Abstract:
A multifunctional control device and method is used to determine a head channel selecting signal for playback heads of a video tape recorder and for controlling a phase shift direction of a video signal according to a desired reproduction mode. The video tape recorder has four heads, a first pair for use during standard play and a second pair for use during super long play. The heads read out recorded video signals and a first switch is connected to the first pair of heads and a second switch is connected to the second pair of heads for selectively providing outputs to corresponding amplifiers, under control of a servo controller. A third switch is connected to the outputs of the amplifiers for providing outputs under control of a microcomputer. The microcomputer controls the servo controller which in turn controls the speed of a drum motor and a capstan motor. The microcomputer also provides a phase shift direction controlling signal. An output of the servo controller is provided to the microcomputer along with an output of a comparator comparing the outputs of the amplifiers.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a multifunctional video tape recorder and particularly to a multifunctional control type video head selecting device and a method thereof, in which a required head can be selected during a special reproducing, and the phase shift direction of the reproduced video signal can be automatically controlled in accordance with the head thus selected. 
     BACKGROUND OF THE INVENTION 
     Generally, a multifunctional video tape recorder has not only a normal function for reproducing tapes in a normal manner, but also has special functions such as still picture reproducing, slow picture reproducing, high speed reproducing, double speed reproducing and the like. In order to perform the above-mentioned functions, the multifunctional video tape recorder is provided with two pairs of heads which are different in their head widths in the double-azimuth head type. Of the two pairs of heads, one pair are used in a standard play i.e., SP, mode while the other pair are used in a super long play i.e., SLP, mode. 
     Therefore, in a multifunctional video tape recorder, the reproducing head should be selected in accordance with the designation of the user, and the phase shift direction of the video signal reproduced in accordance with the head thus selected has to be controlled. The controlling of the phase shift direction of the video signal shifted occurs in the video signal reproducing processor unit. In a VHS-type video tape recorder, the phase of the video signal is advanced by 90° for every horizontal line for a given track and conversely, the phase is delayed by 90° for every horizontal line for the adjacent track to the given track, so that a crosstalk component of the reproduced video signal will be removed. The conventional circuit for head selecting and phase shift direction controlling is constituted as shown in FIG. 1, and this circuit will be described as to its operation below. 
     A microcomputer 100 generates function control data for the reproducing function designated by the user, and this data is supplied to both a servo controller 104 and a multifunctional controller 105. The servo controller 104 controls the speeds of a drum motor M1 and a capstan motor M2 through lines 2 and 3 respectively, by means of the function controlling data which is supplied from the microcomputer 100 through a bus line 1, while the servo controller 104 also controls switching operations of first and second switches SW1, SW2 through a line 4, and sends a head channel selection signal to a multifunctional controller 105. 
     The multifunctional controller 105 outputs an amplifier selecting signal through a line 6 in accordance with a function control data supplied through bus line 1, the head channel selecting signal supplied through line 4, and a comparing signal supplied through a line 5 from a comparator 103, while the multifunctional controller 105 also outputs a phase shift direction controlling signal through a line 7. Then the switching operation of third switch SW3 is controlled in accordance with the amplifier selecting signal. 
     First the normal reproducing function will be described. The normal reproducing function can be described based on a classification into the standard play mode and the super long play mode, and special reproducing can also be described based on a classification into the standard play mode and the super long play mode. 
     First in the case of the standard play mode in the normal reproducing function, the first switch SW1 alternately supplies to a first amplifier 101 video signals read out by first and second heads SP1, SP2 in response to the head channel selecting signal. The first amplifier 101 which receives the video signals through the first switch SW1 amplifies the video signals at a constant amplifying rate, and supplies them to the third switch SW3, while the third switch SW3 outputs the output signals of the first amplifier 101 through a line 8 in accordance with the amplifier selecting signal. 
     Meanwhile, the phase shift direction controlling signal is generated in response to the azimuth angle of the selected head according to the first and second heads SP1, SP2 which are alternately selected. Thus, if the first head SP1 having an azimuth angle of +6° is selected, the phase shift direction controlling signal is generated as a high logic state while, if the second head SP2 having an azimuth angle of -6° is selected, the phase shift direction controlling signal is generated as a low logic state. 
