JP2009295769A - Led flash unit and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flash unit capable of emitting light with high luminance, while having a small and thin body, and capable of coping with red-eye prevention function, at photo shooting, seriography and motion video. <P>SOLUTION: An auxiliary power 21 has energy density of 5 Wh/kg or higher, and a current of 0.8 A or larger is made to flow to a LED 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a flash device used in electronic devices such as a digital camera and a mobile phone with a digital camera function, and more particularly to an LED flash device having an LED light source.

  Digital cameras equipped with flash devices (strobe devices) are currently popular because clear pictures can be obtained even at night. The principle will be described with reference to a simple circuit diagram shown in FIG. The flash device shown in FIG. 1 includes a battery unit, a DC-DC converter (boost), a discharge capacitor, a trigger circuit, and a xenon discharge tube. The voltage of the battery unit is boosted to a predetermined voltage (usually 250 to 500 V) by the DC-DC converter, and charged to the discharge capacitor. When the trigger circuit is switched on, the electric charge of the discharge capacitor is discharged through the primary side of the transformer of the trigger circuit, and a pulse voltage of several thousand volts is generated on the secondary side. When this pulse voltage is applied to a discharge tube filled with xenon gas, the gas in the tube is ionized and the xenon gas emits light instantaneously (50 to 100 μsec). Since the spectrum of xenon gas emission light is close to that of sunlight, such a flash device has been used since the days of film analog cameras.

  However, such a flash device has a problem when used for a mobile phone or the like. That is, it is necessary to use an electrolytic capacitor having a high withstand voltage and capable of withstanding instantaneous discharge as a discharge capacitor, but its size is large, and it is difficult to mount it on electronic devices such as small and thin digital cameras and mobile phones. . Even if it is installed, the size of electronic equipment will be increased. For example, a Sony Ericsson mobile phone K800i (both are trademarks or registered trademarks) is equipped with a flash device using a xenon discharge tube, and a cylindrical electrolytic capacitor (diameter 7 mm, length 18 mm) as a discharge capacitor. Since two are mounted, the thickness of the mobile phone is as thick as 20 mm.

  In recent years, an LED flash device having an LED light source has attracted attention as a method for reducing the size of the flash device. A simple circuit diagram of a conventional low-brightness type LED flash device is shown in FIG. When such a circuit is applied to a high-luminance type LED flash device, the following problems occur. In order to cause the LED to emit light with high brightness, for example, two LEDs for 1A (ampere) must be arranged in parallel, and about 5 V needs to be applied to each LED. When a boost converter is used as the LED flash driver and the conversion efficiency is 85%, the required current I is “I = (5 [V] /3.3 [V] / 85%) × 2 = 3. 6 [A] ", which exceeds the output current of a secondary battery for a mobile phone that is generally used.

  In order to overcome this problem, Non-Patent Document 1 discloses a technique using a high-capacity supercapacitor. In this technology, by using a high-capacity supercapacitor (dimensions: 37 x 17 x 2.4 t [mm]), two 1A LEDs can be illuminated with high brightness for 150 milliseconds. Yes. However, it is stated that a charging time of about 10 seconds is required when the charging current is assumed to be 300 mA. For this reason, since the luminance decreases when the light is lit for 150 milliseconds or longer, it is very difficult to emit a preliminary flash for preventing red-eye, for example, or to continuously fire the LED flash. Furthermore, it is impossible to realize a high brightness movie illumination function (torch function) in a dark place in view of the capacity of the super capacitor.

  In addition, the technique regarding an LED flash apparatus is disclosed by patent document 1, for example. Moreover, the technique regarding a diode laser is disclosed by patent document 2, for example. A technique related to a flash device using a discharge tube is disclosed in, for example, Patent Document 3. Moreover, the technique regarding the uninterruptible power supply device using a capacitor | condenser is disclosed by patent document 4, for example. A technique related to an uninterruptible power supply using a lithium ion secondary battery is disclosed in Patent Document 5, for example. Moreover, the technique regarding the power supply device which used the capacitor | condenser and the low voltage diode together for the solar cell module is disclosed by patent document 6, for example. Moreover, the technique regarding the output recovery | restoration of a lithium ion secondary battery is disclosed by patent document 7, for example.

http://www.powermanagementdesignline.com/showArticle.jhtml?printableArticle=true&articleId=188100789 JP 2007-121755 A JP 2007-519259 A JP 2006-208974 A JP 2001-197686 A JP 2002-058170 A JP 2006-0676759 A JP 2006-107864 A

  As described above, the LED flash device is advantageous in that it can be reduced in size as compared with the flash device using the discharge tube so far, but the problem that must be solved as described above in order to perform high-luminance emission or the like. There is a desire to improve these points.

