Recording apparatus

Abstract: Apparatus and method for recording and/or reproducing an image frame in plural blocks utilizes a memory for storing an image signal for one field. The image signal for one field is then divided into n blocks by reading the image signal from the memory n times where n is an integer equal to at least two. The n divided image signals are then subjected to one-channel signal processing, and the respective image signals subjected to the signal processing are then recorded on a recording medium sequentially in different tracks. During reproduction, if little time is available, only selected ones of the n blocks are read and the entire image is interpolated therefrom.

Description: The invention relates to a recording apparatus for recording various kinds of information signals, such as digital image signals and the like, on a recording medium, such as a magnetic tape or the like. US-A-4,745,482 describes a recording apparatus comprising a memory means for storing an image signal for at least one picture, a control means for grouping said image signal into n blocks and reading said image signal, a signal processing means for processing said image signal and a recording means for recording the processed image signal. Apparatuses have been generally known which record various kinds of digital signals, such as image signals, voice signals and the like, on a magnetic tape carried within a small cassette. In such a magnetic recording/reproducing apparatus, the above-described information signals are transmitted through a transmission system within the apparatus at a predetermined speed, and signal processing and other kinds of processing, such as recording/reproducing processing and the like, are performed. It is preferred that the transmission speed of a signal in the above-described magnetic recording/reproducing apparatus is low in consideration of processing speeds of various kinds of signals. However, if the transmission speed is lowered, a long time is needed for recording when recording an image signal which has a large amount of information. That is, if the transmission speed is set to about 768 bits (kilobits)/sec {2(ch) x 32 (KHz (kilohertz)} x 12 (bits)} which is sufficient for the transmission of a voice signal, a time of about 4.8 seconds is needed for recording an image signal for one frame [3.7 Mbits (megabits)(640 (picture elements) x 480 (picture elements) x 1.5 (Y + C)}] which is more or less sufficient as an image signal. Accordingly, when, for example, the above-described magnetic recording/reproducing apparatus is used for an electronic still-picture camera, the camera has the disadvantage that the shutter timing is restricted, and hence a successive photographing function (which is an indispensable function for a camera) is also restricted. The above-described disadvantage due to the slow transmission speed also causes a problem in a reproducing operation as well as in a recording operation because a long time is needed for a reproducing operation. Furthermore, the use of a magnetic tape as a recording medium has the disadvantage that more time is needed for searching for recording and reproducing positions, causing inconvenience to the user. The present invention has been made in consideration of the above-described problems. It is an object of the present invention to reduce inconvenience in the time required to record and reproduce an image signal having a relatively large capacity while suppressing the transmission speed. This object is accomplished, according to the present invention, by a recording apparatus having the features indicated in claim 1. The invention is further developed by the features of the dependent claims. According to the apparatuses having the above-described configurations, it is possible to solve inconvenience in handling image information having a large capacity with a slow transmission speed. That is, by dividing an image signal for one field into a plurality of blocks and sequentially recording images in respective blocks, it is possible to delete images in units of a block whenever necessary, and thereby to shorten the recording time. Other objects and features of the present invention will become more apparent from the following description taken in connection with the accompanying drawings. FIGS. 1(A) and 1(B) are block diagrams showing the configuration of an embodiment of the magnetic recording/reproducing apparatus according to the present invention; FIG. 2 is a perspective view showing a cassette according to the present invention; FIG. 3 is a schematic plan view showing a principal part of a cassette mounting unit; FIG. 4 is a diagram schematically showing an arrangement of picture elements of an image signal for one field; FIGS. 5(A) - 5(D) are diagrams schematically showing arrangements of picture elements in respective divided blocks; FIG. 6 illustrates diagrams schematically showing recorded patterns of respective blocks constituting an image signal for one field, and recorded patterns of image signals for a plurality of fields; FIGs. 7(A) and 7(B) are flowcharts showing a recording operation; FIG. 8 is a flowchart showing a quick-feed operation; FIG. 9 is a diagram schematically showing reproduced picture frames by a