JPS639378A - Magnetic recorder - Google Patents

Abstract

PURPOSE:To photograph a still picture of very high picture quality worthy of looking by making PCM still picture recording 1 unit picture of 1 frame or 1 field of moving picture while making recording of moving picture. CONSTITUTION:PCM still picture recording is made at a period of 240 frames such as frame pictures F1, F241..., or at a period of 8 seconds. A frame picture F1 is taken in a frame memory 56, and after a specified time, recording is made over plural continuous tracks TRp.i-TRp.j in form of PCM signals 1H by 1H. When recording of PCM still picture of the frame picture F1 is terminated, next still picture frame cycle TC is started. Here, a frame picture 241 is PCM still picture recorded over continuous 420 tracks similarly to above-stated.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a magnetic recording device such as a video tape recorder (VTR), and in particular to a magnetic recording device having a simple configuration and a high-quality still image recording function. Regarding equipment.

(Prior art) Recently, cameras and V
A so-called camera-integrated VTR that incorporates a TR is gaining popularity.

These camera-integrated VTRs are characterized by their small size and light weight, making them suitable for taking video while traveling or at sports events, but their image quality is not sufficient for general use. Various improvements have been made over time.

For example, the image pickup tube and image sensor, which are said to be the heart of a video camera, have been made to have higher sensitivity and resolution, especially COD.
In this case, the number of pixels has increased to about 250,000, the resolution has been improved by about 30%, and smear and moire phenomena have been reduced.

Regarding circuits, efforts have been made to improve the S/N ratio by improving emphasis circuits and comb filters.

Furthermore, since the camera and VTR are directly connected, a circuit that mixes the luminance signal and chrominance signal and a circuit that separates both signals are omitted, so the bands of the luminance signal and chrominance signal are no longer compressed, and the resolution increases. There is also the advantage of improved color reproducibility that is unique to integration.

By the way, when taking video, it is common to take videos of moving people or objects, and it is rare to actively take pictures of still things.In fact, when playing back, you only want to take a single frame of the video that you think is important. I often view still images by playing them back.

When playing still images on a VTR, image blur and noise appear, but this is a tracking error phenomenon that occurs because the head does not accurately trace the video track where the image to be played is recorded. However, recently, playback heads specifically designed for still images have been installed to reduce blur and noise.

In recent years, video printers that convert video images into hard copies have been developed, so it is thought that the ability to easily print and enjoy video still images will become popular.

(Problem to be solved by the invention) However, since still images are viewed as visual information that contains information that does not change over time, unlike videos, still images require considerably higher image quality. Ru. Therefore, if the reproduced video signal contains jitter, dropouts, etc., image deterioration phenomena such as shaking, distortion, color unevenness, and noise may appear in the image, and the still image may not be able to withstand close attention. Moreover, when such still images are hard-copied, the low image quality becomes even more noticeable.

Therefore, video, especially camera-integrated VT as mentioned above,
Although the popularity of R has been remarkable, it is still far from as good as silver halide photography in terms of image quality, and users prefer VTRs with built-in cameras or portable separate cameras for video shooting, and silver halide still cameras for still images. It is used differently,
Sometimes they are forced to carry both a video camera and a still camera.

Therefore, if we consider video systems by dividing them into imaging systems, recording systems, and hard copy systems, we can see that in the imaging system, the development of 400,000 pixel CCDs is progressing, and the appearance of CCDs is likely to be imminent, and in the hard copy system, The image quality has improved considerably recently, and it is only a matter of time before it reaches a level that is satisfactory for practical use. Therefore, the remaining recording system is the key, and although various signal processing circuits have been developed or improved to improve image quality, still images of high quality sufficient for viewing have not been obtained.

SUMMARY OF THE INVENTION In view of these problems, it is an object of the present invention to provide a magnetic recording device that records still images of high quality sufficient for viewing in parallel with recording moving images. That is, when the magnetic recording device of the present invention is applied to, for example, a camera-integrated VTR, it becomes possible to simultaneously shoot moving images and to shoot extremely high-quality still images with a single video recorder.

