US 6,888,570 B1 · Image pickup device and exposure control method in the image pickup device

Abstract

An image pickup device comprises a CCD solid-state imaging element composed of a charge accumulation section and a charge transfer section, a CCD driver for driving the imaging element, a mechanical shutter for switching between the transmitting state and shading state of the subject's image on the imaging element, and a controller for controlling the CCD driver and mechanical shutter. The controller, closes, opens and closes the mechanical shutter in that order. After having discharged charges in the first closing, the device refrains from driving the vertical transfer channel during the period that the channel is exposed to light rays and ends exposure in the presence of a charge transfer pulse. Moreover, in a low-speed shutter, the image pickup device switches to exposure end with the mechanical shutter.

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Claims24

Dependent claims

A device for photographing an image of a subject, comprising:

a solid-state imaging device which has an imaging surface composed of a large number of pixel elements struck by light rays from the subject, which includes a charge accumulating section for converting the incident light rays into charges by the pixel elements and accumulating the charges, a charge transfer section for receiving the charges from the charge accumulating section and transferring them, and a output section for outputting the transferred charges as an image signal;
driving means which generates a normal driving signal in a normal driving mode to drive the accumulating section and the transfer section for transferring the charges accumulated in the charge accumulating section to the charge transfer section at a normal transfer rate and causing the imaging device to output the image signal from the output section, and which further generates a charge discharging signal for discharging the charges from the charge accumulating section outside the imaging device and a high transfer rate driving signal for transferring the charges in the charge transfer section at a high transfer rate higher than the normal transfer rate in a charge discharge mode;
optical shutter means which is capable of switching between an opening mode that permits light rays to impinge on the imaging surface of the imaging device and a closing mode that inhibits light rays from impinging on the imaging surface, the optical shutter having a delay in switching from the closing mode to the opening mode or from the opening mode to the closing mode;
and
exposure control means for controlling the amount of light rays that reaches the imaging surface by controlling the driving means and shutter means, wherein
the exposure control means switches the shutter means to the closing mode at a first time in response to the start in photographing the image of the subject,
causes the driving means to start to supply the charge discharging signal to the imaging device at the first time, thereby discharging the accumulated charges from the accumulating section to the outside of the imaging device in the charge discharge mode,
causes the driving means to start to supply a high transfer rate driving signal to the imaging device at the first time, thereby driving the charge transfer section at high transfer rate for a specific period, the charges being transferred in the charge transfer section to the outside of the imaging device via the output section in the charge discharge mode,
causes the driving means to stop supplying the high transfer rate driving signal to the imaging device at a second time, thereby stopping the driving of the charge transfer section,
switches the shutter means from the closing mode to the opening mode after the second time and keeps the shutter means in the opening mode after a third time,
causes the driving means to stop supplying the charge discharging signal to the imaging device at a time substantially equal to or before the third time and the charge accumulating section to start to accumulate charges,
switches the shutter means to the closing mode at a fourth time within a exposure period from the third time, and
causes the driving means to supply a normal driving signal to the imaging device at a fifth time, until when the shutter means has been kept in the closing mode since the fourth time, thereby driving the charge transfer section in the normal driving mode, which causes the charge transfer section to output an image signal outside the imaging device.

10 more elements

A device for photographing an image of a subject, comprising:

a solid-state imaging device which has an imaging surface composed of a large number of pixel elements struck by light rays from the subject, which includes a charge accumulating section for converting the incident light rays into charges by the pixel elements and accumulating the charges, a charge transfer section for receiving the charges from the charge accumulating section and transferring them, and a output section for outputting the transferred charges as an image signal;
driving means which generates a normal driving signal in a normal driving mode to drive the accumulating section and the transfer section for transferring the charges accumulated in the charge accumulating section to the charge transfer section at a normal transfer rate and causing the imaging device to output the image signal from the output section, and which further generates a charge discharging signal for discharging the charges from the charge accumulating section outside the imaging device and a high transfer rate driving signal for transferring the charges in the charge transfer section at a high transfer rate higher than the normal transfer rate in a charge discharge mode;
optical shutter means which is capable of switching between an opening mode that permits light rays to impinge on the imaging surface of the imaging device and a closing mode that inhibits light rays from impinging on the imaging surface, the optical shutter having a delay in switching from the closing mode to the opening mode or from the opening mode to the closing mode;
and
exposure control means which controls the amount of light rays that reaches the imaging surface by controlling the driving means and shutter means and includes means for determining an exposure time and means for comparing the determined exposure time with a reference exposure time and setting one of a first and a second photographic mode, wherein, in the first photographic mode,
the exposure control means switches the shutter means to the closing mode at a first time in response to the start in photographing the image of the subject,
causes the driving means to start to supply the charge discharging signal to the imaging device at the first time, thereby discharging the accumulated charges from the accumulating section to the outside of the imaging device in the charge discharge mode,
causes the driving means to start to supply a high transfer rate driving signal to the imaging device at the first time, thereby driving the charge transfer section at high transfer rate for a first specific period, the charges being transferred in the charge transfer section to the outside of the imaging device via the output section in the charge discharge mode,
causes the driving means to stop supplying the high transfer rate driving signal to the imaging device at a second time, thereby stopping the driving of the charge transfer section,
switches the shutter means from the closing mode to the opening mode after the second time and keeps the shutter means in the opening mode after a third time,
causes the driving means to stop supplying the charge discharging signal to the imaging device at a time substantially equal to or before the third time and the charge accumulating section to start to accumulate charges,
switches the shutter means to the closing mode at a fourth time within the exposure time from the third time, and
causes the driving means to supply a normal driving signal to the imaging device at a fifth time, until when the shutter means has been kept in the closing mode since the fourth time, thereby driving the charge transfer section in the normal driving mode, which causes the charge transfer section to output an image signal outside the imaging device;
in the second photographic mode,
the exposure control means switches the shutter means to the closing mode at the first time in response to the start in photographing the image of the subject,
causes the driving means to start to supply a charge discharging signal to the imaging device at the first time, thereby discharging the accumulated charges from the charge accumulating section to the outside of the imaging device,
causes the driving means to start to supply a high transfer rate driving signal to the imaging device at the first time, thereby driving the charge transfer section at high transfer rate for a second specific period, which transfers the charges in the charge transfer section outside the imaging device,
causes the driving means to stop supplying the high transfer rate driving signal to the imaging device at the second time, thereby stopping the driving of the charge transfer section,
switches the shutter means from the closing mode to the opening mode after the second time and keeps the shutter means in the opening mode at the third time,
causes the driving means to stop supplying the charge discharging signal to the imaging device at the third time and the charge accumulating section to start to accumulate charges,
switches the shutter means to the closing mode at the fourth time that the exposure time has elapsed since the third time, the exposure time ending before the delay dt in the optical shutter means has elapsed since the fourth time, and
causes the driving means to supply a high transfer rate driving signal to the imaging device at the sixth time that the delay dt in the optical shutter means has elapsed since the fourth time, thereby driving the charge transfer section at high transfer rate for a third specific period and discharging the charges in the charge transfer section to the outside of the imaging device, and at the fifth time that the specific period of the high transfer rate driving has elapsed, causes the driving means to supply a normal driving signal to the imaging device, thereby driving the charge transfer section in the normal mode, which causes the charge transfer section to output an image signal outside the imaging device.

19 more elements

A method of controlling the amount of light rays that reaches an imaging surface by controlling driving means and shutter means in an image pickup device including

a solid-state imaging device which has an imaging surface composed of a large number of pixel elements struck by light rays from the subject, which includes a charge accumulating section for converting the incident light rays into charges by the pixel elements and accumulating the charges, a charge transfer section for receiving the charges from the charge accumulating section and transferring them, and a output section for outputting the transferred charges as an image signal;
driving means which generates a normal driving signal in a normal driving mode to drive the accumulating section and the transfer section for transferring the charges accumulated in the charge accumulating section to the charge transfer section at a normal transfer rate and causing the imaging device to output the image signal from the output section, and which further generates a charge discharging signal for discharging the charges from the charge accumulating section outside the imaging device and a high transfer rate driving signal for transferring the charges in the charge transfer section at a high transfer rate higher than the normal transfer rate in a charge discharge mode;
and
optical shutter means which is capable of switching between an opening mode that permits light rays to impinge on the imaging surface of the imaging device and a closing mode that inhibits light rays from impinging on the imaging surface, the optical shutter having a delay in switching from the closing mode to the opening mode or from the opening mode to the closing mode, the method comprising the steps of:
switching the shutter means to the closing mode at a first time in response to the start in photographing the image of the subject,
causing the driving means to start to supply a charge discharging signal to the imaging device at the first time, thereby discharging the accumulated charged from the charge accumulating section to the outside of the imaging device,
causing the driving means to start to supply a high transfer rate driving signal to the imaging device at the first time, thereby driving the charge transfer section at high transfer rate for a specific period or longer, which transfers the charges in the charge transfer section outside the imaging device,
causing the driving means to stop supplying the high transfer rate driving signal to the imaging device at a second time, thereby stopping the driving of the charge transfer section,
switching the shutter means from the closing mode to the opening mode after the second time and keeping the shutter means in the opening mode at a third time,
causing the driving means to stop supplying the charge discharging signal to the imaging device at a time substantially equal to or before the third time and the charge accumulating section to start to accumulate charges,
switching the shutter means to the closing mode at a fourth time within a exposure time from the third time, and
causing the driving means to supply a normal driving signal to the imaging device at a fifth time, until when the shutter means has been kept in the closing mode since the fourth time, thereby driving the charge transfer section in the normal driving mode, which causes the charge transfer section to output an image signal outside the imaging device.

