Abstract:
A recording and reproducing apparatus includes a memory unit for memorizing information to identify a recording block that was recorded immediately before, and a control unit for referring to the memory unit (upon switching from a recording mode to a reproducing mode) to reproduce a signal from the recording block that was recorded immediately before.

Description:
This application is a continuation of application Ser. No. 07/552,807 filed Jul. 16, 1990, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a recording or reproducing apparatus for an image recording medium. 
     2. Description of the Related Art 
     A format for recording an image signal of a field on each of 50 concentric tracks formed on a magnetic disk has been agreed on by the Still Video Committee, and the agreed upon format is commonly used as the image recording medium for electronic still cameras or the like. 
     In electronic still cameras, in order to avoid double recording of the image signal, the recorded/unrecorded states of the tracks of the magnetic disk are searched in advance, and the result of the search is stored as a table in an internal memory and is referred to at the subsequent recording or reproduction. Also, in order to enable immediate recording of the image on the magnetic disk, at the start of power supply or at the loading of the magnetic disk, the presence or absence of a RF reproduction signal is detected in succession from the innermost 50th track toward the outer tracks, and the magnetic head waits on a track immediately inside the first recorded track found. 
     In the still video floppy disk, the empty tracks may be present in a scattered manner, because the recorded image may have been erased. Consequently, empty tracks may be present outside the empty track on which the magnetic head was positioned by the search operation at the loading of the magnetic disk. Conventionally, in the table indicating the recorded/unrecorded state of each track (hereinafter called track table), each track is given a 2-bit flag, which is set as “11” for a confirmed recorded track, “01” for a confirmed unrecorded track, or “00” for an unconfirmed track. 
     Thus, at the loading of the magnetic disk or immediately after the start of power supply, the flags of said track table are initialized to “00”. In the initial positioning operation of the magnetic head, the first recorded track found in the search from the inside is given a flag “11”, while the inner tracks are given flags “01”, and the outer tracks are given “00” because they have not yet been searched. 
     In the interval reproduction mode in which the recorded tracks only are reproduced in succession at a predetermined interval, access is not made to the tracks having a flag “01” in the track table, but is made to the tracks having “00” to check the recorded/unrecorded state by the RF reproduction signal. If the track is recorded, the recorded signal is reproduced and the corresponding flag is changed to “11”. If the track is unrecorded, reproduction is not conducted and the flag is changed to “01”. The recorded tracks are reproduced in succession in this manner by checking of the recorded/unrecorded state. 
     However, in such a conventional structure using 2 bits for each track, a memory area as large as 100 bits is required for 50 tracks. Such a memory area is often formed in a RAM integrated in a one-chip microcomputer, but such track information should preferably be as small as possible, because the entire memory capacity is limited. 
     Also in a electronic still camera with a conventional reproducing function, the outer-most track of the still video floppy disk is reproduced automatically when the operating mode is switched from recording to reproduction. 
     In such a structure, however, in case of observing the recorded image immediately after the image has been recorded on the floppy disk in the recording mode, cumbersome operations are required including first switching the recording mode to the reproduction mode thereby setting the magnetic head on the first track, and then returning the magnetic head to the track recorded immediately before by means of manual manipulation of up- and down-switches. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a recording or reproducing apparatus capable of individually or entirely resolving the above-mentioned drawbacks. 
     Another object of the present invention is to provide a reproducing apparatus capable of controlling the recording areas on the recording medium with a reduced memory capacity. 
     The foregoing objects can be attained, according to a preferred embodiment of the present invention, by a reproducing apparatus for a recording medium having plural areas for signal recording, comprising detection means for detecting the recorded/unrecorded state of each of the plural areas; first memory means having a memory area for memorizing a recorded or unrecorded state of each of the plural areas; and second memory means for memorizing the result of confirmation of the recorded/unrecorded state by the detection means, the information indicating the range of areas memorized in the first memory means, whereby the first memory means is not required to store the information indicating that the recorded/unrecorded state is not yet confirmed and can therefore be reduced in the memory capacity. 
     Still another object of the present invention is to provide a record reproducing apparatus capable of rapidly reproducing serially recorded images. 
     Still another object of the present invention is to provide a reproducing apparatus capable of reproducing an image recorded immediately before by means of a simple operation. 
     Still another object of the present invention is to provide a recording or reproducing apparatus having novel functions. 