multiframe quick-feed reproducing operation; and FIG. 10 is a diagram schematically showing data used when interpolating data in other blocks using data in the first block. The preferred embodiment of the present invention will now be explained in detail with reference to FIGS. 1(A) through FIG. 10. FIGS. 1(A) and 1(B) are block diagrams showing the configuration of an embodiment of the magnetic recording/reproducing apparatus according to the present invention. FIG. 1(B) illustrates FIG. 1(A) in more detail. In the present embodiment, digitized image signals, voice signals and the like are selectively recorded on respective tracks, which will be described later, on a magnetic tape received within a small cassette as shown in FIG. 2. As shown in FIGS. 2 and 3, the above-described cassette C receives a magnetic tape Tp wound between a pair of tape reels disposed within the main body of the cassette C. The magnetic tape faces the outside via a cover 1 disposed at the front of the cassette C. On a side of the cassette C is formed a magnetic recording member 2, on which index information relative to the amount of information recorded on the magnetic tape, and the like is recorded. In the present embodiment using the magnetic tape within the cassette C as a recording medium, photographing light from an object incident upon a sensor 4, such as a CCD (charge-coupled device) or the like, via an optical system 3 (having a diaphragm mechanism, an autofocusing mechanism and the like), is subjected to photoelectric conversion. An image signal thereby obtained is amplified by a predetermined amount by a preamplifier (not shown), and is then converted into a digital signal having a predetermined number of bits by an A/D (analog-to-digital) converter 5. The sampling frequency of the A/D converter 5 in the present embodiment is 32 KHz, and the quantization bits comprise eight bits. A voice signal is supplied to the A/D converter 5 from a microphone 21 via input terminal 16. The digitized image signal and the like are first stored in a memory circuit 7 having a storage capacity of at least one frame via a digital signal processing circuit 6. The stored image signal and the like are sampled in a predetermined number of blocks (4 blocks in the present embodiment), as will be described later, and are sequentially read in units of a block. After being subjected to predetermined signal processing, such as compression, addition of error correcting codes, encoding and the like, for every data in respective blocks by the digital signal processing circuit 6, the read image signals and the like are supplied to a recording/reproducing unit 8, where the signals are recorded on the magnetic tape within the cassette C mounted in a cassette mounting unit 9 while each block is allocated to one track or a plurality of tracks. The number of recorded tracks for data in one block may be arbitrarily set in accordance with the transmission speed of the apparatus. The signal processing circuit 6 includes a compressor 6a for performing the above-described signal processing, an error correcting code adder 6b, and an encoder 6c for performing an encoding operation, such as (8 10) transformation, mirror transformation or the like, for reducing a low-frequency component. The circuit 6 also includes a decoder 6d for performing processing (to be described later) of reproduced digital signals, an error correction circuit 6e, an expander 6f, an interpolation circuit 6g, and switching circuits 6h and 6i for switching signal lines when, for example, inputting (recording) and outputting (reproducing) a signal. The recording/reproducing unit 8 includes a rotating drum 10 (FIG. 3) having two rotating heads He1 and He2 for recording and reproducing image signals and the like on the magnetic tape Tp. As shown in FIG. 3, when the cassette C is mounted in the cassette mounting unit 9 of the recording/reproducing unit 8, the rotating drum 10 moves to the inside of the cassette C, and is pressed against the magnetic tape guided by tape guides 11 and 12 at the front of the cassette C. Thus, in, the present embodiment, it is possible to wind the magnetic tape over an angle range of about 100° around an outer circumference of the rotating drum 10 without loading the magnetic tape. The rotating drum 10 is inclined at a predetermined angle relative to the longitudinal direction of the magnetic tape. Hence, by running the magnetic tape by a reel driving means (not shown) while rotating the rotating drum 10, image signals, voice signals, photographing information (index signals), which will be described later, and the like are obliquely recorded on the magnetic tape, as shown in FIG. 6. The reel driving means supplies a supply-side reel with a predetermined amount of load, thereby providing a contact pressure between the magnetic tape and the rotating heads. The recording/reproducing unit 8 also includes a magnetic head He3 for recording and reproducing index information to and from the magnetic recording member 2 formed on the side of the cassette C. The magnetic head He3 contacts the magnetic recording member 2 in accordance with a mounting operation of the cassette C in the cassette mounting unit 9. Index information relative to the recorded amounts (the number of recorded