Abstract:
An apparatus for recording and reproducing video signals on a recording medium includes a mechanism for transporting the recording medium with respect to recording and reproducing elements of the apparatus. A control arrangement operates to control the speed of movement of the transport mechanism in response to a supply of electrical power, and selecting circuitry is arranged to select a particular electrical power source to supply the electrical power to the control arrangement.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention: 
     This invention relates to video signal recording and reproducing apparatus capable of permitting recordings out of doors and capable of variable speed reproduction. 
     2. Description of the Prior Art: 
     The present invention may be embodied in the following example of a conventional magnetic recording and reproducing apparatus using magnetic tape as the recording medium (hereinafter referred to as &#34;VTR&#34;). 
     The conventional VTR operates in such a manner that a magnetic tape is brought into contact against a cylindrical tape guide including a magnetic head over a predetermined angular distance, and, while video signals are being recorded on said tape for every one field or two fields in one of the successively formed inclined tracks, the tape is transported at a constant speed when the aforesaid video signals are being recorded or reproduced. 
     When reproducing the thus-recorded video signals on the magnetic tape, the tape may be transported at a different speed from that at which the recording was made, thereby slow motion, high speed reproduction and other speed-changed reproductions are made possible. The aforesaid high speed reproduction is advantageous for skipping an identified portion of the recorded tape, or searching. 
     When in normal recording or reproducing operation, it is customary in the conventional VTR or tape recorder that a pinch roller and a capstan contact across the magnetic tape, and the aforesaid capstan is driven to rotate by an electric motor or other suitable drive source, thus running the tape. 
     Also for high speed reproduction in addition to the normal speed, there are known two methods of transporting the tape at high speed. One method is that after the tape is taken out of contact with the pinch roller and capstan, the reel-driving rotors are caused to rotate at a high speed, or the so-called &#34;fast&#34; feed or &#34;fast&#34; rewind mode is set on the VTR to carry out high speed reproduction. The other method is that the capstan is caused to rotate at a higher speed than when in the normal recording or reproducing mode. 
     The former method, owing to the fact that the running speeds of the tape when in the fast feed and fast rewind modes are generally considerably higher than when in the recording mode, is relatively easy to realize for high speed reproduction. However, it has a disadvantage in that as the diameter of the wound tape changes, the running speed of the tape changes correspondingly. 
     The latter method, because the tape speed depends upon the number of revolutions of the capstan motor, does provide for a small change in the running speed. However, since the number of revolutions of the capstan motor depends upon the drive voltage, and because, in the case of a portable type VTR utilizing a battery, the availability of the electrical power source is limited, it has been found that in actual practice high speed reproduction cannot be carried out at greatly increased speeds. 
     SUMMARY OF THE INVENTION 
     The present invention has been made to eliminate the above-described drawbacks and, if embodied in a VTR, will provide a type of VTR in which, when in a reproducing mode, the tape speed is selectively controlled by obtaining at least two voltages. The capstan motor is arranged to operate, when in the reproducing mode, with either the same voltage as in the recording mode, with the tape transport moving at the same speed as in recording, or with a higher voltage than the aforesaid voltage to move the tape transport at a higher speed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of an embodiment of a VTR according to the present invention, connected to a video camera. 
     FIG. 2 illustrates the details of internal construction of the VTR. 
     FIG. 3 illustrates the VTR in a reproducing position where an AC adapter and a television set are employed. 
     FIG. 4 is an electrical circuit diagram, partly in block form, of an embodiment of the VTR according to the present invention. 
     FIG. 5 illustrates another embodiment of the VTR according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In FIG. 1 there is shown a VTR according to an embodiment of the invention as connected with a video camera. The drawing shows the video camera 1, the VTR 2, and video battery 3 used as an electrical power source for the video camera and VTR. A cable 4 transmits video signals and electrical energy between the video camera 1 and the VTR 2 when recording is carried out. 
     FIG. 2 illustrates the internal construction of the VTR 2 where a magnetic tape T pulled out of a cassette 5 passes through a full width eraser head 6, a cylindrical tape guide 7 including a rotary magnetic head, and a control and sound recording and reproducing head 8 to be held across a pinch roller 9 and a capstan 10, and therefrom advanced to a takeup reel 11 within the cassette 5. A supply reel 16 is contained in the same cassette 5. The capstan 10 has a fly wheel 12 concentrically fixed thereto, said fly wheel 12 being rotatably connected to a pulley 14 fixed to a shaft of the capstan motor 13 by an endless belt 15. 