By the way, if you just want to add a still image recording function,
Since various still image recording devices are available, it is easy to incorporate them into video, and in fact, several attempts have been made to date. However, all of these resulted in amplifiers that were significantly heavier and more expensive, resulting in unbalanced products. In other words, in order for video with a still image recording function to become popular among general users, it is of course necessary to be able to support high image quality, but it is also required to have a small increase in weight, and for example, it is necessary to have a mechanism. It should not be possible, and it should not be something that would significantly increase costs. However, a magnetic recording device that satisfies such requirements has not yet been realized.

Therefore, another object of the present invention is to realize a magnetic recording device that can record high-quality still images with little increase in weight and at low cost, in order to provide a well-balanced and popular product. There is a particular thing.

(Means for Solving the Problems) The configuration of the present invention for achieving the above object is such that a magnetic tape runs in a state where it is wound diagonally at a predetermined angle around a cylinder to which a rotating magnetic head is attached, and the magnetic head In a helical scanning magnetic recording device, in which an analog video signal of a moving image is recorded for one unit image, such as one field or one frame, each time the tape is scanned diagonally, time is recorded as part of one scanning period of the magnetic head. Means for recording PCM still images in segments is provided, and the PCM still image recording means includes means for converting an analog video signal of a moving image into a digital video signal, and a means for converting the digital video signal for one unit image at a predetermined ratio. The present invention is characterized by comprising means for time axis expansion, and means for converting the time axis expanded deinotal video signal for one unit image into a PCM signal and recording it over a plurality of consecutive head scanning periods.

(Function) In the present invention, a moving image and a still image are recorded together in a time-divided manner each time the magnetic head scans the magnetic tape. Moving images are magnetically recorded in the form of analog video signals as usual, but still images are magnetically recorded in the form of PCM signals.

Such a still image is given as one unit image of a moving image, for example, 1 frame, and is obtained by being extracted from the moving image.

The extracted digital video signal for one unit image is time-axis expanded at a predetermined rate, and then transferred to a PC by a predetermined amount.
It is recorded in the form of an M signal during a part of the head scanning period, and it takes a plurality of head scanning periods to record the entire one unit image.

In this way, when a moving image is recorded for a certain period of time, one part (one frame) of the moving image is recorded as a PCM still image.

The reproduced still images obtained from the PCM still image recording of the present invention are not affected by time base errors caused by jitter components due to PCM recording, and are resistant to dropouts and other characteristic deterioration, so the image quality is extremely high and sufficient for viewing. It is durable and has excellent storage stability.

(Embodiment) An embodiment in which the present invention is applied to an 8 mm video will be described below with reference to the attached drawings.

Millimeter video format First, the 8mm video formant will be outlined with reference to FIGS. 4 and 5.

As is well known, 8mm video is produced by the ``8mm Video Conference''.
The main differences from the conventional VH8 system and β system are that the tape width is narrower, the audio signal recording method, and the tracking method.

FIG. 4 shows the track arrangement on a magnetic tape for 8 mm video. The tape width is 8 mm, and the material is coated or vapor-deposited metal tape. Each track is formed diagonally on the magnetic tape by helical scanning in the same manner as before, but a PCM area (hereinafter referred to as PCM )TRP
is provided. In each video track TRv, a video signal (V 1 deo) is recorded using the low-pass conversion color difference signal recording method as in the past, and an FM audio signal (
AFM) and tracking pilot signal (TPS) are frequency-multiplexed and recorded. On the other hand, each PCM) rank TRP
The audio signal is time-compressed and recorded in PCM, and a trunking pilot signal (TPS) is superimposed and recorded. However, this PCM recording is treated as an option, and dubbing (after recording) is also possible.

As shown in FIG. 5, the PCM track TRP is usually 18
A drum wrap of o° is obtained by increasing the angle by 36°. As you can see from the opening position in this figure, one video head CH-1 is connected to the video track TRY.
When recording ends, the other video head CH-2 performs PCM recording on the next PCM track TRP.

Again in FIG. 4, a cue track TRQ for recording a cue signal and an audio track TRA for recording an after-recording audio signal, each using a fixed head, are optionally provided on both the upper and lower sides of each scanning track TR.

