WO2001006760A1 - Dispositif electromagnetique servant a actionner un appareil photographique a film electronique - Google Patents

Dispositif electromagnetique servant a actionner un appareil photographique a film electronique Download PDF

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Publication number
WO2001006760A1
WO2001006760A1 PCT/US2000/019339 US0019339W WO0106760A1 WO 2001006760 A1 WO2001006760 A1 WO 2001006760A1 US 0019339 W US0019339 W US 0019339W WO 0106760 A1 WO0106760 A1 WO 0106760A1
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WO
WIPO (PCT)
Prior art keywords
camera
pressure
electromagnetic
shutter
shutter button
Prior art date
Application number
PCT/US2000/019339
Other languages
English (en)
Inventor
Itzhak Sapir
Original Assignee
Silicon Film Technologies, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Silicon Film Technologies, Inc. filed Critical Silicon Film Technologies, Inc.
Priority to AU63487/00A priority Critical patent/AU6348700A/en
Publication of WO2001006760A1 publication Critical patent/WO2001006760A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/50—Constructional details
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof

Definitions

  • the present invention relates to photographic cameras, and more particularly to electronic cameras for creating digital images using an electronic image sensor. Description of the Related Art
  • image recording typically is performed by sequentially projecting optical images onto photographic film. Photons strike light-sensitive chemical grains in the photographic film to form latent images. The latent images are later developed by chemical processing to be viewed directly (as slides) or print on photographic paper.
  • electronic cameras use an electronic image sensor to capture an optical image and convert the optical image into an electrical image signal. Processing circuits in the electronic camera then convert the electrical image signal into digital data (digital images) suitable for use by a computer or computer network.
  • the digital images can be, stored, transmitted over a network, displayed on a computer display, printed on a computer printer, etc.
  • the digital images can also be easily edited or modified in format, resolution, and color mapping. Special optical effects can also be added.
  • the present invention solves these and other problems by providing an electronic film (E-film) apparatus that reversibly converts a conventional film camera body into an E-film camera.
  • the electronic film apparatus includes one or more state sensors that sense the operating state of the camera body without requiring modification or cooperation by the camera body.
  • the state sensors sense that the camera shutter is about to open, before the shutter actually opens, thereby allowing the imager and associated circuitry to be powered up and initialized prior to the operation of the shutter.
  • the state sensors include an electromagnetic sensor. In one embodiment, the state sensors include an acoustic sensor. In one embodiment, the state sensors include an optical sensor. The data gathered by the sensors is used to determine the operating state of the camera. Based on the operating state of the camera, the E-film apparatus operates in various power modes, include very low power modes (e.g. sleep modes), low power modes (e.g. standby modes, digital audio modes), and full power modes (e.g. image acquisition modes). In one embodiment, the E-film apparatus uses data from the state sensors to determine when to initiate image acquisition. In one embodiment, the E-film apparatus uses data from the state sensors to determine when to terminate image acquisition.
  • very low power modes e.g. sleep modes
  • low power modes e.g. standby modes, digital audio modes
  • full power modes e.g. image acquisition modes
  • the E-film apparatus includes an E-film cartridge that reversibly converts a conventional 35mm film camera into an E-film camera.
  • the 35mm camera can be a single lens reflex (SLR) camera, a point-and- shoot camera, a rangefinder camera, and the like.
  • the E-film apparatus includes a replaceable camera back that converts a conventional camera, such as a 35 mm camera, medium format cameras, ideal format cameras, large format camera, and the like, into an E-film camera.
  • the electromagnetic sensor includes a loop or coil that converts electromagnetic fields into an electrical signal.
  • the envelope of the electrical signal is detected by an envelope detector. The amplitude of a portion of the envelope is compared to a threshold and, if the envelope exceeds the threshold, the E- film apparatus enters image acquisition mode.
  • the acoustic sensor includes a microphone or other vibration sensor that senses vibrations in the camera due to operation of the mechanical aspects of the camera body such as motion of a shutter button, motion of a mirror (as in a SLR camera) and/or motion of a mechanical shutter. The microphone converts vibrations in the camera body into an electrical signal.
  • the envelope of the electrical signal from the microphone is detected by an envelope detector. The amplitude of a portion of the detected acoustic envelope is compared to a threshold and, if the envelope exceeds the threshold, the E-film apparatus enters an image acquisition mode.
  • the E-film apparatus enters an acoustic sampling (i.e. digital audio) mode.
  • a signal processor such as a digital signal processor
  • the electrical signals from the microphone are provided to an analog-to-digital converter and converted into a string of digital samples.
  • the digital samples are provided to the signal processor.
  • the signal processor computes a frequency spectrum of the digital samples and compares the computed frequency spectrum to an expected frequency spectrum. If the computed frequency spectrum is sufficiently similar to the expected frequency spectrum, then the E-film apparatus provides power to the image sensor and begins image acquisition.
  • the computed frequency spectrum and the expected frequency spectrum are compared by computing a cross-correlation between the two spectrums.
  • the E-film apparatus senses opening of the camera shutter by illuminating the shutter with a light source and measuring the light reflected by the shutter.
  • the light source is an infrared source.
