KR20080043590A - Mobile camera apparatus with variable flash - Google Patents

Abstract

A mobile camera apparatus equipped with a variable flash is provided to secure proper flash light quantity in indoor environment and to acquire photographs with uniform brightness in general environment. A mobile camera apparatus comprises an image sensor unit(100), a flash control unit(200), a PWM/electric current converting unit(300) and a variable flash(400). The image sensor unit generates an AGC signal(Vagc) for controlling the size of an image signal automatically. The flash control unit converts the AGC signal of the image sensor unit into a PWM signal. The PWM/electric current converting unit converts the PWM signal of the flash control unit into driving current. The flash generates light according to the size of the driving current from the PWM/electric current converting unit.

Description

Mobile camera device with variable flash {MOBILE CAMERA APPARATUS WITH VARIABLE FLASH}

1 is a block diagram of a portable camera device according to the prior art.

FIG. 2 is an operation flowchart of the portable camera device of FIG. 1.

3 is a block diagram of a portable camera device according to an embodiment of the present invention.

4 is an operation flowchart of the portable camera device of FIG. 3.

5 is a pulse width correlation graph of the AGC signal Vagc and the PWM signal of FIG. 3.

Explanation of symbols on the main parts of the drawings

100: image sensor unit 110: camera image sensor

120: image sensing processor 200: flash control unit

300: PWM / current converter 400: flash

Vagc: AGC Signal

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable camera device applied to a mobile phone and the like, and in particular, by controlling the flash using a PWM method using an automatic gain control signal (Vagc) of a camera image sensor, the shutter speed of the camera in a indoor environment is reduced. It is possible to prevent the light, to ensure the appropriate amount of flash light in an indoor environment, and to implement a variable light flash accordingly, and to obtain a captured picture of a constant brightness in a general environment without additional hardware. A portable camera device having a variable flash that can be.

Recently, with the development of the information technology (IT) industry, the most attention-grabbing industry among the IT industry is the mobile phone industry. The mobile phone is in progress toward the generalization of multi-convergence with multi-convergence functions such as camera function, MP3, etc. in addition to the phone function among the general people, and the camera function is universal enough to replace the digital camera. It is because of the advantage of taking pictures and using the app.

Currently, cameras employed in mobile phones do not employ mechanical shutters due to volume and size constraints, so that many mobile phones employ flash that can compensate for brightness. A conventional portable camera device employing such a flash will be described with reference to FIGS. 1 and 2.

1 is a block diagram of a portable camera device according to the prior art.

Referring to FIG. 1, a portable camera apparatus according to the related art includes an operation unit 11 including a shutter and a function button of a camera, a light metering device 12 for measuring light quantity, and a light metering device 12. A control unit (MSM) 13 for controlling the flash-on during shooting when the measured light amount is lower than the preset reference light, and controlling the flash-off during shooting when the measured light amount is higher than the reference light amount; A flash camera 14 operating under the control of the control unit 13 and a display unit 15 for screen output of necessary information on the operation.

FIG. 2 is an operation flowchart of the portable camera device of FIG. 1. Referring to FIG. 2, in the mobile camera device shown in FIG. 1, the mobile phone flashlight is kept at a constant light quantity, and thus, a very bright portion higher than the reference light quantity. Since it is controlled on or off in two stages of a very dark portion lower than the amount of light, there is a problem that can not be properly adjusted according to the amount of ambient light.

Accordingly, when the flash is adjusted in the two steps as described above, there is a problem that the flash is turned on in the indoor environment and the picture is blurred by the light.

On the other hand, in order to reduce such a phenomenon, a technique for adjusting the amount of flash light by measuring the amount of light by employing a separate metering device has been developed, but there is a problem that additional costs are generated due to the additional metering device.

The present invention has been proposed to solve the above problems, the object of which is to control the flash by the PWM method using the automatic gain control signal (Vagc) of the camera image sensor, the shutter speed of the camera in the indoor environment (shutter speed ) To prevent falling, to ensure the appropriate flash light amount in the indoor environment, and to implement a variable light flash, and to capture a constant brightness in the general environment without additional hardware It is to provide a portable camera device having a variable flash to obtain a picture.

In order to achieve the above object of the present invention, a portable camera device having a variable flash according to an embodiment of the present invention, the image sensor unit for generating an AGC signal for automatically adjusting the size of the image signal; A flash controller converting the AGC signal of the image sensor unit into a PWM signal; A PWM / current converter configured to convert the PWM signal of the flash controller into a driving current; And a flash generating light having a light amount corresponding to the magnitude of the driving current from the PWM / current converter.

The image sensor unit may include a camera image sensor generating a video signal by capturing a subject image and adjusting the magnitude of the video signal according to the AGC signal; And an image sensing processor configured to generate the AGC signal according to the magnitude of the image signal from the camera image sensor and output the AGC signal to the camera image sensor and the flash controller.

The flash control unit previously prepares an AGC / PWM mapping table by matching pulse widths according to AGC signal magnitudes, and finds a pulse width corresponding to the magnitude of an AGC signal from the image sensor in the AGC / PWM mapping table. The PWM signal having the found pulse width is generated and output to the PWM / current converter.

