JP2006208974A - Portable terminal device equipped with camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively use a flash light discharge tube, as an auxiliary light, mounted on a portable terminal device equipped with a camera, even in a closed-up mode to realize high performance and multi-functionality of a portable terminal device that is equipped with a camera, and to improve its usage value. <P>SOLUTION: When stroboscopic photographing is conducted in a closed-up mode, a light-emission amount of a flash light discharge tube 112 is decreased down to 50% of a light-emitted amount in a normal photographic mode or lower so as to prevent halation of an object. The light-emitted amount can be adjusted by controlling the total amount of accumulated electric charges, a resistance value interposed in a discharge current route, or the number of flash light discharge tubes to be used. For example, after electric charges accumulated in an electrolytic capacitor CS, a short-circuiting switch 106 is turned on to discharge the electric charges, and thereby the total amount of electric charges, supplied to a flash light discharge tube 112, is controlled. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a camera-equipped mobile terminal device capable of flash photography.

  In recent years, active product development has been promoted under the product concept of enhancing the camera function of a mobile phone terminal with a camera and bringing it closer to a digital camera.

  As part of the product development, a proposal has been made to add a strobe shooting function in order to enable night shooting even with a camera provided in a mobile phone terminal (see Patent Document 1).

  As flash light sources for flash photography, there are LED (light emitting diode) and flash discharge tube. LED has the advantage of being compact and has low power consumption, but on the other hand, it emits light in a small amount, and because it is a point light source, it has a cone-shaped projection, making it difficult to evenly irradiate a rectangular shooting area. There are also disadvantages.

  A flash discharge tube is inferior in terms of compactness compared to an LED, but on the other hand, it has the advantage that it can project a large amount of light and can shoot a subject at a far distance even at night.

In the technique of Patent Document 1, a flash discharge tube is used as a flash light source.
JP 2001-320622 A

  The usage method of the camera function in the camera-equipped mobile phone terminal has many points in common with the digital camera, but there is also a usage method unique to the mobile phone terminal. One of them is the use of close-up mode.

  Since a general camera is used to photograph a subject while looking through the viewfinder, it can be said that it is not very suitable for photographing a close subject. On the other hand, the camera-equipped mobile phone terminal can be easily photographed while being held in one hand and close to the subject.

  In consideration of the advantages of such mobile phone terminals, close-up mode (also called macro shooting mode or close-up shooting mode) is provided as the camera shooting mode of the mobile phone terminal, and close-up shooting of plants etc. Proposals have also been made for products that can be taken close to a distance of about 10 cm.

  As a usage mode of the close-up mode, there is also a usage method for the purpose of “recording information” for recording information on a necessary page such as a timetable in addition to a mode of “photographing a subject” such as a plant. .

The inventor of the present invention studied to enable flash photography even in the close-up mode so that the close-up mode can be taken even in a dark environment. In particular, flash photography using a flash discharge tube was studied, and the following findings (1) to (3) were obtained.
(1) In other words, as described above, when a flash discharge tube is used, there is an advantage that a large amount of light can be projected even at night, and even a subject located at a far distance can be photographed while ensuring contrast. However, it has been found that when the flash discharge tube is used in the close-up mode, the characteristic that the light emission intensity is high works in a bad direction and the subject is likely to be overexposed.
(2) In the close-up mode, shooting is performed at an interval of 10 cm to several tens of centimeters from the subject. Therefore, a strong auxiliary light source tends to cause overexposure, and rather a weak auxiliary light source such as an LED is used. It can be said that it is preferable. However, preparing a flash discharge tube for strobe shooting in the normal shooting mode and preparing an LED for strobe shooting in the close-up mode results in an increase in the size of the device. It is difficult to realize in
(3) In the above-mentioned “use for information recording” in the close-up mode, there is no need for a camera-specific concept of taking a beautiful subject, and even if the image quality is a little bad, if information can be recorded while preventing overexposure, There is practical value. Even when a subject such as a plant is photographed in close proximity, it is considered that the user does not require high image quality in consideration of photographing using a camera attached to the mobile phone terminal in a dark environment.

  The present invention has been made based on such considerations. The flash discharge tube as an auxiliary light source mounted on the camera-equipped mobile terminal device can be effectively used even in the close-up mode. The purpose is to realize functionality and multi-functionality, and to increase the use value.

  The mobile terminal device with a camera of the present invention is a mobile terminal device with a camera that has a normal shooting mode and a close-up mode, and is capable of flash photography in both the normal shooting mode and the close-up mode. A flash light-emitting unit including a flash discharge tube as an auxiliary light source having a structure capable of stepwise switching the amount to a plurality of discrete light emission amounts, and the flash discharge tube when performing flash photography in close-up mode A flash light emission control unit that automatically adjusts the light emission amount to be lower than the light emission amount in the normal shooting mode.