  • the infrared source provides short pulses of light and operates at a relatively low duty cycle.
  • the infrared source is operated only when other sensors, such as the electromagnetic or acoustic sensors have provided data indicating that operation of the shutter appears to be eminent.
  • One embodiment includes an ElectroMagnetic Field (EMF) device that attaches to a camera shutter button.
  • the EMF device can be attached to the shutter button using threads, adhesives, and the like.
  • the EMF device emits an electromagnetic signal that is received by an electromagnetic sensor on an E-film cartridge.
  • the E-film cartridge is configured to begin an image capture process in response to a suitable elect electromagnetic signal.
  • the EMF device includes a pressure-sensitive piezoelectric circuit that emits a short pulse of electromagnetic radiation when stressed.
  • the EMF device emits an electromagnetic signal to begin the image taking process before the EMF device has been pressed with sufficient force to cause the camera shutter to open.
  • Figure 1 shows a conventional single lens reflex camera and an electronic film cartridge.
  • Figure 2 shows an electronic film cartridge having an electromagnetic sensor, an acoustic sensor, an optical source, and an optical sensor.
  • Figure 3 shows a conventional single lens reflex camera with an electronic film back that includes an electromagnetic sensor, an acoustic sensor, an optical source, and an optical sensor.
  • Figure 4 shows major mechanical operational elements of a single lens reflex camera including a mirror, a mirror actuator, a shutter, and a shutter actuator.
  • Figure 5 is a block diagram of the functional elements of a single lens reflex camera wherein the electromagnetic and acoustic emissions from the functional elements are indicative of a camera state.
  • FIG 5 is a block diagram showing functional elements of an electronic film apparatus, such as an E-film cartridge, that senses the camera state shown in Figure 5.
  • an electronic film apparatus such as an E-film cartridge
  • Figure 7 is a flowchart showing the operation of an E-film cartridge including transitions from lower-power modes to higher-powered modes.
  • Figure 8 is a plot showing electromagnetic emissions of a typical SLR camera during a picture-taking operation sequence.
  • Figure 9 shows details of the plots from Figure 8 near the time when the shutter opens.
  • Figure 10 is a circuit diagram showing one embodiment of an electromagnetic sensor suitable for use in an E- film apparatus.
  • Figure 11 is a timeline showing operation of a SLR camera during a picture-taking sequence, including operation of the mirror and shutter.
  • Figure 12 is plot showing acoustic emissions of a typical SLR camera during the timeline sequence shown in Figure 11.
  • Figure 13 is a schematic diagram of the mechanical elements of a focal plane shutter as is typically found in a SLR camera.
  • Figure 14 is a mechanical schematic showing elements of a focal plane shutter as found in a typical single lens reflex camera with an optical sensor for measuring operation of the shutter.
  • Figure 14B shows operation on the shutter of Figure 14A immediately after release of the first shutter curtain.
  • Figure 14C shows operation of the focal plane shutter shown in Figure 14A when the first curtain has opened completely.
  • Figure 14D shows operation of the focal plane shutter off Figure 14A immediately after release of the second curtain.
  • Figure 14E shows operation of the focal plane shutter shown in Figure 14A when the second curtain has completely closed.
  • Figure 15 shows time and frequency domain plots of the optical signature of a SLR camera when the mirror is moving from the down position to the up position prior to release of the first shutter curtain.
  • Figure 16 is a flowchart of the operation of an E-film apparatus using a two-stage acoustic sensor to detect camera state and picture-taking functions.
  • Figure 17 is the block diagram of a two-stage acoustic sensor system having an analog stage for sensing initial mirror movement and a digital stage for sensing later movement and verifying camera state prior to release of the first shutter curtain.
  • Figure 18A shows an EMF device attached to a shutter button.
  • Figure 18B shows an EMF device that attaches to a shutter button using screw threads.
  • Figure 18C shows an EMF device that attaches to a shutter button using an adhesive.
  • Figure 1 shows a standard 35mm single lens reflex camera 110 having a camera body 132, a camera lens 130, and a camera back 128.
  • a shutter button 118 is disposed on an upper surface of the camera body 132.
  • Figure 1 shows a rear view of the camera 110 with the back 128 open.
  • an image (focal) plane area 114 corresponds to a region where the lens 130 produces a focused image.
  • a pressure plate 108 is disposed on an inner surface of the camera back 128. The pressure plate 108 is provided to press a photographic film against the image plane to improve sharpness of the image produced on the film.
  • FIG 1 also shows on electronic film cartridge (E-film cartridge) 112.
  • the E-film 112 includes an optional on/off switch 120 and an optional pressure sensor 122.
  • the optional switch 120 is provided to allow a user to turn the E-film cartridge on and off.
  • the optional pressure sensor 122 is provided to allow the E-film cartridge 1 12 to sense that the E-film cartridge 112 has been placed inside the camera body 132 and that the back 128 has been closed.
  • the E-film cartridge 112 operates in different power modes (e.g., off, sleep mode, low-power mode, etc. ) depending on whether the E-film cartridge is in the camera (with the back closed) or outside the camera.
  • Figure 2 shows additional details of the E-film cartridge 112.