The portable camera device may be implemented in a mobile communication terminal that performs a mobile communication function.

The portable camera device may be implemented in a mobile phone device for carrying out a mobile phone call.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention is not limited to the embodiments described, and the embodiments of the present invention are used to assist in understanding the technical spirit of the present invention. In the drawings referred to in the present invention, components having substantially the same configuration and function will use the same reference numerals.

3 is a block diagram of a portable camera device according to an embodiment of the present invention.

Referring to FIG. 3, the portable camera device according to an embodiment of the present invention includes an image sensor unit 100 for generating an AGC signal Vagc for automatically adjusting the magnitude of an image signal, and the image sensor unit 100. Flash control unit 200 for converting the AGC signal (Vagc) of the PWM signal, PWM / current conversion unit 300 for converting the PWM signal of the flash control unit 200 into a drive current, and the PWM / current conversion unit And a flash 400 for generating light having a light amount according to the magnitude of the driving current from the 300.

The image sensor unit 100 generates a video signal by capturing a subject image, and adjusts the size of the video signal according to the AGC signal Vagc, and the camera image sensor ( The image sensing processor 120 generates the AGC signal Vagc according to the magnitude of the image signal from the 110 and outputs the AGC signal Vagc to the camera image sensor 110 and the flash controller 200.

The flash control unit 200 previously prepares an AGC / PWM mapping table by matching pulse widths according to the magnitudes of AGC signals, and sets the pulse widths corresponding to the magnitudes of AGC signals from the image sensor 100 to the AGC / PWM mapping table. In the PWM mapping table, a PWM signal having the found pulse width is generated and output to the PWM / current converter 300.

The portable camera device may be implemented in a mobile communication terminal that performs a mobile communication function or a mobile phone device that performs a mobile call.

Here, the mobile communication terminal corresponds to a terminal capable of carrying and communicating, such as a personal digital assistant (PDA) or a small notebook.

In addition, the mobile telephone apparatus corresponds to a terminal capable of carrying a telephone while carrying a mobile phone or PDA.

Meanwhile, the portable camera device may be implemented in a portable terminal such as an MP3 player.

Here, 50 is an operation unit including a shutter and a function button of a camera, and 500 is a display unit for screen output of necessary information on operation.

4 is an operation flowchart of the portable camera device of FIG. 3. In FIG. 4, S100 is a process of determining a camera shutter selection. S200 is a process of detecting the AGC signal of the image sensor unit. S300 is a process of converting the AGC signal into a PWM signal. S400 is a process of converting a PWM signal into a driving current. S500 is a process of operating the flash with the amount of light as large as the driving current at the time of shooting. S600 is a process of storing the captured image.

5 is a pulse width correlation graph of the AGC signal Vagc and the PWM signal of FIG. 3, in which the vertical axis represents AGC signal magnitude [V], and the horizontal axis represents duty (% duty ratio) of the pulse width.

Hereinafter, the operation and effects of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIGS. 3 to 5, the operation of the portable camera device having the variable flash according to the embodiment of the present invention will be described. First, the flash control unit 200 illustrated in FIG. 3 determines whether to select a camera shutter. (Corresponds to S100 of FIG. 4). At this time, when the flash control unit 200 determines that the camera shutter is selected, the following operation is performed.

On the other hand, the image sensor unit 100 of the portable camera device generates an AGC signal (Vagc) for automatically adjusting the size of the video signal to output to the flash control unit 200, the flash control unit 200 is the AGC signal ( Vagc) is detected (corresponding to S200 of FIG. 4).

For example, when the image sensor unit 100 includes a camera image sensor 110 and an image sensing processor 120, the camera image sensor 110 generates an image signal by capturing a subject image. The magnitude of the video signal is adjusted according to the AGC signal Vagc. The image sensing processor 120 generates the AGC signal Vagc according to the magnitude of the image signal from the camera image sensor 110 and outputs the AGC signal Vagc to the camera image sensor 110 and the flash controller 200.

The flash control unit 200 converts the AGC signal Vagc of the image sensor unit 100 into a PWM signal and outputs the PWM signal to the PWM / current converter 300 (corresponding to S300 of FIG. 4).

In more detail, the flash controller 200 prepares an AGC / PWM mapping table by matching pulse widths according to magnitudes of AGC signals in advance, and sets the magnitude of the AGC signals from the image sensor 100. The pulse width corresponding to the pulse width is found in the AGC / PWM mapping table, and a PWM signal having the found pulse width is generated and output to the PWM / current converter 300.

The AGC / PWM mapping table may be expressed as shown in Table 1 below.

AGC signal Pulse width V1 10% V2 20% V3 30% V4 40% V5 50% V6 60% V7 70% V8 80% V9 90% V10 100%

In the AGC / PWM mapping table shown in Table 1, for a plurality of voltages V1 to V10 included in the AGC voltage Vagc, for example, V1 is 1.1V, V1 is 1.2V, and V3 is 1.3V. V4 is 1.4V, V5 is 1.5V, V6 is 1.6V, V7 is 1.7V, V8 is 1.8V, V9 is 1.9V, and V10 is 2V.