frames and the number of blocks) is supplied from a system controller 13 including a microcomputer or the like to the magnetic head He3 via an information recording unit 14. In addition to supplying the above-described information, the system controller 13 supplies the digital signal processing circuit 6 with the above-described photographing information, such as the dates of photographing operations, whether or not a strobe has been used, and the like, and the number of photographed frames and retrieval information relative to the number of recorded blocks for every predetermined number of photographed frames to record such information together with image signals and the like. In accordance with the operation of an operation unit 17 having two-stage shutter release switches SW1 and SW2, a successive photographing mode setting switch SW3, a reproducing mode setting switch SW4 and the like, the system controller 13 performs the system control for the entire apparatus (such as the control of the above-described optical system 3 and sensor 4, the read control (subsampling control) of the memory circuit 7, mode control and the like). Next, an explanation will be provided of a subsampling operation of an image signal and recorded patterns. In the present embodiment, by controlling a reading operation of an image signal for one frame (for example, 640 x 480 picture elements) as shown in FIG. 4 from the memory circuit 7, the image signal for one frame is subjected to subsampling into four blocks, as shown in FIGS. 5(A) through 5(D). That is, the first block samples odd-numbered picture elements on odd-numbered lines, the second block samples even-numbered picture elements on even-numbered lines, the third block samples even-numbered picture elements on odd-numbered lines, and the fourth block samples odd-numbered picture elements on even-numbered lines. These blocks are sequentially recorded on respective predetermined tracks, as shown in FIG. 6. In FIG. 6, the first, second, third and fourth blocks of the image signal for the first frame are recorded on areas 1-a, 1-b, 1-c and 1-d, respectively. The first block of an image signal for the second frame is recorded on an area 2-a. Each area comprises one track or a plurality of tracks. The above-described photographing information is recorded on the leading track of each block. For every unit consisting of a certain number (in the present embodiment, one unit comprises 16 frames) of image signals, each composed of blocks, for respective frames, the above-described retrieval information relative to the total number of recorded blocks and the number of frames within the unit is recorded together with the photographing information. The method of sampling is not limited to the above-described method, but other methods and arrangements of sampled picture elements may also be adopted. In the present embodiment, after being subjected to predetermined signal processing, such as decoding, error correction, expansion and the like, by the signal processing circuit 6 for every data in respective blocks, digital image signals reproduced by the recording/reproducing unit 8 are first stored in the memory circuit 7 in units of a block. Subsequently, the digital image signals read from the memory circuit 7 are supplied, as they are or by being interpolated, to a D/A (digital-to-analog) converter 18 via the signal processing circuit 6, and are converted into analog image signals. The converted analog signals are output to a monitor 20 or the like via output terminal 19. The reading operation of the signals from the memory circuit 7 is controlled by the system controller 13 operating in accordance with the operation of the reproducing mode setting switch SW4. Next, an explanation will be provided of the operation of the above-described magnetic recording/reproducing apparatus. FIGS. 7(A) and 7(B) are flowcharts showing a recording operation. First, when the cassette C has been inserted and mounted in the cassette mounting unit 9 of the recording/reproducing unit 8 (S1), index information recorded on the side of the cassette C is read (S2) to detect the recording status of the entire magnetic tape, for example, whether or not unrecorded portions are present. Next, the apparatus confirms whether or not the apparatus is in a standby state for recording (S3). If the apparatus is in a standby state, the magnetic tape is run at a high speed to read the retrieval information from the magnetic tape (S4). Subsequently, the apparatus detects whether or not the retrieval information coincides with the index information, that is, whether or not any unrecorded portion is present within image signal recording areas for a plurality of frames represented by the retrieval information (S5). If the result is affirmative, the running speed of the magnetic tape is set to a normal speed to detect an unrecorded position (S6). As described above, in the present embodiment, since it is possible to approximately know an unrecorded position when the cassette C has been mounted, the magnetic tape can be run at a high speed to that position only by intermittent reading operations of the retrieval information. Thus, it is possible to greatly improve the so-called cueing speed to find a recorded position. Also when