  • the front surface of a flag portion of the E-film cartridge 1 12 includes an image sensor 206, an optional electromagnetic sensor 204, an optional acoustic sensor 202, an optional optical sensor 210, and an optional optical source 220.
  • the E-film cartridge 112 When placed inside the camera 110, the E-film cartridge 112 turns the conventional camera 110 into an electronic camera allowing electronic digital pictures to be acquired and stored in the electronic film cartridge 1 12.
  • the digital pictures stored in the electronic film cartridge 112 can be later downloaded into computer for display, printing, editing, etc.
  • the camera 110 can be turned into an electronic camera by using an electronic film back 300 shown in Figure 3.
  • the electronic film back 300 includes the optional on/off switch 120, the image sensor 260, the optional acoustic sensor 202, the optional electromagnetic sensor 204, the optional optical sensor 210, and the optinal source 220.
  • a latch mechanism 302 is provided on the electronic film back 300 to hold the film back 300 closed against the camera body 132.
  • the latch 302 can be used to perform a function similar to that of the pressure sensor 122 on the E-film cartridge 112 insomuch as the latch can be used to sense that the back 300 is mounted on the camera body 132 and the back 300 is closed.
  • Figure 4 is a schematic diagram showing major mechanical elements of the camera 110, including a mirror 402 and a shutter 404.
  • a mirror 402 When the camera 110 is not in a picture-taking mode, light entering the camera 110 is focused by one or more lenses and reflected by the mirror 402 up to a pe ⁇ taprism 412.
  • the pentaprism 412 redirect the light from the mirror out through an eyepiece 430 to a user 420.
  • Figure 4 also shows various electronic and electro-mechanical aspects of the camera 1 10 including a power source 426 (such as a battery) that provides energy to power the circuits of an electronic control system (processor) 406. Outputs from a metering sensor 424 are provided to a metering input of the electronic control system 406. A mirror control output from electronic control system 406 is provided to a mirror actuator 408. A mechanical linkage links the mirror actuator 408 to the mirror 402 allowing the actuator 408 to cause the mirror to move up and down. In a normal, idle state, the mirror 402 is in a "down" position allowing light to be reflected into the pentaprism 412.
  • a power source 426 such as a battery
  • Outputs from a metering sensor 424 are provided to a metering input of the electronic control system 406.
  • a mirror control output from electronic control system 406 is provided to a mirror actuator 408.
  • a mechanical linkage links the mirror actuator 408 to the mirror 402
  • the mirror actuator 408 causes the mirror 402 to swing up, thereby allowing light from the lens to fall on the shutter 404.
  • the shutter 404 is opened, the light falls on photographic film or an electronic image sensor 206 disposed behind the shutter 404.
  • a shutter control output from the electronic control module 406 is provided to a shutter actuator 410 to open and close the shutter 404.
  • FIG. 5 is a block diagram showing the functional blocks of the camera 110.
  • a flash control output from the processor 406 is provided to a flash control module 518.
  • the flash control module 518 can be a control circuit that controls the operation of an external flash. Alternatively, the flash control module 518 can include an internal flash built into the camera 110.
  • the mirror control output from the processor 406 is provided to the mirror actuator 408.
  • the shutter control output from the processor 406 is provided to the shutter actuator 410.
  • a motor control output from the processor 406 is provided to a motor 520.
  • the motor 520 is optional and provides automatic wind and rewind operations.
  • An output from shutter button 1 18 is provided to the processor 406.
  • An output from the metering sensors 504 is provided to the processor 406.
  • a metering output from the processor 406 is provided to a metering display 502.
  • the camera state 530 can be sensed by sensing emissions from the various functional blocks in the camera 110.
  • Suitable sensors include acoustic sensors (such as the sensor 202) to sense acoustic emissions, electromagnetic sensors (such as the sensor 204) to sense electromagnetic emissions, and the like.
  • Optical sensors such as the sensor 210 can also be used in connection with sources such as the optical source 220 to sense the position of various elements of the camera 110.
  • the operation of the various emissions from the camera 1 10 can be sensed to deduce the camera state 530.
  • the mirror actuator 408 is typically an electro-mechanical device such as a motor or solenoid that produces electromagnetic emissions having an electromagnetic signature or "fingerprint” and acoustic emissions having an acoustic signature or "fingerprint.”
  • the shutter actuator 410 is also typically an electro-mechanical device that produces an electromagnetic signature and an acoustic signature.
  • the processor 406 typically produces an electromagnetic signature.
  • Figure 6 is a block diagram of the functional elements of an electronic image capture device such as the E- film cartridge 1 12 or the electronic film back 300.
  • the E-film cartridge 112 is used as an example of electronic image capture device with the understanding that the electronic camera back 300 or other electronic image capture devices can be used as well.
  • the E-film cartridge 112 includes a power source 620, an optional power switch 610, and camera state sensors 624.
  • the power switch 610 can include for example the on/off switch 120 and/or the pressure sensor 122. Outputs from the switch 610 are provided to a power source 620 to control operation and power modes of the E-film cartridge 112.