  The light emission amount of the flash discharge tube can be adjusted stepwise, and the light emission amount is switched and controlled in accordance with the normal photographing mode / close-up mode. The amount of flash light in the close-up mode is significantly reduced compared to the amount of flash light in the normal shooting mode. Thus, even in the close-up mode, it is possible to perform strobe shooting without worrying about overexposure. The use of the close-up mode of a camera-equipped mobile terminal device is considered to be a type of recording information, and it is considered that high image quality is not required even when a subject such as a plant is taken close-up. Even if the amount cannot be finely adjusted, no practical problem occurs. Therefore, using a common auxiliary light source (flash discharge tube) mounted on one camera-equipped mobile terminal device, flash photography can be performed in both the normal shooting mode and the close-up mode, and the camera-equipped mobile terminal. High functionality and multi-function of the device are realized.

  Further, in one aspect of the camera-equipped mobile terminal device according to the present invention, when the close-up mode is selected by a user's device operation, the flash light emission control unit sets the light emission amount of the flash discharge tube to the selected close-up mode. In response to the above, the light emission amount is automatically adjusted to a predetermined amount so as to prevent overexposure.

  When the close-up mode is selected by the user's device operation, the flash emission amount is automatically switched in conjunction with the close-up mode selection by the device operation. Since the strobe light amount is automatically switched, there is no need for troublesome adjustment on the user side.

  Further, in another aspect of the camera-equipped mobile terminal device of the present invention, when the close-up mode is automatically selected based on the distance to the subject, the flash emission controller controls the emission amount of the flash discharge tube. The light emission amount is automatically adjusted to a predetermined amount corresponding to the selected close-up mode.

  When the close-up mode is selected when the distance to the subject is measured with a mobile terminal device with a camera and the distance is equal to or less than a predetermined threshold, the close-up mode is selected based on the result of the distance measurement. In conjunction with this, the flash output can also be switched automatically. Since the strobe light amount is automatically switched, there is no need for troublesome adjustment on the user side.

  In another aspect of the portable terminal device with a camera according to the present invention, the flash light emission control unit reduces the light emission amount of the flash discharge tube in the close-up mode to be ½ or less of the light emission amount in the normal photographing mode.

  Unlike the fine adjustment of the light amount of the strobe within the same shooting mode, the light amount is dramatically switched step by step between different modes. When the flash emission amount in the normal shooting mode is 100%, the emission amount is suppressed to at least 50% or less (specifically, 30% in the close-up mode). A flash discharge tube with high emission intensity is commonly used in both normal shooting mode (generally shooting a subject several meters away) and close-up mode (for example, the distance to the subject is about 10 centimeters). For this reason, it is desirable to perform such a large amount of light switching control.

  Further, in another aspect of the camera-equipped mobile terminal device of the present invention, the gain setting of the variable gain amplifier that amplifies the imaging signal of the subject is changed in conjunction with the adjustment of the light emission amount of the flash discharge tube in the close-up mode. To control exposure.

  Along with the switching of the strobe emission amount corresponding to the close-up mode, the gain setting of the variable gain amplifier (AGC amplifier) that amplifies the imaging signal of the subject is also changed to optimize the exposure control. Thereby, the contrast of the strobe image in the close-up mode can be further improved.

  Further, in another aspect of the camera-equipped mobile terminal device of the present invention, the flash light emission control unit adjusts the light emission amount in consideration of the measurement result of ambient illuminance when adjusting the light emission amount of the flash discharge tube in the close-up mode. Make fine adjustments.

  For example, a plurality of light intensity values are set as the strobe light emission amount in the close-up mode, and the optimal light intensity value is set according to the ambient illuminance at that time (for example, whether it is completely dark or dim). To choose. Useful for improving the quality of images obtained by flash photography in close-up mode.

  In another aspect of the camera-equipped mobile terminal device of the present invention, the flash light emitting unit adjusts the amount of light emitted from the flash discharge tube by adjusting the amount of charge stored in the charge storage capacitor.

  As a method for switching and controlling the strobe light emission amount, a method for adjusting the total amount of electric charge supplied to the flash discharge tube is adopted. Since the total amount of charge itself is controlled, there is a merit that it is easy to accurately control the light emission amount.

  In another aspect of the camera-equipped mobile terminal device of the present invention, the flash light emitting unit includes a switch for short-circuiting both ends of the charge storage capacitor to discharge the stored charge, and the switch closing time is set. By controlling, the light emission amount of the flash discharge tube is adjusted.

  After the charge is stored in the charge storage capacitor, the short switch is closed to discharge the charge, thereby adjusting the total amount of charge. One charge storage capacitor and a short switch are required, and there is an advantage that the configuration is simple.

  In another aspect of the camera-equipped mobile terminal device of the present invention, the flash light emitting unit includes a plurality of charge storage capacitors and a switch for opening and closing a charge / discharge path for each of the charge storage capacitors. The amount of light emitted from the flash discharge tube can be adjusted by selecting the charge storage capacitor that is actually used by controlling the opening and closing of the switch.