a cueing operation is performed by assigning a position to be reproduced, the operation can be performed at a high speed. Subsequently, the standby state for recording operation is performed again (S7), and the apparatus detects whether or not the power supply of the apparatus is turned off or the cassette C is ejected (S8). If the power supply is turned off, the latest retrieval information is newly recorded (S9), new index information is recorded (S10), the cassette C is ejected (S11), and the process is terminated (S12). If the power supply is turned off and the cassette C is not ejected at step S8, the shutter release switch SW1 is switched on (S13), and the power supply of the photographing system is also turned on (S14), as shown in FIG. 7(B). Subsequently, the apparatus detects whether or not the apparatus is in the successive photographing mode (S15). If the apparatus is not in the successive photographing mode, the apparatus detects whether or not any signal is being recorded on the magnetic tape (S16). If no signal is being recorded on the magnetic tape, an image signal obtained by an exposing operation caused by switching on the shutter release switch SW2 (S17) is written in the memory circuit 5 (S18). A photometric calculation or the like is performed with a predetermined timing between the switching operations of the shutter release switch SW1 and the shutter release switch SW2. After switching on the shutter release switch SW2, an exposing operation, the drive of an electronic shutter, and a reading operation of the sensor are performed. Subsequently, image signals in respective blocks read by being sampled from the memory circuit 7 as described above are subjected to the above-described signal processing, and are sequentially recorded on the magnetic tape (S19). The recording operation continues until all the blocks are recorded (S20). If any signal is being recorded at step S16, the apparatus determines whether or not the apparatus is in an image destruction prohibiting mode (S21). The image destruction prohibiting mode is a mode to prohibit a new recording operation of the next block until at least all the blocks in the course of recording are recorded, because unrecorded picture-element data disappear within respective blocks if the recording operation is interrupted. If the apparatus is not in the image destruction prohibiting mode, an image destruction warning is issued from a display means 22 composed of an LED (light-emitting diode) or the like (S22), the recording operation is stopped (S23), and the process proceeds to step S17. If the apparatus is in the image destruction prohibiting mode at step S21, a time T w needed to record the remaining blocks is calculated (S24). The apparatus then detects which of the time T w and a predetermined time T c1 is longer (S25). The time T c1 is a time needed to record one block. If the time T w is shorter than the time T c1 , blocks can be recorded until the third block, but the fourth block cannot be recorded, because the fourth block can be recorded only until its midsection. Hence, recording is performed until the third block (S26). If the time T w is longer than the time T c1 at step S25, the apparatus detects which of the time T w and another time T c2 is longer (S27). The time T c2 is a time needed to record two blocks. If the time T w is shorter than the time T c2 , blocks can be recorded until the second block, but the third block cannot be recorded. Hence, recording is performed until the second block (S28). If the time T w is longer than the time T c2 , recording is performed until the first block (S29). The recording operation is continued until recording as described above has been completed (S30). The process proceeds to step S17 when recording has been completed until a predetermined block. If the apparatus is set to the successive photographing mode at the above-described step S15, the recording mode is uniquely set to recording until the second block (S31), and the process proceeds to the above-described step S19. When recording has been completed at step S20, the process returns to the above-described step S7. As described above, in the present embodiment, an image signal for one frame is equally divided into four blocks, and respective blocks are sequentially recorded. Hence, when it is necessary to continuously perform recording operations within a short time as in the successive photographing mode, it is possible to remove restrictions on the recording operation due to a slow transmission speed. Next, an explanation will be provided of a quick-feed reproducing operation in the magnetic recording/reproducing apparatus of the present embodiment with reference to the flowchart shown in FIG. 8. The quick-feed operation in the present embodiment includes a multiframe quick-feed operation as shown in FIG. 9 in addition to a normal quick-feed operation. That is, in the multiframe quick-feed operation, only first blocks in respective image signals are sequentially reproduced on respective divided picture frames of a divided-in-four picture frame. In the normal quick-feed operation, arbitrary blocks (for example, first blocks) of respective image signals are sequentially reproduced. The multi frame quick-feed operation will now be