The tracking threat pilot signal (TPS) is based on the automatic track finding (ATF) method, and TPS of four different frequencies f1 to f4 selected within the band of approximately 100kHz to 180kHz are sequentially sent to each scanning track TR. recorded. Then, during reproduction, tracking servo is applied so that accurate tracing is performed by detecting head displacement based on the frequency difference between adjacent TPSs. Therefore, in 8 mm video, fixed head type control tracks are not provided.

The 8mm video format has been outlined above, but according to this embodiment, as will be described later, a part of the video is recorded as a PCM still image on the 8mm video PCM rack TRP. PCM still image recording is performed in almost the same PCM format as PCM audio recording. In this way, the PCM encoder for PCM audio is used as is for the still image recording function.

Actually, I'm tired.

FIG. 1 shows the main structure of the 8 mm video according to this embodiment.

In this figure, light from a subject passes through a lens 10 and forms an image on the imaging surface of a CCD 12.

The CCD 12 converts the image formed thereon into an electrical signal and stores it, and is driven by a drive circuit 14 to perform horizontal and vertical scanning and output a video signal. This video signal is supplied to the camera processing circuit 18, where it undergoes signal processing such as noise reduction and gamma correction.

From the camera process circuit 16, the luminance signal Y and the color signal C into which the synchronization signal S has been inserted are supplied to the modulation/recording circuit 18, where the luminance signal Y is FM modulated and the color signal C is FM-modulated.
The frequency is converted from 58 MHz to approximately 743 kHz and subjected to phase conversion (PI) processing at that time. Thus, the FM luminance signal YFM and the low frequency conversion color signal C are output from the modulation/recording circuit 18.
A video signal V1deo is output, which is a mixture of the video signal V1deo and the video signal V1deo, which is mixed with the FM audio signal AFM from the FM modulator 22 in the mixing circuit 24 and sent to the magnetic head 28 via the changeover switches 25 and 28. .30
The lines are connected alternately at the field period.

Note that 20 is a microphone that provides the audio signal AU to the FM modulator 22.

The magnetic head 28.30 is attached to a slit 32a in the substantially center of the cylinder 32, and is driven to rotate by a spindle motor 34 at the same number of rotations as the frame frequency (30 rotations per second). A magnetic tape 36 is wound diagonally 221 degrees around the cylinder 32 and is run at a constant speed by a tape running mechanism such as a capstan.
30 alternately scans the magnetic tape 36 diagonally, and each time an analog signal such as the video signal V Idea is recorded on the video track TRV.

A magnet piece and a fixed head (not shown) are attached to the cylinder 32, and the fixed head connects the magnetic nodes 28 and 30.
A pulse PG representing the rotational phase of is generated, and this pulse P
G is applied to the servo circuit 38. The servo circuit 38 is
The pulse PG is the reference pulse P from the synchronization signal generation circuit 40.
Controls the spindle motor 34 so that the rotation of the head is synchronized with the reference pulse PS by comparing the phase with S, and
A servo is applied to the capstan motor 42 to keep the traveling speed of the magnetic tape 36 constant.

Further, the servo circuit 38 provides switch switching signals SWI and SW2 to the switches 25 and 26, respectively.

The components described so far are standard equipment for 8mm video, and are almost common to the VH8 system and the β system.

Next, the PCM still image recording system of this embodiment will be explained. From the camera process circuit 18, a luminance signal Y and a color difference signal RY,
B-Y is output, and their analog signals Y, R-Y,
B-Y is, for example, 4 according to the component encoding method.
:1:1 relationship between the sampling frequency and the selector switch 50. The A/D converters 52 and 54 convert it into digital signals YD1 (RY)D and (B-Y)D. Therefore, in the case of 4:1:1 component encoding, the changeover switch 50 switches to the terminals 50a and Sob once each within a period in which the luminance signal Y is sampled four times, and thereby The color difference signals R-Y and B-Y are each sampled once. Such a switching operation of the changeover switch 50 is performed in response to a switching signal SQ from the synchronization signal generator 40. Further, a clock signal CL for sampling and A/D conversion is provided from the synchronization signal generator 40 to the A/D converters 52 and 54.