  • a first power control output from the camera state sensor 624 is provided to the power source 620 and a second power control output from the camera state sensor 624 is provided to a processor 630.
  • the camera state sensor 624 includes sensors and sensor systems such as an electromagnetic sensor system 685 and an audio sensor system 680.
  • the E-film cartridge 112 also includes the image sensor 206. An output from the image sensor 206 is provided to an analog-to-digital converter 628.
  • a digital output from the analog-to-digital converter 628 is provided to the processor 630.
  • the processor 630 communicates with an internal memory 631 and internal storage 612 to process and store images captured from the image sensor 206.
  • the processor 630 also communicates with an interface port 634.
  • the interface port 634 communicates with external storage and display devices 636 to allow the user to display captured images, store captured images, download captured images, and in general manipulate images captured by the E-film cartridge 112.
  • FIG. 7 is a flowchart 700, beginning with a start block 701, that shows overall operation of the E-film cartridge 112.
  • the flowchart 700 advances from the start block 701 to a process block 702 when the E-film cartridge 112 is mounted in the camera 110.
  • the process advances to a process block 703 when the camera back 128 is closed.
  • the process advances to process block 704 where the E-film cartridge 112 powers up into a low-power mode.
  • E-film cartridge 112 is typically powered into the low-power mode based on an input from the pressure sensor/switch 122.
  • the process advances to a process block 705 wherein the E-film cartridge 112 "listens" to the electromagnetic and/or acoustic emissions from the camera 110.
  • the E-film cartridge can listen to electromagnetic emissions produced by the camera 110, acoustic emissions produced by the camera 110, or other indicators of the camera state 503.
  • the process advances to a process block 706 were the processor 630 uses the measured emission data to determine the camera state 530.
  • the process advances to a process block 707 where the power source 624 powers-up circuits in the E-film cartridge 112 needed to acquire and process an image.
  • the process advances to process block 708 where an image is acquired.
  • the process advances to the process block 709 where the power source powers down the image processing circuits and the E-film cartridge 112 again enters a low-power mode.
  • the process returns to the process block 705 and listens to the camera. This process comprising process blocks 705-709 continues until the camera back 128 is opened, whereupon the process advances to a process block 710.
  • Figure 8 is a plot having a curve 802 that shows electromagnetic emissions produced by a typical 35mm single lens reflex (SLR) camera.
  • Figure 8 also shows a curve 804 that shows the optical signal produced by placing an optical sensor behind the shutter 404 (thus showing when the shutter is open and closed).
  • the curve 804 shows a leading edge when the shutter 404 opens and a falling edge when the shutter 404 closes.
  • Figure 9 is a plot showing curves 902 and 904 similar to those shown in Figure 8.
  • Figure 9 shows an expansion of the curves 802, and 804 near the time when the shutter 404 opens.
  • Examination of the curve 902 shows an electromagnetic pulse at a time a few milliseconds before the shutter 404 opens.
  • the curve 904, corresponding to the optical signal measured through the opened shutter also shows some electromagnetic interference picked up by the leads attached to the optical sensor.
  • Data in the curve 902 shows significant electromagnetic emissions before the opening of the shutter 404 that can be sensed by the sensor 204 and used in the E-film cartridge 112 to trigger the image capture process.
  • Figure 10 shows one embodiment of an electromagnetic sensor that can be used as the sensor 204.
  • the sensor 1000 includes a coil 1004.
  • a first terminal on the coil 1004 is provided to a first terminal of a resistor 1010.
  • a second terminal of the resistor 1010 is provided to an inverting input of an operational amplifier 1008.
  • An output of the operational amplifier 1008 is provided to and an anode of a diode 1006.
  • a cathode of the diode 1006 is provided to the inverting input of the operational amplifier 1008.
  • a second terminal of the coil 1004 is provided to a first terminal of a resistor 1014, to a first terminal of a capacitor 1012, and to a first terminal of a capacitor 1016.
  • the second terminal of the capacitor 1016, and a second terminal of the resistor 1014 are provided to ground.
  • the second terminal of the capacitor 1012 is provided to a non-inverting input of the operational amplifier 10008 and to a non-inverting input of and operational amplifier 1024.
  • a power supply voltage V+ is provided to a first terminal of a resistor 1018.
  • a second terminal of the resistor 1018 is provided to a first terminal of a resistor 1019 and to an inverting input of the amplifier 1024.
  • a second terminal of the resistor 1019 is provided to a first terminal of a resistor 1020, to a first terminal of a resistor 1022, and to a first terminal of a capacitor 1021.
  • a second terminal of the capacitor 1021, and the second terminal of the resistor 1022, are both provided to ground.
  • the second terminal of the resistor 1020 is provided to a non- inverting input of the amplifier 1024.
  • An output of the amplifier 1024 is provided as an output signal 1030.
  • the sensor 1000 converts a detected electromagnetic signal into a digital signal that can be used to activate the circuits of E-film cartridge 112 in preparation for capturing an image.
  • the coil 1004 operates as an antenna for electromagnetic signals generated by the camera 110.
  • the first operational amplifier 1008 serves to buffer, detect, and amplify the signal sensed by the coil 1004.
