JP4244624B2 - camera - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a camera in which the influence of dust floating in a photographing optical path on image photographing is suppressed.
[0002]
[Prior art]
In a camera such as a single-lens reflex camera in which the taking lens can be exchanged, dust may enter the camera when the lens is exchanged. Even when the lens is not exchanged, dust is generated from the sliding portion as the quick return mirror and the shutter mechanism are driven. Such dust floats in the photographing optical path and adheres to the film surface.
[0003]
In the digital camera, an image sensor such as a CCD is used instead of a film. An optical member such as a cover glass for protecting the image sensor and an optical filter is disposed in the vicinity of the image pickup surface of the image sensor. When foreign matter such as dust adheres to the surface of these optical members, there arises a problem that the foreign matter is reflected in the image.
[0004]
In particular, a crystal such as a quartz plate having birefringence characteristics is used for the optical filter. Since these crystals have a piezoelectric effect, they are easily charged, and dust is more likely to adhere due to charging. For this reason, a technique is known in which the charge due to charging is neutralized to suppress the adhesion of dust (for example, see Patent Document 1).
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 2000-29132
[Problems to be solved by the invention]
However, in the conventional technology described above, even if dust can be prevented from adhering to the Coulomb force by preventing charging, the dust floating in the vicinity of the image sensor is not reduced. Therefore, it was difficult to prevent floating dust from adhering to the optical member or the like.
[0007]
The present invention provides a camera that charges dust floating in a photographing optical path and collects the dust or keeps it away from an optical member.
[0008]
[Means for Solving the Problems]
The camera according to the present invention has an image pickup device that converts an optical image formed by the taking lens into an electric signal, an optical member that is disposed between the taking lens and the image pickup device, and dust that floats in the shooting optical path. A charging means for charging to a polarity; a transparent electrode provided on the surface of the optical member to which a voltage is applied so as to be charged to the same polarity as the charging polarity by the charging means; A dust collecting device including a dust collecting member charged to a polarity opposite to the charging polarity by the charging means, wherein the dust collecting member collects floating dust.
A shutter that can be switched between a light-blocking state that blocks the light beam incident on the image sensor from the photographing lens and an open state that allows the light beam to pass therethrough is provided, and the shutter is opened when dust floating is collected by the dust collector. Preferably it is switched to a state.
A plurality of power supply devices can be selectively used as the power supply for the dust collector, and the power consumption of the dust collector may be controlled based on the identification result of the identification means for identifying the power supply device.
The dust collection state of the dust collector may be detected by the dust collection state detection means, and the detection result may be presented to the presentation means in a recognizable form.
The dust detection means may detect dust on the dust collector or the transparent electrode, and when dust is detected, the dust collector may be operated for a predetermined time.
The attachment / detachment state of the detachable photographic lens may be detected by the attachment / detachment detection means, and when the detachment of the photographic lens or subsequent attachment is detected, the dust collecting device may be operated for a predetermined time.
The number of shutter switching operations may be detected by the switching number detecting means, and when the detected number of switching operations reaches a predetermined number, the dust collector may be operated for a predetermined time.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a camera according to the present invention. The camera shown in FIG. 1 is an interchangeable lens single-lens reflex digital still camera 1. The interchangeable lens barrel 2 is detachably attached to a lens mount 3 provided on the front surface of the camera 1 body. The subject light L that has passed through the photographing lens 4 is divided into two light beams by the main mirror 5a of the quick return mirror 5, and the reflected light beam is guided to the finder optical system. On the other hand, the transmitted light beam is reflected by the sub mirror 5b provided on the back side of the quick return mirror 5 and used as the AF light beam.
[0010]
The light beam reflected by the main mirror 5 a is imaged on the finder screen 6. The subject image formed on the finder screen 6 can be observed from the finder eyepiece window 9 via the pentaprism 7 and the eyepiece lens 8. At the time of shooting, the quick return mirror 5 is flipped up out of the optical path, and the shutter unit 10 is opened to form a subject image on the imaging surface of the image sensor 11.
