JPH04369977A - Slow motion camera - Google Patents

Abstract

PURPOSE:To obtain a slow motion picture without after image and picture distortion by using a solid-state image pickup element (CCD) as a photoelectric conversion element. CONSTITUTION:A prism group 16 is arranged on the emitting surface of an image pickup lens 2, and the prism group 16 resolves the light (subject) from an object 1 collected by the image pickup lens 2 into red, green, and blue lights and approximately halves the lights. On the emitting surface of the prism group 16, CCDs 17 to 22 are arranged, and the subject outputted from the prism group 16 is formed while transmitted to the CCDs 17 to 22. The CCDs 17 to 22 performs photoelectric conversion using a photodiode arranged on each light receiving part. In this case, the subject with the amplitude separated is photographed while deviating the time respectively by a plurarity of CCDs 17 to 22, and the storage time of the signal charge to each CCD 17 to 22 is shortened than the signal charge transfer time of each CCD 17 to 22.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television camera, and more particularly to a slow motion camera device that improves the dynamic resolution of a television camera, clearly captures the movement of a subject, and obtains good images.

0002

2. Description of the Related Art Conventional slow motion camera device technology will be briefly described.

[0003] A well-known method for photographing an object moving at extremely high speed in slow motion and clearly observing its movement is to photograph it with a high-speed film camera and project it at a low speed. This method has a major drawback in that it takes too much time to photograph, develop, and reproduce (project).

On the other hand, as a slow-motion camera device using a television camera, the scanning speed of a normal television camera (in the NTSC system, the horizontal scanning frequency is about 15.734 kHz, the field frequency is 59.94 H)
It is well known that a device has been put into practical use that obtains slow-motion images by speeding up z), recording it on a videotape recorder at high speed, and playing back the videotape recorded at high speed at a standard speed.

[0005] A well-known slow motion camera device will be briefly explained below with reference to the drawings. In FIG. 4, 1 is a subject, 2 is an imaging lens, 3 is a three-color separation prism, 4 to 6 are image pickup tubes, 7 to 9 are deflection coils, 10 to 12 are preamplifiers, 13 is a process, encoder, and frequency conversion circuit, 14 is a deflection circuit. A television camera is constituted by these elements numbered 2 to 14. 15 is a VTR.

To simplify the explanation of the operation, a television camera is referred to as a slow-motion camera device that operates at three times the speed of a standard television camera, that is, can record and play back slow motion at 1/3 times the speed. explain. Compared to a standard television camera (NTSC has a horizontal scan frequency of about 15.734 kHz and a field frequency of 59.94 Hz), this slow-motion camera has a horizontal scan frequency of 47.202 kHz and a field frequency of 17.98 Hz. Operate. standard 3
In order to operate at twice the speed, the deflection circuit 14 supplies a deflection signal with three times the frequency to the deflection coils 7-9. Although the actual deflection coil requires two directions, horizontal and vertical, one of the deflection coils is not shown in FIG.

After the object image from the object 1 is focused by the imaging lens 2, it is separated into red (R) by the three-color separation prism 3.
), green (G), and blue (B), and is separated into three primary colors:
6. The subject images formed on the image pickup tubes 4 to 6 are photoelectrically converted by the image pickup tubes. The photoelectrically converted subject image is converted by an electron beam deflected by a deflection yoke.
It is read out as a signal current, amplified by preamplifiers 10 to 20, and taken out as red, green, and blue signal voltages.
The signal is supplied to the process encoder circuit 13. The process encoder circuit 13 converts the red, green, and blue signals into a composite color television signal at three times the standard speed, and then the frequency conversion circuit converts it into a normal frequency color television signal, which is then supplied to the VTR 15. do. VTR15
has three recording heads, and the recording drum rotates when recording standard NTSC signals.
The tape being recorded is running at three times the standard speed. Therefore, a video signal at three times the standard speed is recorded on the VTR tape. If the tape recorded in this manner is played back at a standard drum rotation speed and a standard tape running speed, a 1/3 speed slow motion image can be obtained.

[0008] Furthermore, a VTR uses one recording head,
There is also a method in which recording is performed by rotating and running the drum and tape at three times the standard speed, and during slow-motion reproduction, the normal rotation and tape running are performed to obtain a slow-motion image at one-third the speed.

[0009]

However, in the slow motion camera device having the above configuration, the dynamic resolution does not improve and the resulting slow motion image has blurred outlines. Further, it has the disadvantage that the image is distorted, for example, the handle of a golf club moving at high speed appears bent as shown in FIG.