Here, the sampling frequency and the number of quantization bits in A/D conversion greatly affect the image quality, so they must be secured at a certain value or higher, and must be selected at least within the Nyquist band. The frequency is required to be 2 MHz or more, preferably 3 MHz or more, and the number of quantization bits is 5 or more bits for the luminance signal Y+S and 3 or more bits for the 9 color difference signals R-Y and B-Y. However, if the number of bits is large (this will complicate the processing circuit and increase the cost, this must be taken into consideration.In the case of this embodiment, the digital data of the 8mm video format is 8 bits, so the number of bits should be adjusted accordingly. The quantization bits are chosen to be 8 bits.The sampling frequency is
For example, the image quality specifications for still images are: ■The frequency characteristics of the luminance signal Y are almost flat up to 4.2MHz, ■The color difference signals R-Y, B
-Y frequency characteristics are set to be almost flat up to 1.0MHz, END of PASSBAND/5TART
of 5TOPBAND When using a filter with a ratio of 1:1.3, 4.2x1.3x2 = 10.92M
Hz...Selected above (+). By the way, in 8mm video, the amount of data bits per field (in other words, each PCM) is the amount of data bits written to the rack TRP.
The amount of bits is determined to be 1050 words (one word is 8 bits). Therefore, in the PCM still image recording of this embodiment, the IH portion of the video signal is transferred to each PCMl-rack TRP.
In the case of 4:l:1 component encoding, the sampling frequency fs for the luminance signal Y is 8 (3/2 x fs/fll) = 8.
From X 1050 = (2), 700 fH (411
, OIMHz), which satisfies the condition (+) above. In this case, the sampling frequency f s/4 for the color difference signals R-Y and B-Y is 175fH (+2.75M
Hz). Furthermore, since 2H worth of video signals are recorded in PCM for each rotation of the cylinder 32, assuming that the number of effective scanning lines for one frame is 420, one frame (
One frame) image will be recorded as a PCM still image.

Now, the digital signals YD, (RY)D, (B-Y)D output from the A/D converter 552.54 are stored in the frame memory for one frame at a writing speed synchronized with the sampling frequency fs. 56. Then, when the magnetic head 28 or 30 scans the PCM track TRP, the IH portion of the video signal is recorded there as PCM.
H-minute digital signal YD1 (RY)D, (B-Y
)D is output from the frame memory 56 at a predetermined reading speed and supplied to a PCM encoder 68, which will be described later. In this way, in the frame memory 56, the digital signal YD
, (RY)D, (B-Y)D are read out during a 36° head scan period, and one frame is read out in a total of, for example, 7 seconds. Time axis expansion of the digital signal is performed. Note that such write/read operations of the frame memory 56 are controlled by a memory controller 58. The controller 58 is supplied with a clock signal CK from the synchronization signal generation circuit 40 and a control signal CT from the system controller 60.

PCM encoder 68 is commercially available for 8 mm video, and performs error correction and modulation similar to that for PCM audio recordings. That is,
An 8-word, 2-parity cross-interleave code is used as an error correction code, and an address, synchronization signal, parity, etc. are added to the data. A CRC code for error detection is also added. Note that the data includes not only the video signal but also an ID word for indexing. Therefore, in the case of this embodiment, this ID word may be used to locate the beginning of a still image, for example. In addition, a type of FM modulation called bi-phase modulation is used for modulation, and with this, the recording system after the PCM encoder 68 can mix analog signals and PCM signals.
It can be shared with signals.

Thus, the digital signal YD1 (RY)D.

(B-Y)D is converted into a PCM signal with an error correction code added by the PCM encoder 68 in 18-minute increments, and sent to the magnetic head 28.30 via the changeover switch 25.28 to the PCM rack TRP of the magnetic tape 36. It is now recorded in . In addition, the changeover switch 25.28 is
1 by the switching signals SWI and SW2 from the servo circuit 38.
They are alternately closed during each head scanning period.