     Second, in the case of the super long play mode in the normal reproducing function, the second switch SW2 supplies to a second amplifier 102 the video signals read out alternately by third and fourth heads SLP1, SLP2. The second amplifier 102 amplifies the video signals incoming through the second switch SW2 at a constant amplifying rate to output them to the third switch SW3, while the third switch SW3 transmits the output signals of the second amplifier 102 through a line 8 in response to the amplifier selecting signal. Then each time the third and fourth heads SLP1, SLP2 are selected, the phase direction controlling signal is generated in response to the azimuth angle of the selected head. Thus, if the third head SLP1 having an azimuth angle of +6° is selected, the phase shift direction controlling signal is generated as a high state while, if the fourth head SLP2 having an azimuth angle of -6° is selected, the phase shift direction controlling signal is generated as a low state. Further, in the case of multifunctional reproducing functions, i.e., in the case of the special functions, the tape runs at a speed different from that of the normal reproducing function and therefore, correct readings can not be made from the tape. 
     Within a single time interval between the change-overs of the head channels, a plurality of video tracks will pass, and therefore, the first to fourth heads SP1, SP2, SLP1, SLP2 will move simultaneously or separately. Therefore, the heads can be selected in synchronization with the comparing signal which is the output of the comparator 103, or the heads can be selected in synchronization with the head channel selecting signal for reading out the video signals from a proper head within a single time interval. In the case of multifunctional reproducing functions, the selections of the heads are made as specified in Table 1--1 below, while the wave patterns of the amplifier selection signals and the phase shift direction controlling signals are shown in FIG. 2. Meanwhile, the heads and amplifiers selected in accordance with the head channel selecting signal and the amplifier selecting signal, and the phase shift direction controlling signal generated in accordance with them, are as shown in Table 1-2 below. 
     
                       TABLE 1-1______________________________________Function          Video head selected______________________________________Normal reproducing             SP: SP1, SP2             SLP: SLP1, SLP2Still picture reproducing             SP: SP2, SLP2             SLP: SP1, SLP1Slow picture reproducing             SP: SP2, SLP2, SP1             SLP: SLP1, SP1, SLP2Double speed reproducing             SP: SP2, SLP2             SLP: SP1, SLP1High speed reproducing             SP: SP1, SP2, SLP1, SLP2             SLP: SLP1, SLP2______________________________________ 
    
     
                       TABLE 1-2______________________________________     OperatingItem      voltage    Selection Remarks______________________________________Head channel     SP:     H      SP2     SP1: +6°selecting         L      SP1     SP2: -6°signal     SLP:    H      SLP1    SLP1: +6°             L      SLP2    SLP2: -6°AMP selecting     H      AMP1    AMP1: SP headsignal            L      AMP2    AMP2: SLP headPhase shift       H      +6°direction         L      -6°controllingsignal______________________________________ 
    
     As described above, the conventional circuit for generating the head channel selecting signal and the phase shift direction controlling signal is very complicated because it selects the amplifiers and generates the phase shift direction controlling signal through a multifunctional controller 105. 
     SUMMARY OF THE INVENTION 
     Therefore, it is a first objective of the present invention to provide a multifunctional control type video head selecting device which is software controlled and used to determine a head channel selecting signal for selecting heads and automatically controlling the phase shift direction controlling signal of the video signal produced in a multifunctional video tape recorder having four heads adopting a double azimuth head type, thereby simplifying a circuit for the multifunctional control type video head selecting device. 
     It is a second object of the present invention to provide a multifunctional control type video head selecting method. 
     In achieving the first object, the device of the present invention comprises: 
     first and second heads for standard plays and for reading out video signals recorded on the tape; third and fourth heads for super long plays and for reading out video signals recorded on the tape; a first switch for selectively outputting the outputs of the first and second heads; a second switch for selectively transmitting the outputs of the third and fourth heads; a third switch connected to the output terminals of the first and second switches, and for outputting through a line the outputs of the first and second switches; a servo controller for generating head channel selecting signal in order to control the switching operations of the first and second switches and to control a drum motor and a capstan motor; a comparator for comparing the outputs of the first and second switches; and a microcomputer for generating control signals in order to control the servo controller, for generating amplifier selecting signals in order to control the switching operations of the third switch in accordance with the head channel selecting signal, i.e., the output of the servo controller, and a comparing signal, i.e., the output of the comparator, and for generating phase shift direction controlling signal in order to control the phase shift direction of the video signal reproduced in response to the azimuth angle of the selected head. 