[0011]
When not photographing, the quick return mirror 5 is disposed on the optical path as shown in FIG. 1, and the shutter unit 10 is closed. In the following description, the image sensor 11 side (right side in the figure) with the shutter unit 10 as a boundary is referred to as an image sensor housing space, and the quick return mirror 5 side (left side in the figure) is referred to as a mirror box.
[0012]
As the image sensor 11, a CCD image sensor or the like is used. The image pickup device 11 is provided with a cover glass 11a for protecting the image pickup unit. An optical low-pass filter 12 is disposed near the front of the image sensor 11. Although not shown, a transparent electrode 16 for preventing dust adhesion is formed on the surface of the optical low-pass filter 12 on the photographing lens side as described later (see FIG. 2).
[0013]
A dust collecting plate 13a is disposed between the optical low-pass filter 12 and the shutter unit 10 in the image sensor housing space, and a dust collecting plate 13b is also disposed in the vicinity of the shutter unit 10 in the mirror box. . For the dust collecting plates 13a and 13b, for example, a metal plate or a conductive sheet is used. In the vicinity of the dust collecting plate 13b, a detector 15 is provided as means for detecting dust adhering to the dust collecting plate 13b. The detector 15 includes, for example, an LED that projects light onto the dust collecting plate 13b and a light receiving element that detects LED light reflected by the dust collecting plate 13b. The reflectance of the dust collecting plate 13b is obtained from the detected reflected light amount, and the dust collection amount is estimated from the reflectance. The detector 15 may be provided on the dust collecting plate 13a side.
[0014]
A charging device 14 for charging the dust in the mirror box is provided in the mirror box. The charging device 14 and the above-described dust collecting plates 13a and 13b constitute a dust collecting device. In the example shown in FIG. 1, the dust collecting plate 13a is provided in the image sensor housing space and the dust collecting plate 13b is provided in the mirror box. However, only one of them may be provided. In that case, the shutter unit 10 is opened during the dust collection operation described later so that both the image sensor housing space and the mirror box are collected by a single dust collection plate.
[0015]
FIG. 2 is a diagram for explaining the dust collecting operation. The dust collecting device (dust collecting plates 13a and 13b and the charging device 14) provided in the mirror box and the image sensor housing space and the image sensor 11 in FIG. It is shown. FIG. 2 shows a case where the shutter unit 10 is in an open state. As described above, the transparent electrode 16 is formed on the surface of the optical low-pass filter 12.
[0016]
The transparent electrode 16, the dust collecting plates 13a and 13b, and the charging device 14 are connected to a DC power source 23, a negative voltage (minus several volts) is applied to the transparent electrode 16, and a positive voltage is applied to the dust collecting plates 13a and 13b. (Plus several volts) is applied. The polarity of the voltage is set when the dust 20 is negatively charged by the charging device 14, and when the dust 20 is positively charged, each voltage is set to the opposite polarity.
[0017]
The charging device 14 is a device that negatively charges the dust 20 in the mirror box. For example, as shown in FIG. 3, the charging device 14 includes an ionization line 30 such as a tungsten wire to which a voltage is applied to minus several hundred volts. . When the air around the ionization line 30 is ionized by corona discharge, the generated positive ions are attracted to the ionization line 30, but the remaining negative ions 21 adhere to the surrounding dust 20 and charge them negatively. The negatively charged dust 20 is attracted and adhered to the dust collecting plates 13a and 13b, which are positive electrodes, by Coulomb force. The negative charge of the attached dust 20 escapes to the dust collecting plate side.
[0018]
On the other hand, since a negative voltage is applied to the transparent electrode 16 formed on the optical low-pass filter 12, a repulsive force due to Coulomb force acts between the negatively charged dust 20. Therefore, the dust 20 is moved away from the optical low-pass filter 12 and finally adheres to the dust collecting plates 13a and 13b. Reference numeral 22 denotes an LED that emits light toward the transparent electrode 16. The LED 22 illuminates the transparent electrode 16, and estimates the amount of dust 20 attached to the transparent electrode 16 based on the amount of transmitted light. The amount of transmitted light is detected by the image sensor 11. That is, the LED 22 functions as a dust detection unit related to the transparent electrode 16.
