JPH0197079A - Image pickup system - Google Patents

Abstract

PURPOSE:To load a small-sized view finder at low cost by setting a scan period in a vertical direction from the upper end to the lower end of a display surface displaying the output of a video camera reading video signals for one field in a second prescribed period shorter than one field period to less than the second prescribed period. CONSTITUTION:An image pickup part 55 scans the screen of an aspect ratio 9:10 by 315 horizontal scanning lines and outputs R, G and B signals with the effective screen as 262.5 lines. The R, G and B signals are turned into a luminance signal Y and two color difference signals I and Q in a matrix circuit 56 are respectively processed, are mixed with FM modulated audio signals which have been time base-compressed into 5/6 in an adder 54, and are supplied to heads Ha and Hb through a switch 11. The heads Ha and Hb respectively record the video signals for one field while they respectively rotate 300 deg.. The R, G and B signals obtained from the image pickup part 55 are supplied to an image-receiving tube 17. The inclination of a vertical deflection current (except for vertical flyback time) and that of a horizontal deflection current are set to 1.2 times as much as a normal receiver, and a picture outputted from the image pickup part 55 can be displayed in a whole display surface.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an imaging system, and particularly to an imaging system that records a video signal obtained by imaging on a recording medium and displays it on a display device.

<Prior Art> In this specification, a camera-integrated video tape recorder (VTR) equipped with a so-called electronic viewfinder will be described as an example of this type of system.

Generally, a so-called rotating two-head helical scan type VTR is known for home use. Figure 5 shows this type of VT
It is a figure which shows the arrangement|positioning of the R head. In FIG. 5, l is a magnetic tape and 2a.

2b is a tape guide for winding the tape 1 around the outer periphery of the rotating drum 3 over an angular range of 180'' or more.

HA and HB are rotating heads that are respectively attached to the rotating drum 3 with a phase difference of 180'' and have different azimuth angles. The video signal for one field is recorded and played back.

In this type of VTR, since the track length of one field's worth of video signals is predetermined in the standard, the diameter of the rotating tram 3 is necessarily determined accordingly. Therefore, the diameter of this drum cannot be made smaller, which hinders the reduction in size and weight of VTRs.

Therefore, the following VTR' has been proposed and implemented as a VTR capable of reducing the drum diameter. FIG. 6 is a diagram showing the head arrangement in a conventional VTR having a small diameter drum. In the figure, Ha and Hb are rotary heads having different azimuth angles, and rotate once during one field period of the video signal. The tape 1 is wound around the drum 4 over an angular range of 300'' or more, and the rotary heads Ha and Hb each record one field of video signals while rotating 300''.

That is, one field's worth of video signal is recorded in a period shorter than the original frame period of the video signal.

Therefore, the video signal recorded by this type of VTR is N.
When assuming a TSC signal, a normal NTSC signal, that is, the vertical scanning frequency (fv) is 60Hz and the horizontal scanning frequency (fv) is 60Hz.
H) or fv is 60Hz instead of 15.75KHz signal, f
Must be H or (15,75xu+) 18.9KHz.

In other words, the video signal recorded by this type of VTR must be a normal television signal time-axis compressed to 5/6 in units of one field, or a signal obtained from a special camera.

The above-mentioned dedicated video camera scans a screen with an aspect ratio of 9:1O (indicated by the dotted line Y in Figure 7).
A screen with an aspect ratio of 3:4, indicated by a solid line X' in the figure, is output as an effective screen within a 5/6 field period, and the head Ha is output.

Record in Hb.

The timing at the time of recording will be explained using the timing chart of FIG. 8. During the period indicated by T in the figure, a video camera (not shown) scans seven screens with an aspect ratio of 9:10, and generates a video signal consisting of 315 consecutive horizontal scans as shown in Figure 8(a). obtain.

