Electronic flash, electronic camera and light emitting head

• US 20060250519A1
• Filed: 07/07/2006
• Published: 11/09/2006
• Est. Priority Date: 07/25/2000
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Kawakami, Chikuni
• Granted Patent: US 8,634,021 B2
• Time in Patent Office: Days
• US Class Current: 348/371
• CPC Class Codes: G03B 15/05 Combinations of cameras with electronic flash apparatus; Electronic flash units
• CPC Class Codes: G03B 2215/0521 movable housing, e.g. bounce-light
• CPC Class Codes: G03B 2215/0535 Built-in diffusor
• CPC Class Codes: G03B 2215/0567 Solid-state light source, e.g. LED, laser
• CPC Class Codes: G03B 2215/0592 installed in front of light emitter
• CPC Class Codes: H04N 23/10 for generating image signals from different wavelengths
• CPC Class Codes: H04N 23/631 Graphical user interfaces [GUI] specially adapted for controlling image capture or setting capture parameters
• CPC Class Codes: H04N 23/667 Camera operation mode switching, e.g. between still and video, sport and normal or high- and low-resolution modes
• CPC Class Codes: H04N 23/673 based on contrast or high frequency components of image signals, e.g. hill climbing method
• CPC Class Codes: H04N 23/74 by influencing the scene brightness using illuminating means
• CPC Class Codes: H04N 23/88 for colour balance, e.g. white-balance circuits or colour temperature control
• CPC Class Codes: H04N 25/713 Transfer or readout registers; Split readout registers or multiple readout registers
• CPC Class Codes: H04N 25/75 Circuitry for providing, modifying or processing image signals from the pixel array
• CPC Class Codes: H04N 5/77 between a recording apparatus and a television camera
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/22 using optical feedback
• CPC Class Codes: H05B 45/325 Pulse-width modulation [PWM]
• CPC Class Codes: H05B 45/37 Converter circuits
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

R, G and B LEDs are used as a light source of an electronic flash. Electric energy is supplied to a capacitor to the LEDs. A system controller controls light emitting amounts of the LEDs so that a color temperature of the electronic flash light becomes a color temperature that has been manually set with a color temperature setting switch or a color temperature of a light source determined by color temperature sensors.

Claims

1. An electronic flash of a camera, comprising:

R, G and B light emitting diodes that are used as an electronic flash light source;

a power supply device; and

a light emission control device that supplies electric energy separately to each of the R, G and B light emitting diodes from the power supply device, and controls ratios between light emission amounts of R, G and B that are emitted from the R, G and B light emitting diodes and a total light emission amount of R, G and B, wherein

the light emission control device performs control to turn on and off the R, G and B light emitting diodes, respectively, with duty ratios corresponding to the ratios between light emission amounts of R, G and B.

2. The electronic flash of a camera as defined in claim 1, wherein the light emission control device comprises:

a light adjusting sensor that determines an amount of reflected light from a subject of light emitted from the light emitting diodes; and

a light emission stopping control device that stops light emission of the light emitting diodes when the amount of received light determined by the light adjusting sensor reaches a predetermined reference value.

3. An electronic flash of a camera, comprising:

R, G and B light emitting diodes that are used as an electronic flash light source;

a power supply device;

a recording device that records at least one light emission color of electronic flash light that is emitted from the R, G and B light emitting diodes;

a designating device that designates reading of a light emission color that is recorded in the recording device; and

a light emission control device that supplies electric energy separately to each of the R, G and B light emitting diodes from the power supply device, and controls ratios between light emission amounts of R, G and B that are emitted from the R, G and B light emitting diodes and a total light emission amount of R, G and B, wherein when a desired light emission color is read from the recording device by the designating device, the light emission control device controls the ratios between light emission amounts of R, G and B so as to generate the light emission color that is read.

4. The electronic flash of a camera as defined in claim 3, wherein the light emission control device comprises:

a light adjusting sensor that determines one of an amount of reflected light from a subject of light emitted from one of the R, G and B light emitting diodes for which a light emitting amount is smallest among the R, G and B light emitting diodes and an amount of reflected light from the subject of light emitted from the R, G and B light emitting diodes;

a first light emission stopping control device that stops light emission of the one of the R, G and B light emitting diodes for which a light emitting amount is smallest when the one of the amounts of received light determined by the light adjusting sensor reaches a predetermined reference value according to the ratios between the light emitting amounts from the R, G and B light emitting diodes;

a measuring device that measures a light emitting time of the light emitting diode that is subjected to light emission control by the first light emission stopping control device;

a calculating device that calculates light emitting times of others of the R, G and B light emitting diodes according to the light emitting time measured by the measuring device and the ratios between the light emitting amounts from the R, G and B light emitting diodes; and

a second light emission stopping control device that stops light emission of the others of the R, G and B light emitting diodes according to the light emitting times calculated by the calculating device.