[0019]
FIG. 4 is a block diagram of the camera, showing a schematic configuration centering on the dust collection mechanism. The CPU 40 controls the entire camera, and also controls the dust collection operation described later. The DC / DC circuit 44 boosts the voltage of the DC power source 23 and applies a high voltage of several hundred volts to the dust collectors 13 a and 13 b and the ionization line 30 of the charging device 14.
[0020]
In the present embodiment, an AC power source 41 can be used in addition to the DC power source 23 as the power source of the camera. An AC power source 41 is connected to the camera via an AC power adapter 42. 43 is an AC power supply recognition switch for recognizing whether or not the AC power adapter 42 is connected to the camera. When the connection is recognized, the AC power supply recognition switch 43 is turned on and the power is switched from the DC power supply 23 to the AC power supply 41. Switch.
[0021]
As the DC power source 23, a primary battery such as a manganese battery or an alkaline battery, or a secondary battery such as a lithium ion battery can be used. Whether the primary battery or the secondary battery is used is determined by the battery determination unit 45. For example, when the primary battery and the secondary battery have the same shape, it cannot be determined which is the battery shape. Furthermore, since the degree of battery consumption is different, it is difficult to simply detect the battery type by the voltage difference. Therefore, in such a case, a switch or the like that is operated by the user to a switch position corresponding to the type of the battery when the battery is loaded is provided as the battery determination unit 45. The CPU 40 determines the type of battery according to the state of the switch.
[0022]
Further, when a dedicated secondary battery is used, the shape thereof is different from that of the primary battery, and a switch that is turned on / off at a portion having a different shape is provided in the battery holder as the battery determination unit 45. The battery type may be automatically determined by detecting the on / off state of the switch.
[0023]
By the way, when the charging device 14 and the dust collecting plates 13a and 13b are operated with the same dust collecting ability as when the AC power source 41 is used when the DC power source 23 is used, battery consumption is large. Then, adjust the dust collection capacity according to the type of power supply. That is, the type of the power source is determined from the state of the AC power source recognition SW 43 and the determination of the battery determination unit 45, and the voltage applied to the ionization line 30 is increased in the order of the primary battery, the secondary battery, and the AC power source.
[0024]
The attachment / detachment state of the interchangeable lens barrel 2 (see FIG. 1) is detected by a lens attachment / detachment switch 46 that is turned on / off according to attachment / detachment. For example, an electrical contact may be provided on the lens mount 3 to detect a conductive state or a non-conductive state in accordance with the attachment / detachment of the interchangeable lens barrel 2. Reference numeral 48 denotes a shutter counter that counts the number of operations of the shutter unit 10, and the count is reset to zero when the dust collection operation is completed as described later. 47 is a dust collection mode button for forcibly performing the dust collection operation. When the dust collection mode button 47 is operated, the dust collection operation is performed for a predetermined time regardless of the dust collection state of the dust collection plates 13a and 13b. .
[0025]
Reference numeral 49 denotes an LCD display device which is used for reproducing and displaying captured images, and also used for warning display and dust collection state described later. The dust detection means 50 includes a detector 15 (FIG. 1) that detects dust adhering to the dust collecting plate 13b and the LED 22 of FIG.
[0026]
<Description of dust collection operation>
The flowchart in FIG. 5 shows an example of the dust collecting operation in the camera of the present embodiment. The flowchart of FIG. 5 starts when the main switch of the camera is turned on. In step S1, the type of power supply is determined. In the present embodiment, as described above, the AC power supply 41 and the DC power supply 23 (primary battery and secondary battery) can be used.
[0027]
If it is determined in step S1 that the power supply is the AC power supply 41, the process proceeds to step S2 where the applied voltage of the ionization line 30 (FIG. 2) is set to Va. On the other hand, if it is determined that the power source is a secondary battery, the process proceeds to step S3 and the applied voltage is set to Vb. If it is determined that the power source is the primary battery, the process proceeds to step S4 and the applied voltage is set to Vc. The magnitude relationship among the applied voltages Va, Vb, and Vc is set such that Va>Vb> Vc, and the higher the applied voltage, the higher the dust collection capability, but the higher the power consumption.
[0028]
In step S5, the dust collection state of the dust collection plate 13b is detected by the detector 15. In this Embodiment, LED light is irradiated to the dust collecting plate 13a, and the reflected light from the reflecting plate 15b in the back of the dust collecting plate 13a is detected. The dust collection state is estimated by detecting the reflectance of the reflecting plate 15b at that time. For example, when the reflectance is equal to or less than a predetermined value R1, it is considered that dust is detected on the dust collecting plate 13a. When the reflectance further decreases to a predetermined value R2 (<R1) or less, it is determined that the dust collecting plates 13a and 13b need to be cleaned, and a warning is given as will be described later. It should be noted that the reflectances R1 and R2 that serve as a reference for determining the amount of collected dust are determined in advance by experiments or the like.
[0029]
In step S6, based on the detection result in step S5, a display of the dust collection state estimated from the reflectance and a warning display for prompting cleaning of the dust collection plates 13a and 13b are displayed on the LCD display device 49 (FIG. 4). . In step S7, based on the result of step S6 and the transmission state of the transparent electrode 16 by illumination of the LED 22, the state of dust adhesion to the dust collecting plate 13a and the transparent electrode 16 is determined. If it is determined that dust is attached to either the dust collector 13a or the transparent electrode 16, the process proceeds to step S8, and if not, the process proceeds to step S9.
[0030]
In step S8, the dust collecting device (charging device 14 and dust collecting plates 13a and 13b) is operated for a predetermined time set in advance to collect dust in the mirror box and the image sensor housing space. When the dust collection operation is completed, the count number of the shutter counter 48 is reset. In step S9, after the most recent dust collection operation is completed, it is determined whether or not the number of shutter operations counted by the shutter counter 48 is a predetermined number or more. If it is determined in step S9 that the number of times is equal to or greater than the predetermined number, the process returns to step S8 to perform the dust collection operation for a predetermined time and then reset the count number. On the other hand, if it is determined that the number is less than the predetermined number, the process proceeds to step S10.
[0031]
In step S10, it is determined whether or not the interchangeable lens barrel 2 has been detached or attached, and if it is determined that the attachment or detachment has been performed, the process returns to step S8 to perform a dust collection operation for a predetermined time. On the other hand, if it is determined that the attachment / detachment is not performed, the process proceeds to step S11. In step S11, it is determined whether or not the dust collection mode button 47 (see FIG. 4) for forcibly performing the dust collection operation for a predetermined time has been operated. If it is determined in step S11 that the dust collection mode button 47 has been operated, the process returns to step S8 to perform a dust collection operation for a predetermined time, and if it is determined that the dust collection mode button 47 has not been operated, a series of processing ends. To do.
[0032]
The process in FIG. 5 is performed every time the camera is turned on. Therefore, after it is determined in step S7 that dust is attached, the dust collecting operation is executed every time the power is turned on until the dust collecting plates 13a and 13b and the transparent substrate 16 are cleaned. It will be. Note that after it is determined in step S7 that it has adhered, for example, a dust collection operation may be performed every predetermined time.
[0033]
Regarding the cleaning process, the interchangeable lens barrel 2 is removed, the quick return mirror 5 is flipped up, and the shutter unit 10 is opened to remove the attached dust. Further, the dust collecting plates 13a and 13b may be detachable, and if a warning is displayed, the dust collecting plates 13a and 13b may be removed and cleaned.
[0034]
As described above, in the camera according to the present invention, the charging device 14 charges the dust 20, and the charged dust 20 is forcibly attached to the dust collecting plates 13 a and 13 b by the Coulomb force (attraction), or conversely, the transparent electrode Since the dust 20 is moved away from the optical low-pass filter 12 by applying a voltage having the same sign as the charging of the dust to 16, it is possible to prevent the dust 20 from adhering to the optical low-pass filter 12 and the image sensor 11. it can. In addition, the dust collecting operation is performed for a predetermined time in anticipation of the timing at which the dust 20 in the mirror box or the image sensor housing space increases according to the number of shutter operations, the removal of the interchangeable lens barrel 2, and the like. It is possible to always maintain a very small state of dust 20 while suppressing power consumption.
[0035]
In the embodiment described above, the warning display is performed using the LCD display device 49 as the presentation means. However, for example, a warning sound may be generated by a speaker. The charging device 14 is a charging means, the dust collecting plates 13a and 13b and the charging device 14 are dust collecting devices, the optical low-pass filter 12 and the cover glass 11a are optical members, and the dust collecting plates 13a and 13b are dust collecting members. , AC power recognition switch 43, battery discrimination unit 45 and CPU 40 are identification means, detector 15 is dust collection state detection means, dust detection means 50 is dust detection means , LCD display device 49 is presentation means, and CPU 40 is The power control means and operation control means , the lens attachment / detachment switch 46 constitutes attachment / detachment detection means, and the shutter counter 48 constitutes switching frequency detection means.
[0036]
The present invention can be applied not only to the above-described lens-interchangeable single-lens reflex digital still camera, but also to a lens-integrated digital still camera or the like. In addition, the present invention is not limited to the above embodiment as long as the characteristics of the present invention are not impaired.
[0037]
【The invention's effect】
As described above, according to the present invention, dust in the photographing optical path is collected by the dust collector, so that it is possible to prevent the dust from adhering to the optical member, the imaging device, and the like.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of a camera according to the present invention.
FIG. 2 is a diagram illustrating a dust collecting operation.
FIG. 3 is a diagram illustrating the principle of charging.
FIG. 4 is a block diagram of the camera, showing a schematic configuration centering on a dust collection mechanism.
FIG. 5 is a flowchart illustrating a dust collecting operation.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Camera 2 Interchangeable lens barrel 4 Shooting lens 5 Quick return mirror 10 Shutter unit 11 Image pick-up element 11a Cover glass 12 Optical low-pass filter 13a, 13b Dust collector 14 Charging device 15 Detector 15b Reflector 16 Transparent electrode 20 Dust 21 Negative ion 22 LED
23 DC power source 30 Ionization line 41 AC power source 43 AC power source recognition SW
45 Battery discrimination unit 46 Lens attachment / detachment switch 47 Dust collection mode button 48 Shutter counter 49 LCD display device 50 Dust detection means

Claims (7)

An image sensor that converts an optical image formed by the taking lens into an electrical signal;
An optical member disposed between the photographing lens and the imaging element;
A charging means for charging dust floating in the photographing optical path to a predetermined polarity; a transparent electrode provided on the surface of the optical member and applied with a voltage so as to be charged to the same polarity as the charging polarity by the charging means; A dust collecting device that is disposed in the vicinity of the photographing lens side of the optical member and includes a dust collecting member that is charged to a polarity opposite to the charging polarity by the charging means;
The camera, wherein the dust collecting member collects the floating dust. The camera of claim 1,
A shutter that can be switched between a light-blocking state for blocking a light beam incident on the image sensor from the photographing lens and an open state for allowing the light beam to pass therethrough, when collecting the floating dust by the dust collector; A camera characterized in that the shutter is switched to an open state. The camera according to claim 1 or 2,
A plurality of power supply devices can be selectively used as a power supply for the dust collector,
Identifying means for identifying which of the plurality of power supply devices is used;
A camera comprising: power control means for controlling power consumption of the dust collector based on the identification result of the identification means. The camera according to any one of claims 1 to 3,
Dust collection state detection means for detecting the dust collection state of the dust collector;
A camera comprising presentation means for presenting the detection result of the dust collection state detection means in a recognizable form. The camera according to any one of claims 1 to 4,
Dust detection means for detecting dust in the dust collector or the transparent electrode;
An operation control means for operating the dust collector for a predetermined time when dust is detected by the dust detection means. The camera according to any one of claims 1 to 4,
The taking lens is detachable from the camera,
Attachment / detachment detecting means for detecting the attachment / detachment state of the photographing lens;
A camera comprising: an operation control unit that operates the dust collecting device for a predetermined time when the detachment of the photographing lens or subsequent mounting is detected by the attachment / detachment detection unit. The camera according to claim 2,
Switching number detecting means for detecting the number of switching operations of the shutter;
An operation control means for operating the dust collector for a predetermined time when the number of switching operations detected by the switching number detecting means reaches a predetermined number.

Images