Among these drawbacks, the cause of the blurring of the outline of the image is due to the afterimage phenomenon of the image pickup tube, and the reason why the handle of a golf club moving at high speed appears curved is due to the difference in signal charge between the upper and lower parts of the screen. This is because the accumulation timing is shifted.

SUMMARY OF THE INVENTION The present invention aims to solve the above-mentioned drawbacks and to provide a slow-motion camera device that can obtain slow-motion images with high dynamic resolution and no image distortion.

0012

Means for Solving the Problems In order to achieve the above object, the present invention provides an imaging lens for forming a subject image on the light receiving surface of a plurality of image sensors, and an imaging lens and an imaging lens for forming an image on the light receiving surface of a plurality of image sensors. An optical system is provided between the surfaces to amplitude-separate a subject image focused by an imaging lens into a plurality of images, and the amplitude-separated subject images are captured by a plurality of image sensors at different times, and By making the accumulation time of signal charges in the image sensor shorter than the signal charge transfer time of the image sensor, compressing the time axis of the image sensor output signal using an electric circuit, and recording and reproducing the time axis compressed signal on a VTR. It has a configuration for obtaining slow motion images.

[0013]

[Operation] With the above-described configuration, the present invention forms images on two series of image sensors, and the two series of image sensors are approximately 1/3 of the standard operation.
A signal charge is accumulated in the photodiode only during the period of , since the recorded tape is recorded on a tape-running VTR and played back at standard speed, it is possible to obtain high-quality slow motion with high dynamic resolution and no image distortion.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

Before explaining the present invention, the principles of the present invention will be explained. In the present invention, a solid-state image sensor is used as a photoelectric conversion element in order to solve the conventional drawbacks. The present invention includes a so-called CCD solid-state imaging system, which has an independent photoelectric conversion section for each pixel, typically a photodiode, etc., and uses a charge-coupled device to transfer signal charges in the vertical and horizontal directions. element.

The simplest means to solve the drawbacks of the prior art is to replace the image pickup tubes 4 to 6 shown in FIG.
There is a method in which a CCD solid-state image sensor is driven at three times the normal speed instead of a solid-state image sensor.

However, it is well known that the CCD solid-state image sensor transfers signal charges obtained by photoelectric conversion using a photodiode in the vertical and horizontal directions and reads them out as signal voltages. Generally, in the case of NTSC system, CC
The number of pixels in the vertical direction of the D solid-state image sensor is approximately 500 pixels, and the number of pixels in the horizontal direction is approximately 500 to 800 pixels.The standard operating speed, that is, the transfer frequency, is 15.734kHz in the vertical direction and The direction transfer frequency is 9.5MHz for 500 pixels and 14MHz for 800 pixels.
．． It is about 32MHz. In order to obtain slow-motion images at 1/3x speed, the CCD solid-state image sensor is
It must be driven at twice the frequency. That is, the vertical direction is 47.202kHz, and the horizontal direction is 28.5-42kHz.
．． Transfer must be performed at frequencies as high as 95 MHz. In the current CCD solid-state image sensor, three major problems occur when signal charges are transferred in the horizontal direction at such a high transfer frequency.

The first problem is that because the horizontal transfer frequency becomes high, sufficient transfer efficiency cannot be obtained, and the screen becomes extremely blurred in the horizontal direction. The blur in the horizontal direction of the screen differs greatly in the left and right directions of the screen; in other words, on the left side of the screen, there is a small number of transfer steps, so the amount of blur is small, and on the right side of the screen, there are many transfer steps, so the amount of blur is extremely high. The second problem is that when a high frequency is transferred in the horizontal direction, the CCD solid-state image sensor itself generates heat, which results in an increase in dark current and a deterioration of the signal-to-noise ratio. The third problem is that it is difficult to realize a drive circuit for driving the CCD solid-state image sensor at such a high frequency. That is, the horizontal transfer stage is capacitive and 10
Needless to say, since the CCD has a capacitance of 0PF or more, it is extremely difficult to realize a drive circuit for applying a drive pulse of several +MHz and an amplitude of several V to the CCD.

The present invention eliminates the above-mentioned disadvantages caused by driving a CCD solid-state image sensor at high speed (approximately three times the standard driving speed) and eliminates the drawbacks of slow-motion cameras using image pickup tubes. It is something to be overcome.