  The total amount of charges is adjusted by increasing or decreasing the number of charge storage capacitors used. There is an advantage that it is easy to control the total amount of charges with high accuracy.

  The camera-equipped mobile terminal device according to claim 1, wherein the flash light-emitting unit controls a resistance value of a resistor interposed in a discharge path of charges accumulated in the charge storage capacitor, whereby the flashlight Adjust the amount of light emitted from the discharge tube.

  The light emission amount of the flash discharge tube is adjusted by changing the resistance value of the discharge path and changing the time constant of discharge (that is, the amount of change in voltage per unit time accompanying the discharge of electric charge).

  In another aspect of the camera-equipped mobile terminal device, the flash light emitting unit is a variable having a plurality of resistors having different resistance values provided in a discharge current path between a charge storage capacitor and the flash discharge tube. The light emission amount of the flash discharge tube is controlled by selecting at least one of the plurality of resistors in the variable resistance unit using a changeover switch.

  By switching the switch, the resistance value interposed in the discharge path is controlled, the discharge time constant is changed, and the light emission amount is adjusted. There is an advantage that the resistance value can be changed in multiple stages with a simple configuration.

  Further, in another aspect of the camera-equipped mobile terminal device of the present invention, the flash light emitting section has a plurality of the flash discharge tubes, and the flash discharge tube is substantially selected by selecting a flash discharge tube to be actually used. Adjust the amount of light emitted.

  The substantial amount of stroboscopic light emission is controlled by the number of flash discharge tubes used. There is an advantage that the amount of flash emission can be changed greatly with a simple configuration.

  According to the present invention, the light emission amount can be switched stepwise in accordance with the normal photographing mode / close-up mode, and the flash light amount in the close-up mode can be significantly reduced compared to the flash light amount in the normal photographing mode. For example, when the flash emission amount in the normal shooting mode is 100%, the flash emission amount is set to 50% or less in the close-up mode. Therefore, even if the flash photography is performed in the close-up mode, the whiteout does not occur.

  Thus, even in the close-up mode, it is possible to perform strobe shooting without worrying about overexposure.

  The use of the close-up mode of the camera-equipped mobile terminal device is considered to be a type of recording information, and there is no practical problem even if fine adjustment of the flash light emission amount is not possible.

  In addition, by adopting a configuration in which the flash emission amount is automatically switched in conjunction with selection of the close-up mode by device operation by the user or selection of the close-up mode based on the measurement result of the distance to the subject. There is no need for troublesome light amount adjustment.

  In addition, by changing the AGC amplifier gain setting and optimizing the exposure control as the strobe emission corresponding to the close-up mode is switched, the contrast of the strobe image in the close-up mode can be further improved. .

  In addition, the image quality of the flash photographed image can be further improved by selecting an optimal light amount value according to the ambient illuminance (for example, whether it is completely dark or dim).

  In addition, as a method for controlling the amount of light emitted from the flash phototube, any of a method for adjusting the amount of stored charge, a method for adjusting the amount of discharge current per unit time, and a method for changing the number of flash discharge tubes are adopted. Thus, a significant change in the amount of light emitted from the flash discharge tube can be easily realized.

  According to the present invention, using a common auxiliary light source (flash discharge tube) mounted on a single portable terminal device with a camera, it is possible to perform strobe shooting in both the normal shooting mode and the close-up mode. High functionality and multi-functionality of the mobile terminal device are achieved, and the use value is improved.

Next, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)

  First, the appearance and usage of an example of a camera-equipped mobile terminal device (referred to as a camera-equipped mobile phone terminal) according to the present invention will be described.

  FIG. 7 is a perspective view for explaining the external appearance of an example of a camera-equipped mobile terminal device (camera-equipped mobile phone terminal) according to the present invention, and FIG. 7A is a perspective view seen from the front side in a state where the housing is folded. (B) is a perspective view in a state where the casing is closed, and (c) is a perspective view seen from the back side in a state where the casing is folded.

  As shown in FIG. 7A, the mobile phone terminal includes an upper casing 200 and a lower casing 202.

  On the main surface of the upper housing 200, a projection window 204 for projecting a flash from a strobe light source, an imaging window 206 for capturing a subject with a built-in camera, and a normal shooting mode / close-up mode switching lever 44.

  Further, on the side surface of the upper casing 200, strobe light emission mode switching keys 46a to 46c (which also function as switching keys for other modes) 46a to 46c are provided. By appropriately operating these keys 46a to 46c, the user can select a preferred light emission mode.

  The strobe flash mode can be broadly divided into “forced flash mode” and “auto flash mode”. The forced light emission mode is a mode in which the user designates light emission of the strobe light source and actively performs flash photography (that is, a mode in which light is always emitted).