  • the amplifier 1024 is configured as to comparator that compares the detected signal with a threshold signal level. When the detected signal level exceeds the selected threshold signal level the output 1030 is said to a logic 1 (true) otherwise the output 1030 is set to a logic 0 (false).
  • the resistor 1010 is 518 ohms
  • the resistor 1014 is 1 megaohm
  • the resistor 1018 is 1 megaohm
  • the resistor 1019 is 2.7k ohms
  • the resistor 1020 is 100k ohms
  • the resistor 1022 is 1 megaohm.
  • the capacitor 1012 is 0.22 uf (microfarads)
  • the capacitor 1016 is 1000 pf (picofarads)
  • the capacitor 1021 is 0.22 uf.
  • the coil 1014 is constructed using 15 turns of wire in a coil approximately 0.7 inches in diameter.
  • the diode 1006 is a small signal diode such as an LL4148
  • the opamps 1008 and 1004 are conventional operational amplifiers, such as an 0PA2244.
  • acoustic emissions can also be used to detect the camera state 530.
  • Acoustic emissions i.e. vibrations
  • Figure 11 is a timeline showing the operation of the major mechanical systems of the camera body 110 during a picture-taking operation beginning when the shutter button 118 is pressed. As shown in Figure 11, pressing the shutter button 118 creates a shutter button event 1 102. Shortly after the shutter button event 1102, the mirror 402 is released creating a mirror release event 1103. The mirror travels upwards until it reaches a full up position at a mirror-up event 1104.
  • a first shutter curtain 1304 (described in connection with Figures 13, and 14A-E below), is released at a first curtain release event 1106.
  • the first shutter curtain 1304 travels across the aperture 114 (typically in a horizontal or vertical direction), until the curtain 1304 reaches the fully opened position, corresponding to a first curtain open event 1107.
  • a second shutter curtain 1306 is released in a second curtain release event 1108.
  • the second shutter curtain 1306 also travels across be aperture 114 until the curtain 1306 reaches a fully closed position at a second curtain closed event 1109.
  • FIG. 12 is a plot showing acoustic emissions by the camera 110 during the picture-taking timeline shown in
  • Figure 12 includes a curve 1201 that shows acoustic emissions by the camera 110, and a curve 1250 that shows light through the shutter. As shown in the curve 1201, acoustic omissions are initially relatively low, corresponding to a general background noise level.
  • the curve 1201 shows a first acoustic pulse 1202, at a time of approximately t - -.07 s (seconds), and a second acoustic pulse 1204 at a time of approximately t - -.05 s.
  • the first acoustic pulse 1202 corresponds approximately to the first mirror release event 1103.
  • the second acoustic pulse 1204 corresponds approximately to the mirror-up event 1104.
  • the pulse 1204 shows a fairly large amplitude corresponding to the impact of the mirror 402 against the camera body when it reaches the full-up position.
  • the first shutter curtain fully open event 1107 is identified as a relatively large acoustic pulse 1208 at approximately t - 7.0 ms (milliseconds) corresponding to a curtain travel time of approximately 1/125 seconds.
  • the pulse 1208 shows a fairly large amplitude due, in part, to the rapid deceleration of the quickly moving curtain 1304.
  • the plot 1201 shows a relatively quiet period during an interval 1220 between the first shutter curtain fully open event 1107 and the second shutter curtain release event 1108.
  • the second shutter curtain release event 1108 is identified as a relatively small acoustic pulse 1210 at a time approximately t - 0.18 s and the second shutter curtain fully closed event 1109 is identified as a relatively large acoustic pulse 1212 approximately 7.0 milliseconds later.
  • the time interval corresponding to the time between the second mirror released event 1110 and the mirror fully down event 1111 is identified in the plot 1201 as a time interval 1228 of approximately 0.06 seconds.
  • the acoustic pulses 1206-1212 in Figure 12, that is, the pulses caused by operation of the shutter, can be understood in light of Figure 13 and Figures 14A-14E which illustrate the operation of a focal plane shutter as is typically used in a SLR camera.
  • the focal plane shutter is shown in a closed position corresponding to a time before the picture is taken.
  • Figure 13 shows the first shutter curtain 1304 and the second shutter curtain 1306.
  • a proximal end of the shutter curtain 1304 is attached to a takeup-spool 1305 and a distal end of the first shutter curtain 1304 is attached to a rib 1316.
  • Figure 13 is illustrative of one embodiment of a focal plane shutter and that other embodiments exist in the art. For example, some focal plane shutters do not use takeup spools, but rather use a plurality of plates that slide past each other. For the present purposes, the embodiment shown in Figure 13 is sufficient to describe important characteristics of focal plane shutters in general. Figure 13 shows the focal plane shutter in the fully "cocked" position ready to begin the picture-taking operation sequence.
  • first rib 1316 and the second rib of 1315 are positioned near a right edge of an aperture 1301 defined by a right baffle 1312 and a left baffle opening 1313.
  • the first shutter curtain 1304 is shown in a relatively expanded position being unwound from the takeup spool 1305.
  • the second shutter curtain 1306 is shown in a relatively contracted position being wound on the second takeup spool 1307.