     Still other objects of the present invention and the advantages thereof will become fully apparent from the following description of the preferred embodiments, to be taken in conjunction with the attached drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram of an embodiment of the present invention; 
     FIGS. 2,  2 A and  2 B are a flow charts of an initializing sequence; 
     FIG. 3 is a memory map of a track information table in an embodiment of the present invention; 
     FIGS. 4,  4 A,  4 B are flow charts of a recording sequence; 
     FIG. 5 is a flow chart of a trackup-shift control sequence; 
     FIGS. 6,  6 A,  6 B are flow charts of a reproducing sequence; 
     FIG. 7 is a flow chart of a track down-shift control sequence; 
     FIGS. 8,  8 A,  8 B are flow charts of an interval reproduction sequence; and 
     FIGS. 9,  9 A,  9 B are flow charts showing a variation of the sequence shown in FIG.  6 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Now the present invention will be clarified in detail by preferred embodiments thereof shown in the attached drawings. 
     FIG. 1 is a block diagram of an embodiment of the present invention, applied to an electronic still camera. There are shown a magnetic disk  10  having 50 tracks numbered from 1 to 50 from the outside; a record/reproducing magnetic head  12 ; a motor  14  for rotating the magnetic disk  10 ; a servo circuit  16  for maintaining the revolution of the motor  14  at a predetermined value; a head moving mechanism  18  for moving the magnetic head  12  in the radial direction of the magnetic disk  10  to a designated track position; a stepping motor  20  for powering the head moving mechanism  18 ; an innermost track detection switch  22  to be closed when the magnetic head  12  is positioned on the innermost track; and a disk detection switch  24  for detecting the loading of the magnetic disk  10 . 
     There are further provided an image pickup circuit  26  for converting an optical image formed by an optical system  27  into an electrical signal; a recording signal processing circuit  28  for applying signal processing such as gamma correction or frequency modulation to the output signal of the image pickup circuit  26  thereby converting it into a signal suitable for recording on the magnetic disk  10 ; a recording amplifier  30 ; a selector switch  31  having a contact “a” for reproduction, a contact “c” for recording and an unconnected-contact “b”; a reproducing amplifier  32 ; a reproduction signal processing circuit  34  for applying signal processing such as FM demodulation to the output of the reproducing amplifier  32  thereby obtaining an image signal; a muting circuit  36  for muting the output of the processing circuit  34  in response to an external control signal; a detection circuit  38  for envelope detection of the output of the reproducing amplifier  32 ; and a comparator circuit  40  for comparing the output voltage of the detection circuit  38  with a predetermined reference voltage. 
     There are further provided a main control circuit  42  for controlling the above-mentioned various units; a memory  44  for storing various data and variables required for the main control circuit  42 ; a sub-control circuit  46  for monitoring switch inputs to be explained later and effecting bidirectional handshake communication with the main control circuit  42 ; mode setting switches  48 ,  50 ,  52  for respectively setting recording, reproducing or lock mode; a switch  54  for starting interval reproduction; a switch  56  for track downshift; a switch  58  for track upshift; a switch  60  for executing the recording operation; and a switch  62  for instructing the preparation for the recording operation. 
     The mode setting switches  48 ,  50 ,  52  are constructed so that only one thereof can be closed at a time and two thereof cannot be closed at the same time. The sub-control circuit  46  transmits the closing of the switch  54 ,  56  or  58  to the main control circuit  42  at the time of such closing. 
     There are further shown a power supply unit  64 ; an OR gate  66  for controlling a switch  68  in response to a control signal from the sub-control circuit  46  or the main control circuit  42 ; and a memory  70  for storing data required for the sub-control circuit  46 . The sub-control circuit  46 , OR gate  66  and memory  70  are constantly powered by the power supply unit  64 , while the main control unit  42  and other units are powered through the switch  68 , which is closed or opened respectively when the OR gate  66  provides a high (H) or low (L) output. The sub-control circuit  46  shifts a signal  66   b  to the H-level when the loaded state of the magnetic disk  10  is detected in the recording or reproducing mode, when the operating mode is switched from recording to reproduction or from reproduction to recording, when the reproduction mode is set by the mode setting switch  50 , or when the recording switch  60  or the recording preparation switch  62  is closed in the recording mode. At the start of power supply, the main control circuit  42  shifts a signal  66   a  to the H-level for communication with the sub-control circuit  46 , which shifts the signal  66   b  to the H-level during the communication. 