  The auto flash mode is a mode in which the strobe light source automatically emits light in response to the ambient illuminance when the ambient illuminance is measured by the camera-equipped mobile phone terminal body and it is determined that the illuminance is insufficient.

  Further, in FIG. 7B, reference numeral 207 is a first liquid crystal display, and reference numeral 48 is an operation key.

  In FIG. 7C, reference numeral 208 denotes a second liquid crystal display. At the time of camera shooting, the image of the subject can be confirmed on the second liquid crystal display.

  A mobile phone terminal having such an external configuration uses a normal shooting mode / close-up mode switching lever 44 (FIG. 7A) to take a picture in a normal shooting mode (shooting a subject several meters away). Mode) and close-up mode (a mode in which a subject is photographed in close proximity with an interval of 10 cm to several tens of cm: sometimes referred to as a macro photography mode or a close-up photography mode) can be switched as appropriate.

  In both the normal shooting mode and the close-up mode, flash photography can be performed in a dark location such as at night.

  In the mobile phone terminal of FIG. 7, since a flash discharge tube with a large amount of light emission is used as a strobe light source, the flash can reach several meters ahead. On the other hand, in the close-up mode, the overexposure of the subject can be prevented by extremely reducing the amount of light emitted from the flash discharge tube.

  FIG. 8 is a diagram showing an example of a usage mode of the camera-equipped mobile phone terminal of the present invention shown in FIG. 7 (a mode of recording timetable information using the close-up mode).

  FIG. 8 shows a situation in which the user sets the cellular phone terminal in the close-up mode and the forced light-emitting mode and projects the flash from the strobe light source toward the page of the timetable in an environment with insufficient illuminance. It shows a state in which a flash is projected and close-up photography is performed.

  That is, since it is inconvenient to carry a timetable, a schedule book, etc., there is a case where a cellular phone terminal is set to a close-up mode, a page on which necessary information is described is photographed and used later.

  For example, when a timetable provided in a station is photographed in the close-up mode at night, the ambient illuminance is low and exposure may be insufficient. In this state, the image is dark even if the image is taken in the normal shooting mode, and necessary information cannot be read.

  In such a case, flash photography is performed in the close-up mode. However, since the subject to be taken close-up (the timetable as the subject) is only about 10 cm away, if the flash intensity is too strong, overexposure will occur and the overexposure phenomenon will occur. Cannot be read.

  Therefore, in the present invention, in the close-up mode, the amount of flash light is extremely reduced stepwise to prevent overexposure and necessary information can be recorded.

  When shooting in close-up mode using a handy portable device such as a mobile phone terminal, the use of information recording as described above is overwhelming rather than the use of shooting beautiful subjects such as plants. It is estimated that there are many. Therefore, priority should be given to prevention of overexposure over image quality, and even if the image quality is slightly worse, if necessary information can be recorded (or the image of the subject is not overexposed in a dark environment). If it can be taken once, it is of practical value.

  As described above, according to the present invention, it becomes possible to perform close-up photography at night or the like using a portable cellular phone terminal, and it is possible to achieve multi-functionality and high functionality of the cellular phone terminal.

  Next, referring to FIG. 1, the system configuration of the mobile phone terminal of the present invention will be described in detail.

  FIG. 1 is a block diagram showing a system configuration of an example of a camera-equipped mobile terminal device (camera-equipped mobile phone terminal) according to the present invention. In the figure, the same reference numerals are assigned to the parts common to FIG.

  As shown in the figure, the camera-equipped mobile phone terminal includes an antenna 10, a wireless unit 12, an audio processing unit 14, a speaker 16, a microphone 18, an optical sensor 20 for measuring ambient illuminance, an A / The D converter 22, the flash emission control unit 24, the flash emission unit 26 (including the flash projection window 204 shown in FIG. 7A), and the imaging unit 28 (FIG. 7A) equipped with a CCD camera A flash shooting window 206 shown), an analog front end 30 for image signals (including an AGC amplifier 31 and an A / D converter 33), an LED 34 and a phototransistor 36 for measuring the distance to the subject. , A camera control unit 38 (including a distance measurement unit 39), a display control unit 40, a display unit 42, a normal shooting mode / close-up mode switch 44, and a strobe Having an optical mode switching key 46, the operation keys 48, a storage device unit 50, a CPU52 for centrally controlling the operation of the entire system, the.

  Switching between the normal shooting mode / close-up mode is performed by a normal shooting mode / close-up mode switching lever 44. Further, the forced light emission mode (always light emission) and the auto issue mode (automatic light emission only when the illuminance is insufficient) can be selected using the strobe light emission mode switching key 46.

  The ambient illuminance is measured by the optical sensor 20, and the measurement signal is converted into a digital signal by the A / D converter 22 and sent to the CPU 52.

  Upon receiving an instruction from the CPU 52, the flash light emission control unit 24 adjusts the light emission amount of the flash discharge tube in the flash light emission unit 26 (its internal structure will be described later with reference to FIGS. 2 to 5).