As is well known, CCD solid-state imaging devices have extremely less afterimage compared to image pickup tubes, and CCD solid-state imaging devices are of a type in which signal charges are read out through vertical and horizontal transfer stages consisting of photodiodes and CCDs. In other words, in an interline solid-state image sensor (hereinafter abbreviated as IT-CCD), the signal charges accumulated in all the photodiodes in the light receiving section are simultaneously transferred to the vertical transfer stage, so the timing of accumulation of signal charges at the top and bottom of the screen is different. Since the images will not shift, when slow-motion playback is performed, the images will look natural as shown in FIG. In other words, if an IT-CCD or FIT-CCD is used instead of an image pickup tube in a slow-motion camera, it is possible to obtain a slow-motion image with high dynamic resolution, that is, with sharp image contours and no image distortion. can. The problem to be solved here is to eliminate the adverse effects caused by driving the CCD solid-state image sensor at several times the normal frequency.

In this embodiment, to simplify the explanation, a triple-speed camera output signal is obtained, and it is transmitted to a VTR at normal playback speed.
An example will be explained in which a 1/3 slow motion image is obtained by reproducing the image.

In FIG. 1, 1 is a subject, 2 is an imaging lens, 16 is a prism group, 17 to 22 are CCD solid-state image sensors, 23 to 28 are preamplifiers, 29 to 34 are process circuits, 35 is a frequency conversion circuit, and 36 is a synchronization signal generator, 3
7 is a CCD drive pulse generator and a CCD drive circuit, 3
8 is a VTR. A subject image from a subject 1 is focused by an imaging lens 2. A prism group 16 is arranged on the exit surface side of the imaging lens, and the prism group 16 separates the light from the object (subject image) focused by the imaging lens 2 into red, green, and blue light. , green, blue light by about 1/
The light is split into two parts. C on the exit surface of the prism group 16
CD image sensors 17 to 22 are arranged, and the subject images output from the prism group 16 are CCDB1 and CCDB2.
, CCDG1, CCDG2, CCDR1, and CCDR2 to form an image. The CCDs 17 to 22 perform photoelectric conversion using photodiodes placed in their respective light receiving sections. The signal charge obtained by photoelectric conversion by the photodiode is transferred to vertical and horizontal transfer stages, taken out from the CCD as a voltage signal, supplied to preamplifiers 23 to 28, and after removing unnecessary noise components, it is converted to an arbitrary amplitude signal. is amplified. The preamplifier output signals are supplied to process circuits 29 to 34, respectively, and subjected to signal processing. Each process circuit 2
After converting the output signals 9 to 34 into standard video signals (television camera output signals), they are supplied to the frequency converter 35. The frequency converter consists of a memory and a memory control circuit. In this example, to simplify the explanation, the input signal (standard frequency, horizontal scanning frequency 15.734
kHz, vertical scanning frequency 59.94 Hz) to three times the frequency (horizontal scanning frequency approximately 47.20 kHz, vertical scanning frequency approximately 180 Hz). The output signal of the frequency converter 35 is supplied to a VTR 38 whose drum rotation speed is three times the standard speed and whose tape running speed is three times the standard speed and is recorded. The synchronization signal generator 36 is for operating all of the slow motion camera devices in a synchronized manner, and the output signal of the synchronization signal generator 36 is used for the frequency converter 35, the process circuits 29 to 34, and the CCD drive pulse. The signal is supplied to a generator 37 and a VTR 38. The output signal of the CCD drive pulse generator 37 is sent to the preamplifiers 23 to 28.
Also supplied. The CCD drive pulse generator and CCD drive circuit 37 output various pulses necessary for driving the CCD. The output signal of the CCD drive circuit 37 is the CCD
17 to CCD 22, and the CCD is driven at a frequency 1.5 times the standard frequency.

However, in order to obtain a triple-speed camera output signal, the first
and a second camera system consisting of CCDB2, CCDG2, and CCDR2 are driven with timings shifted by 1/2 field, and CCD17 to C
The accumulation time for each photodiode of the CD 28 must be set to 1/3 of the accumulation time when driven at the standard frequency.

