JP3783284B2 - Imaging device - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to an imaging device that captures a subject image and outputs an obtained image signal.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an imaging apparatus using an imaging element such as a CCD (Charge Coupled Devise), for example, a video camera, an object image formed on the CCD via an optical system including a condenser lens is captured by the CCD. Photoelectrically converted, image processing signals from the CCD are subjected to white balance adjustment processing, gamma (γ) correction processing, white clip processing, knee processing, and other process processing, and the resulting video signal is output as video It is said.
[0003]
Further, in recent image pickup devices, when the accumulated charges accumulated in the plurality of light receiving portions constituting the CCD are taken out, the accumulated charge in the light receiving portion corresponding to the odd field (odd field) and the even field (even field). There is a method in which a so-called all-pixel reading method is used in which the accumulated charge of the corresponding light receiving unit is read simultaneously every vertical blanking period.
[0004]
That is, in the case of this all-pixel readout method, the image pickup signal read from the light receiving section corresponding to the odd field (hereinafter referred to as the odd field imaging signal) and the light receiving section corresponding to the even field in the CCD output. The read imaging signal (hereinafter referred to as an even field imaging signal) is obtained by imaging at the same time. More specifically, referring to FIG. 4, in the case of the all-pixel readout method, as shown in FIG. ₁ And evenfield imaging signal E ₁ Are imaged at the same time, and the odd-field image signal O ₂ And evenfield imaging signal E ₂ Odd field imaging signal O _Three And evenfield imaging signal O _Three ... Are also obtained by imaging at the same time.
[0005]
On the other hand, video signals output from the video camera to the outside correspond to, for example, the NTSC (National Television System Committee) system, the PAL (Phase Alternation by Line) system, the SECAM (sequential a memoire color television system) system, and the like. If it is, it will be output in the order of odd field and even field. For this reason, as shown in FIG. 4B, the odd-field imaging signal O ₁ And evenfield imaging signal E ₁ In this case, the image signal O generated from the imaging signal of the odd field first. ₁ (Hereinafter referred to as an odd-field image signal) is output, and then the image signal E generated from the even-field imaging signal is output. ₁ (Hereinafter referred to as an even field image signal) is output, and the next odd field imaging signal O is output. ₂ And evenfield imaging signal E ₂ Is discarded and the imaging signal O of the next odd field is _Three And evenfield imaging signal O _Three Then, the image signal O of the odd field is firstly displayed. _Three Is output, and then the even field image signal E _Three Will be output. The same applies to the imaging signals of the subsequent fields.
[0006]
As described above, in the above-described all-pixel readout imaging device, the odd-field and even-field imaging signals obtained by imaging with the CCD at the same time are divided in time so that the even field comes after the odd field. At the same time, an odd-field image signal and an even-field image signal generated from the respective imaging signals are connected in order and output as a video signal.
[0007]
[Problems to be solved by the invention]
The video signal output from the video camera is sent to an external device. As the external device, a monitor device, a digital still recorder, a digital printer, or the like can be considered. The digital still recorder is an image recording apparatus that extracts and records still images from moving image signals, and the digital printer is a printing apparatus that extracts and prints still images from moving image signals.
[0008]
By the way, the video signal output from the video camera is a moving image signal. However, in the digital still recorder and the digital printer, one frame is generated from two continuous fields of the moving image signal output from the video camera. Minute images are generated, and this frame image is taken out as a still image.
[0009]
However, the digital still recorder and the digital printer usually do not perform field discrimination for the output moving image signal of the video camera. For this reason, in these digital still recorders and digital printers, the image for the two consecutive fields taken out from the output moving image signal of the video camera when the frame image is generated is taken by the video camera at the same time. Things can happen that are n’t.
[0010]
Here, when the subject photographed by the video camera is stationary and the photographing is performed with the video camera still, the frame image is generated by the digital still recorder or the digital printer. Even if the images for the two consecutive fields are taken at different times, for example, there are few problems.
[0011]
However, when the subject photographed by the video camera is moving, or when photographing is performed while the video camera is moved by panning or tilting, the above-mentioned digital still recorder or digital printer is photographed at different times. If the frame image is generated from one field, the frame image is shifted for each field, and the quality of the finally obtained still image is deteriorated.