     In achieving the second object, the method of the present invention comprises: 
     a first step of checking the key data which is inputted by means of a key to make an indication as to whether the reproducing function designated by the user is a normal reproducing function, a still picture reproducing function, a double speed reproducing function, a slow picture reproducing function, or a high speed reproducing function, each time the head channel selecting signal is inputted; 
     a second step for making a judgment on whether the running mode is a standard play mode or not, after checking the running speed of the tape, in the case where a normal reproducing function is detected in the first step; 
     a third step for making a judgment as to whether a standard play mode is being run, after checking the running speed of the tape, in the case where a still picture reproducing function or a double speed reproducing function is detected in the first step above; 
     a fourth step for making a judgement as to whether a standard play mode is being run, after checking the running speed of the tape upon inputting of a comparing signal, in the case where a high speed reproducing function is detected in the first step; 
     a fifth step for making a judgment as to whether a standard play mode is being run, after checking the running speed of the tape, in the case where a slow picture reproducing function is detected in the first step; 
     a sixth step for making a judgment as to whether a tape running state is encountered, in the case where a standard play mode is detected in the fifth step; 
     a seventh step for making a judgment as to whether a tape running state is encountered, in the case where a standard play mode is not detected in the fifth step; 
     an eighth step for selecting the first amplifier, and for generating a phase shift direction controlling signal having a phase opposite to that of the head channel selecting signal, in the case where a standard play mode is detected in the second step; 
     a ninth step for selecting the second amplifier, and for generating a phase shift direction controlling signal having the same phase as that of the head channel selecting signal, in the case where a standard play mode is not detected in the second step; 
     a tenth step for alternately selecting the first and second amplifiers in such a manner that the amplifier selecting signal should have the same phase as that of the head channel selecting signal, and for generating a phase shift direction controlling signal having a ground logic state, in the case where either a standard play mode is encountered in the third step or a tape running state is not encountered in the seventh step; 
     an eleventh step for alternately selecting the first and second amplifiers in such a manner that the amplifier selecting signal should have a phase opposite to that of head channel selecting signal, and for generating a phase shift direction controlling signal having a high logic state in the case where either a standard play mode is not encountered in the third step, or a tape running state is not encountered in the sixth step; 
     a twelfth step for alternately selecting the first and second amplifiers in such a manner that the amplifier selecting signal should have the same phase as that of the comparing signal, for generating a phase shift direction controlling signal having a phase opposite to that of the comparing signal if the head channel selecting signal has a logic state of a high logic level, and for generating a phase shift direction controlling signal having the same phase as that of the comparing signal if the head channel selecting signal has a ground logic state, in the case where a standard play mode is encountered in the fourth step, or a tape running state is encountered in the sixth step; and 
     a thirteenth step for selecting the second amplifier, and for generating a phase shift direction controlling signal having the same phase as that of the head channel selecting signal, in the case where a standard play mode is not encountered in the fourth step or a tape running state is encountered in the sixth step. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above objects and other advantages of the present invention will become more apparent by describing the preferred embodiment of the present invention in more detail with reference to the attached drawings in which: 
     FIG. 1 illustrates the conventional circuit; 
     FIG. 2 illustrates the operating wave patterns of different modes for the circuit of FIG. 1; 
     FIG. 3 illustrates the circuit of the multifunctional control type video head selecting device according to the present invention; and 
     FIG. 4 illustrates the flow chart for the multifunctional control type video head selecting method according to the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 3 illustrates the circuit of the multifunctional control type video head selecting device according to the present invention, which comprises: first and second heads SP1, SP2, for standard play and for reading the video signals recorded on the tape; a first amplifier 101 for amplifying and outputting the outputs of the first and second heads SP1, SP2; third and fourth heads SLP1, SLP2 for super long plays and for reading the video signals recorded on the tape; a second amplifier 102 for amplifying and outputting the outputs of the third and fourth heads SLP1, SLP2; a first switch SW1 connected between the first and second heads SP1, SP2 and the first amplifier 101, and for selectively outputting the output of the first head SP1 or of the second head SP2 connected between the third and fourth heads SLP1, SLP2 and the second amplifier 102, and for transferring selectively the output of the third head SLP1 or of the fourth head SLP2 to the second amplifier 102; a third switch SW3 connected to the output terminals of the first and second amplifiers 101, 102, and for selectively outputting the output of the first amplifier 101 or of the second amplifier 102 through a line 8; a servo controller 104 for generating head channel selecting signal in order to control a drum motor M1 and a capstan motor M2, and to control the switching operations of the first and second switches SW1, SW2; a comparator 103 comparing the outputs of the first and second amplifiers 101, 102; and a microcomputer 100 for controlling the operations of the servo controller 104 for generating amplifier selecting signals in order to control the switching operations of the third switch SW3 in accordance with the head channel selecting signal, i.e., the output of the servo controller 104, and a comparing signal, i.e., the output of the comparator 103, and for generating phase shift direction controlling signal in order to control the phase shift direction of the video signal reproduced in response to the azimuth angle of the selected head. 
