JPS5826233B2 - Gazoki Rokusai Seisouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image recording and reproducing apparatus for extending a television image frame by frame.

2. Description of the Related Art An image recording and reproducing apparatus has been proposed in which a television image transmitted intermittently from a television camera is continuously displayed on a television monitor even during periods when the television image is interrupted.

For example, in an X-ray television system, in order to reduce the amount of X-rays that a patient is exposed to during X-ray fluoroscopy, a vertical blanking period is used every one to several frames of the television signal to emit pulsed X-rays. X This allows continuous observation even during periods when the radiation is interrupted.

Here, the level of the first field video signal to be read out and the level of the second field video signal are not necessarily the same due to the response characteristics of the image pickup tube. The level may be lower, or the video signal of the first field may be lower (depending on the image pickup tube).

Various methods have been proposed to correct this, but gamma (
γ) It is extremely difficult to maintain the same level, including image quality, due to changes in characteristics.

If two fields' worth of video signals are recorded as is, the first field's video signal will be recorded as follows:
[A level difference occurs between the second field and the video signal level, and this level difference inevitably causes flicker.

This makes the image very difficult to see.

Also, unless the human body is kept still during fluoroscopy, such as by stopping breathing, the organs of the human body move, so there will be a time lag between the video signals of the first and second fields, and if recorded in one frame, the organs of the human body will move. Since the image of the first field and the image of the second field are different, the image becomes a blurred image.

This condition tends to occur when fast movements are brought to a standstill.

To solve this problem, record in one field instead of one frame, and during playback, the skew distortion of the TV monitor and the roughness of the scan line structure of the image (which will be noticeable if the scanning line structure is not interlaced) are avoided. In order to prevent this, the operation is changed to the video signal of one field, which is played back sequentially in the field period, and the signal is delayed by % of the horizontal scanning period.
A plan has been taken to apparently interlace the images.

FIGS. 1 and 2 are diagrams showing conventional examples of the delay scanning.

In FIG. 1, reference numeral 1 denotes a magnetic disk which is rotated by a periodic motor at 3,600 per minute (60 Hz) and is configured so that one field of video signals is recorded in just one rotation.

Reference numeral 2 denotes a magnetic head for both recording and reproduction, which initially records one field of video signals from a television camera onto the magnetic disk 1, and reproduces this signal sequentially at field intervals from the next field onward.

Although this field reproduction signal is omitted in the figure, it is switched for each field by a gate switch, and the odd field signal valve is delayed by % of the horizontal scanning period by a delay element 3.

A continuous frame signal is obtained from the raw video signal of one field at the time of initial recording.

To explain this with reference to FIG. 3, first, one field of video signal A from a television camera is recorded on the magnetic disk 1.

This is sequentially reproduced at the field period as signal A' from the next field onward.

Then, by gate operation, the odd field is transferred to the delay element 3.
(this will be referred to as signal A), and the original video signal A is mixed so as to be temporally continuous and supplied to a television monitor as shown in d to obtain an apparently interlaced video. ing.

Figure 2 shows another conventional example, where 4 is a magnetic sheet per minute i, soo.
It is configured so that one frame (two fields) of video signal can be recorded in just one rotation.

Reference numeral 5 indicates a magnetic head for recording and reproducing, and 6 indicates a magnetic head exclusively for reproducing, which is formed at a geometric angle φ equal to % of the horizontal scanning period in the rotational direction from a position of the magnetic sheet 4 facing the magnetic head 5.

It is located at a different position. In this configuration, one field of video signals from a television camera is recorded on the magnetic sheet 4 by the magnetic head 5.

Then, from the next field onward, the magnetic head 6,
The data is reproduced via the magnetic head 5.

Using this and the video signal at the time of initial recording, we obtain a time-continuous video signal as shown in Figure 3d, similar to the case in Figure 1.
It is supplied to a television monitor to produce an apparently interlaced image.

Note that the gate operations for recording, reproducing, mixing, etc. of video signals are performed by well-known gate operations.

However, these conventional devices have the following problems.

That is, in order to obtain a frame signal that is apparently interlaced, in the first conventional example, the odd field signal valve is delayed by % of the horizontal scanning period via the delay element 3.
The performance of this delay element has many effects on the reproduced image after being delayed by % of the horizontal scanning period.

For example, if the delay element is a normal one, the frequency is narrow and spurious etc. become noticeable, and increasing the accuracy of the delay element by exactly % of the horizontal scanning period is not only expensive, but even if the delay element is Even if the accuracy is improved, the accuracy is lower than that of a signal that is reproduced directly from a recorded signal.

In addition, in the conventional example shown in FIG. 2, the delay operation is delayed by the reproducing magnetic head 6 due to mechanical positional relationship, but since the rotation speed of the magnetic sheet 4 is slow at 1,800 revolutions per minute, the frequency The thin acid becomes narrower, and one way to compensate for this is to increase the diameter of the magnetic sheet, but this would result in an increase in mechanical size.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the conventional devices, and to provide a compact, high-performance image recording and reproducing device with little deterioration in image quality.

A feature of the present invention is that the same field video signal is simultaneously recorded on two tracks, and during playback, one playback video signal is shifted from the other playback video signal by % of the horizontal scanning period using a playback magnetic head dedicated to each track. The reproduced image signal is alternately switched field by field and supplied to a television monitor as a pseudo-continuous video signal.

Hereinafter, the present invention will be described in detail along with examples.

FIG. 4 is a diagram showing a schematic configuration of an embodiment of the present invention.

In Figure 4, 7 rotates at 3,600 revolutions per minute, and 1 revolution per minute.
A magnetic disk on which a field video signal can be recorded, 8 is a first channel of the magnetic disk 7, and 9 is a second channel.