[0012]
That is, for example, as shown in FIG. 4B, the output video signal from the video camera repeats an odd-field image signal and an even-field image signal in this order. When generating a frame image, for example, the even-field image signal E is used as the continuous two-field image signal. ₁ And Oddfield image signal O _Three And the even-field image signal E ₁ And Oddfield image signal O _Three Are taken at different times, so that the frame images generated from them are shifted in field images, and therefore the quality of the still image finally obtained is lowered.
[0013]
Therefore, the present invention has been made in view of the above-described problems. For example, an imaging apparatus for enabling a good still image to be generated in an external device such as a digital still recorder or a digital printer. The purpose is to provide.
[0014]
[Means for Solving the Problems]
An imaging apparatus according to the present invention includes an optical system that forms a subject image, and a conversion unit that photoelectrically converts incident light from the optical system and generates image signals of the first field and the second field captured at the same time. Storage means for storing the image signal, write / read control means for controlling writing and reading of the image signal in the storage means, and the storage means for the first field and the second field from the conversion means. Trigger pulse generating means for generating a write trigger pulse indicating the timing for writing an image signal, and the first field of the field determination pulse for determining the first field and the second field according to the write trigger pulse. Write enable generation means for generating a write enable signal synchronized with the timing, and In response to the field discrimination pulse, the first field image signal and the second field image signal are read out in this order and output to the outside, and the write enable is synchronized with the output timing of the first field at this time. The above-described problem is solved by outputting the signal to the outside as a signal for taking in the image signal.
[0015]
That is, according to the present invention, the image signal and the write enable signal are synchronized, and the image signal and the write enable signal are output to the outside. Therefore, the external device can capture the image signal in synchronization with the write enable signal.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0017]
FIG. 1 shows an example of the internal configuration of a video camera 30 as an embodiment of the imaging apparatus of the present invention.
[0018]
The video camera 30 employs the all-pixel readout method, and further uses so-called three-plate CCDs that generate imaging signals of red (R) light, green (G) light, and blue (B) light using three CCDs. The example which applied is given. Of course, in consideration of cost reduction and downsizing of the configuration, it is possible to use a normal video camera that uses only one CCD instead of a three-plate CCD. The present invention is also applicable in this case.
[0019]
In FIG. 1, light from a subject or the like incident through an optical system 1 is guided to a color separation prism 2. The optical system 1 includes an imaging lens for forming an image on a CCD, which is a conversion means for photoelectrically converting light from a subject, for example, for adjusting the amount of light or setting the depth of field as necessary. It has an aperture mechanism, a lens drive mechanism for focusing, and the like, and further includes an infrared cut filter, an ultraviolet cut filter, and the like as necessary. Further, the color separation prism 2 is constituted by, for example, a dichroic prism, and the incident light that has passed through the optical system 1 is separated into red (R) light, green (G) light, and blue (B) light, and these are separated. Of the light of each color, R light is converted into R CCD 3 _R To G light CCD3 _G To the B CCD 3 for B light _B Lead to each.
[0020]
These CCD3 _R , 3 _G , 3 _B From the above, in accordance with CCD readout pulses such as a vertical transfer pulse and a horizontal transfer pulse from the timing generator 20, the accumulated photocharges are taken out as R, G, and B imaging signals, respectively. These CCD3 _R , 3 _G , 3 _B Then, when taking out the accumulated charges accumulated in the plurality of light receiving portions constituting the CCD, respectively, the light accumulated in the light receiving portion corresponding to the odd field as the first field and the light receiving portion corresponding to the even field as the second field. A so-called all-pixel readout method is used in which the accumulated charges are simultaneously read out. In the video camera 30 of FIG. _R , 3 _G , 3 _B It is also possible to apply a so-called pixel shift technique for suppressing pseudo signals and improving resolution by shifting the positions of the pixels and fixing them. When this pixel shifting method is used, each CCD 3 _R , 3 _G , 3 _B The arrangement of CCD 3 for R and B _R , 3 _B CCD3 for G _G Are offset by a ½ pixel pitch in the horizontal direction. When this pixel shifting method is applied, each CCD 3 _R , 3 _G , 3 _B The G image signal and the R and G image signals are sampled in a complementary manner, and a video signal having a frequency of 1/2 or more of the sampling frequency does not become a pseudo signal, so that a high resolution can be obtained. become.