  Therefore, an object of the present invention is to provide a flash device capable of emitting light with high brightness even though it is small and thin, and capable of preventing red-eye prevention, continuous shooting, and moving pictures during photography, and such a flash. It is to provide an electronic device equipped with a device.

  According to the present invention, an LED as a light source, an auxiliary power source for driving the LED, a controller for controlling the light emission state of the LED including a flash pulse width, and a booster circuit for generating a voltage necessary for light emission of the LED And an LED flash device having a current switch for turning on / off the current flowing through the LED according to the control of the controller, the auxiliary power supply has an energy density of 5 Wh / kg or more and Thus, an LED flash device is obtained in which a current of 0.8 A or more is applied.

  Further, a charging circuit for charging the auxiliary power supply may be further included.

Further, the LED flash device is mounted on an electronic device, and an internal resistance (R _in (main power source)) of a main power source for driving the entire electronic device and an internal resistance (R _in (auxiliary power source)) of the auxiliary power source. The ratio (R _in (main power supply) / R _in (auxiliary power supply)) may be 1 or more.

  The auxiliary power source may also serve as a backup power source that supplies power to the electronic device in cooperation with or in place of the main power source for the operation of the electronic device other than the flash device.

  Furthermore, the auxiliary power supply may be connected in parallel with the main power supply. Alternatively, the auxiliary power source may be constituted by a plurality of high-power batteries connected in series with each other.

  The auxiliary power source may be an organic radical secondary battery, a lithium ion secondary battery, or a lithium ion capacitor.

  According to the present invention, there is also obtained an electronic apparatus that is equipped with the LED flash device.

  Although the LED flash device according to the present invention is small and thin, the LED flash device can emit light with high brightness, and can cope with a red-eye prevention function, continuous shooting, and moving images when taking a picture.

  Hereinafter, LED flash devices according to embodiments of the present invention will be described.

  The LED flash device can be mounted on an electronic device such as a mobile phone with a digital camera function, and controls a light emission state of an LED including a light source, an auxiliary power source for driving the LED, and a flash pulse width. And a booster circuit that generates a voltage necessary for light emission of the LED, and a current switch that turns on / off the current flowing through the LED in accordance with the control of the controller.

Here, the booster circuit of the flash device according to the present invention will be described. This booster circuit can selectively take a plurality of boosted values. FIG. 3 shows a circuit diagram of a charge pump used as a booster circuit. In this charge pump, assuming that the capacitor is in the position of FIG. 3A, the capacitor (C1) is charged to the terminal voltage _Vdd by the input voltage source. On the other hand, in the state of FIG. 3 (b), C1 is in series with the voltage source under S2, so that the voltage at point a in the figure rises to twice V _dd . At the same time, since S3 is closed, a voltage obtained by boosting V _dd twice is obtained at the output. If a similar circuit is connected to the charge pump, it is possible to output a voltage of 3 times, 4 times or more of _Vdd .

  Now, especially in this apparatus, the energy density of the auxiliary power source is 5 Wh / kg or more, and a current of 0.8 A or more is applied to the LED.

  As the auxiliary power source in the present invention, specifically, a so-called high output battery such as an organic radical secondary battery, a lithium ion secondary battery, or a lithium ion capacitor is used.

  Next, the characteristics of the comparative example using a high-capacity, high-power supercapacitor as an auxiliary power source of the flash device and the present invention using a high-power battery were compared. Table 1 shows a comparison of both basic performances.

Here, a comparison is made when the flash pulse width PW _flash : 150 milliseconds is realized. The conditions of LED flash emission are as follows: LED current I _LED : 2A, flash pulse width PW _flash : 150 milliseconds, forward voltage LED _forward : 4.2V, current switch resistance: typically 50 mΩ (maximum less than 100 mΩ) Capacitor charging voltage: 5.3V.

[Super capacitor (comparative example)]
Forward voltage LED _forward : 4.2V (1)
Voltage drop ΔV _{sw at the} current switch:
ΔV _sw = 2 [A] × 0.05 (maximum less than 0.1) [Ω] = 0.1 [V] <0.2 [V] (2)
Voltage drop across the capacitor: ΔVd
ΔVd = I _LED xESR + I _LED × PW _flash / C = 2 [A] × 0.1 [Ω] +2 [A] × 0.15 [sec / C]
Therefore, ΔVd = 5.3 [V] − (1) − (2) = 5.3-4.2−0.2 = 0.9 [V]
Therefore, the capacitor capacity C is 0.43F, which satisfies the standard value. That is, the supercapacitor has a capacity of 0.55 F and an LED current of 2 A or more (calculated value 2.5 A).