The first channel 8 is provided with a recording magnetic head (hereinafter simply referred to as a recording head) WHL and a reproducing head RH1 at an arbitrary angle φ1 in the rotational direction therefrom.

Further, the recording head WH1 of the first channel is inserted into the second channel 9, and from this recording head WH1, φ
The recording head WH2 is located in the rotation direction by an angle of 4, and the reproducing head RI-(2 is provided.

Also, 10 is a modulator, 11.12 is a recording amplifier, 13, 1
4 is a regenerative amplifier, C1 and C2 are gate switches, and 15 is a demodulator.

16 is a synchronous separation circuit, and 17 is a gate signal generator.

In the above configuration, when one field of video signal intermittently transmitted from a television camera is input to terminal C, it is FM-modulated by modulator 10.

This signal is branched and amplified by recording amplifiers 11 and 12, and simultaneously recorded on the first channel 8 and second channel 9 of the magnetic disk 7 via the recording heads WH1 and WH2 connected to each.

The video signal recorded by the recording head WH1 is transferred to the magnetic disk 7.
After rotating by an angle of φ1, the reproducing head RH1 sequentially reproduces the data at a field period.

On the other hand, the video signal recorded on the second channel 9 by the recording head WH2 at the same time is sequentially reproduced at the field period by the reproducing head RH2 after the magnetic disk 7 has rotated by an angle of φ2.

In other words, the reproduction signal of the field corresponding to the first channel is always equal to the reproduction signal of the second channel, which is a percentage of the horizontal scanning period.
It is reproduced as a signal delayed by the amount of time.

Each field reproduction signal is transmitted to a reproduction amplifier 13.14.
via gate switch G1. G2 alternately switches each field to produce a temporally continuous signal.

That is, first, the gate switch G1 is opened to allow the field reproduction signal of the first channel to pass, and then the gate switch G2 is opened to allow the field reproduction signal of the second channel to pass.

Thereafter, a frame signal is obtained by the field playback signal of the first channel and the field playback signal of the second channel in a similar manner so as to be temporally continuous, and an apparently interlaced TV image appears on the TV monitor. .

FIG. 5 is a time chart for explaining these operations, and the symbols of the signals corresponding to these are added to the block diagram of FIG. 4.

Note that the angle φ1 between the recording head WH1 and the reproducing head RH1 and the angle φ4 between the recording head WH1 and the recording head WH2 are 0<φ1 unless restricted by mechanical arrangement.
It can be arranged at any angle between 2π and 0<φ4<2π.

This means that in order to mount the reproducing heads RH1 and RH2 by shifting the H position of the horizontal scanning period on one track,
Although it is very difficult due to the mechanical size of each head, if the tracks are arranged in a staggered manner as in the present invention, for example,
By using tracks shifted by 1 crfL in the diametrical direction of the magnetic sheet, it is easy to arrange the recording heads WH1, WH2 and the reproducing heads RH1, RH2 so that they do not overlap, and they can be placed anywhere.

In addition, even if it is shifted by about 1 crn in the diametrical direction, electrically,
is hardly affected.

In other words, if the positional relationship between the recording heads WH1 and WH2 of each channel is maintained so that the video signals reproduced by the reproduction heads RH1 and RH2 of each channel are shifted by % of the horizontal scanning period, the relationship between O and 2π is maintained. You can place it anywhere.

In addition, if you want to use a large recording head and reproducing head, you can replace the recording head and reproducing head of the first channel and the recording head and reproducing head of the second channel with the recording head and reproducing head of the fourth channel.
As shown in the figure, they may be arranged so that the distance is about π/2.

It should be noted that the present invention is not limited to the embodiments described above, and can of course be modified in various ways without changing the gist thereof.

As described above, according to the present invention, a two-channel magnetic disk capable of recording and reproducing data in a field period, and two sets of recording heads and reproducing heads are appropriately arranged on the magnetic disk, and the delay is delayed by % of the horizontal scanning period. Since the recorded signal can be reproduced as the recorded signal, the apparatus becomes small and inexpensive without using an expensive delay element as in the conventional case, and a stable frame signal with high precision can be obtained.

As a result, the amount of X-rays to which a patient is exposed during X-ray fluoroscopy can be reduced, and an X-ray television image that is extremely good for diagnosis can be obtained.

[Brief explanation of drawings]

Figures 1 and 2 are schematic configuration diagrams of the recording and reproducing section of the conventional device;
FIG. 3 is an explanatory diagram of the operation of the conventional device, FIG. 4 is a block diagram of the configuration of an embodiment of the present invention, and FIG. 5 is a time chart. 7...Magnetic disk, WHL, WH2...
...Record head, RHl, RH2...Reproduction head, 10...Modulator, 11.12...
Recording amplifier, 15° river/° demodulator, 16... Synchronization separation circuit, 17... Gate signal generator, G1
．． G2...Gate switch.

Claims (1)

[Claims] 1. A two-channel endless magnetic disk capable of repeatedly recording and reproducing in a field period in an image recording reproducing device that continuously displays intermittent images on a television monitor even during periods of interruption; separately arranged on the periphery of the endless magnetic disk, and the two
two recording magnetic heads for simultaneously recording the same video signal on two channels; and two recording magnetic heads disposed at the periphery of the endless magnetic disk such that one has a phase difference of % of the horizontal scanning period from the other; Two reproducing magnetic heads for reproducing recorded video signals, and means for alternately switching the video signals reproduced by the respective reproducing magnetic heads field by field and supplying them to a television monitor as pseudo-continuous video signals. An image track reproducing device characterized by: