction and the relay and plunger are operated only when the tape is changed from opaque to transparent between the light source and the photoresponsive element and not vice versa. Therefore, there is no fear of misoperation of the control means.

In FIGS. 4 and 5 are shown the practical embodiments of the electric circuit of the controlling means in accordance with the invention. In FIG. 4, the reference character T indicates a phototransistor faced to the light source disposed beyond the tape and set to be turned on at the instant when the tape is changed from opaque to transparent between the phototransistor T, and the light source. When the phototransistor T, is turned on, a definite voltage is applied across the load resistance R This voltage is differentiated through a differentiation circuit including a capacitor C and a resistor R, and impedance R, (R is an input impedance of the transistor T and only the positive component of the differentiated signal is amplified through a third transistor T The amplified signal drives the relay RI-I to operate the plunger P. The reference character T, indicates an emitter follower for making the input impedance R larger and output impedance small. But in the case that the power source voltage is high or a relay which is operable with small current is employed, the emitter follower T can be eliminated by making the emitter resistance of the Transistor T larger. The time constant of differentiation is determined as C X R,R R,+R,). This time constant is set to be sufficiently longer than the operating duration of the relay and plunger (about 0.1 sec.) and longer than the time required for the tape controlling mechanism to operate.

FIG. 5 shows an embodiment of the present invention wherein a conductive tape is employed instead of the transparent tape. The reference character a indicates a nonconductive tape and b indicates a conductive tape connected with the nonconductive tape a. When the conductive tape b is brought into contact with a couple of electric contacts A, B, the power source voltage is applied across the load resistance R and this voltage is differentiated through a differentiation circuit including C, R, and R as the above case shown in FIG. 4. The differentiated signal is amplified through a pulse amplifier T through an emitter follower T and then the relay RH and plunger P are operated to stop the tape. In this embodiment shown in FIG. 5, there is no consumption of the power when both contacts are not in contact with the conductive tape. And a large current flows through the relay and plunger at the instant when the conductive tape b is brought into contact with the electric contacts A, B, and after the relay and plunger are turned off there is only a small consumption of power even if the conductive tape is in contact with the electric contacts A and B since the power is consumed only at the load resistance R,.

It will be readily understood that the same circuit can be employed and the same effect or result can be obtained in the case that a light reflective tape is employed in combination with the light source and a photoresponsive element, though only the embodiments utilizing the transparent tape in combination with the photoresponsive element and a conductive tape in combination with the electric contacts have been described hereinabove and illustrated in the drawing.

Another embodiment of the electric circuit is shown in FIG. 6 in which the electric signal from the phototransistor T, is differentiated through the differentiation circuit including C, and R,. The positive component of the differentiated signal is taken out through a diode D, and used for triggering the multivibrator including transistors T, and T The output of the single stabilized multi-vibrator is amplified through a transistor T and may be used for driving the relay RH to operate the plunger P. Alternatively, a power transistor may be used as the transistor T to directly drive the plunger P.

In FIG. 7, an application of the present invention in a magazine type VTR is illustrated. In FIG. 7B, the recording or reproducing condition of the VTR is shown and in FIG. 7A, the quick rewinding or quick feeding condition of the VTR is shown. In FIGS. 7A and 7B, the reference numeral 16 indicates a tape magazine including a supply reel 17 and a takeup reel 18. The both ends of the tape in the magazine 16 are fixed to the