[High output battery (invention)]
Forward voltage LED _forward : 4.2V (1)
Voltage drop ΔV _{sw at the} current switch:
ΔV _sw = 2 [A] × 0.05 (maximum less than 0.1) [Ω] = 0.1 [V] <0.2 [V] (2)
Voltage drop ΔVd of radical battery in two series cells:
ΔVd = 3.5 [V] × 2-4.2 [V] −0.2 [V] = 2.6 [V]
Since the equivalent series resistance is 1.5Ω in a single cell, the equivalent series resistance R in two series cells is:
R = 1.5 [Ω] × 2 = 3 [Ω]
Therefore, the LED current I _LED :
I _LED = 2.6 [V] / 3 [Ω] = 0.87 [A]
Therefore, in the case of a high-power battery, the LED current is about 0.87A.

Table 2 shows the arrangement of values at the flash pulse width PW _flash : 150 milliseconds. The cell volume [cc / A (or cm ³ / A)] required to flow the output current 1A is 0.6 cc / A for the supercapacitor of the comparative example, whereas the high-power battery of the present invention is 0. .55cc / A, both of which are equivalent.

Further, the comparison in the case of realizing the flash pulse width PW _flash : 300 milliseconds was performed in the same manner as described above. As a result, the values of the flash pulse width PW _flash : 300 milliseconds are shown in Table 3. Flash pulse width PW _flash : The cell volume [cc / A] required to flow 1 A output in 300 milliseconds is 1.18 cc / A for the supercapacitor of the comparative example, whereas the high output battery of the present invention 0.55 cc / A. That is, it can be seen that a high-power battery having a large capacity has a small cell volume and can be miniaturized.

As such a long flash pulse width PW _flash , it may be considered that continuous firing is performed to prevent red eyes (one pulse is 70 milliseconds, and when four pulses are fired, it is 280 milliseconds). Moreover, since the capacity | capacitance will become empty in the super capacitor of a comparative example if it discharges once, you have to charge about 10 seconds. On the other hand, since the capacity of the high output battery of the present invention is high, the capacity is not emptied by one discharge, and continuous firing (10 to 20 times) is possible.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention (a flash device and a mobile phone with a digital camera function as an electronic device in which the flash device is mounted) will be described below with reference to the drawings.

[Example 1]
Embodiment 1 of the present invention is an LED flash device using a plurality of high-power batteries connected in series as an auxiliary power source for driving LEDs.

  Referring to FIG. 4, the LED flash device according to the first embodiment of the present invention is mounted on a mobile phone (not shown) with a digital camera function, and includes a high output type LED 10 as a light source and an LED 10 driving device. The auxiliary power supply 21, the controller 50 that controls the light emission state of the LED 10 including the flash pulse width, the booster circuit 40 that generates a voltage necessary for the light emission of the LED 10, and the current flowing through the LED 10 according to the control of the controller 50 is turned on / off. And a current switch 60 to be turned off. Incidentally, reference numeral 30 in the drawing is a main power source for driving the entire mobile phone (not shown).

  The energy density of the auxiliary power source 21 is 5 Wh / kg or more. The LED 10 is energized with a current of 0.8 A or more.

  In this embodiment, the auxiliary power source 21 for driving the high power type LED 10 is configured by high power batteries (organic radical secondary batteries) 21a and 21b connected in series.

  When an LED control signal is input from an upper circuit (a circuit of a mobile phone with a digital camera function (not shown)), the controller 50 outputs an on signal to the booster circuit 40 and an on / off signal of the LED 10 to the current switch 60. In addition, a flash / torch selection signal is output.

  In this embodiment, since the auxiliary power source 21 is a high-power battery (organic radical secondary battery), it is not necessary to pass a large current (1A class) through the booster circuit 40. Therefore, the booster circuit 40 may be the current control boost converter shown in FIG. 2 or the charge pump type shown in FIG. In the case of a boost converter, the inductor L may be a small inductance.

  By such a booster circuit 40, the high-power batteries 21a and 21b connected in series are charged to 7 to 8V, the current switch 60 is set in the conduction mode in accordance with the on / off signal from the controller 50, and a large current flash pulse is emitted from the LED 10 Is input.

In this embodiment, since the high-power batteries 21a and 21b are connected in series, the voltage at the midpoint drifts due to the difference in internal resistance between the two batteries and an excessive voltage is applied to one cell. It is necessary to provide a cell balance circuit for preventing. The simplest cell balance circuit is a method using two cell balance resistors as shown in FIG. However, in this case, due to a leakage current from the balance resistance, the holding time (duration) of the main power supply 30 (V _BATT ) is reduced. As a solution, “when the portable terminal is not in the camera mode, an off signal is sent from the controller 50 to the booster circuit 40 to put the booster circuit 40 in a standby state”, “a high-resistance, low-current operational amplifier is used. “Using an active balance circuit” can be considered.