  In the normal shooting mode, the light emission amount is large, and in the close-up mode, the light emission amount is remarkably reduced (specifically, about 20% to 50% of the light emission amount in the normal shooting mode).

  The camera control unit 38 controls the imaging timing and exposure time of the imaging unit 28 equipped with a CCD camera, and adjusts the gain of an AGC amplifier (variable gain control amplifier) corresponding to the normal shooting mode / close-up mode. Execute exposure control. The distance measuring means 39 also calculates the distance to the subject and sends the calculation result to the CPU 52.

  When the operation mode or the light emission mode is selected, the CPU 52 controls the entire system while taking into account the ambient illuminance information and the distance information to the subject, and exerts a predetermined function.

  Next, the internal structure of the flash light emitting unit 26 including a flash discharge tube will be described with reference to FIGS.

  The flash light emitting unit 26 has a structure capable of stepwise switching the light emission amount of the built-in flash discharge tube to a plurality of predetermined light emission amounts (discrete light emission values). As described above, when flash photography is performed in close-up mode, the light emission amount of the flash discharge tube is automatically adjusted to a light emission amount that is lower than the light emission amount in the normal photographing mode and that can prevent overexposure of the subject. .

  As a method for greatly changing the light emission amount of the flash phototube (a stepwise switching control method of the light emission amount), a method for adjusting the accumulated charge amount (first method) and a current amount per unit time of the discharge current are adjusted. There are a method (second method) and a method (third method) of changing the number of flash discharge tubes.

  2 and 4 performs the light emission amount adjustment by the first method, the flash light emission unit of FIG. 3 performs the light emission amount adjustment by the second method, and the flash light emission unit of FIG. The light emission amount is adjusted by the third method.

  FIG. 2 shows an example of the internal structure of the flash light emitting unit (a structure in which a path for discharging the stored charge of the charge storage capacitor is provided and the total amount of stored charge is controlled by controlling the discharge time). FIG.

  As shown in FIG. 2, the flash light emitting unit 26 includes a voltage source 100 (battery or the like that is a power source of a mobile phone terminal), a booster circuit unit 102, a charge storage capacitor (electrolytic capacitor) CS, and a charge storage unit. A short switch (MOS switch) 106 for adjusting the total amount of charge by short-circuiting both ends of the capacitor CS and discharging the charge, a trigger switch SW1, voltage dividing resistors R1 and R2, and a capacitor C1 (trigger for trigger) A function of accumulating charges and a function of cutting a direct current), a spark coil 108 (having a primary winding and a secondary winding), a trigger electrode 110, a flash discharge tube (xenon discharge tube) 112, Have.

  First, a basic light emission operation will be described (this basic light emission operation is the same in the examples of FIGS. 3 to 5).

  In the case of performing flash photography, the voltage generated from the voltage source 100 is boosted to about 250V to 500V by the booster circuit unit 102. The boosted voltage charges the charge storage capacitor CS.

  In this state, when the trigger switch SW1 is closed for a moment, the trigger charge stored in the capacitor C1 is instantaneously discharged, and an alternating current is generated, and the alternating current is generated on the primary winding of the spark coil 108. Flowing into.

  As a result, a boosted voltage is generated on the secondary winding side of the spark coil 108, and the boosted voltage is applied to the trigger electrode 110, whereby the xenon gas sealed in the flash discharge tube 112 is ionized. To do.

  Since the resistance in the discharge tube decreases due to the ionization of the xenon gas, the charge accumulated in the charge storage capacitor CS flows into the flash discharge tube 112 at the same time, and a discharge occurs between both electrodes of the flash discharge tube. Arise.

  The light emission amount of the flash can be controlled by the amount of current flowing into the flash discharge tube 112 (that is, the total amount of charges accumulated in the charge storage capacitor CS).

  Therefore, in the example of FIG. 2, after the electric charge is accumulated in the electric charge accumulating capacitor CS, the flash emission controller 24 closes the short switch 106 to discharge the electric charge, and the discharge time is adjusted by adjusting the on time of the short switch. As a result, the total amount of charges held in the charge storage capacitor CS is adjusted.

  The structure shown in FIG. 2 has an advantage that the configuration is simple because only one charge storage capacitor and a short switch are required to adjust the light emission amount of the flash.

  FIG. 3 shows another example of the internal structure of the flash light emitting part (a variable resistor is provided in the path for discharging the charge stored in the charge storage capacitor to the flash discharge tube, and the amount of light emission is controlled by controlling the discharge time constant. It is a circuit diagram showing a structure adopting a control method.

  The basic structure of the flash light emitting unit of FIG. 3 is the same as that of the flash light emitting unit of FIG. However, FIG. 3 is different in that the variable resistor 120 is provided in a path for discharging the charge accumulated in the charge storage capacitor CS to the flash discharge tube, and the light emission amount is controlled by controlling the time constant of discharge.