[0021]
CCD3 above _R , 3 _G , 3 _B The timing generator 11 that generates the CCD readout pulse supplied to the signal generator includes, for example, a high-frequency oscillator, and generates the CCD readout pulse based on a vertical drive pulse VD and a horizontal drive pulse HD from a sink generator 12 described later.
[0022]
CCD3 above _R , 3 _G , 3 _B The R, G, and B imaging signals from the sampling circuit 4 provided in correspondence with each other. _R , 4 _G , 4 _B Sent to. These sampling circuits 4 _R , 4 _G , 4 _B Then, the random noise of the CCD is reduced by performing correlated double sampling on each of the supplied imaging signals.
[0023]
These sampling circuits 4 _R , 4 _G , 4 _B Each of the R, G, and B imaging signals subjected to correlated double sampling in FIG. _R , 5 _G , 5 _B After being amplified by the analog / digital conversion circuit (hereinafter referred to as A / D conversion circuit) 6 _R , 6 _G , 6 _B Respectively converted into digital signals. Here, each A / D conversion circuit 6 _R , 6 _G , 6 _B Then, each CCD3 _R , 3 _G , 3 _B Each image pickup signal is digitally converted by using a clock having the same frequency as the sampling clock in FIG. In the example of FIG. 1, the A / D conversion circuit 6 _R , 6 _G , 6 _B However, it is also possible to use one that digitally converts the R, G, and B imaging signals in one chip. For example, when the above-described pixel shifting method is applied, the A / D conversion circuit 6 for G _G In the A / D conversion circuit 6 for R and B, the pixel shifting effect can be obtained. _R , 6 _B Digital conversion is performed with a clock whose phase is 180 degrees behind.
[0024]
A / D conversion circuit 6 _R , 6 _G , 6 _B R, G, B imaging signals output from the above, that is, the CCD 13 _R , 13 _G , 13 _B Each pixel data corresponding to each light receiving unit is sent to a video memory 7 which is a frame memory. In the video memory 7, writing and reading are controlled by the memory controller 13. Further, the video memory 7 is not limited to a single configuration, and three video memories 7 corresponding to R, G, and B can be provided.
[0025]
The memory controller 13 performs write address control for storing the R, G, and B pixel data in, for example, different storage areas for the video memory 7, and the all-pixel reading method is applied. Of all the pixel data of each CCD, that is, one frame of pixel data, the pixel data corresponding to the odd field as the first field and the pixel data corresponding to the even field as the second field are shifted in time. The read address is controlled to be read out. Note that pixel data write timing control and read timing control to the video memory 7 by the memory controller 13 will be described later.
[0026]
Pixel data read out from the video memory 7, that is, each digital imaging signal corresponding to R, G, B is sent to the digital process circuit 9. The digital process circuit 9 performs various digital adjustment processing such as γ (gamma) processing, white balance adjustment, white clip processing, knee processing, etc. on the supplied digital image signals of R, G, B. Apply. For example, when the pixel shifting method is applied, the digital process circuit 9 performs processing at a frequency twice that of the CCD sampling clock in order to maintain the pixel shifting effect. The various adjustment processes in the process circuit 9 can also be performed in the analog region. In this case, each digital image pickup signal from the video memory 7 is analog-converted by the digital / analog conversion circuit and sent to the analog process circuit.
[0027]
The R, G, B digital video signals obtained by the digital process circuit 9 are sent to the output circuit 10. The output circuit 10 is an output driver, for example, and outputs the digital video signal to an external device connected via the video output terminal 11. When the process circuit 9 has an analog configuration, the output circuit 10 also has an analog configuration. The output circuit 10 can also convert the R, G, B component video signals into composite video signals. In this case, the output circuit 10 is provided with a matrix circuit for converting R, G, B component video signals into composite video signals. In addition, the output circuit 10 may have three configurations corresponding to the above R, G, and B.
[0028]
The video signal output from the video output terminal 11 is supplied to an external device connected by, for example, a cable. The external device will be described later.
[0029]
Here, in the video camera 30 of the present configuration example, the video signal is output, and the external signal connected to the video output terminal 11 via a cable or the like is instructed to capture the video signal. It is also possible to output an external output write enable signal. That is, this external output write enable signal is a signal for instructing the capture timing when the external device captures, for example, a video signal. As described above with reference to FIG. In order to prevent a single frame image from being generated from an even field image and an odd field image captured at different times, for example, an odd field timing of a video signal is provided to an external device. Is for.
[0030]
The video camera of this configuration example generates the external output write enable signal with the following configuration. A state of generation of the external output write enable signal will be described with reference to the timing chart of FIG. 2 and the configuration of FIG.
[0031]
In FIG. 1, a sync generator 12 generates a synchronization signal, supplies the generated synchronization signal to each unit, a horizontal drive pulse HD, a vertical drive pulse VD as shown in FIG. 2, and the all-pixel readout method. 2 is used to set the timing for dividing an image of one frame obtained by the above into odd field and even field, and a synchronization signal used when writing data to the video memory 7 as shown in FIG. A certain write enable signal WEN is output. The horizontal drive pulse HD and the vertical drive pulse VD are sent to the timing generator 20 and the memory controller 13. The field discrimination pulse FLD is sent to the memory controller 13, a trigger switching circuit 14 and an external output write enable generation circuit 16 which will be described later. The write enable signal WEN is sent to the memory controller 13. The vertical drive pulse VD is also sent to the microcomputer 15. The field discrimination pulse FLD in the example of FIG. 2 is composed of repetitive pulses in which the odd field is at the “H (high)” level and the even field is at the “L (low)” level, and the rise timing of these pulses. Strictly speaking, it is shifted by, for example, 3H (H is a horizontal scanning period) from the falling timing of the vertical drive pulse VD.
[0032]
The microcomputer 15 controls each component in the video camera 30 and also has a function as trigger pulse generating means for generating an internal trigger pulse based on the vertical drive pulse VD. The internal trigger pulse is formed by arranging isolated pulses at predetermined time intervals, and each isolated pulse is generated in synchronization with the rising edge of the vertical drive pulse VD. The predetermined time interval of the internal trigger pulse can be set in advance as a fixed time interval, or can be arbitrarily set as an input set value from the trigger pulse setting input unit 19, for example. . As the trigger pulse setting input unit 19, various devices such as a set time changeover switch, a set time variable volume, or a set time input key can be used. As the predetermined time interval, for example, a time interval of about 2 to 10 minutes can be considered, and the timing chart of FIG. 2 shows an example of an internal trigger pulse having a time interval of 2 frames, for example. ing.
[0033]
Here, the microcomputer 15 measures the predetermined time interval by counting the vertical drive pulse VD, and can discriminate between an odd field and an even field without using the field discrimination pulse FLD. ing. Therefore, the microcomputer 15 can generate the internal trigger pulse at a timing synchronized with the odd field. That is, the microcomputer 15 generates an internal trigger pulse corresponding to the falling timing of the vertical drive pulse VD within the time when the odd pulse of the field determination pulse FLD exists.
[0034]
The trigger switching circuit 14 can recognize, for example, an odd field by detecting the field discriminating pulse FLD (for example, discriminating the level), and an internal trigger pulse synchronized with the odd field is supplied from the microcomputer 15. The internal trigger pulse is sent to the memory controller 13 as a write trigger pulse.
[0035]
The memory controller 13 generates the write address control signal and the read address control signal for the video memory 7 as described above, and the video memory when the write enable signal WEN is supplied from the sync generator 12. 7 is permitted to write data into the memory 7. Here, when a write trigger pulse synchronized with the odd field is supplied from the trigger switching circuit 14, the memory controller 13 causes the video memory 7 to capture data at the timing of the write trigger pulse. As a result, the image signal obtained by the all pixel readout type CCD, that is, the pixel data for one frame imaged at the same time is written in the video memory 7. Further, when the memory controller 13 causes the video memory 7 to capture data at the timing of the write trigger pulse, the memory controller 13 odds pixel data for one frame stored in the video memory 7 until the next write trigger pulse is received. Memory control is performed so that the fields are repeatedly read in order from the odd field in the order of field → even field → odd field →. In the memory controller 13, the data read timing for each field is generated based on the vertical drive pulse VD and the horizontal drive pulse HD, and which data of the odd field or even field is read out. The determination is made based on the field determination pulse FLD.