[Example 2]
Embodiment 2 of the present invention is an LED flash device in which an auxiliary power source (high power battery) for driving an LED is connected in parallel to a main power source that drives the entire electronic device on which the LED flash device is mounted.

  Referring to FIG. 5, the LED flash device according to the second embodiment of the present invention is mounted on a mobile phone (not shown) with a digital camera function, and includes a high output type LED 10 as a light source and an LED 10 driving device. The auxiliary power supply 22, the controller 50 that controls the light emission state of the LED 10 including the flash pulse width, the booster circuit 40 that generates a voltage necessary for the light emission of the LED 10, and the current flowing through the LED 10 according to the control of the controller 50 is turned on / off. And a current switch 60 to be turned off. Incidentally, reference numeral 30 in the drawing is a main power source for driving the entire mobile phone (not shown).

  The energy density of the auxiliary power source 22 is 5 Wh / kg or more. The LED 10 is energized with a current of 0.8 A or more.

  In the present embodiment, the auxiliary power source 22 for driving the high power type LED 10 is a high power battery connected in parallel with the main power source 30.

  When an LED control signal is input from an upper circuit (a circuit of a mobile phone with a digital camera function (not shown)), the controller 50 outputs an on signal to the booster circuit 40 and an on / off signal of the LED 10 to the current switch 60. In addition, a flash / torch selection signal is output.

  In the present embodiment, since the current for turning on the high output type LED 10 passes through the booster circuit 40, the booster circuit 40 is preferably the current control boost converter shown in FIG. In the case of the present embodiment, the inductor L needs to have a large inductance even in the boost converter.

  In the present embodiment, the auxiliary power source 22 is arranged in parallel to the main power source 30, and charging of the auxiliary power source 22 may be in a floating state, so that a complicated charging circuit is unnecessary. However, the auxiliary power source 22 (high power battery) is required to have durability in the float state.

  Further, the voltage drop during the high output discharge of the auxiliary power supply 22 is the same as that of the main power supply 30. When the electronic device on which the LED flash device is mounted is a mobile phone as in this embodiment, the main power supply 30 can discharge a current of about 3 A in full charge and about 1.5 A in a low battery state. . Assuming that about 0.8 A is consumed during operations such as display and communication of the mobile phone, the current value that can be discharged to the LED in the low battery state is considered to be about 0.7 A. If the discharge current of the LED 10 is about 1.5 A, it is necessary to discharge about 0.8 A with a high-power auxiliary battery, and the auxiliary power source 22 requires at least a discharge current equivalent to that of the main power source 30. That is, the internal resistance of the auxiliary power supply 22 needs to be equal to or less than the internal resistance of the main power supply 30.

[Example 3]
In the third embodiment of the present invention, an auxiliary power source (high power battery) for driving the LED is connected in parallel to the main power source that drives the entire electronic device on which the LED flash device is mounted. LED flash device having a charging circuit in between.

  Referring to FIG. 6, the LED flash device according to the third embodiment of the present invention is mounted on a mobile phone (not shown) with a digital camera function, and includes a high output type LED 10 as a light source and an LED 10 driving device. The auxiliary power supply 22, the controller 50 that controls the light emission state of the LED 10 including the flash pulse width, the booster circuit 40 that generates a voltage necessary for the light emission of the LED 10, and the current flowing through the LED 10 according to the control of the controller 50 is turned on / off. And a current switch 60 to be turned off. Incidentally, reference numeral 30 in the drawing is a main power source for driving the entire mobile phone (not shown).

  The energy density of the auxiliary power source 22 is 5 Wh / kg or more. The LED 10 is energized with a current of 0.8 A or more.

  In the present embodiment, the auxiliary power source 22 for driving the high power type LED 10 is a high power battery connected in parallel with the main power source 30. Further, a charging circuit 70 is provided between the main power supply 30 and the auxiliary power supply 22. The charging circuit 70 includes an overdischarge / overcharge protection circuit.

  When an LED control signal is input from an upper circuit (a circuit of a mobile phone with a digital camera function (not shown)), the controller 50 outputs an on signal to the booster circuit 40 and an on / off signal of the LED 10 to the current switch 60. In addition, a flash / torch selection signal is output.

  Also in the present embodiment, as in the second embodiment, the current for turning on the high output type LED 10 passes through the booster circuit 40. Therefore, the current control boost converter shown in FIG. is there. In the case of the present embodiment, the inductor L needs to have a large inductance even in the boost converter.