     In FIG. 3, there is shown the VTR 2 of the invention as connected to an AC adapter 26 in a reproducing position, where a television set 17 is connected to an RF converter output terminal of the VTR 2. 
     FIG. 4 is a block diagram illustrating an embodiment of the VTR according to the present invention. A DC source circuit 22 comprises a rectifier circuit receptive of a home alternating current source for producing DC current, and a constant voltage circuit for driving the VTR. Power terminals 23 and 24 are on the AC adapter 26 with the terminal 24 supplying a voltage almost equal to the voltage of the battery 3, and the terminal 23 supplying a higher voltage than that appearing at the terminal 24. FIG. 4 also shows a power source changeover switch 21; a constant voltage circuit 19; a capstan motor control circuit 18 for sensing and controlling the number of revolutions of the capstan motor 13; a capstan motor drive circuit 25 for driving the capstan motor 13; a mode changeover switch 20 having positions at which the motor 13 rotates at normal and high speeds for the normal reproduction modes and the high speed reproduction or high speed search mode, respectively. 
     The operation of this embodiment is next explained by reference to the drawings. When in recording, as illustrated in FIG. 1, the camera 1 and the VTR 2 are coupled with each other whereby the battery 3 serves as the power source for the capstan motor 13 of FIG. 2. This VTR 2 may be otherwise of a unified form incorporating the camera 1 therein, and the battery 3 may be otherwise located in the VTR 2. 
     In FIG. 4, the electrical power supplied from the battery 3 is applied through the switch 21 in its &#34;a&#34; position to the constant voltage circuit 19 and therefrom through an electrical power supply line A to a signal processing circuit (not shown) and the capstan motor control circuit 18, and further therefrom through the changeover switch 20 in its &#34;a&#34; position to the capstan motor drive circuit 25. The capstan motor control circuit 18 operates in such a manner that the speed of rotation of the capstan motor 13 is adjusted to a predetermined level as sensed. The capstan motor control circuit 18 forms a closed loop together with the capstan motor drive circuit 25 and the capstan motor 13 so that fine adjustment of the aforesaid speed of rotation is controlled. 
     When the thus recorded magnetic tape is to be reproduced, a unit including the DC source, for example, an AC adapter, tuner or the like is coupled to the VTR, and the switch 21 is moved to its &#34;b&#34; position where the DC electrical power source circuit 22 serves as the electrical power source for the VTR. 
     It is of course possible that even when in recording, if there is no need to use the battery 3, for example, when indoor shooting, or recording of television signals is made, instead of using the battery, the DC electrical power source circuit 22 can be used as the electrical power source. 
     When in the normal reproduction, the electrical power source changeover switch 21 is moved to its &#34;b&#34; position and the mode changeover switch 20 is left unchanged from &#34;a&#34; position, thus energizing the motor 13. As illustrated in FIG. 2, while the control signals recorded in the vicinity of the edge of the tape T are being reproduced by the control head 8, the video signal tracks which are slant recorded on the magnetic tape T in sequence, are traced to be reproduced by the rotary head incorporated in the cylindrical tape guide 7. At this time, the capstan motor 13 is driven by the same voltage as in the normal recording, and its speed is controlled in the above-described manner. 
     Further, when high speed searching is desired, setting of the high speed search mode causes the switch 20 to be moved to &#34;b&#34; position where the high voltage for the high speed search is supplied from the terminal 23 of the AC adapter 26 so that the capstan 10 rotates at the higher speed than when in the normal reproduction mode, thus permitting high speed reproduction. 
     FIG. 5 illustrates another embodiment of the VTR according to the present invention where the same reference characters have been employed to denote similar parts to those shown in FIG. 4. A relay 27 is responsive to flow of current for setting a switch 21&#39; in &#34;b&#34; position, and responsive to no flow of current will set the switch 21&#39; in &#34;a&#34; position. 
     According to the construction of this embodiment, upon connection of an AC adapter 26 or other suitable external electrical power source, the relay 27 is supplied with current, thereby the switch 21&#39; is automatically changed over to &#34;b&#34; position to render the VTR cooperative with the external electrical power source. 
     As has been described above, according to the present invention, the range of selectively controllable tape speeds when in the reproduction mode can be extended remarkably by the use of means of very simple construction, and further the use of an external electrical power source makes it possible to increase the tape speed for the high speed reproduction by the capstan drive. Moreover, with the limitation of the occurrences of using the battery to outdoor recordings, premature consumption of electrical energy of the battery can be prevented. Since this can be achieved by providing a changeover switch of simple structure, it does not involve an increase of the circuit volume in the VTR. Thus, the present invention has a great advantage at the portable VTR.