  The variable resistor 120 includes switches (SW2 to SWn, SW3 to SWn + 1) and resistor groups having different resistance values (including short lines, resistors R3... Resistor Rn).

  Then, by controlling the opening / closing of each switch (SW2-SWn, SW3-SWn + 1) by the flash light emission control unit 24, the resistance value of the discharge path can be changed. As the resistance value increases, the time constant increases and the amount of change in voltage per unit time is suppressed, so the amount of light emitted from the flash discharge tube 112 decreases.

  The method of adjusting the light emission amount of the flash discharge tube by changing the resistance value of the discharge path can accurately control the time constant of the discharge with simple control of switching the resistance value (that is, adjusting the light emission amount with high accuracy). There is a merit that

  FIG. 4 shows another example of the internal structure of the flash light emitting unit (a structure in which a plurality of charge storage capacitors are provided, the total amount of charges is controlled by switching the number of capacitors used, and the light emission amount is adjusted. FIG.

  As shown in the drawing, a plurality of charge storage capacitors CS1 to CSn and switches S1 to Sn provided in the charge / discharge paths of the charge storage capacitors CS1 to CSn are provided.

  The total amount of electric charge (current amount) supplied to the flash discharge tube 12 can be controlled by switching the opening and closing of the switches S1 to Sn by the flash light emission control unit 24. Therefore, the light emission amount of the flash discharge tube 112 can be controlled. Can be adjusted. There is an advantage that the total amount of electric charges can be controlled with high accuracy only by switching the switch.

  FIG. 5 is a circuit diagram showing another example of the internal structure of the flash light emitting section (a structure in which a plurality of flash discharge tubes are provided and a method of adjusting the light emission amount by switching the number of flash discharge tubes to be used) is adopted. is there.

  As shown in the drawing, a plurality of flash discharge tubes (112a to 112n) and switches (SK1 to SKn) provided corresponding to each of the flash discharge tubes (112a to 112n) are provided.

  The amount of light emission can be adjusted by controlling the opening and closing of the switches (SK1 to SKn) by the flash light emission controller 24 and adjusting the number of flash discharge tubes to be used. This method has an advantage that the dynamic range of light emission intensity (adjustable range) can be expanded.

  FIG. 6 is a flowchart showing the main steps of strobe emission control and exposure control in the camera-equipped mobile phone terminal of FIG. These controls are performed by the CPU 52, the flash emission control unit 24, and the camera control unit 38 of FIG.

  In FIG. 6, steps indicated by dotted lines indicate optional steps.

  When a user takes a picture of a subject using a camera-equipped mobile phone terminal, it is first determined whether or not the mode is a forced light emission mode (ST1).

  If it is the forced light emission mode, the process proceeds to ST5. If it is not the forced emission mode, it is next determined whether or not it is the automatic emission mode (ST2).

  In ST2, if the auto flash mode is not set, flash photography is not necessary. On the other hand, in the auto flash mode, the ambient illuminance is measured (ST3), the measured value is compared with a predetermined threshold value, and if the measured illuminance is less than or equal to the threshold value, strobe shooting is required. Judgment is made (ST4) and the process proceeds to ST5.

  In ST5, it is determined whether the mode is the normal shooting mode or the close-up mode. This determination is made based on the current position of the normal photography mode / close-up mode switching lever 44 shown in FIG. When the distance to the subject is automatically measured and the distance is smaller than the threshold value, automatic switching to the close-up mode may be performed (in this case, the user The lever switching operation is not required.

  In ST5, in the case of the normal shooting mode, the flash emission amount is set to 100% (ST6), and then exposure control for the normal shooting mode (CCD camera exposure time control and AGC amplifier 31 gain control). Etc.) (ST7).

  On the other hand, in ST5, when the close-up mode is set, in order to prevent overexposure of the subject, the flash emission amount is set to, for example, 30% of the normal shooting (ST8), and then the exposure for the close-up mode is performed. Control (such as exposure time control of the CCD camera and gain control of the AGC amplifier 31) is performed (ST9).

  The above is the basic control operation, but as shown by the dotted line, some optional steps can be executed to perform finer control.

  That is, when the close-up mode is selected in ST5, the distance to the subject is measured without immediately determining the amount of strobe light (ST10), and when the distance is equal to or greater than a threshold (for example, 30 cm) (ST11). The flash emission amount is set to 50% in the normal shooting mode (ST12).

  That is, even in the close-up mode, the distance to the subject may be as short as 10 cm or as long as 50 cm, so if the distance is long, the strobe light amount is set slightly higher and the light emission amount Is a fine adjustment.

  In addition, although the basic strobe light amount in the close-up mode is fixed at 30% (50%) during normal shooting, the strobe light amount can be finely adjusted based on this while taking into account the ambient illuminance. it can.

  That is, as shown in ST13, the ambient illuminance can be measured, and the strobe light amount can be finely adjusted based on the measurement result (if the light is dark, the light amount can be slightly increased).