As shown in FIG. 5, the AGC voltage gradually increases, and as a result, the pulse width gradually widens.

The PWM / current converter 300 converts the PWM signal of the flash controller 200 into a drive current and outputs it to the flash 400 (corresponding to S400 of FIG. 4).

At this time, the amount of driving current is increased according to the pulse width of the PWM signal to adjust the amount of flash light. For example, when the pulse width of the PWM signal is 10%, it is converted into a driving current that can turn on the flash by 10%. When the pulse width of the PWM signal is 20%, the flash is 20%. When the pulse width of the PWM signal is 30%, the pulse width of the PWM signal is converted to the magnitude of the drive current that can turn on the flash by 30%, and the pulse width of the PWM signal is 40%. In the case of the pulse width of the PWM signal is converted to the drive current that can be turned on by 40%, when the pulse width of the PWM signal is 50% is converted to the magnitude of the drive current can be turned on by 50%, When the pulse width of the PWM signal is 60%, the driving current is converted into the magnitude of the driving current that can turn on the flash by 60%. When the pulse width of the PWM signal is 70%, the driving can turn on the flash by 70%. Converted into the magnitude of the current, the PWM signal When the pulse width is 80%, it is converted into a driving current that can turn on the flash by 80%. When the pulse width of the PWM signal is 90%, the magnitude of the driving current that can turn on the flash by 90%. When the pulse width of the PWM signal is 100%, it is converted to the magnitude of the driving current that can turn on the flash by 100%.

The flash 400 generates light having a light amount corresponding to the magnitude of the driving current from the PWM / current converter 300 (corresponding to S500 of FIG. 4).

At this time, the amount of light of the flash is adjusted according to the magnitude of the driving current. For example, the flash generates 10% light according to a driving current capable of turning on the flash by 10%, and the flash generates 20% light according to the driving current capable of turning on the flash by 20%. The flash generates 30% light according to the drive current capable of turning on the flash by 30%, and the flash generates 40% light according to the drive current capable of turning on the flash by 40%. The flash generates 50% light according to the driving current which can turn on the flash by 50%, and the flash generates 60% light according to the driving current which can turn the flash on by 60%, The flash generates 70% of light according to a drive current capable of turning on by 70%, and the flash generates 80% of light and drives 90% of flash in accordance with a drive current capable of turning on the flash by 80%. As long as you can According to the driving current, the flash generates light by 90%, and according to the driving current capable of turning on the flash by 100%, the flash generates 100% light.

Through the operation of the portable camera device, the portable camera device stores the obtained image (corresponding to S600 of FIG. 4).

In the present invention as described above, by using a software (SW) to measure the brightness of the light, and to adjust the brightness to adjust the brightness, it is possible to automatically adjust the brightness of the picture taken, for example, When it is dark indoors, the frame rate of the camera is reduced, and accordingly, the amount of flash light is controlled by a pulse width modulator (PWM). According to the present invention, a variable flash system can be implemented without additional hardware (H / W) additional cost.

According to the present invention as described above, in a portable camera device applied to a mobile phone or the like, by controlling the flash by the PWM method using the automatic gain control signal (Vagc) of the camera image sensor, the shutter speed of the camera in the indoor environment (shutter speed) ) To prevent falling, to ensure the appropriate flash light amount in the indoor environment, and to implement a variable light flash, and to capture a constant brightness in the general environment without additional hardware There is an effect to get a picture.

The present invention described above is not limited to the above-described embodiment and the accompanying drawings, but is defined by the claims, and the apparatus of the present invention may be substituted, modified, and modified in various ways without departing from the spirit of the present invention. It is apparent to those skilled in the art that modifications are possible.

Claims (5)

An image sensor unit generating an AGC signal for automatically adjusting the magnitude of an image signal; A flash controller converting the AGC signal of the image sensor unit into a PWM signal; A PWM / current converter configured to convert the PWM signal of the flash controller into a driving current; And Flash for generating light having a light amount according to the magnitude of the drive current from the PWM / current converter Portable camera device having a variable flash, characterized in that it comprises a. The method of claim 1, wherein the image sensor unit, A camera image sensor generating a video signal by capturing a subject image and adjusting a magnitude of the video signal according to the AGC signal; And The image sensing processor generates the AGC signal according to the magnitude of the image signal from the camera image sensor and outputs the AGC signal to the camera image sensor and the flash controller. Portable camera device having a variable flash, characterized in that it comprises a. The method of claim 1, wherein the flash control unit, The pulse widths of the AGC signals are matched in advance and prepared in the AGC / PWM mapping table. The pulse widths corresponding to the magnitudes of the AGC signals from the image sensor are found in the AGC / PWM mapping table. And a PWM signal generated and outputted to the PWM / current converter. The portable camera device of claim 1, wherein Portable camera device having a variable flash, characterized in that implemented in a mobile communication terminal performing a mobile communication function. The portable camera device of claim 1, wherein A portable camera device having a variable flash, characterized in that implemented in a mobile phone device for carrying out a mobile call.

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