  • Photographic film 1302 is disposed behind the aperture 1301 as defined by the baffles 1312 and 1313.
  • the film 1302 is positioned in an image plane of a lens.
  • Figure 14 shows the focal plane shutter from Figure 13 but with the film 1302 removed and replaced by an optical sensor 1402 disposed near the right baffle 1312.
  • the configuration shown in Figure 14, having the optical sensor 1402 corresponds to the test setup used to measure the acoustic signatures shown in Figure 12.
  • Operation of the focal plane shutter, as shown in Figures 14A-14E, can be used to relate the various operational states of the shutter to the optical and acoustic data shown in Figure 12.
  • the curve 1250 shown in Figure 12 corresponds to an output signal from the optical sensor 1402.
  • the curve 1250 is adjusted so that a leading edge is aligned with the time t - 0.0.
  • the small acoustic pulse 1206, corresponding to release of the first curtain 1304, is aligned with the time t - 0.0.
  • Figure 14B shows the shutter at a time when the first shutter curtain 1304 is partially open (shortly after the release event 1106) such that be first rib 1316 has moved slightly left of the baffle 1312, allowing light to travel through the shutter aperture and reach the optical sensor 1402.
  • Figure 14C shows the focal plane shutter curtain 1304 fully open with the first rib 1316 positioned behind the left baffle 1313 such that the aperture 1301 is completely open.
  • the optical sensor 210 provides functionality similar to that of the optical sensor 1402 (shown in Figure 14A) and can thus be used to detect the opening (or closing) of the shutter curtains 1304 and 1306.
  • An optional optical source 220 i.e. an infrared source
  • the optical sensor 210 will detect the illumination reflected by the curtain.
  • the optical signal provided by the source 220 is a pulsed signal, having a relatively short duration to avoid fogging the image sensed by the image sensor 206.
  • the use of the optical sensor 210 to detect the opening of the shutter curtains 1304, 1306 has a drawback in that the optical sensor 210 will have no advance warning that the shutter is about to open. Thus, the optical sensor 210 cannot tell the power supply 620 to power-up the imager 206 and associated circuits in advance. This means that for very fast shutter speeds, the imager 206 may miss a portion of the image.
  • first mirror release event 1102 and the mirror up event 1 103 occur well before the first curtain release event 1104.
  • the two acoustic pulses 1202 and 1204, occurring before first shutter curtain release event 1104 are advantageously used by an acoustic sensor system to determine the camera state 530 to predict that the shutter is about to open.
  • Figure 15 shows a plot 1502 corresponding to the curve that includes the pulses 1202 and 1204.
  • Figure 15 also shows a frequency domain plot 1504 corresponding to a frequency domain representation (Fourier transform) of the pulse 1204.
  • Each camera produces a frequency domain signature 1504 having an expected frequency domain representation.
  • This frequency domain signature is governed primarily by the construction of the camera 110 and is relatively uniform from camera to camera for a particular camera model. Thus, this frequency domain signature can be used as a "fingerprint" to verify that the acoustic signal being measured is indeed the mirror-up event 1104, which typically proceeds the first shutter curtain release event 1107.
  • the pulse 1202 which proceeds the pulse 1204 by approximately 10.0 milliseconds, can be used to wake-up the sampling circuits to sample and process the acoustic pulse 1204.
  • the pulse 1202 can be detected by using a relatively low power analog circuit based on a threshold detector.
  • the analog sensor system 680 is a two-stage sensor having a first stage and a second stage. The first stage uses low- power analog detection. The second stage uses digital signal processing.
  • a flowchart 1600 in Figure 16 begins with at a start block 1601.
  • the flowchart 1600 advances from the start block 1601 to a process block 1602 where a first audio pulse is detected by the first stage (typically an analog sensor).
  • the process advances to a decision block 1603 where the envelope of the audio pulse is compared with a threshold level. If the audio pulse does not exceed the threshold level, then the process returns to the process block 1602. If the envelope of the audio pulse does exceed the threshold level, then the process advances to a process block 1604.
  • the E-film cartridge 112 powers up into a low-power digital-audio processing mode.
  • the processor 630 In the digital audio processing mode, power is provided to the processor 630, such as a digital signal processor (DSP). Power is also supplied to sampling and conversion circuits configured to sample the acoustic signal and convert the sampled signal into a digital format for use by the processor 630. The process then advances to a process block 1605 where a sequence of audio samples is collected.
  • DSP digital signal processor
  • the process After collecting the audio samples, the process advances to a process block 1606 where the frequency domain spectrum of the audio samples is computed. After computing the frequency domain spectrum, the process advances to a process block 1607 where the computed spectrum is compared with an expected spectrum.
  • the expected spectrum being the frequency domain signature of an event, such as the mirror-up event for a specified make and model of camera 110.
  • the expected spectrum is obtained, for example, by measuring the spectrum produced by a desired make and model of camera.
  • the data for the expected spectrum can be measured from a single occurrence of the desired event, or by averaging together the data produced by several occurrences of the desired event.