     Now reference is made to FIG. 2 for explaining the sequence at the loading of the magnetic disk  10 . The sub-control circuit  46  is constantly powered by the power supply unit  64 , and detects the loading of the magnetic disk  10  by the disk detecting switch  24 . In response to a detection, the sub-control circuit  46  investigates the state of the mode setting switches  48 ,  50 ,  52 , and, if the locking mode is not set, closes the switch  68  through the OR gate  66 , thereby powering the main control circuit  42  and other circuit units. 
     In response to the start of power supply, the main control circuit  42  connects the switch  31  to the contact b, sets the muting circuit  36  at the muting state, and shifts the signal  66   a  to the H-level. Then the sub-control circuit  46  sends an initialization command to the main control circuit  42  (step S 1 ), and transmits the recording or reproducing mode according to the state of the mode setting switches  48 ,  50 ,  52 . The initialization command is sent when the magnetic disk  10  is loaded anew, or when the power supply to the main control circuit  42  is interrupted for example by the replacement of the power supply unit  64  after the loading of the magnetic disk  10 . The main control circuit  42  rotates the magnetic disk  10  by the servo circuit  16  and the motor  14 , and moves the magnetic head  12  track by track toward the inside until the innermost track detection switch  22  is closed (steps S 2 , S 3 ). Then the main control circuit  42  sets a track number “50” as a memory variable T in the RAM  44 , initializes the track table with “O” as shown in FIG. 3, and connects the switch  31  to the contact a (step S 4 ). FIG. 3 shows the track table in the RAM  44 . The track table in the present embodiment has a capacity of 7 bytes with addresses a-g, in which 1 bit is assigned to each track. The same table is prepared as a back-up in the RAM  70 . 
     The reproduction output of the magnetic head  12  is transmitted through the switch  31  and the reproducing amplifier  32 , then subjected to envelope detection in the detection circuit  38 , and compared with the reference voltage in the comparator circuit  40 . The presence or absence of recorded signal can be identified in this manner. A recorded flag is set in a bit position of the track table corresponding to the track in the presence of the recorded signal, or is reset in the absence of the recorded signal (steps S 5 , S 6  and S 7 ). Then the main control circuit  42  sends the information on the recorded flag for the track T to the sub-control circuit  46 , which stores the information in the track table of RAM  70  (step S 8 ). 
     If the track T under access is not recorded (step S 9 ), or if the track is recorded but the recording mode is not selected (step S 10 ), the state of the tracks is checked track by track downwards (steps S 12 , S 5 -S 10 ) until the  1 st track is reached (step S 11 ). On the other hand, if the track T is recorded and the recording mode is selected (step S 9 , S 10 ), the magnetic head is shifted to the next track if the track T is not the 50th track, or remains in the track T if it is the 50th (steps S 13 , S 14 ), and the main control circuit  42  sends an initialization completion command to the sub-control circuit  46  (step S 15 ). Also in case the recording mode is selected (step S 16 ), the main control circuit  42  shifts the signal  66   a  to the L-level thereby opening the switch  68  (step S 17 ), but, in case the recording mode is not selected, it cancels the muting of the muting circuit  36 . 
     As explained above, if the magnetic disk  10  is loaded in the recording mode, the recorded state of the tracks is investigated from the innermost track toward the outside, and the initialization is completed by positioning the magnetic head on an empty track immediately inside the recorded tracks. The initialization is completed on the 1st track if all the tracks are unrecorded, or on the 50th track if the innermost (50th) track is recorded. 
     On the other hand, if the magnetic disk is loaded in the reproducing mode, the recorded state is investigated in succession from the 50th track to the 1st track, and the initialization is completed on the 1st track. 
     After the initialization in the recording mode, the switch  68  is turned off to interrupt the power supply to the main control circuit  42  and other circuits, and the sub-control circuit  46  alone remains active. Consequently the track table in the RAM  44  and the track number T under access are erased, but the same set of data are stored in the RAM  70 . 