  As described above, according to the present invention, it is possible to perform proper flash photography in both the normal photography mode and the close-up photography mode using the common auxiliary light source, and the usability of the camera-equipped mobile phone terminal is improved.

  As described above, according to the present invention, the light emission amount is switched in a stepwise manner according to the normal shooting mode / close-up mode, and the flash light amount in the close-up mode is significantly higher than the flash light amount in the normal shooting mode. Can be reduced.

  For example, when the flash emission amount in the normal shooting mode is 100%, the flash emission amount is set to 50% or less in the close-up mode. Therefore, even if the flash photography is performed in the close-up mode, the whiteout does not occur.

  Thus, even in the close-up mode, it is possible to perform strobe shooting without worrying about overexposure.

  In addition, the use of the close-up mode of the camera-equipped mobile terminal device is considered to be a type of recording information, and even in the case of close-up photography of plants, etc. It is considered that the image quality of an image taken using a camera attached to a terminal device is often not a problem from the beginning. Therefore, even if the flash emission amount cannot be finely adjusted, no practical problem occurs.

  In addition, by adopting a configuration in which the flash emission amount is automatically switched in conjunction with selection of the close-up mode by device operation by the user or selection of the close-up mode based on the measurement result of the distance to the subject. There is no need for troublesome light amount adjustment.

  In addition, by changing the AGC amplifier gain setting and optimizing the exposure control as the strobe emission corresponding to the close-up mode is switched, the contrast of the strobe image in the close-up mode can be further improved. .

  In addition, the image quality of the flash photographed image can be further improved by selecting an optimal light amount value according to the ambient illuminance (for example, whether it is completely dark or dim).

  In addition, as a method for controlling the amount of light emitted from the flash phototube, any of a method for adjusting the amount of stored charge, a method for adjusting the amount of discharge current per unit time, and a method for changing the number of flash discharge tubes are adopted. Thus, a significant change in the amount of light emitted from the flash discharge tube can be easily realized.

  According to the present invention, using a common auxiliary light source (flash discharge tube) mounted on a single portable terminal device with a camera, it is possible to perform strobe shooting in both the normal shooting mode and the close-up mode, and with a camera. High functionality and multiple functions of the mobile terminal device are achieved, and the value of use is improved.

  As described above, the switching of the strobe light amount in the flash discharge tube has been described, but the present invention can be variously applied to other modes.

  For example, in the future, if the brightness of the LED is further improved and the amount of light equivalent to that of the flash discharge tube can be secured, the LED light source may be the mainstream of the strobe light source. Also in this case, for example, the amount of light emission can be controlled by switching the forward voltage of the LED in accordance with the normal photographing mode / close-up mode, and the overexposure during close-up can be effectively prevented.

  The camera-equipped mobile terminal device includes a PDA (personal digital assistance) terminal in addition to the mobile phone terminal. In addition, the mobile terminal device to which the present invention is applied may be any type of device as long as it is a small and light device capable of performing close-up photography using a strobe regardless of the presence or absence of a communication function. .

  The present invention has an effect of enabling strobe photography in both the normal shooting mode and the close-up mode, and realizing high functionality and multi-functionality of the camera-equipped mobile terminal device. It can be used for terminal devices (mobile phone terminals with cameras, PDA terminals with cameras, etc.).

The block diagram which shows the system configuration | structure of an example (mobile phone terminal with a camera) of the portable terminal device with a camera of this invention A circuit diagram showing an example of an internal structure of a flash light emitting unit (a structure in which a path for discharging stored charge of a charge storage capacitor is provided and a total amount of stored charge is controlled by controlling a discharge time) Another example of the internal structure of the flash light emitting part (a method of controlling the amount of light emission by providing a variable resistor in the path for discharging the charge accumulated in the charge storage capacitor to the flash discharge tube and controlling the discharge time constant Circuit diagram showing the structure adopted) A circuit showing another example of the internal structure of the flash light emitting unit (a structure in which a plurality of charge storage capacitors are provided and the total amount of charges is controlled by adjusting the number of capacitors used to adjust the light emission amount). Figure A circuit diagram showing another example of the internal structure of the flash light emitting section (a structure in which a plurality of flash discharge tubes are provided and a method of adjusting the light emission amount by switching the number of flash discharge tubes to be used) is adopted. FIG. 1 is a flowchart showing the main steps of strobe emission control and exposure control in the camera-equipped mobile phone terminal of FIG. It is a perspective view for demonstrating the external appearance of an example (mobile phone terminal with a camera) of the portable terminal device with a camera of this invention, (a) is the perspective view seen from the surface side in the state which folded the housing | casing, b) is a perspective view in a state where the casing is closed, and (c) is a perspective view seen from the back side in a state in which the casing is folded. The figure which shows an example (mode which records the information of a timetable using close-up mode) of the usage condition of the mobile telephone terminal with a camera of this invention shown by FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Antenna 12 Radio | wireless part 14 Audio | voice processing part 16 Speaker 18 Microphone 20 Optical sensor 22 A / D converter 24 Ambient illuminance measurement 24 Flash emission control part 26 Flash emission part 28 Imaging part 30 equipped with CCD camera 30 For imaging signal The analog front end 30
31 AGC amplifier 33 A / D converter 34 LED for measuring the distance to the subject
36 Phototransistor 38 Camera control unit 39 Distance measurement unit 40 Display control unit 42 Display unit 44 Normal shooting mode / close-up mode switching lever 46 Strobe light emission mode switching key 48 Operation key 50 Storage unit 52 CPU
106 Short switch (MOS switch)
108 Spark coil 110 Trigger electrode 112 Flash discharge tube 200 Upper housing 202 Lower housing 204 Strobe light projection window 206 Imaging window 207 First liquid crystal display 208 Second liquid crystal display 300 Timetable CS Charge storage capacitor (electrolytic capacitor) )
C1 Trigger charge storage capacitor (also DC cut capacitor)
R1, R2 Voltage dividing resistor SW1 Trigger switch