5. An electronic camera that stores color image signals of a subject image on recording medium captured with a taking lens and an imaging device, the electronic camera comprising:

R, G and B light emitting diodes that are used as an electronic flash light source;

a power supply device;

a determining device that determines ratios between R, G and B of the color image signals based on color image signals of a subject image captured with the imaging device before a shooting; and

a light emission control device that supplies electric energy separately to each of the R, G and B light emitting diodes from the power supply device, and controls ratios between light emission amounts of R, G and B that are emitted from the R, G and B light emitting diodes and a total light emission amount of R, G and B, wherein the light emission control device controls the ratios between light emission amounts of R, G and B in correspondence to the ratios between R, G and B that are determined by the determining device.

6. The electronic camera as defined in claim 5, wherein the light emission control device comprises:

a light adjusting sensor that determines one of an amount of reflected light from a subject of light emitted from one of the R, G and B light emitting diodes for which a light emitting amount is smallest among the R, G and B light emitting diodes and an amount of reflected light from the subject of light emitted from the R, G and B light emitting diodes;

a first light emission stopping control device that stops light emission of the one of the R, G and B light emitting diodes for which a light emitting amount is smallest when the one of the amounts determined by the light adjusting sensor reaches a predetermined reference value according to the ratios between the light emitting amounts from the R, G and B light emitting diodes;

a measuring device that measures a light emitting time of the light emitting diode that is subjected to light emission control by the first light emission stopping control device;

a calculating device that calculates light emitting times of others of the R, G and B light emitting diodes according to the light emitting time measured by the measuring device and the ratios between the light emitting amounts from the R, G and B light emitting diodes; and

a second light emission stopping control device that stops light emission of the others of the R, G and B light emitting diodes according to the light emitting times calculated by the calculating device.

7. An electronic flash of a camera, comprising:

light emitting diodes that are used as an electronic flash light source;

a power supply device; and

a light emission control device that supplies electric energy to the light emitting diodes from the power supply device, and controls light emission amounts that are emitted from the light emitting diodes;

wherein the light emission control device includes;

a switching device for supplying electric energy from the power supply device to the light emitting diodes;

an electric current determining device that determines an electric current flowing to the light emitting diodes; and

a pulse width controlling device that performs control to turn the switching device on and off by use of a pulse signal that is controlled by a duty ratio so that an electric current that is determined by the electric current determining device becomes a desired constant current.

8. The electronic flash of a camera as defined in claim 7, wherein

the light emission control device comprises a coil that is connected in series with the light emitting diodes, and a diode in which a cathode side is connected with the coil and an anode side is grounded to a ground, and wherein

the light emission control device flows electric current from the power supply device to the light emitting diodes via the coil while the switching device is turned on, and flows electric current to the light emitting diodes via the diode and the coil by an induced electromotive force of the coil when the switching device is turned off.

9. The electronic flash of a camera as defined in claim 7, wherein the light emission control device comprises:

a light adjusting sensor that determines an amount of reflected light from a subject of light emitted from the light emitting diodes; and

a light emission stopping control device that stops light emission of the light emitting diodes when the amount of received light determined by the light adjusting sensor reaches a predetermined reference value.

10. The electronic flash of a camera as defined in claim 7, wherein,

the light emitting diodes comprise R, G and B light emitting diodes;

the switching device and the electric current determining device are provided for the R, G and B light emitting diodes, respectively; and

the pulse width controlling device performs control to turn the respective switching devices of the R, G and B light emitting diodes on and off by use of pulse signals that are controlled by respective duty ratios so that a ratio of light emission levels of R, G and B that are emitted from the R, G and B light emitting diodes becomes a desired ratio.

11. The electronic flash of a camera as defined in claim 7, wherein the power supply device comprises:

a battery;

a boosting device that boosts a power supply voltage from the battery; and

a capacitor with a large capacity that is charged by a voltage that is boosted by the boosting device.

12. The electronic flash of a camera as defined in claim 7, further comprising:

a temperature sensor that determines a temperature of the light emitting diode;

wherein, based on a temperature determined by the temperature sensor, the light emission control device supplies electric energy to the light emitting diodes so as to obtain a desired light emission amount regardless of the temperature.