     Now reference is made to FIG. 4 for explaining the operation when the recording preparation switch  62  is turned on in the recording mode in a state where the sub-control circuit  46  alone is active after the initialization. In response to the closing of the switch  62 , the sub-control circuit  46  shifts the signal  66   b  to the H-level, thereby closing the switch  68  and supplying the main control circuit  42  with electric power. The main control circuit  42  shifts the signal  66   a  to the H-level to maintain the switch  68  on, thereby rotating the magnetic disk  10  and connecting the switch  31  to the contact b. The sub-control circuit  46  sends, to the main control circuit  42 , mode information (indicating the recording mode in this state) (step S 20 ), a current track number T0 (step S 21 ) and track table information (step S 22 ). The main control circuit  42  sets the current track number To, received from the sub-control circuit  46 , as the memory variable T (step S 23 ), and sets the variable T as a memory variable T1 (step S 24 ). 
     The main control circuit  42  refers to the bit for the track T1 in the track table, and discriminates whether it is recorded (“1”) (step S 25 ). If the track is already recorded, the variable T1 is increased on the track table (step S 27 ) until an unrecorded track is found (step S 25 ) or the 50th track is reached (step S 26 ). If the 50th track is reached before an empty track is found (step S 26 ), the absence of empty track is informed to the sub-control circuit  46  (step S 28 ), which in response shifts the signal  66   a  to the L-level, thereby turning off the switch  68  (step S 35 ) and terminating the sequence. 
     If the track T1 is identified as unrecorded by the bit “0” on the track table (step S 25 ), said track T1 identified as unrecorded is compared with the current track T (step S 29 ), and, if they are not same, the variable T is increased to shift up the magnetic head  12  until they become equal (step S 30 ). If T1 is equal to T (step S 29 ), the state of the recording switch  60  is investigated (step S 31 ). If it is on, the image pickup circuit  26  is activated, and the switch  31  is connected to the contact c to record the obtained field image signal on the magnetic disk  10  (step S 33 ). The main control circuit  42  changes the corresponding bit of the track table to “1”, and transmits the current track number T and information that the track has been recorded, to the sub-control circuit  46  (step S 34 ). Thereafter the sequence returns to the step S 24  and looks for an empty track in the routine of the steps S 25 -S 27 . 
     If the recording switch  60  is off (step S 31 ) but the recording mode is selected (step S 32 ), the sequence returns to the step S 31  to await the closing of the recording switch  60  is closed. Also if the recording mode is not selected (step S 32 ), the switch  68  is turned off (step S 35 ) and the sequence is terminated. 
     FIG. 5 is a detailed flow chart of the track upshift control of step S 30 . If the current track is the innermost 50th track (step S 40 ), the sequence returns to the main flow. If it is not the 50th track (step S 40 ), the magnetic head  12  is shifted inwards by a track (step S 41 ), and the variable T is increased by one (step S 42 ). Then it is investigated, on the track table, whether the track T is already recorded, and this information and the value of variable T are transmitted to the sub-control circuit  46  (step S 43 ). 
     The recording of an image signal is conducted as explained above, finding empty tracks up to the 50th track. 
     Now reference is made to FIG. 6 for explaining the function of the reproduction mode. The reproducing mode is selected by closing the reproduction mode switch  52  in a state in which the lock mode switch  52  or the recording mode switch  48  is on. The sub-control circuit  46  shifts the signal  66   b  to the H-level to close the switch  68 , thereby supplying the main control circuit  42  with electric power. The main control circuit  42  also shifts the signal  66   a  to the H-level to maintain the switch  68  in the onstate, thereby rotating the magnetic disk  10 , connecting the switch  31  to the contact b and setting the muting circuit  36  in the muting state. The sub-control circuit  46  sends, to the main control circuit  42 , the mode information (indicating the reproducing mode) (step S 50 ), current track number T0 (step S 51 ), information on the track table (step S 52 ) and destination track number T1 of the head (step S 53 ). The main control circuit  42  sets the current track number T0, received from the sub-control circuit  46 , as the memory variable T (step S 54 ), then compares the current track number T with the destination track number T1 (step S 55 ), and effects track upshift or downshift so as to reach a condition T=T1 (steps S 56 , S 57 , S 58 ). 
     When the magnetic head  12  moves to the destination track T1, the reproducing operation is started (step S 59 ). More specifically, the switch  31  is connected to the contact a, whereby the output of the magnetic head  12  is supplied through switch  31  and the reproducing amplifier  32  to the processing circuit  34 , and subjected therein to a reproducing process such as demodulation to obtain the reproduced image signal. When the main control circuit  42  cancels the muting state of the muting circuit  36  (step S 60 ), the reproduced image signal is released. 