  In the present embodiment, since the charging circuit 70 is provided between the main power supply 30 and the auxiliary power supply 22, the voltage difference depending on the state of the main power supply 30 (high voltage (about 4.2V) in full charge), low In the battery state, the voltage of the auxiliary power source 22 is kept constant without depending on a low voltage (about 3.2 V). In addition, charging to the auxiliary power source 22 can control constant current charging, constant voltage charging, and the like, and the long-term reliability of the auxiliary power source 22 that is a battery with high output is improved. Moreover, since the discharge of the LED 10 is mainly driven by the auxiliary power supply 22, it is not necessary to supply a large current (1A class) to the charging circuit.

[Example 4]
In Embodiment 4 of the present invention, an auxiliary power source (high power battery) for driving an LED is connected in parallel to a main power source that drives the entire electronic device on which the LED flash device is mounted, and between the main power source and the auxiliary power source. In addition, the LED flash device includes a charging circuit, and an auxiliary power source also serves as a backup power source that cooperates with the main power source or alternatively supplies power to the electronic device for the operation of the electronic device.

  Referring to FIG. 7, the LED flash device according to the fourth embodiment of the present invention is mounted on a mobile phone (not shown) with a digital camera function, and includes a high output type LED 10 as a light source and an LED 10 driving device. The auxiliary power supply 22, the controller 50 that controls the light emission state of the LED 10 including the flash pulse width, the booster circuit 40 that generates a voltage necessary for the light emission of the LED 10, and the current flowing through the LED 10 according to the control of the controller 50 is turned on / off. A current switch 60 to be turned off and a second controller 80 to be described later are included. In the figure, reference numeral 100 denotes a mobile phone with a digital camera function, and reference numeral 30 denotes a main power source for driving the entire mobile phone. In the figure, the mobile phone 100 and the main power supply 30 and the flash device are depicted separately, but the main power supply 30 and the flash device can also be regarded as components of the mobile phone 100.

  The energy density of the auxiliary power source 22 is 5 Wh / kg or more. The LED 10 is energized with a current of 0.8 A or more.

  Also in this embodiment, the auxiliary power source 22 for driving the high power type LED 10 is a high power battery connected in parallel with the main power source 30. Further, a charging circuit 70 is provided between the main power supply 30 and the auxiliary power supply 22. The charging circuit 70 includes an overdischarge / overcharge protection circuit.

  When an LED control signal is input from a higher-level circuit (one circuit of the mobile phone 100 with a digital camera function), the controller 50 outputs an ON signal to the booster circuit 40 and an ON / OFF signal of the LED 10 to the current switch 60. In addition, a flash / torch selection signal is output.

  Also in the present embodiment, since the charging circuit 70 is provided between the main power supply 30 and the auxiliary power supply 22 as in the third embodiment, the voltage difference depending on the state of the main power supply 30 (high voltage ( In the low battery state, the voltage of the auxiliary power source 22 is kept constant without depending on the low voltage (about 3.2 V). In addition, charging to the auxiliary power source 22 can control constant current charging, constant voltage charging, and the like, and the long-term reliability of the auxiliary power source 22 that is a battery with high output is improved.

  Further, in this embodiment, when the voltage of the main power supply 30 decreases and a telephone call or the like becomes impossible, power is supplied from the auxiliary power supply 22 to the mobile phone 100 via the second controller 80, so Calls and emails are possible. Since the auxiliary power source 22 which is a high-power battery can discharge about 2 A and the discharge is considered to correspond to 100 C, the capacity of the high-power battery is about 20 mAh. This capacity is, for example, about 1/40 of the capacity of the main power supply 30 of the mobile phone 100, and it can be seen that emergency calls and mails are sufficiently possible.

[Example 5]
In the fifth embodiment of the present invention, specific structures of the auxiliary power source 21 of the first embodiment and the auxiliary power sources 22 of the second to fourth embodiments, which are high-power batteries, will be described.

  As the auxiliary power source 21 and the auxiliary power source 22 in Examples 1 to 4, a thin organic radical secondary battery is used. The basic structure of a thin organic radical secondary battery is composed of a radical positive electrode using a stable radical compound as a positive electrode active material, a separator made of porous polypropylene or cellulose, a negative electrode made of metallic lithium, Li-predoped carbon, and the like. A positive electrode lead connected to the negative electrode, a negative electrode lead connected to the negative electrode, an electrolyte, and an exterior film for sealing them. As the exterior film, an aluminum laminate film having a low water vapor permeability is used.

[Radical cathode]
As a cathode active material in a radical cathode, a nitroxide having a nitroxide radical represented by the formula (I) in the chemical formula 1 in the reduced state and an oxoammonium (nitroxide cation) represented by the formula (II) in the oxidized state as a partial structure in the molecule A radical polymer can be used.