[0036]
In the external output write enable generation circuit 16, the external output write is supplied to the external device based on the write trigger pulse from the trigger switching circuit 14, the vertical drive pulse VD and the field determination pulse FLD from the sync generator 12. Generate an enable signal. That is, the external output write enable generation circuit 16 recognizes an odd field by detecting the field discriminating pulse FLD (for example, discriminating the level), and the write trigger pulse from the trigger switching circuit 14 is supplied. Then, an external output write enable signal synchronized with the odd field timing is generated and sent to the external output write enable signal output terminal 18. More specifically, as shown in FIG. 2, the external output write enable signal is, for example, 1V (V is a vertical scanning period) each time the trigger switching circuit 14 generates the write trigger pulse. The external output write enable generation circuit 16 is supplied with the write trigger pulse and immediately before the first odd pulse of the field determination pulse FLD is supplied. An external output write enable signal is generated so that a falling pulse is generated at the falling timing of the vertical drive pulse VD. Note that in the external output write enable generation circuit 16, the odd pulse actually rises with a shift of 3H (H is a horizontal scanning period) from the vertical drive pulse VD and the fall timing of the vertical drive pulse VD. From the field discrimination pulse FLD, a pseudo field discrimination pulse in which an odd pulse rises at the fall timing of the vertical drive pulse VD is generated, and the fall pulse is generated at the rise timing of the odd pulse of the pseudo field discrimination pulse. A write enable signal is generated. In the example of FIG. 2, the write enable signal for external output is a low active signal, but it may be a high active signal, depending on the specifications of the external device connected to the video camera. Can be set. This write enable signal is sent to the external device via the write enable output terminal 18.
[0037]
As described above, an external device to which a video signal is input via the video output terminal 11 receives the external output write enable signal via the external output write enable output terminal 18, thereby An operation synchronized with the odd field of the signal can be performed.
[0038]
That is, as an external device, for example, as in the digital still recorder or the digital printer as described above, one frame image is generated from images of two consecutive fields in the video signal from the video camera 30, Even if a frame image is taken out as a still image, these external devices can take in the video signal supplied from the video camera 30 based on the external output light enable signal. Such a problem does not occur.
[0039]
In other words, since the external device can capture the video signal supplied from the video camera 30 from the odd field, as described above, one frame image is obtained from the images of the two fields taken at different times as described above. Nothing happens, so it is possible to record or print a high quality still image.
[0040]
Note that it is conceivable to manufacture an external device that can generate an image of one frame by performing field correction processing, for example, even if two field images are taken at different times. Since a configuration for performing field correction processing is required, the cost is high, and the obtained frame image is also degraded in quality compared to the frame image generated from two field images taken at the same time. It will be a thing.
[0041]
By the way, the video camera 30 of this configuration example can also input an external trigger pulse from the terminal 17. This external trigger pulse is supplied to the video camera 30 by an external device capable of generating a trigger pulse similar to the internal trigger pulse, for example. When the external trigger pulse is supplied, the trigger switching circuit 14 generates a write trigger pulse to be sent to the memory controller 13 based on the external trigger pulse. However, the trigger switching circuit 14 at this time recognizes the odd field by detecting the field discriminating pulse FLD from the sync generator 12 inside the video camera 30 (for example, discriminating the level), and supplies the external trigger pulse. When it is done, a write trigger pulse synchronized with the odd field timing is generated and sent to the memory controller 13. Accordingly, the memory controller 13 in this case controls the writing of the video memory 7 by the writing trigger pulse generated based on the external trigger pulse. For this reason, the external device is set from the video memory 7. Data synchronized with the external trigger pulse is extracted. Thus, the video signal extracted from the video memory 7 and output from the video output terminal 11 is sent to an external device. Since the external device receives a video signal synchronized with the external trigger pulse generated by itself, it is possible to generate a frame image from two fields captured at the same time by the video camera 30. In the case of the video camera 30 that can input the external trigger pulse in this way, for example, the trigger pulse setting input unit 19 is provided with a switch for selecting switching between the internal trigger pulse and the external trigger pulse, and the external trigger pulse is set. When in use, the switch for switching is switched to the external trigger pulse side. At this time, the microcomputer 15 supplies a switching control signal for using the external trigger pulse to the trigger switching circuit 14. As a result, the trigger switching circuit 14 generates a write trigger pulse using the external trigger pulse from the external trigger pulse input terminal 17.