Hereinafter, using FIG. 2, CCD17, CCD1
9. First camera series consisting of CCD21 and CCD18
, CCD 20, and CCD 22 will now be explained. In FIG. 2, (a) shows a field period of a normal television system (NTSC system in this embodiment), where 1F represents a first field period and 2F represents a second field period. FIGS. 2(b) and 2(c) show the operation timings of the CCDs of the first camera series and the second camera series, respectively. In this embodiment, a well-known CCD solid-state image sensor is used. Since the CCD solid-state image sensor is well known, its explanation will be omitted. In the figure, the period marked as accumulation indicates the period of signal charge accumulation in the photodiode of the solid-state image sensor, and at the timing marked as readout, the signal charge accumulated in the photodiode is read out to the vertical transfer stage. Vertical and horizontal transfer of signal charges is performed during the period marked as transfer.
It is extracted from the CD as a voltage signal. Figure 2(d),
(e) is C of the first camera series and the second camera series
It shows the timing of the shutter pulse applied to the CD. As is well known, in a CCD solid-state image sensing device, by applying a high voltage pulse to the substrate of the CCD, signal charges accumulated in the photodiode can be drawn out to the substrate, that is, discarded. Therefore, the accumulation period for accumulating signal charges in the photodiode of the CCD image sensor can be controlled by manipulating the timing of applying the shutter pulse. The signal charge accumulation period is the period from after the shutter pulse is applied until the CCD read pulse is applied to the CCD.

FIGS. 2(f) and 2(g) show CCDs 17, 19,
21, that is, the first camera series and CCDs 18, 20,
22, that is, the output signal of the second camera series, that is, the output signal of the process circuits (29) to (34). The CCDs of the first camera series and the second camera series are relatively 18
It is driven with a phase of 0° (timing shifted by 1/2 field). Therefore, the first camera series and the second camera series have a normal field period (N
(59.94Hz for TSC), the output signal is 1/
The timing is shifted by three fields at a time. However, the drive timings of the shutter and CCD are changed so that the accumulation of signal charges changes sequentially from the first CCD series to the second CCD series to the first CCD series. C.C.
The output signals of D17 to CCD22 are supplied to the frequency converter 35 after being subjected to signal processing via a preamplifier and a process circuit. The frequency converter 35 is composed of three field memories and a memory control circuit, and converts the input frequency and output frequency. In other words, when storing in memory, it is stored at the normal frequency (Fig. 2 (f) (g
), and when reading from the memory, it is read at a frequency twice the frequency to be stored (written to the memory), and by switching the signals of the three field memories, the first camera series and the second camera images with a frequency three times the standard frequency can be obtained in the order of the first camera series and the first camera series. In the VTR 38, the drum rotates at three times the standard speed and the tape runs at three times the standard speed, and the output signal of the frequency converter 35 is recorded on a video tape. If a recorded videotape is played back at standard speed, slow motion images at 1/3 speed can be obtained.

As described above, according to the slow motion camera device according to the embodiment of the present invention, an object image is formed on two series of photographing elements, and these photographing elements have a speed of 1/3 of the standard operating speed.
The signal charge is accumulated for only a period of Play back to get slow motion images at 1/3x speed.

In this embodiment, after the subject image is separated into three colors, the subject image of the separated colors is amplitude-separated and divided into two.
Although we have explained the case where the subject image is separated into a series of images, it cannot be said that the same effect can be obtained by separating the amplitude of the subject image using a prism group and capturing the amplitude-separated subject image with a single-chip camera. Don't wait. Also, VT as a recording medium.
Although the description has been made using R as an example, the recording medium may be a semiconductor memory or an optical disk.

[0028]

As is clear from the above embodiments, the present invention provides a slow motion camera device that can obtain slow motion images with high dynamic resolution, sharp image contours, and no image distortion. Can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a slow motion camera device according to the present invention.

[Figure 2] Timing chart of the solid-state image sensor and video signals in the device

[Figure 3] A schematic diagram showing an image when a moving object is imaged using the CCD solid-state image sensor in the same device.

[Figure 4] Block diagram showing the configuration of a conventional slow motion camera device

[Figure 5] Schematic diagram showing reproduced images in the same device

[Explanation of symbols]

2 Imaging lens 16 Prism group 17-22 CCD solid-state image sensor 37 CCD drive pulse generator, CCD drive circuit 36
synchronous signal generator

Claims (1)

[Claims] 1. An imaging lens for forming a subject image on a light-receiving surface of a plurality of image sensors, and a subject whose light is focused by the imaging lens between the imaging lens and the imaging surface of the plurality of image sensors. comprising an optical system that amplitude-separates an image into a plurality of images, captures the amplitude-separated subject images from the plurality of image pickup elements at different times, and accumulates signal charges in the image pickup elements; A slow motion camera device in which the time is shorter than the signal charge transfer time of the image sensor.