  The molecular weight of the nitroxide radical polymer is preferably 500 or more, and more preferably 5000 or more. This is because when the molecular weight is 500 or more, it is difficult to dissolve in the battery electrolyte, and when the molecular weight is 5000 or more, it is almost insoluble. The shape of the polymer may be any of a chain shape, a branched shape, and a network shape. Moreover, the structure which bridge | crosslinked with the crosslinking agent may be sufficient.

  Moreover, when forming an electrode using a nitroxide radical polymer, a conductive support agent can also be mixed in order to reduce impedance. Examples of the material for the conductivity-imparting agent include carbonaceous fine particles such as graphite, carbon black, and acetylene black, and conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene, and polyacene.

  A binding agent can also be used in order to strengthen the bond between the nitroxide radical polymer and the conductivity-imparting agent. Examples of such binders include polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, styrene / butadiene copolymer rubber, polypropylene, and polyethylene. Resin binders such as polyimide and various polyurethanes.

  The radical positive electrode can be formed on a positive electrode current collector. As the positive electrode current collector, a foil made of nickel, aluminum, copper, gold, silver, aluminum alloy, stainless steel, carbon, or the like, or a metal flat plate should be used. Can do.

[Negative electrode]
As the negative electrode, lithium metal, lithium alloy Li, or pre-doped carbon can be used. The shape and manufacturing method may be, for example, a thin film, a powdered product, a fiber, or a flake. These negative electrode active materials can be used alone or in combination. The negative electrode can be formed on a foil, a metal flat plate, or the like made of nickel, aluminum, copper, gold, silver, an aluminum alloy, stainless steel, carbon, or the like.

[Electrolytes]
The electrolyte performs charge carrier transport between both electrodes of the negative electrode and the positive electrode, and generally preferably has an ionic conductivity of 10 ⁻⁵ to 10 ⁻¹ S / cm at 20 ° C. As the electrolyte, for example, an electrolytic solution in which an electrolyte salt is dissolved in a solvent can be used. Examples of the electrolyte salt include LiPF ₆ , LiClO ₄ , LiBF ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, Li (CF ₃ SO ₂ ) ₃ C Conventionally known materials such as Li (C ₂ F ₅ SO ₂ ) ₃ C can be used.

  When a solvent is used for the electrolytic solution, examples of the solvent include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, tetrahydrofuran, dioxolane, sulfolane, dimethylformamide, dimethylacetamide, N-methyl-2- An organic solvent such as pyrrolidone can be used. These solvents can be used alone or in admixture of two or more.

[Separator]
A separator such as a porous film made of polyethylene, polypropylene, or the like, a cellulose film, or a nonwoven fabric may be used so that the radical positive electrode and the negative electrode do not come into contact with each other.

[Battery shape]
In the present invention, from the viewpoint of miniaturization and thinning, the battery shape is preferably sealed with a laminate film. This is produced by sealing an electrode laminate such as the positive electrode, negative electrode, and separator described above with a laminate film made of a metal foil such as an aluminum foil and a synthetic resin film.

  Next, an example of manufacturing a thin organic radical secondary battery will be described. 8A and 8B show an example of manufacturing a single-layer battery. Homogenizer of 1.68 g of polyradical compound represented by formula (1) in chemical formula 2 in fine powder, 0.6 g of carbon powder, 96 mg of carboxymethylcellulose (CMC), 24 mg of polytetrafluoroethylene (PTFE) and 7.2 mL of water The mixture was stirred to prepare a uniform slurry. This slurry was applied onto an aluminum foil (thickness: 20 μm) with an electrode production coater, and further dried at 80 ° C. for 3 minutes to form a radical positive electrode layer having a thickness of 100 μm.

  Next, the positive electrode thus obtained was punched into a predetermined size. An aluminum lead having a length of 3 cm and a width of 3 mm was welded to the aluminum foil surface of the positive electrode. Further, a lithium-laminated copper foil (lithium thickness 30 μm) was punched out to a predetermined size in the same manner as the positive electrode to form a metal lithium negative electrode, and a nickel lead having a length of 3 cm and a width of 3 mm was welded to the copper foil surface. In order of the positive electrode, the porous polypropylene separator, and the negative electrode, the radical positive electrode layer and the metallic lithium negative electrode were opposed to each other to form an electrode pair with a nickel lead.

A bag-like case was formed by heat-sealing three sides of two heat-sealable aluminum laminate films, and a pair of nickel-leaded electrodes was inserted. An electrolytic solution [ethylene carbonate / diethyl carbonate mixed solution containing 1.0 to 1.5 mol / L LiPF ₆ electrolyte salt (mixing ratio 3: 7)] was placed in an aluminum laminate case. At this time, the end of the nickel lead of the electrode with the nickel lead was taken out by 1 cm, and one side of the aluminum laminate case that was not welded was thermally fused. As a result, the electrode and the electrolyte were completely sealed in the aluminum laminate case.