reels

17 and 18. The reference numeral 19 indicates a light source which is inserted into the magazine through an opening provided on the cover of the magazine 16. This light source 19 is located in one side of the tape 28 and a photoresponsive element 20 is disposed outside the magazine and located in the opposite side of the tape with respect to the light source 19 as shown in FIG. 7A. In this case, the magazine 16 should be made of a transparent material. The light source 19 is secured to the recording and reproducing apparatus body and the light source 19 comes into the magazine when the magazine 16 is put into the apparatus. It will be understood that the photoresponsive element 20 is also provided so as to come into the magazine when the magazine is put into the recording apparatus. The reference numeral 21 indicates an electric circuit as described above. The tape 28 is fed by a capstan 22 and a pinch roller 23 rotatable in contact therewith. The reference numeral 24 denotes an erasing head, 25 denotes a sound recording reproducing head serving also as a head for catching a control signal. The numerals 26 denote a couple of movable post which are in the position as shown in FIG. 73 at the time of recording and reproducing and in the position as shown in FIG. 7A at the time of quick feeding and rewinding. The reference numeral 27 indicates a tape guide drum including a rotary magnetic head therein. Even in the case that the position of the running tape is different according to the condition of the tape feed such as recording, reproducing, quick feeding, rewinding and the like as in the case as shown in FIGS. 7A and 713, it is possible to control the tape feed without fail regardless of the tape feed situation by properly selecting the position of the photoresponsive element and the light source. The position of the element and the light source shown in FIGS. 7A and 7B is one of the properly selected positions to perform a steady controlling of the tape feed regardless of the situation of the tape.

It should be understood that the present invention can be effected with a simple construction as well in the tape deck of the open reel type other than the magazine type, and further in the one reel type recorder using a magazine for detecting the end of the tape in the magazine.

As described above, the present invention provides a steady automatic tape feed controlling means which consumes little power and is of simple construction. The device in accordance with the present invention is therefore very much suitable for a magazine type VTR and the like which is driven by battery.

What is claimed is:

1. An automatic tape feed controlling means comprising means for detecting the prescribed position of a running tape and generating an electric signal as the output of the detection, means for differentiating said electric signal, means for rectifying the output of the differentiating means, and means for controlling a tape feeding mechanism of said tape according to the signal based on the output of the rectifying means.

2. An automatic tape feed controlling means comprising means for detecting the prescribed position of a running tape and generating an electric signal as the output of the detection, means for differentiating said electric signal, an impedance converter having a high input impedance and low output impedance having the difierentiated output of the differentiating means as an input signal, a pulse amplifier having the output signal of said impedance converter as an input signal, and a relay driven by the output of said amplifier, whereby the tape feeding mechanism is controlled by controlling a plunger with said relay.

3. An automatic tape feed controlling means comprising means for detecting the prescribed position of a running tape and generating an electric signal as the output of the detection, means for differentiating said electric signal, means for rectifying the output of the difierentiating means, a single stablized multivibrator having the output of the rectifying means as a trigger signal, and means for controlling a tape feeding mechanism according to a signal based on the output of said multi-vibrator.

4. An automatic tape feed controlling means adapted to be used in a tape magazine type deck comprising a light source, a photoresponsive element to receive the light from said light source, said light source and photoresponsive element being fixed on said deck and at least one of which is located at such a position as to be inserted into said magazine through a cut away provided thereon when the magazine is loaded in the deck, said light source and photoresponsive element being located at the position in the opposite side of the tape in the magazine, means for differentiating an electric signal generated from said photoresponsive element when a transparent portion of the tape passes between said light source and said photoresponsive element, and means for controlling the tape feeding means by a signal based on a rectified component of the differentiated signal.

Claims

2. An automatic tape feed controlling means comprising means for detecting the prescribed position of a running tape and generating an electric signal as the output of the detection, means for differentiating said electric signal, an impedance converter having a high input impedance and low output impedance having the differentiated output of the differentiating means as an input signal, a pulse amplifier having the output signal of said impedance converter as an input signal, and a relay driven by the output of said amplifier, whereby the tape feeding mechanism is controlled by controlling a plunger with said relay.

3. An automatic tape feed controlling means comprising means for detecting the prescribed position of a running tape and generating an electric signal as the output of the detection, means for differentiating said electric signal, means for rectifying the output of the differentiating means, a single stablized multivibrator having the output of the rectifying means as a trigger signal, and means for controlling a tape feeding mechanism according to a signal based on the output of said multi-vibrator.