However, since the heads Ha and Hb actually trace the tape L for 5/6 of the time in each field period, 262.5 horizontal scans are shown in Figure 8 (
As shown in b), the video signal is taken out and recorded on a magnetic tape as a video signal with an aspect ratio of 3:4. At this time head H
Since a and Hb are traced alternately on the magnetic tape, the sixth
The VTR with the head arrangement shown in the figure can perform recording similar to the VTR with the head arrangement shown in FIG. However, since it is necessary to provide a slight phase difference between the heads Ha and Hb at this time, it is necessary to appropriately delay the video signal of the first field or the second field.

If a video signal is recorded as described above with the head arrangement as shown in FIG. 6, the drum diameter can be reduced to the VTR 315 shown in FIG.

<Problems to be solved by the invention> A camera-integrated V consisting of a camera and a VTR as described above
In TR, the video signal handled is different from a normal video signal, and there is no video signal for 1/6 of the L field period.Therefore, this type of camera-integrated VTR is equipped with an electronic viewfinder. has not been traditionally considered.

Therefore, it is conceivable to use variable extension or field memory to extend the time axis to 615 times with one field worth of video signal output from the camera as one unit, and form a video signal similar to a normal video signal. However, providing these variable delay lines and field memories, as well as providing a control circuit for them, increases the scale of the device, which is not desirable for reducing the size, weight, and cost of the camera-integrated VTR.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a low-cost imaging system that is small and lightweight and includes an electronic viewfinder.

<Means for Solving the Problems> With this objective in mind, the imaging system of the present invention transmits video signals for l fields every first predetermined period to a second predetermined period shorter than the first predetermined period. a video camera that reads data over a period of time, and a track is formed on a recording medium at each of the first predetermined periods, and one field worth of video signal output from the video camera is recorded on each track for the second predetermined period. and a display device in which a scanning period in the vertical direction from the top end to the bottom end of the display surface for displaying an image related to the video signal output from the video camera is equal to or less than the second predetermined time period. It is something.

By configuring as described above, the video signal output from the camera can be displayed as is on the display device, and a low-cost, compact imaging system can be provided without providing a variable delay line, field memory, etc. .

<Embodiment> An embodiment in which the present invention is applied to a system including a VTR having a head arrangement as shown in FIG. 6 will be described below.

FIG. 1 is a block diagram showing a schematic configuration of the main parts of an image recording system as an embodiment of the present invention, where 1 is a magnetic tape, and Ha and Hb are rotating helads arranged in the same manner as in FIG. 6. .

The audio signal obtained from the microphone 51 is supplied to a time-base compression circuit 52 and is time-base compressed to 5/6 in l field units. This time axis compression circuit 52 can be easily realized by using a memory capable of storing, for example, an l-field periodic audio signal, and by setting its reading speed to 615 times the writing speed.

The audio signal output from the time axis compression circuit 52 is subjected to well-known processing such as FM modulation and pre-emphasis in an audio signal recording processing circuit 53 and then supplied to an adder 54 . However, the operating frequency of the processing circuit 53 is 1.2 times that of a VTR having a normal head arrangement as shown in FIG.

As described above, the imaging unit 55 scans a screen with an aspect ratio of 9:1O using 315 horizontal scanning lines, and outputs the effective screen as 262.5 lines as R2O and B signals. These R, G, and B signals are combined with a luminance signal (Y) in a matrix circuit.
The two color difference signals (I, Q) are processed, and Y is subjected to processing such as FM modulation in a luminance signal recording processing circuit 57 and supplied to an adder 54. I and Q are quadrature two-phase modulated by a low frequency carrier signal in a balanced modulator 58 so that they are arranged in a band lower than the band of the FM modulated audio signal output from the audio signal recording processing circuit 53, and the carrier color is Get a signal. This carrier color signal is sent to an adder 54 via a carrier color signal recording processing circuit 59 that performs processing such as ACC and side hand emphasis.
is supplied to

The adder 54 records the mixed signal of the FM modulated luminance signal, the low frequency carrier color signal and the FM modulated audio signal on the magnetic tape L by the heads Ha and Hb via the R side terminal of the switch 4''1. The pattern recorded in this way is printed on a conventional V-shaped head having the head arrangement shown in FIG.
It is well known that a pattern similar to TR can be formed.