9 more elements

A method of controlling the amount of light that reaches an imaging surface by controlling driving means and shutter means in an image pickup device including

a solid-state imaging device which has an imaging surface composed of a large number of pixel elements struck by light rays from the subject, which includes a charge accumulating section for converting the incident light rays into charges by the pixel elements and accumulating the charges, a charge transfer section for receiving the charges from the charge accumulating section and transferring them, and a output section for outputting the transferred charges as an image signal;
driving means which generates a normal driving signal in a normal driving mode to drive the accumulating section and the transfer section for transferring the charges accumulated in the charge accumulating section to the charge transfer section at a normal transfer rate and causing the imaging device to output the image signal from the output section, and which further generates a charge discharging signal for discharging the charges from the charge accumulating section outside the imaging device and a high transfer rate driving signal for transferring the charges in the charge transfer section at a high transfer rate higher than the normal transfer rate in a charge discharge mode;
and
optical shutter means which is capable of switching between an opening mode that permits light rays to impinge on the imaging surface of the imaging device and a closing mode that inhibits light rays from impinging on the imaging surface, the optical shutter having a delay in switching from the closing mode to the opening mode or from the opening mode to the closing mode,
the method comprising the steps of
determining an exposure time;
comparing the determined exposure time with a reference exposure time and setting one of a first and a second photographic mode;
in the first photographic mode,
switching the shutter means to the closing mode at a first time in response to the start in photographing the image of the subject,
causing the driving means to start to supply a charge discharging signal to the imaging device at the first time, thereby discharging the accumulated charged from the charge accumulating section to the outside of the imaging device,
causing the driving means to start to supply a high transfer rate driving signal to the imaging device at the first time, thereby driving the charge transfer section at high transfer rate for a specific period or longer, which transfers the charges in the charge transfer section outside the imaging device,
causing the driving means to stop supplying the high transfer rate driving signal to the imaging device at a second time, thereby stopping the driving of the charge transfer section,
switching the shutter means from the closing mode to the opening mode after the second time and keeping the shutter means in the opening mode at a third time,
causing the driving means to stop supplying the charge discharging signal to the imaging device at a time substantially equal to or before the third time and the charge accumulating section to start to accumulate charges,
switching the shutter means to the closing mode at a fourth time within a exposure time from the third time, and
causing the driving means to supply a normal driving signal to the imaging device at a fifth time, until when the shutter means has been kept in the closing mode since the fourth time, thereby driving the charge transfer section in the normal driving mode, which causes the charge transfer section to output an image signal outside the imaging device;
and
in the second photographic mode,
switching the shutter means to the closing mode at the first time in response to the start in photographing the image of the subject;
causing the driving means to start to supply a charge discharging signal to the imaging device at the first time, thereby discharging the accumulated charges from the charge accumulating section to the outside of the imaging device;
causing the driving means to start to supply a high transfer rate driving signal to the imaging device at the first time, thereby driving the charge transfer section at high transfer rate for a specific period or longer, which transfers the charges in the charge transfer section outside the imaging device;
causing the driving means to stop supplying the high transfer rate driving signal to the imaging device at the second time, thereby stopping the driving of the charge transfer section;
switching the shutter means from the closing mode to the opening mode after the second time and keeping the shutter means in the opening mode at the third time;
causing the driving means to stop supplying the charge discharging signal to the imaging device at a time substantially equal to or before the third time and the charge accumulating section to start to accumulate charges;
switching the shutter means to the closing mode at the fourth time that the exposure period has elapsed since the third time, the exposure period ending before the delay dt in the optical shutter means has elapsed since the fourth time;
and
causing the driving means to supply a high transfer rate driving signal to the solid-state image pickup device at the sixth time that the delay dt in the optical shutter means has elapsed since the fourth time, thereby driving the charge transfer section at high transfer rate for a specific period or longer and discharging the charges in the charge transfer section to the outside of the imaging device, and at the fifth time that the specific period of the high transfer rate driving has elapsed, causing the driving means to supply a normal driving signal to the imaging device, thereby driving the charge transfer section normally, which causes the charge transfer section to output an image signal outside the imaging device.

24 more elements

A device for photographing an image of a subject, comprising:

a solid-state imaging device including a charge accumulating section on which the image is projected, for converting the image into charges and accumulating the charges, a charge transfer section for receiving the accumulated charges from the charge accumulating section and transferring them, and a output section for outputting the transferred charges as an image signal;
driving means for driving the charge accumulating section to accumulate the charges, the charge transfer section to transfer the charges from the charge accumulating section to the output section via the transfer section at a normal transfer rate, and the outputting section to output the image signal in a normal driving mode;
optical shutter means which is capable of switching between an opening mode for permitting the image to project the image on the accumulating section and a closing mode for inhibiting the image from being projected on the accumulating section, the optical shutter means having a delay in switching from the closing mode to the opening mode or from the opening mode to the closing mode;
and
exposure control means for controlling the driving means and the shutter means and including means for determining an exposure time and means for comparing the determined exposure time with a reference exposure time and setting one of a first and a second photographic mode, wherein, in the first photographic mode,
the exposure control means switches the shutter means to the closing mode,
causes the driving means to start to discharge the charges from the accumulating section to the outside the imaging device,
causes the driving means to drive the charge transfer section at a high transfer rate during a predetermined period, which transfers the charges in the charge transfer section to the outside the imaging device,
causes the driving means to stop the transfer of the charges in the charge transfer section,
switches the shutter means from the closing mode to the opening mode,
causes the driving means to stop the discharge of the charges from the accumulating section,
causes the driving means to the accumulating section to start to accumulate charges during a predetermined exposure period,
switches the shutter means to the closing mode, and
causes the driving means to drive the charge transfer section in the normal mode, and to output an image signal from the output section, and
in the second photographic mode,
the exposure control means switches the shutter means to the closing mode,
causes the driving means to start to discharge the charges from the accumulating section to the outside the imaging device,
causes the driving means to drive the charge transfer section at a high transfer rate during a predetermined period, which transfers the charges in the charge transfer section to the outside the imaging device,
causes the driving means to stop the transfer of the charges in the charge transfer section,
switches the shutter means from the closing mode to the opening mode,
causes the driving means to stop the discharge of the charges from the accumulating section,
causes the driving means to the accumulating section to start to accumulate charges during a predetermined exposure period,
switches the shutter means to the closing mode,
causes the driving means to drive the charge transfer section in the normal mode, and to output an image signal from the output section,
causes the driving means to drive the charge transfer section a high transfer rate during a predetermined transfer period after the shutter means is switched in the closing mode, and
causing the driving means to drive the accumulating section and the charge transfer section after the predetermined transfer period in the normal transfer mode,
wherein the reference exposure time is set to TC=dt/2 to 2 dt, where dt means a delay in the optical shutter means.

24 more elements

A method of controlling a device for photographing an image of a subject, the device comprising:

a solid-state imaging device including a charge accumulating section on which the image is projected, for converting the image into charges and accumulating the charges, a charge transfer section for receiving the accumulated charges from the charge accumulating section and transferring them, and a output section for outputting the transferred charges as an image signal;
driving means for driving the charge accumulating section to accumulate the charges, the charge transfer section to transfer the charges from the charge accumulating section to the output section via the transfer section at a normal transfer rate, and the outputting section to output the image signal in a normal driving mode;
and
optical shutter means which is capable of switching between an opening mode for permitting the image to project the image on the accumulating section and a closing mode for inhibiting the image from being projected on the accumulating section, the optical shutter means having a delay in switching from the closing mode to the opening mode or from the opening mode to the closing mode;
the method comprising steps of
comparing the determined exposure time with a reference exposure time;
and
setting one of a first and a second photographic mode,
wherein, in the first photographic mode,
switching the shutter means to the closing mode,
causing the driving means to start to discharge the charges from the accumulating section to the outside the imaging device,
causing the driving means to drive the charge transfer section at a high transfer rate during a predetermined period, which transfers the charges in the charge transfer section to the outside the imaging device,
causing the driving means to stop the transfer of the charges in the charge transfer section,
switching the shutter means from the closing mode to the opening mode,
causing the driving means to stop the discharge of the charges from the accumulating section,
causing the driving means to the accumulating section to start to accumulate charges during a predetermined exposure period,
switching the shutter means to the closing mode, and
causing the driving means to drive the charge transfer section in the normal mode, and to output an image signal from the output section;
in the second photographing mode,
switching the shutter means to the closing mode,
causing the driving means to start to discharge the charges from the accumulating section to the outside the imaging device,
causing the driving means to drive the charge transfer section at a high transfer rate during a predetermined period, which transfers the charges in the charge transfer section to the outside the imaging device,
causing the driving means to stop the transfer of the charges in the charge transfer section,
switching the shutter means from the closing mode to the opening mode,
causing the driving means to stop the discharge of the charges from the accumulating section,
causing the driving means to the accumulating section to start to accumulate charges during a predetermined exposure period,
switching the shutter means to the closing mode,
causing the driving means to drive the charge transfer section in the normal mode, and to output an image signal from the output section,
causing the driving means to drive the charge transfer section a high transfer rate during a predetermined transfer period after the shutter means is switched in the closing mode, and
causing the driving means to drive the accumulating section and the charge transfer section after the predetermined transfer period in the normal transfer mode,
wherein the reference exposure time is set to TC dt/2 to 2 dt, where dt means a delay in the optical shutter means.

28 more elements

Dependencies are inferred from the claim text.

Description12,202 words

Summary7,224 words

#This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-327211, filed Nov. 17, 1999, the entire contents of which are incorporated herein by reference.

#This invention relates to an image pickup device using a solid-state imaging element, such as a CCD, that converts the picked-up optical image into an electric signal and an exposure control method in the image pickup device, and more particularly to an image pickup device capable of alleviating smears and an exposure control method in the image pickup device.

#In recent years, electronic image pickup devices for converting the picked-up optical image into an electric signal have been widely used. Of such electronic image pickup devices, digital cameras for picking up still pictures are beginning to have the performance comparable to silver-bromide analog cameras. In this specification, unless otherwise specified, explanation will be given on the assumption that an electronic image pickup device is an electronic still camera with a digital circuit system, or a digital camera. The techniques of the present invention can be applied to analog electronic image pickup devices, or analog electronic still cameras. In the explanation, however, a case where the present invention is applied to a digital camera will be explained, taking the digital camera as a typical electronic image pickup device.

Brief description of the drawings5 figures

#The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention.

#FIGS. 1A to 1D are timing charts showing the timing of each signal in exposure control in a conventional image pickup device;

#FIG. 2 is a block diagram of a digital camera according to a first embodiment of the present invention;

Detailed description4,819 words

#Hereinafter, referring to the accompanying drawings, image pickup devices according to embodiments of the present invention will be explained in detail.

#FIG. 2 is a block diagram of a digital camera according to a first embodiment of the present invention.

#In FIG. 2, numeral 101 indicates a photographic lens system composed of lenses for directing the light rays from a subject into a camera. The lens system 101 is driven by a lens driving mechanism 102 in such a manner that the lens system is focused on the subject. An exposure control mechanism 103 for controlling exposure includes a stop and a driving mechanism for driving the stop and is provided to limit the amount of incident light passed through the lens system 101, thereby controlling the stop. The light rays passed through the exposure control mechanism 103 are directed via a mechanical shutter 104 to a CCD color image pickup element 105 with a color filter on the incident surface of the light rays. Thus, an image corresponding to the subject is formed on the CCD color image pickup element 105. The mechanical shutter 104 such as a guillotine shutter or a focal-plane shutter used in a conventional analog camera is typical one of optical shutters. There is another one of optical shutter such as a liquid-crystal shutter or PLZT ceramic shutter and so on.

Image pickup device and exposure control method in the image pickup device

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Image pickup device and exposure control method in the image pickup device

Life of this patent

Life of this patent

Abstract

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Drawings

Claims24

Description12,202 words

Drawings

Classification3 codes

Life of this patent

Description12,202 words