     Thereafter the main control circuit  42  knows the states of the switches through communication with the sub-control circuit  46 , and, during the reproducing mode (step S 65 ), effects the corresponding operations. More specifically, the track upshift control is conducted in response to the actuation of the upshift switch  58  (steps S 61 , S 67 ), and the track downshift control is conducted in response to the actuation of the downshift switch  50  (steps S 62 , S 68 ). When the interval switch  54  is closed (step S 63 ), there is investigated the state of an interval mode flag indicating whether the interval mode has been selected is investigation (step S 69 ), and the flag is reset if it is on (step S 70 ). If it is off, the flag is set, then an interval time, for example 5 seconds, is set in an interval timer  17  (step S 71 ), and interval reproduction control is conducted (step S 72 ). The content of the interval timer  17  is stepwise decreased every second to zero while the main control circuit  42  is powered. If the interval mode flag has been set (step S 64 ), there is conducted the interval reproduction control (step S 72 ). 
     When the reproduction mode switch  50  is turned off, the main control circuit  42  shifts the signal  66   a  to the L-level, thereby closing the switch  68  (step S 66 ). 
     FIG. 7 is a detailed flow chart of the track downshift control of the step S 58 . If the current track T is the 1st track (step S 80 ), the sequence returns to the main flow. If it is not the 1st track, the magnetic head  12  is moved to the outside by one track (step S 81 ), and the variable T is decreased by one (step S 82 ). Then there is discriminated whether the value T is equal to or larger than the value T0 received in the step S 51  (step S 83 ), and, if not, the value T is set as the variable T0 (step S 84 ). Then the switch  31  is connected to the contact a and the RF signal is detected to discriminate whether the track is already recorded (step S 85 ). Because of step S 84 , the variable T0 always indicates the minimum track number subjected to reproduction since the start of the reproducing operation. 
     If T is equal to or larger than T0 (step S 83 ) or if the RF signal is detected (step S 85 ), the track number and the information whether the track is already recorded are transmitted to the sub-control circuit  46  (step S 86 ). 
     Now reference is made to FIG. 8 for explaining the detail of the interval reproduction control of the step S 72  in FIG.  6 . In the interval reproduction, the recorded tracks only are reproduced at a constant interval in the order of track numbers. After the reproduction of the innermost track, the magnetic head moves to the outermost recorded track to cyclically repeat the reproducing operation. At first there is discriminated whether the interval timer is “0” (step S 90 ), and, if not, there is discriminated on the track table whether the track is already recorded (step S 91 ). If the interval timer is “0” in step S 90  or if the track is identified as unrecorded in the step S 91 , the current track number T is set as T1 (step S 92 ), and a recorded track is searched for by a stepwise increment of T1 on the track table until the 50th track is reached (steps S 94 , S 95 ). When a recorded track is found (step S 96 ), there is discriminated whether the recorded track T1 is next to the current track T (step S 96 ), and, if not, the muting is applied (step S 97 ) and track upshift is conducted until T1=T is reached (steps S 98 , S 99 ). Thereafter the muting state is cancelled (step S 100 ), then the interval time of 5 seconds is set in the interval timer (step S 101 ), and the sequence returns to the main flow. Also if the track is identified as recorded in the step S 91 , the sequence returns to the main flow. 
     As explained above, the recorded tracks are reproduced in succession at a predetermined interval from the current track toward the 50th track, by referring to the track table. 
     When the 50th track is reached by the increment of the value T1 (step S 93 ), muting is applied (step S 102 ) and there is discriminated whether the value T0 (minimum track number reproduced to this point) is “1” (step S 103 ). A state T0=1 indicates that the content of the track table in the RAM  44  or  70  is all confirmed, wherein bits “0” indicate unrecorded tracks. On the other hand, if T0 is not “1”, the bits “0” on the track table from the 1st track to a track immediately before T0 indicate that the confirmation of recorded/unrecorded state is not yet conducted. 
     If T0 is not “1” (step S 103 ), track downshift is conducted until To becomes “1” (steps S 104 , S 105 ), then the value T is set as T1 and the sequence proceeds to step S 95 . Thus all the contents of the track table are confirmed by the track downshift of step S 104 . 