  • the process block 1607 calculates a cross-correlation between the computed spectrum (that is, the spectrum computed from the time-sample data) and the expected spectrum. In one embodiment, the process block 1607 calculates an error (such as, for example, maximum error, a mean squared error, RMS error, and the like). In one embodiment, the process block 1607 is a maximum likelihood estimator. In one embodiment, the process block 1607 uses a neural network to compare the two spectra. In one embodiment, the process block 1607 compares the measured (sampled) time-domain waveform with an expected time-domain waveform. After the process block 1607, the process then advances to a decision block 1608. In the decision block
  • the process returns to the process block 1602. This occurs, for example, when the initial audio pulse was not due to a mirror release event 1103 but rather some other event that produced vibrations or acoustic signals in the camera, such as, for example, closing the camera back, jostling the camera, dropping the camera, changing lenses, etc. If however, in the decision block 1608, it is determined that the computed spectrum is sufficiently similar to the expected spectrum, then the process advances to a process block 1609.
  • the decision block 1608 decides based on a probability (e.g., by using a cross-correlation computed in the process block 1607, since cross-correlations are related to probabilities) that the event was a mirror release event.
  • the decision block 1608 uses a probability factor of approximately 70 percent, that is, the decision block 1608 indicates a match if it decides that there is better than a 70 percent chance that the event was a mirror flip.
  • the decision block 1608 advances to the process block 1609 if it decides that it is more likely than not (i.e. better than 50 percent chance) that the event was a mirror flip.
  • Other embodiments use percentages in the range of 50 percent to 95 percent.
  • the E-film cartridge 112 is brought up into a full-power or image acquisition mode.
  • the image acquisition mode power is applied to the image sensor 206 and associated processing and storage circuits.
  • the process advances to a process 1610 where the imager is reset.
  • Image acquisition then begins in a subsequent process block 161 1.
  • the process then advances to a decision block 1612 that determines when image acquisition is complete. If image acquisition is not complete, the process returns to the process block 1611 to continue collecting the image.
  • the process advances to a process block 1613. In the process plot
  • the image is processed and stored in the internal storage 612. After storing the image, the process advances to a decision block 1614 to determine whether a dark-current image is needed. If no dark-current image is needed, then the process immediately advances to a process block 1618.
  • the process advances to a process block 1615 where the imager 260 is again reset. After the reset, the process advances to a process block 1616 where a dark current image is collected. After collecting the dark current image, the process advances to a process block 1617 were the dark current image is stored in the memory 612. After the dark current image is stored, the process advances to the process block 1618.
  • the imager 260 and associated circuits are powered down and the process advances to the process block 1619.
  • the processor 1630 is powered down and the E-film cartridge 112 reenters the low-power sleep mode. Upon re-entering the low-power sleep mode, the process returns to the process block 1602.
  • FIG 17 is a block diagram of a two-stage acoustic sensor system 680 used in connection with the flow chart 1600 shown in Figure 16.
  • the acoustic system 680 includes the acoustic sensor 202. Output from the acoustic sensor 202 is provided to an input of an amplifier 1702. Output from the amplifier 1702 is provided to input of a detector 1704 and to an input of a filter 1713.
  • An output from the detector 1704 is provided to input of an integrator 1706.
  • An output from the integrator is provided to input of an integrator 1706.
  • a threshold block 1710 is provided to a second input of the comparator 1708.
  • An output from the comparator 1708 is provided to the power system 620.
  • An output from the filter 1713 is provided to an analog input of an analog-to-digital converter 1712.
  • a digital output from the analog-to-digital converter 1712 is provided to the processor 630.
  • the acoustic sensor 202 detects an acoustic emission from the camera 110 and converts the emission into an electrical signal that is amplified by the amplifier 1702.
  • the envelope of the amplified signal is calculated by the detector 1704 acting in concert with the integrator 1706.
  • the output from integrator 1706 is the envelope signal.
  • the output from the comparator 1708 is provided to the power system 620.
  • the power system 620 will power-up the processor 630, analog-to-digital converter
  • the lowpass filter 1713 is an anti-alias and filter for the analog-to-digital converter 1712.
  • the output of the analog-to-digital converter 1712 is provided to the processor 630 allowing the processor 630 to compute the spectrum of the audio signal sensed by the sensor 202.
  • Non-SLR cameras most notably simple rangefinder cameras and fixed-focus cameras, do not include the mirror 402. Thus, in a non-SLR camera, the sounds created by the movement of the mirror 402 cannot be used to trigger the image capture process. Moreover, many high-end SLR cameras provide a mirror lockup feature to lock the mirror 402 in the open (picture-taking) position. This mirror lockup feature is commonly used with high magnification photography (e.g. photo-micrography or long telephoto lenses) because at high magnifications the vibration caused by the motion of the mirror can reduce image sharpness.
  • the electromagnetic radiation produced by the camera can be sensed by the electromagnetic sensor 204 and used to start the image capture process in the E-film cartridge 112. However, some cameras produce very little electromagnetic radiation, and some cameras (e.g., purely mechanical cameras) produce no significant electromagnetic radiation. For such cameras, an alternate way of triggering the image capture process for the E-film cartridge 112 is desired.
  • FIG 18A shows an ElectroMagnetic Field (EMF) device 1800 that attaches to a camera shutter button 1802 on a camera 1801.