Claims (12)

A portable terminal device with a camera, which has a normal shooting mode and a close-up mode, and is capable of flash photography in both the normal shooting mode and the close-up mode,
A flash light emitting unit including a flash discharge tube as an auxiliary light source having a structure capable of stepwise switching the light emission amount to a plurality of discrete light emission amounts;
A flash emission control unit that automatically adjusts the light emission amount of the flash discharge tube to a light emission amount lower than the light emission amount in the normal photography mode when performing flash photography in the close-up mode;
A portable terminal device with a camera, comprising: It is a portable terminal device with a camera according to claim 1,
When the close-up mode is selected by the user's device operation, the flash light emission control unit supports the close-up mode so that the light emission amount of the flash discharge tube is a light amount that can prevent overexposure. The camera-equipped mobile terminal device is automatically adjusted to a predetermined light emission amount. It is a portable terminal device with a camera according to claim 1,
When the close-up mode is automatically selected based on the distance to the subject, the flash light emission control unit sets the light emission amount of the flash discharge tube to a predetermined light emission corresponding to the selected close-up mode. A camera-equipped mobile terminal device that automatically adjusts to the amount. It is a portable terminal device with a camera according to claim 1,
The camera-equipped mobile terminal device, wherein the flash light emission control unit reduces the light emission amount of the flash discharge tube in the close-up mode to ½ or less of the light emission amount in the normal photographing mode. It is a portable terminal device with a camera according to claim 1,
A portable terminal device with a camera, wherein exposure control is performed by changing a gain setting of a variable gain amplifier that amplifies an imaging signal of a subject in conjunction with adjustment of a light emission amount of the flash discharge tube in close-up mode . It is a portable terminal device with a camera according to claim 1,
The portable terminal device with a camera, wherein the flash light emission control unit finely adjusts the light emission amount in consideration of the measurement result of ambient illuminance when adjusting the light emission amount of the flash discharge tube in the close-up mode. It is a portable terminal device with a camera according to claim 1,
The camera-equipped mobile terminal device, wherein the flash light emitting unit adjusts a light emission amount of the flash discharge tube by adjusting a charge amount accumulated in a charge storage capacitor. It is a portable terminal device with a camera according to claim 7,
The flash light emitting unit has a switch for short-circuiting both ends of the charge storage capacitor to discharge the stored charge, and the light emission amount of the flash discharge tube can be adjusted by controlling the closing time of the switch. A portable terminal device with a camera, which is possible. It is a portable terminal device with a camera according to claim 7,
The flash light emitting unit includes a plurality of charge storage capacitors and a switch for opening / closing a charge / discharge path for each of the charge storage capacitors, and actually controlling the opening / closing of the switches. A camera-equipped mobile terminal device capable of adjusting a light emission amount of the flash discharge tube by selecting a charge storage capacitor to be used. It is a portable terminal device with a camera according to claim 1,
The flash light emitting unit controls a resistance value of a resistor interposed in a discharge path of charges accumulated in a charge storage capacitor, and thereby adjusts a light emission amount of the flash discharge tube. Terminal device. It is a portable terminal device with a camera according to claim 10,
The flash light emitting unit includes a variable resistance unit having a plurality of resistances having different resistance values provided in a discharge current path between a charge storage capacitor and the flash discharge tube, and the variable light source unit is changed using a changeover switch. A camera-equipped mobile terminal device, wherein the light emission amount of the flash discharge tube can be controlled by selecting at least one of the plurality of resistors in the resistor section. It is a portable terminal device with a camera according to claim 1,
The flash light emitting unit has a plurality of the flash discharge tubes, and adjusts the substantial light emission amount of the flash discharge tube by selecting the number of flash discharge tubes actually used. Mobile terminal device.

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