As described above, the manufacturing method of the single-layer battery cell has been described. However, by stacking these, the capacity can be increased and the output can be increased. FIG. 9 shows a schematic cross-sectional view of the internal structure of the organic radical secondary battery cell. Four layers of positive electrodes coated on both sides were laminated (a total of eight positive electrode layers), and a separator and a negative electrode were arranged corresponding to each. The positive electrode was 25 × 10 mm per layer, and the total was 8 layers × 2.5 cm ² / layer = 20 cm ² . The volume of the cell was 0.625 cm ³ (cell thickness: 2.5 mm) excluding the exterior body and the tab portion. The positive electrode radical material was poly (2,2,6,6, -tetramethylpiperidinoxyl vinyl ether) (PTVE) represented by chemical formula (2).

  The characteristics of the battery shown above were evaluated. A schematic diagram of the circuit used for the evaluation is shown in FIG. The circuit used for the evaluation is similar to the LED flash device shown in FIG. 5, but does not have a main power source because it measures only the characteristics of a high-power battery as an auxiliary power source.

Change ΔV (ΔV = V _{S_batt} (open state) −V _{S_batt} (state in which a predetermined current is passed)) of the battery voltage V _batt when the pulse width at the time of measurement is 200 milliseconds, and the flowed current density I The relation with [A / cm ² ] is shown in FIG. The characteristics slightly differ depending on the amount and concentration of the electrolytic solution and the presence or absence of additives. In addition, the relationship between ΔV and I is not linear, and is slightly nonlinear.

The internal resistance R (R = ΔV / (I [A / cm ² ] × S [cm ² ] (: 20 cm ² ))) of the battery normalized by the electrode area S based on the relationship of FIG. , ΔV is shown in FIG. Corresponding to the non-linearity shown in FIG. 11A, the standardized internal resistance of the battery tends to decrease as ΔV increases.

In addition, in FIG. 11 (a) and FIG.11 (b), as what can be used for the auxiliary power supply which is a high output battery in this invention, in addition to two types of organic radical secondary batteries, a lithium ion secondary battery, The ΔV-I relationship and the internal resistance value of the lithium ion capacitor are also shown. The internal resistance of the standardized batteries of the lithium ion secondary battery and the lithium ion capacitor hardly changed with respect to ΔV and was constant. The lithium ion secondary battery was 17-20 Ωcm ² and the lithium ion capacitor was 8 Ωcm ² .

  If the internal resistance of the battery is constant, in order to obtain the maximum output (I × V) [W], it is desirable to discharge at about half of the voltage in the open state. In consideration of the conversion efficiency of the booster circuit 40, ΔV is preferably 0.6 to 1.0V. In such a voltage region, it can be seen that the internal resistance of the organic radical secondary battery is lower than that of the lithium ion secondary battery and is equivalent to that of the lithium ion capacitor. In addition, the organic radical secondary battery has a higher capacity per unit electrode area than the lithium ion capacitor, and can increase the number of times of fire more than the lithium ion capacitor.

  From these results, the organic radical secondary battery is suitable as an auxiliary power source for LED flash.

[Example 6]
Example 6 of the present invention describes a lithium ion capacitor that can be used as the auxiliary power source 21 of Example 1 and the auxiliary power source 22 of Examples 2 to 4 which are high-power batteries.

  FIG. 12 shows a cell configuration and an equivalent circuit of a lithium ion capacitor.

  Lithium salt is used for the electrolyte salt, the positive electrode has an electric double layer as a power storage mechanism, and the negative electrode is preliminarily doped with lithium ions in a carbon-based material to widen the potential width and maximize the capacity (this operation is called pre-doping) ).

  Since the capacitance of the cell fully draws the capacitance of the electric double layer of the positive electrode, it is possible to obtain a capacitance about twice that of a conventional capacitor.

  Since the negative electrode potential is about 1.5 V lower than that of the conventional negative electrode, the cell voltage, which was about 2.3 to 2.7 V, can be improved to about 3.8 to 4.2 V to a level equivalent to a lithium ion secondary battery. .

Since the energy E of the cell is calculated by E = (CV ² ) / 2 by the capacity C and the voltage V, it is possible to expect an energy density that is four times or more that of the prior art. Even when the upper limit potential of the positive electrode is lowered to improve the durability, a cell voltage of about 3.6 V can be obtained.

  The manufacturing method is also easy, and the materials and manufacturing processes can be transferred from existing technologies for electric double layer capacitors and lithium ion secondary batteries. In particular, when compared with a commercially available electric double layer capacitor, it is expected to suppress the cost for obtaining the same energy performance.

[Example 7]
Example 7 of this invention demonstrates the lithium ion secondary battery which can be used as the auxiliary power supply 21 of Example 1 which is a high output battery, and the auxiliary power supply 22 of Examples 2-4.