     On the-other hand, if T0 is “1” (step S 103 ), a value “1” is set as the T1 (step S 107 ), and there is discriminated whether the track T1 is already recorded (step S 108 ). If it is not recorded, T1 is increased to “50” and there is discriminated whether the track is recorded (steps S 109 , S 110 ). If it is recorded, track downshift is conducted until T1 becomes equal to T (steps S 112 , S 113 ), and the sequence proceeds to step S 100 . Also if T1 reaches “50” without finding a recorded track (step S 109 ), all the tracks are identified as unrecorded. The main control circuit  42  sends, to the sub-control circuit  46 , an error code indicating that the interval reproduction is not possible (step S 111 ), and the sequence proceeds to the step S 100 . 
     Thus, at the transfer from the innermost recorded track to the outermost recorded track in the interval reproduction mode, the reproduced minimum track number T0 is monitored, and, if it is not “1”, track downshift is conducted to effect the RF signal detection on the unconfirmed tracks, thereby completing the track table. 
     The value T1 in step S 53  in FIG. 6 may also be a track number which is recorded last in the recording mode. In this case an image recorded immediately before is automatically reproduced. 
     FIG. 9 shows a variation of the flow chart shown in FIG.  6 . In FIG. 9, the same steps as those in FIG. 6 are represented by the same numbers, and the following description will be given only on different steps. 
     In FIG. 9, when the reproduction mode switch  50  is turned off in a state in which the switches  58  and  56  are both off (step S 165 ), the main control circuit  42  shifts the signal  66   a  to the L-level thereby closing the switch  68  (step S 166 ), while the sub-control circuit  46  stores the current track number T as a variable T2 in the RAM  70  (step S 169 ). Thus, when the sequence proceeds to the step S 166  in the reproducing mode, the variable T representing the current track number in the RAM  70  is same as T2. 
     In the recording mode, as shown in FIG. 4, the magnetic head is moved, after a recording operation, to an unrecorded track at the inside, and, even when there are certain recorded tracks at the inside, an unrecorded track is searched for, avoiding such recorded tracks. Consequently, when the operating mode is switched from recording to reproduction, the magnetic head is not positioned on the track recorded immediately before. In the present embodiment, the number of the track recorded immediately before is memorized as T2, and the magnetic head is moved to the track T2 by the steps S 55 -S 58 , thereby reproducing the image recorded immediately before, regardless of the presence of recorded tracks on the way of head movement. 
     The lock mode in the present embodiment retains the conditions of the immediately preceding recording or reproducing mode. Consequently a mode change from the recording mode through the lock mode to the reproduction mode is equivalent to a change from the recording mode to the reproduction mode. 
     In the variation shown in FIG. 9, at the switching from the reproduction mode to the recording mode, the sub-control circuit  46  may be so constructed as to set “1” as the variable T2 in the RAM  70 . In this manner the magnetic head  12  makes access to the 1st track when the operating mode returns to reproduction without the recording operation. 
     In the embodiment shown in FIG. 6, when the operating mode is switched to reproduction, the track table is considered to be fixed for track numbers equal to or higher than a track T0 currently accessed by the magnetic head, and the RF signal detection is conducted in case of access to the track numbers smaller than T0. It is also possible, however, to compare the outermost (namely minimum) track number with track bit “1” with T0 by referring to the track table supplied from the sub-control circuit  46  immediately after step S 54  shown in FIG. 6, to set the smaller number as T0 thereby assuming that the track table is confirmed for track number equal to or larger than T0, and to effect the RF signal detection in case of access to tracks of smaller track numbers. 
     The sub-control circuit  46  may also be so designed as to store, in the RAM  70 , the minimum one of the track numbers transmitted from the main control circuit  42 , to transmit the minimum number as T0 to the main control circuit  42  immediately after step S 54 , and to effect the RF signal detection only in case of access to a track number smaller than T0. 
     The recording medium in the foregoing embodiment has been limited to a magnetic disk, but the present invention is likewise applicable to other recording media such as a magnetic tape, an optical disk, a magneto-optical disk or a solid-state memory, for example, a semiconductor memory. 
     As will be apparent from the foregoing description, the above-explained embodiments allow information on the recorded/unrecorded state of the recording medium to be stored using a very limited memory capacity, and to efficiently execute the interval reproduction mode. 
     Also the foregoing embodiments allow an image recorded immediately before, to be reproduced when the operating mode is switched from recording to reproduction, regardless of the position of the recording area under access for recording, so that the confirmation of recorded image is facilitated.