  • EMF ElectroMagnetic Field
  • Figure 18B the EMF device 1800 attaches to the shutter button 1802 using threads.
  • Figure 18C the EMF device 1800 attaches to the shutter button 1802 using an adhesive layer 1805.
  • Suitable adhesives for the adhesive layer 1805 include, for example, liquid adhesives, double-sided adhesive tapes, and the like.
  • the adhesive layer 1805 is useful, for example, when the shutter button 1802 is not provided with threads, as is the case with some modern cameras of the point-and-shoot variety.
  • the EMF device 1800 When pressed, the EMF device 1800 emits an electromagnetic signal that is received by the electromagnetic sensor 204 shown in Figure 2.
  • the EMF device includes a pressure-sensitive piezoelectric circuit that emits a short pulse of electromagnetic radiation when stressed. Pressing the EMF device 1800 stresses the piezoelectric material, causing the piezoelectric material to emit a short electromagnetic pulse. The electromagnetic pulse is received by the electromagnetic sensor 204 to initiate the image capture process.
  • the EMF device 1800 is configured to stress the piezoelectric material such that the short pulse of electromagnetic energy occurs before the shutter button 1802 is sufficiently depressed to cause the camera 1801 to open the shutter. In this way, the EMF device 1800 can wake up the E-film cartridge 1 12 before the shutter opens.
  • the EMF device 1800 is provided with a battery that provides power to an electromagnetic-generating circuit through a pressure switch or other pressure-sensitive device. When the EMF device 1800 is pressed the battery powers the electromagnetic-generating circuit and causes the electromagnetic-generating circuit to radiate enough electromagnetic energy to the electromagnetic sensor 204 to wake up the E-film cartridge.
  • the EMF device 1800 produces an electromagnetic pulse with an expected shape.
  • the E- film cartridge 112 detects a shape of an envelope of the electromagnetic radiation received by the electromagnetic sensor 204.
  • the E-film cartridge begins the picture taking process if the envelope of the electromagnetic radiation received by the electromagnetic sensor 204 is sufficiently similar to the expected shape of the envelope of the electromagnetic radiation from the EMF device 1800.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Studio Devices (AREA)

Abstract

L'invention concerne un dispositif à champ électromagnétique (EMF) qui se fixe à un déclencheur d'appareil photographique. Ce dispositif à champ électromagnétique peut se fixer sur le déclencheur au moyen de fils, d'adhésifs et de dispositifs analogues. Lorsqu'on exerce une pression sur ce dispositif à champ électromagnétique, il émet un signal électromagnétique qui est reçu par un capteur électromagnétique situé sur une cartouche de film électronique. Cette cartouche permet de démarrer un processus de saisie d'image en réponse à un signal électromagnétique approprié. Dans un mode de réalisation, ce dispositif à champ électromagnétique comporte un circuit piézo-électrique sensible à la pression qui, sous l'effet d'une pression, produit une courte impulsion de rayonnement électromagnétique. Dans un autre mode de réalisation, ce dispositif à champ électromagnétique émet un signal électromagnétique afin de déclencher le processus de prise d'image avant qu'une pression suffisamment forte ne soit appliquée sur le dispositif à champ électromagnétique afin de provoquer l'ouverture de l'obturateur de l'appareil photographique.
PCT/US2000/019339 1999-07-16 2000-07-14 Dispositif electromagnetique servant a actionner un appareil photographique a film electronique WO2001006760A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU63487/00A AU6348700A (en) 1999-07-16 2000-07-14 Electromagnetic device for operating an electronic film camera

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
US14443399P 1999-07-16 1999-07-16
US60/144,433 1999-07-16
US44001999A 1999-11-12 1999-11-12
US09/440,019 1999-11-12
US61585300A 2000-07-14 2000-07-14
US09/615,853 2000-07-14

Publications (1)

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WO2001006760A1 true WO2001006760A1 (fr) 2001-01-25

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AU (1) AU6348700A (fr)
WO (1) WO2001006760A1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4199245A (en) * 1977-08-19 1980-04-22 Minolta Camera Kabushiki Kaisha Power source switch for cameras
US4916476A (en) * 1989-02-14 1990-04-10 Eastman Kodak Company Method and circuit for converting a conventional camera into an electro-optical camera
EP0665672A2 (fr) * 1994-01-28 1995-08-02 Polaroid Corporation Module d'imagerie électronique
WO2000029904A1 (fr) * 1998-11-13 2000-05-25 Silicon Film Technologies, Inc. Systeme et procede de commande d'un appareil photographique a film electronique

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4199245A (en) * 1977-08-19 1980-04-22 Minolta Camera Kabushiki Kaisha Power source switch for cameras
US4916476A (en) * 1989-02-14 1990-04-10 Eastman Kodak Company Method and circuit for converting a conventional camera into an electro-optical camera
EP0665672A2 (fr) * 1994-01-28 1995-08-02 Polaroid Corporation Module d'imagerie électronique
WO2000029904A1 (fr) * 1998-11-13 2000-05-25 Silicon Film Technologies, Inc. Systeme et procede de commande d'un appareil photographique a film electronique

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