     FIG. 4 illustrates the flow chart of the multifunctional control type video head selecting method according to the present invention, which comprises: 
     a first step of checking the key data which is inputted by means of a key to make an indication as to whether the reproducing function designated by the user is a normal reproducing function, a still picture reproducing function, a double speed reproducing function, a slow picture reproducing function or a high speed reproducing function, each time the head channel selecting signal is inputted; 
     a second step for making a judgment as to whether a standard play mode is being run, after checking the running speed of the tape, in the case where a normal reproducing function is detected in the first step; 
     a third step for making a judgment as to whether a standard play mode is being run, after checking the running speed of the tape, in the case where a still picture reproducing mode or a double speed reproducing mode is detected in the first step; 
     a fourth step for making a judgment as to whether a standard play mode is being run, after checking the running speed of the tape upon inputting of a comparing signal, in the case where a high speed reproducing function is detected in the first step; 
     a fifth step for making a judgment as to whether a standard play mode is being run, after checking the running speed of the tape, in the case where a slow picture reproducing function is detected in the first step; 
     a sixth step for making a judgment as to whether a tape running state is encountered, in the case where a standard play mode is detected in the fifth step; 
     a seventh step for making a judgment as to whether a tape running state is encountered, in the case where a standard play mode is not detected in the fifth step; 
     an eighth step for selecting the first amplifier 101, and for generating a phase shift direction controlling signal having a phase opposite to that of the head channel selecting signal, in the case where a standard play mode is detected in the second step; 
     a ninth step for selecting the second amplifier 102, and for generating a phase shift direction controlling signal having the same phase as that of the head channel selecting signal, in the case where a standard play mode is not detected in the second step; 
     a tenth step for alternately selecting the first and second amplifiers 101, 102 in such a manner that the amplifier selecting signal should have the same phase as that of the head channel selecting signal, and for generating a phase shift direction controlling signal having a low logic state, in the case where either a standard play mode is detected in the third step or a tape running state is not detected in the seventh step; 
     an eleventh step for alternately selecting the first and second amplifiers 101, 102 in such a manner that the amplifier selecting signal should have a phase opposite to that of the head channel selecting signal, and for generating a phase direction controlling signal having a logic state in the case where either a standard play mode is not detected in the third step, or a tape running state is not detected in the seventh step; 
     a twelfth step for alternately selecting the first and second amplifiers 101, 102 in such a manner that the amplifier selecting signal should have the same phase as that of the comparing signal, for generating a phase shift direction controlling signal having a phase opposite to that of the comparing signal if the head channel selecting signal has a logic state of a high level, and for generating a phase shift direction controlling signal having the same phase as that of the comparing signal if the head channel selecting signal has a logic state of a certain level, and for generating a phase shift direction controlling signal having the same phase as that of the comparing signal if the head channel selecting signal has a ground logic state, in the case where either a standard play mode is detected in the fourth step, or a tape running state is detected in the sixth step; and 
     a thirteenth step for selecting the second amplifier 102, and for generating a phase shift direction controlling signal having the same phase as that of the head channel selecting signal, in the case where either a standard play mode is not detected in the fourth step or a tape running state is detected in the seventh step. 