explained in detail. First, as shown in FIG. 8, when a quick-feed switch is switched on (S40), the apparatus detects whether or not the mode set by the above-described reproducing mode setting switch SW4 is a multiframe quick-feed mode (S41). If the set mode is the multiframe quick-feed mode, data of a predetermined block of the image signal for the first frame are received in the memory circuit 7 (S42). The data are then read and are subjected to D/A conversion. The converted data are reproduced on a 1/4 picture frame of the monitor 20 (S43). Next, the apparatus detects whether or not the quick-feed switch has been switched on (operated) again (S44). If the quick-feed switch has been switched on, the magnetic tape is moved to the next data area, that is, the tape position where the image signal for the second frame is recorded (S45). At this time, the magnetic tape may be fed using an intermittent feeding method wherein the feed amount is changed in accordance with the number of tracks needed to record data for one picture frame. When new data have been received in the memory circuit 7, data are moved in the memory (S46). The process then returns to step S42 to repeat the above-described operation. Thus, the latest image on the monitor 20 is always positioned at the upper left of the picture frame. Hence, a searching operation can be easily performed. If the quick-feed switch has not been switched on at step S44, data of the remaining blocks are received in the memory circuit 7 to provide data of all the blocks for one picture frame (S47). The data are then subjected to D/A conversion, and the converted data are reproduced on the monitor 20 (S48). If the mode is not the multiframe quick-feed mode at the above-described step S41, data of the first block of the image signal for the first frame are first received in the memory circuit d7 (S49). Data of surrounding picture elements are interpolated from the data of the first block by the above-described interpolation circuit 6g to obtain data for one picture frame (S50), as shown in FIG. 10. The data for one picture frame as a result of the interpolation are reproduced on the monitor 20 (S51). Next, the apparatus detects whether or not the quick-feed switch has been switched on (operated) again (S52). If the switch has not been switched on, the magnetic tape is moved to the tape position where the next data area, that is, the image signal for the second frame is recorded (S53). The process then returns to step S49 to repeat the above-described operation. If the quick-feed switch has not been switched on at step S52, data of the remaining blocks are received in the memory circuit 7 (S47), and the received data are reproduced on the monitor 20 (S48). As described above, according to the present embodiment, by reading image signals recorded in units of a block in units of minimum necessary blocks whenever necessary, a high-speed reproducing operation as described above can be realized without being restricted by the transmission speed. Furthermore, in the present embodiment, since image signals are processed after first being written in a memory when performing a recording or reproducing operation, freedom in processing may be increased in that, for example, signal processing can be independently performed for every data of respective blocks. Moreover, when performing a normal reproducing operation with the apparatus of the present embodiment, respective data of the first through fourth blocks are sequentially received in the memory circuit 7, within which the data of respective blocks are synthesized. The data of respective blocks thus received are sequentially reproduced on the monitor 20. At this time, data of picture elements whose data are not yet present may, of course, be interpolated using the received data. That is, when, for example, data have been received until the data of the second block, the data of the third and fourth blocks (which have not yet been received) may be interpolated using the data of the first and second blocks (which have already been received) until the data of the third and fourth blocks are received, and the resultant data may be reproduced. It is thereby possible to improve the quality of an image reproduced until all image signals for one frame are received. Although, in the foregoing embodiment, an image signal for one frame is sampled and divided into four blocks, the number of divided blocks may be larger or smaller than four in consideration of the required image quality, the operation speed (time) and the like. Although, in the foregoing embodiment, the sampling frequency and quantization bits of the A/D converter 5 are constant, these factors may be changed between image signal recording and reproducing operations and voice signal recording and reproducing operations. The cassette according to the present invention is not limited to that which receives a magnetic tape, but the cassette may receive various kinds of recording media, such as a magnetic disk, an optical disk or the like. Furthermore, the signals to be recorded and reproduced are not limited to image signals and voice signals. As is apparent from the foregoing explanation, according to the present invention, it is possible to reduce inconvenience when image