That is, when the head 28 scans the tape 38, the switch 25 is closed and the switch 26 is opened. Then, the switch 25 first starts the PCM recording period (PCM recording period).
M) During the rack scanning period), the terminal is switched to 25A and P is
The PCM signal from the CM encoder 68 is sent to the head 28, and during the next moving image recording period (video track scanning period), it is switched to the terminal 25B and the analog video signal V Idea from the mixer 24 and the FM audio signal AFM are sent to the head 28. send to Similarly, the head 30
During the scanning period, the switch 28 is connected to the terminal 26A.

28B, while the switch 25 is in an open state.

The system controller 60 receives the system clock SC from the synchronization signal generation circuit 40 and also receives the system clock SC from the servo circuit 3.
It receives the head phase pulse PG from 8, gives instructions to the memory controller 58 to write and read data in the frame memory 56, and controls other parts of the system.

In addition, in FIG. 1, the tracking pyro signal (T
A circuit for recording PS) is omitted.

Next, referring to FIG. 2, the operation of PCM still image recording according to this embodiment will be explained.

In Fig. 2 (A), the images taken by the CCD 12 are Fl,
F2. F3. . . . This shows how a moving image is formed by changing frame by frame one after another. Each frame image Fl is in the form of an analog video signal Video as described above, and is transmitted over two consecutive video trunks TR on the magnetic tape 36 shown in FIG. 2(B).
v, ia+ TRV, Ib4;: recorded rel.

Now, PCM still image recording according to this embodiment is performed at a constant period TC.
In FIG. 2, frame images Fl,
Fi4r, . . . PCM still image recording is performed at an 8-second period in terms of 240 frames per hour.

First, the frame image Fl is taken into the frame memory 56 shown in FIG.

B-Y is converted into digital signals YD, (RY)D, and (B-Y)D at a predetermined sampling frequency and quantization bits, and the data is input to the frame memory 56. Such data input for one frame is performed under the control of the system controller 60.

The frame image Fl captured in the frame memory 56 in this way is transmitted to a plurality of consecutive PCM racks TRP+i-'I':
It is recorded over R'+j. In this example, the number of effective scanning lines is 420, so 420 PCs
M) Rack T RP, 31a ” T RP, 240b
18 minutes of PCM signals F1 and P1 to Fl-P420 are respectively recorded, and the recording time is 7 seconds. In addition, P
CM) Rack "l'RP, 30 PCs before 31a"
M l-rack T RP, Ia-T RP, 30b
Still image data is not recorded in the period (1 second has elapsed), but header HE, control data CD, etc. are recorded.

In this way, when the PCM still image recording of frame image F1 is completed, the next still image frame cycle TC begins, in which frame image F241 is recorded as PCM still image over 420 consecutive PCM tracks in the same manner as described above. The image will be recorded.

As mentioned above, in this embodiment, while video recording is performed without interruption in accordance with the 8 mm format,
One frame (one frame image Fl) in the video is selected at a fixed period, and an 8 mm format PCM) rack (area) is selected.
PCM still images are recorded.

Therefore, the head 28, 30 or the playback head may rotate unevenly, or the tape 36 may expand or contract.

When running unevenness occurs, the reproduced signal will be accompanied by jitter, but P
Since jitter is effectively removed from the PCM signal reproduced from the CM) rack during the PCM reproduction process, a reproduced still image without shaking or distortion can be obtained. This reproduced still image is created by combining 18 minutes of PCM signals read from each of the above 420 PCM ranks and generating a standard analog video signal for one frame through PCM demodulation and D/A conversion. formed by

In addition, dropouts inevitably occur in VTRs due to scratches on the tape or head, adhesion of dust, etc., but these can be easily restored by the powerful error correction ability of PCM. %, the effect of dropout is almost eliminated and good reproduced still images can be obtained. In addition, various image quality deterioration phenomena associated with analog recording are hardly observed in still images recorded in PCM according to this embodiment, and the recording stability and reproduction repeatability are also excellent.

In this way, according to this embodiment, one frame of the video is recorded in PCM while the video is being shot, so it can be recorded later on the PC.
If you use M playback and display it on a TV screen or make a hard copy, you can enjoy extremely high-quality still image playback comparable to silver halide photographs. Further, since PCM recording is performed on the same magnetic tape 36 using the same magnetic heads 28 and 30 as those used for recording moving pictures, no special mechanism is required and there is no increase in weight or shape. Furthermore, using an 8mm video PCM) rack,
Since PCM still images are recorded in almost the same PCM format as PCM audio, the PCM encoder for PCM audio can be used as is for the still image recording function, which is a great advantage in terms of cost.