The R, G, and B signals obtained from the imaging section 55 are supplied to the picture tube 17. Further, the luminance signal synchronously added by the matrix circuit 56 is supplied to the synchronization separation circuit 18, which determines the deflection timing of the subsequent vertical and horizontal deflection circuits 19 and 20.

3 is a diagram for explaining the operation of the vertical deflection circuit 19, FIG. 4 is a diagram for explaining the operation of the horizontal deflection circuit 20, and FIG. 2 is a diagram for explaining the operation of the picture tube 17.
FIG. 3 is a diagram schematically showing a display surface 17a of FIG.

As is well known, the vertical and horizontal deflection circuits provide a sawtooth flow to each deflection coil. However, in the deflection circuit of this system, the deflection speed, that is, the scanning speed on the screen is 1.2 times that of a television receiver to which a normal video signal is supplied.

3(a) shows the envelope waveform of the video signal output from the imaging unit 55, FIG. 3(b) shows the vertical synchronization signal, and FIG. 3(c) shows the vertical deflection current input to the vertical deflection coil 21. The slope of the vertical deflection current is 1.2 times that of a normal receiver, excluding the vertical retrace period T, and the difference in deflection current while the effective screen is displayed (indicated by Iυ in the figure) is It is set so that the electron beam is deflected by a distance #Dυ or more from the upper end to the lower end of the display surface 17a in the figure.

FIG. 4(a) schematically shows the video signal output from the imaging section 55, and FIG. 4(b) shows the horizontal deflection current input to the horizontal deflection coil 22.The slope of this horizontal deflection current is also
This is 1.2 times that of a normal receiver. Here, since the horizontal scanning period is 5/6 of the normal video signal, the difference Ih between the maximum value and the minimum value of the horizontal deflection current is the same as that of a normal TV receiver, and the distance Dh between the left and right ends on the display surface 17a It is set to give the above deflection to the electron beam.

In this way, the image related to the video signal output from the imaging section 55 can be displayed on the entire display surface.

According to the imaging system configured as described above, it is possible to use a small-diameter rotary head drum as shown in FIG. 6 and to mount an electronic viewfinder without using a large-capacity memory or the like.

In the above embodiments, a picture tube is used as the image display element, but a liquid crystal display may also be used. In this case as well, the horizontal and vertical scanning speeds are set to 1
．． It is sufficient to vertically scan from the top end to the bottom end of the display surface during a period of 5/6 field or less in which the reproduction signal is doubled.

<Effects of the Invention> As described above, according to the present invention, it is possible to obtain an imaging system equipped with an electronic viewfinder that is small, lightweight, and low cost.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a schematic configuration of a system as an embodiment of the present invention, Fig. 2 is a diagram schematically showing a display surface, Fig. 3 is a timing chart showing vertical deflection operation, and Fig. 4 is a horizontal diagram. The timing chart in Figure 5 showing the deflection operation is for a rotating two-head helical scan type VTR.
Figure 6 shows the head arrangement of a conventional VTR with a small diameter rotating head drum.
The figure which shows head arrangement in . FIG. 7 is a diagram for explaining scanning by a VTR-dedicated video camera having the head arrangement shown in FIG. FIG. 8 is a timing chart during recording in a VTR having the head arrangement shown in FIG. 1 is a magnetic tape, 17 is a picture tube, 17a is a display surface, 18
19 is a synchronous separation circuit, 19 is a vertical deflection circuit, 20 is a horizontal deflection circuit, 21 and 22 are deflection coils, 55 is an imaging unit, H
a, Hb is a rotating head.

Claims (1)

[Claims] a video camera that reads one field of video signals every first predetermined period in a second predetermined period shorter than the first predetermined period; and a video camera that forms a track on a recording medium every first predetermined period. , a recorder for recording one field worth of video signal output from the video camera in each track for the second predetermined period, and a display screen for displaying an image related to the video signal output from the video camera from the upper end of the display surface. An imaging system comprising a display device whose vertical scanning period to the bottom end is equal to or less than the second predetermined period.