     The present invention constituted as above will be described in more detail referring to FIGS. 3 and 4. 
     Referring to FIG. 3, the first switch SW1 performs switching operations in accordance with the logic state of the head channel selecting signal applied through line 4 and therefore, the first switch SW1 will send either the output of the first head SP1 to the first amplifier 101, or the output of the first head SP2 to the first amplifier 101. 
     The second switch SW2 also performs switching operations in accordance with the logic state of the head channel selecting signal supplied through the line 4, and therefore, the second switch will send either the output of the third head SLP1 to the second amplifier 102 or the output of the fourth head SLP2 to the second amplifier 102. 
     The third switch SW3 performs switching operations in accordance with the logic state of the amplifier selecting signal, and therefore, the third switch SW3 will send either the output of the first amplifier 101 through line 8 or the output of the second amplifier 102 through line 8. 
     The comparator 103 compares the outputs of the first and second amplifiers 101, 102, and outputs the compared signals through a line 5 to the microcomputer 100. 
     The servo controller 104 controls the drum motor M1 and the capstan motor M2 through lines 2, 3 and outputs the head channel selecting signal through the line 4 to both the first and second switches SW1, SW2 and the microcomputer 100. 
     The servo controller 104 controls the drum motor M1 and the capstan motor M2 through lines 2, 3, and outputs the head channel selecting signal through the line 4 to both the first and second switch SW1, SW2 and the microcomputer 100. 
     Then, the microcomputer 100 controls the operations of the servo controller 104 and at the same time, generates an amplifier selecting signal after receipt of: a head channel selecting signal through the line 4 from the servo controller 104; a comparing signal through the line 5 form the comparator 103; and a reproducing function signal designated by the user, the amplifier selecting signal being supplied through a line 6 to the third switch SW3. As a result, the third switch SW3 will select an amplifier, and the phase shift direction controlling signal will be outputted through a line 7. 
     FIG. 4 illustrates the flow chart of a part of the present invention which is performed by microcomputer 100 of FIG. 3. Here, the microcomputer 100 inputs a head channel selecting signal, H&#39;D SW in FIG. 4, from a block 200 through the line 4 to the servo controller 104 while, at blocks 201 to 205, the microcomputer 100 checks user inputted key data in order to make a judgment as to whether the data designates a normal reproducing function, a still picture reproducing function, a high speed picture reproducing function, a slow picture reproducing function, or a double speed reproducing function. 
     If it is found that a normal reproducing function is designated through the blocks 201-205, the microcomputer 100 will check the running speed of the tape through the servo controller 104, and will also check whether a standard play mode is running in block 206. 
     If a standard play mode is detected in block 206, the microcomputer 100 will generate an amplifier selecting signal, AMP SW in FIG. 4, of a high level, with the result that the first amplifier 101 will be selected, and that the first and second heads SP1, SP2 will be selected. The phase shift direction controlling signal, ROTARY in FIG. 4, will have a phase opposite to that of the head channel selecting signal in order to control the phase shift direction of the video signal reproduced in response to the azimuth angle of the selected head. That is, if the head channel selecting signal is at a low state, the first head SP1 having a gap angle of +6° is selected, thereby the phase shift direction controlling signal will be generated as a high state. On the other hand, if the head channel selecting signal is at a high state, the second head SP2 having a gap angle of -6° is selected, thereby the phase shift direction controlling signal will be generated as a low state. Therefore, the phase shift direction controlling signal should be at an opposite state relative to that of the head channel selecting signal in block 207. 
     If a standard play mode is not encountered at block 206, the microcomputer 100 will generate an amplifier selecting signal having a low state to select the second amplifier 102, and the phase shift direction controlling signal and the head channel selecting signal will be in phase. That is, if the head channel selecting signal is at a high state, third head SLP1 having the gap angle of +6° is selected, thereby the phase shift direction controlling signal will also be at a high state. On the other hand, if the head channel selecting signal is at a low state, fourth head SLP2 having the gap angle of -6° is selected, thereby the phase shift direction controlling signal should be also at a low state in block 208. 