That is, the 8 mm video according to this embodiment is a popular camera-integrated video that is lightweight, low cost, and has the functions of a high-quality still camera.

Although one embodiment has been described above, the present invention is not limited to this, and various modifications and changes can be made within the scope of the technical idea. For example, the sampling frequency, quantization characteristics, recording time mode, etc. can be selected as appropriate, and some examples are shown in FIG.

In FIG. 3, specification A is selected in the embodiment described above.

The B specification is for the case where H blank (horizontal blanking period) is not recorded, and the sampling frequency is increased accordingly due to the high image quality specifications, but the number of effect pixels (PIXEL) and recording P
The number of CM tracks and recording time are the same as the A specification.

The C specification uses a line-sequential method that records the color difference signals R-Y and B-Y alternately for each IH, and under the condition that no H blank is recorded.
(PCM) This is a method in which 2H worth of video signals are recorded in a PCM rack. With this specification, the number of recording PCM1-ranks and the recording time are each halved, but the image becomes slightly rougher because the sampling frequency is low.

The D specification has the same conditions as the C specification, but the sampling frequency is relatively high to prioritize image quality, and the recording PC
M) The number of racks and recording time have increased slightly.

Although the above four specifications have been illustrated, other specifications are of course possible. In addition, in the embodiment described above, the PC
Although M still images are recorded, it is also possible to record on a field-by-field basis.

Although the present invention is advantageously applied to 8mm video as described above, it is also applicable not only to camera-integrated VTRs of other standards, but also to portable separate-type VTRs, and even to so-called stationary VTRs. Apply to transfer TV images to PC
It is also possible to record M still images.

(Effects of the Invention) As described above, according to the present invention, while recording a moving image, one unit image such as one frame or one field of the moving image is recorded as a PCM still image. In the case of video, it is possible to shoot moving images and still images of extremely high quality that are sufficient for viewing.

Furthermore, since the present invention records PCM still images on a common magnetic tape using the same magnetic head as that used for video recording, it is possible to create a popular product that does not require any special mechanism and is lightweight, low cost, and well-balanced. Can be provided.

In particular, when the present invention is applied to 8 mm video, a special advantage is obtained in that the PCM circuit and other components for the 8 mm video format can be used as they are.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the main configuration of an 8 mm video to which an embodiment of the present invention is applied; FIG. 2 is a diagram for explaining the operation of PCM still image recording according to the above embodiment; 4 shows a track arrangement on a magnetic tape in an 8 mm video format, and FIG. The tape winding in the format is a diagram showing the angle. 14...Camera process circuit, 25.28...
・Selector switch, 28.30...magnetic head,
32...Cylinder, 36...Magnetic tape,
38-track servo circuit, 40...synchronization signal generation circuit, 50-track selection switch, 52.54...A
/D converter, 56...frame memory, 5
8 memory controller, 60... system controller, 68... PCM encoder.

Claims (3)

[Claims] (1) A magnetic tape runs diagonally around a cylinder equipped with a rotating magnetic head at a predetermined angle, and each time the magnetic head scans the magnetic tape diagonally, the analog video signal of a moving image is In a helical scanning magnetic recording device that records one unit image such as a field or one frame, PCM is time-divided into a part of one scanning period of the magnetic head.
Means for recording still images is provided, and the PCM still image recording means includes means for converting the analog video signal of the moving image into a digital video signal, and converting the digital video signal for one unit image into a time axis at a predetermined ratio. A magnetic recording device comprising: means for decompressing; and means for converting the time-axis expanded digital video signal for one unit image into a PCM signal and recording it over a plurality of consecutive head scanning periods. (2) The magnetic recording device according to claim 1, wherein the PCM signal is recorded in a PCM area that is an extension of a video track in which the analog video signal of the moving image is recorded. (3) The magnetic recording device according to claim 1, wherein an audio signal is frequency multiplexed and recorded on a video track on which an analog video signal of the moving image is recorded.