  Similar to the organic radical secondary battery shown in FIG. 8, the lithium ion secondary battery in the present invention has a configuration in which a negative electrode and a positive electrode are superposed via a separator containing an electrolytic solution.

In order to enhance conductivity, lithium manganate (LiMn ₂ O ₄ ) whose particle surface is coated with carbon is used. The carbon coverage was 15% by weight, and the composition of the positive electrode was active material / conductivity imparting agent / binder = 80/15/5. Ketjen black was used as the conductivity-imparting agent, and polyvinylidene fluoride was used as the binder. The thickness of the positive electrode is 80 microns.

  On the other hand, graphite was used as the negative electrode active material. The composition of the negative electrode was graphite / conductivity imparting agent / binder = 90/1/9. Ketjen black was used as the conductivity-imparting agent, and polyvinylidene fluoride was used as the binder. The thickness of the negative electrode is 40 microns.

As the electrolytic solution, a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC) was used. The mixing ratio of EC and DEC was EC / DEC = 3/7. 1.0M lithium hexafluorophosphate (LiPF ₆ ) is used as the supporting salt.

  When a lithium ion secondary battery is used, the internal resistance of the battery is high, but the capacity is large, and therefore, it is suitable for a torch function for movie shooting, that is, high-intensity LED lighting for a long time.

  The present invention is not limited to the embodiments described above, and it goes without saying that various modifications are possible within the technical scope described in the claims.

It is a circuit diagram which shows the principle of the conventional strobe function. It is a simple circuit diagram of a conventional low-brightness LED flash function. FIG. 6 is a circuit diagram of a charge pump system used as a conventional booster circuit 40. It is a block diagram which shows the LED flash apparatus by Example 1 of this invention. It is a block diagram which shows the LED flash apparatus by Example 2 of this invention. It is a block diagram which shows the LED flash apparatus by Example 3 of this invention. It is a block diagram which shows the LED flash apparatus by Example 4 of this invention. It is a figure for demonstrating Example 5 of this invention, (a) is a figure for demonstrating the manufacturing method of the organic radical secondary battery as a high output battery, (b) is the manufactured single It is a perspective view which shows the organic radical secondary battery of a cell. 1 is a schematic cross-sectional view showing an organic radical secondary battery in which a plurality of cells are stacked as a high-power battery of the present invention. It is a figure which shows the circuit for evaluating the characteristic of the high output battery of this invention. It is a figure which shows the characteristic of the high output battery of this invention, (a) shows the relationship between (DELTA) V and I, (b) has shown the relationship between (DELTA) V and the internal resistance R of a battery. It is a figure which shows the schematic structure inside the lithium ion capacitor as a high output battery of this invention, and an equivalent circuit.

Explanation of symbols

10 LED
21, 22 Auxiliary power supply 21a, 21b High-power battery (organic radical secondary battery)
40 Booster Circuit 50 Controller 60 Current Switch 70 Charging Circuit 80 Second Controller 100 Mobile Phone

Claims (10)

An LED as a light source, an auxiliary power source for driving the LED, a controller for controlling the light emission state of the LED including a flash pulse width, a booster circuit for generating a voltage necessary for light emission of the LED, and control of the controller An LED flash device having a current switch for turning on / off a current flowing in the LED according to
The auxiliary power supply has an energy density of 5 Wh / kg or more, and the LED is supplied with a current of 0.8 A or more.   The LED flash device according to claim 1, further comprising a charging circuit for charging the auxiliary power source. The LED flash device is mounted on an electronic device,
A ratio (R _in (main power) / R _in ( _in ) of the internal resistance (R _in (main power))) of the main power source for driving the entire electronic device and the internal resistance (R _in (auxiliary power source)) of the auxiliary power source. 3. The LED flash device according to claim 1, wherein the auxiliary power supply)) is 1 or more.   4. The LED flash device according to claim 3, wherein the auxiliary power supply also serves as a backup power supply for supplying power to the electronic device in cooperation with or in place of the main power supply for the operation of the electronic device other than the flash device.   The LED flash device according to claim 3 or 4, wherein the auxiliary power source is connected in parallel with the main power source.   The LED flash device according to any one of claims 1 to 5, wherein the auxiliary power source includes a plurality of batteries connected in series with each other.   The LED flash device according to any one of claims 1 to 6, wherein the auxiliary power source is an organic radical secondary battery.   The LED flash device according to any one of claims 1 to 6, wherein the auxiliary power source is a lithium ion secondary battery.   The LED flash device according to any one of claims 1 to 6, wherein the auxiliary power source is a lithium ion capacitor.   An electronic device comprising the LED flash device according to any one of claims 1 to 9.

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