     If a still picture reproducing function or a double speed reproducing function is encountered at blocks 203,204, the microcomputer 100 will check the running speed of the tape through the servo controller 104 to ultimately make a judgment as to whether a standard play mode is being run in blocks 209 and 215. 
     If a standard play mode is encountered in block 209, the microcomputer 100 will make such an arrangement that the amplifier selecting signal and the head channel selecting signal will be in phase. That is, if the head channel selecting signal is at a high level, then the second head SP2 and the third head SLP1 will be activated, and further, if the amplifier selecting signal is at a high state, then the second head SP2 will be selected. Further, if the head channel selecting signal is at a low state, and if the amplifier selecting signal is also at a low state, then the fourth head SLP2 will be activated. Accordingly, under the above-mentioned condition, the second and fourth heads SP2, SLP2 having the gap angle of -6° will be selected, thereby the phase shift direction controlling signal will have a low state in block 211. 
     If a standard play mode is not detected in block 209, the microcomputer 100 will assume that a super long play mode is being run, and will generate an amplifier selecting signal having a phase opposite to that of the head channel selecting signal. Therefore, the first and third heads SP1, SLP1 having the gap angle of +6° will be selected, and the phase shift direction controlling signal will be at a high state in block 210. 
     If a high speed reproducing function is detected in block 205, the microcomputer 100 will receive a comparing signal, ENV DET in FIG. 4, through line 5 from the comparator 103 in block 212 and then, will check the running speed of the tape through the servo controller 104 to make a judgment whether a standard play mode is being run in block 213. 
     If a standard play mode is detected in block 213, the microcomputer 100 will generate an amplifier selecting signal and a phase shift direction controlling signal in accordance with the comparing signal, in such a manner that, if the comparing signal has a high state, the standard play heads SP1, SP2 will be activated, and if the comparing signal has a low state, the super long play heads will be activated. The amplifier selecting signal will have the same phase as that of the comparing signal. 
     The phase shift direction controlling signal have to control the phase shift direction of the video signal reproduced in response to the azimuth angle of the head selected, therefore, they are operated in accordance with the comparing signal and the head channel selecting signal. That is, if the head channel selecting signal is at a high level, the phase shift direction controlling signal will have a phase opposite to that of the comparing signal while, if the head channel selecting signal is at a low state, then the phase shift direction controlling signal will have a same phase as that of the comparing signal in block 214. 
     If a standard play mode is not detected at block 213, the microcomputer will assume that a super long play mode is being run, and will generate an amplifier selecting signal and a phase shift direction controlling signal in block 218, in the same manner as in block 208. 
     If a slow picture reproducing function is designated at block 204, the microcomputer 100 will check the running speed of the tape to make a judgment whether a standard play mode is being run in block 215. 
     If a standard play mode is detected at block 215, the microcomputer 100 will check through the servo controller 104 to see whether the tape is in a running state or in a stationary state in block 216. 
     The slow picture reproducing function includes alternate repetitions of the still picture reproducing function and the normal reproducing function, and therefore, when the tape is stationary, the second and fourth heads SP2, SLP2 will be selected while, when the tape is running, the first and second heads SP1, SP2 will be selected. 
     If it is detected that the tape is running at block 216, the microcomputer 100 will carry out block 214. If it is detected that the tape is not running at block 216, the microcomputer 100 will assume that the tape is stationary, and will carry out block 210. 
     If a standard play mode is not detected at block 215, the microcomputer 100 will assume that an super long play mode is being run, and will direct the servo controller 104 to check whether the tape is stationary or running in block 217. 
     If the tape is running at block 217, the microcomputer 100 will carry out block 218. 
     If the tape is stationary at block 217, the microcomputer 100 will carry out block 211. 
     As described above, the device of the present invention does not carry out the selection of the heads and the controlling of the phase shift direction of the video signal reproduced by hardware means as in the conventional device, but carries out the various functions by software means resulting in the advantages of achieving a simplified circuit by removing complicated hardware circuitry and saving manufacturing costs. Also, during a slow picture reproducing mode, the noise from head selection can be prevented because the slow picture reproducing mode is carried out in the same manner as a high speed reproducing mode during the tape running interval.