information having a large capacity is handled with a slow transmission speed. That is, by dividing an image signal for one frame into a plurality of blocks and sequentially recording images in the divided blocks, it is possible to delete data in units of a block whenever necessary, and thereby to shorten a recording time. Also when reproducing images, it is possible to perform, for example, a high-speed reproducing operation by reproducing only minimum necessary blocks. Furthermore, by recording information indicating a recording status on a cassette which receives a recording medium, it is possible to improve the control of the apparatus in which the cassette is mounted. According to the present embodiment, since signal processing is performed while reading digital image signals first stored in the memory circuit 7 in units of a block, it is possible to realize the signal processing by a single-channel signal processing system, and hence to provide a small circuit scale. Moreover, since independent signal processing is performed in units of a block, data can be independently restored for every block in a reproducing operation. Thus, by reproducing at least data for one block, an image for one picture frame can be obtained. Although, in the foregoing embodiment, during a recording operation, signal processing for digital image signals is performed entirely after the signals have been read from the memory circuit 7, the compressor 6a or the like, for example, may be provided before (at the input side) the memory circuit 7, as shown by one-dot chain lines in FIG. 1(B). It is thereby possible to reduce the capacity of the memory circuit 7. As described above, by supplying signals to the memory circuit 7 via the above-described signal processing unit 6, it is possible to properly distribute signal processing in the signal processing unit 6 before and after the memory circuit 7. Although, in the foregoing embodiment, reproduced signals are directly processed during a reproducing operation, the reproduced signals may, for example, be first received in the memory circuit 7 via signal lines l 1 and l 2 shown by broken lines in FIG. 1(B), and the above-described signal processing may be performed after distributing the reproduced signals in respective blocks. It is thereby possible to perform signal processing in a state wherein all the data of respective blocks are received, even if the tracking of the above-described magnetic heads He1 and He2 in a reproducing operation is more or less incorrect, or the tracking control is not performed. At that time, the rate of reproduction (rate of provision) of the data of respective blocks within the memory circuit 7 may be detected, and the running of the magnetic tape may be controlled in accordance with the result of detection. Alternatively, the supply of reproduced signals from the recording/reproducing unit 8 to the memory circuit 8 or the signal processing circuit 6 may be switched by the switch 6h while watching a reproduced image on the monitor 20. The individual components shown in outline ore designated by blocks in the Drawings are all well-known in the image recording/reproducing arts and their specific construction and operation are not critical to the operation or best mode for carrying out the invention.

Claims: A recording apparatus comprising (a) memory means (7) for storing an image signal for at least one picture, (b) read out controlling means (13) for grouping said image signal into n blocks and reading said image signal, (c) signal processing means (6) for processing said image signal, and (d) recording means (8) for recording the processed image signal, characterized by (e) mode setting means (SW3) for setting an operation mode of said recording means (8), wherein said recording means (8) is adapted to record predetermined blocks out of said n blocks in accordance with the operation mode, and thereby to shorten a recording time. A recording apparatus according to Claim 1, wherein said controlling means (13) divides said image signal into n blocks by subsampling the signal while changing reading positions of the signal from said memory means (7) at every n-time reading operation. A recording apparatus according to Claim 1, wherein each of the n divided image signals comprises a signal for each picture element obtained by equally subsampling each picture element constituting the image for one field. A recording apparatus according to Claim 1, wherein said signal processing means (6) includes a compressor (6a). A recording apparatus according to Claim 1, wherein said signal processing means (6) includes an error correcting code adder (6b). A recording apparatus according to Claim 1, wherein said signal processing means (6) includes an encoder (6c). A recording apparatus according to Claim 1, wherein said recording means (8) includes a plurality of rotating heads (He1, He2) for helical scanning a magnetic tape.

Inventors: MISUMI HIROYOSHI, MIYAMOTO RYOUSUKE, NAKAZATO SABUROU, UDAGAWA YOSHIROU, YAMAGATA SHIGEO, MISUMI, HIROYOSHI, MIYAMOTO, RYOUSUKE, NAKAZATO, SABUROU, UDAGAWA, YOSHIROU, YAMAGATA, SHIGEO
Applicants: CANON KK, CANON KABUSHIKI KAISHA
Application year: 1991
Main classification: H04N1
IPC codes: G11B23, G11B27, G11B20, H04N5, H04N9, H04N1, G11B15