[0042]
Next, FIG. 3 shows a system configuration example to which the video camera 30 of the configuration example of the present invention is applied.
[0043]
In FIG. 3, the video output terminal of the video camera 30 of the configuration example of the present invention is connected to a monitor device 31. The monitor device 31 displays the video signal supplied from the video camera 30 on a display. The video signal supplied to the monitor device 31 is also sent to the digital printer 32 and the digital still recorder 33. These digital printer 32 and digital still recorder 33 correspond to the external device described above. Therefore, the video camera 30 of this configuration example sends the external output write enable signal to the digital printer 32 and the digital still recorder 33.
[0044]
【The invention's effect】
In the imaging apparatus of the present invention, an image signal obtained by photoelectrically converting incident light from the optical system is written to and read from the storage means in accordance with the internal trigger pulse, and the image signal read from the storage means is externally read out. In addition, a write enable signal synchronized with the internal trigger pulse is also output to the outside, so that an external device such as a digital still recorder or a digital printer can generate a good still image. Become.
[Brief description of the drawings]
FIG. 1 is a block circuit diagram showing a schematic internal configuration of a video camera of a configuration example of the present invention.
FIG. 2 is a timing chart for explaining the operation of the main configuration of the video camera according to the configuration example of the present invention;
FIG. 3 is a diagram illustrating a system configuration example to which the video camera of the present invention is applied.
FIG. 4 is a diagram used for explaining CCD output and video output in an all-pixel readout method.
[Explanation of symbols]
1 optical system, 2 prism, 3 _R , 3 _G , 3 _B CCD, 6 _R , 6 _G , 6 _B A / D conversion circuit, 7 video memory, 9 process circuit, 10 output circuit, 12 sync generator, 13 memory controller, 14 trigger switching circuit, 15 microcomputer, 16 write enable generation circuit for external output, 19 trigger pulse setting input Department, 30 video camera

Claims (4)

An optical system for forming a subject image;
Conversion means for photoelectrically converting incident light from the optical system to generate image signals of the first field and the second field captured at the same time;
Storage means for storing the image signal;
Write / read control means for controlling writing and reading of image signals in the storage means;
Trigger pulse generating means for generating a write trigger pulse indicating timing when the image signals of the first field and the second field from the converting means are written to the storage means;
Write enable generating means for generating a write enable signal synchronized with the timing of the first field of the field discrimination pulse for discriminating between the first field and the second field in response to the write trigger pulse;
From the storage means in response to the field discrimination pulse output to the outside read out an image signal of the image signal and the second field of the first field in this order, the output timing of the first field of the time An image pickup apparatus, wherein the synchronized light enable signal is output to the outside as a capture control signal for the image signal .   The writing / reading control means writes image signals for one frame of the first field and the second field taken at the same time from the conversion means to the storage means in accordance with the write trigger pulse, and the storage means 2. The image pickup apparatus according to claim 1, wherein the image signal for one frame stored in is divided into the first field and the second field after the write trigger pulse and is repeatedly read in this order.   The trigger pulse generation means includes variable setting means for generating the write trigger pulse in response to an internal trigger pulse generated every predetermined time and variably setting the predetermined time interval of the internal trigger pulse. Item 2. The imaging device according to Item 1.   The trigger pulse generating means includes trigger switching means for switching between an external trigger pulse supplied from outside and the internal trigger pulse, and generates the write trigger pulse in response to the pulse from the trigger switching means. The imaging apparatus according to claim 1.

Images