KR101162264B1 - Image sensor and photographing apparatus having the same - Google Patents

Abstract

The present invention relates to an image sensor and a photographing apparatus including the same, and discloses a technique for automatically controlling brightness of an infrared light emitting diode (IR-LED). The present invention, the light receiving unit for sensing the brightness information of the image data, the internal logic control unit for outputting a control signal for controlling the current supplied to the light emitting device when the brightness information is determined outside the range of the predetermined appropriate brightness, and the internal And a light emission controller configured to adjust a current value flowing through the light emitting device according to a level of brightness information according to a control signal applied through a logic controller.

Description

An image sensor and a photographing device including the same {IMAGE SENSOR AND PHOTOGRAPHING APPARATUS HAVING THE SAME}

Embodiments of the present invention relate to an image sensor and a photographing apparatus including the same, and more particularly, to a technology for converting an external optical image signal into an electrical image signal.

In general, an image sensor is a device that converts an external optical image signal into an electrical image signal.

In particular, CMOS image sensors are image sensors fabricated using CMOS fabrication techniques. In the CMOS image sensor, each pixel stores the light signal radiated from the corresponding part of the object after converting it into electrons using a photodiode, and converts the amount of charge appearing in proportion to the accumulated number of electrons into a voltage signal and outputs the voltage signal. Use

Image sensors are largely divided into CMOS image sensors using complementary-MOS (CMOS) technology and CCD image sensors using Charge Coupled Device (CCD) technology, all of which are manufactured using semiconductor technology.

Such a CMOS image sensor is a device widely used in various electronic products, for example, a mobile phone, a camera for a personal computer (PC), a video camera, a digital camera, and the like.

The CMOS image sensor is simpler to drive than the CCD used as an image sensor, and it is possible to integrate a signal processing circuit into one chip so that a system on chip (SoC) can be used to make the module smaller. Let's do it.

In addition, since the conventional set-up (CMOS) technology can be used interchangeably, there are many advantages such as lowering the manufacturing cost, so the demand is increasing rapidly.

In general, a photographing apparatus including an image sensor such as a digital camera, a camcorder, and a portable terminal in which a camera function is implemented, acquires an image signal by capturing an image input through a lens with an image sensor.

The video signal is converted into digital video data and displayed on a liquid crystal screen as a preview screen. When the user presses the shutter key while the preview image is displayed, the image data is compressed and stored as photo data.

1 is a block diagram of a photographing apparatus including a conventional image sensor.

The conventional photographing apparatus includes an illuminance sensor 1, a micro controller unit (MCU) 10, a light emitting element 20, and an image sensor 30.

Here, the microcontroller unit 10 includes an analog digital converter (ADC) 11.

In addition, the light emitting device 20 may include a light emitting diode (LED) or an infrared (IR) light emitting diode (LED).

First, the illuminance sensor 1 detects the brightness information of the surroundings, and the brightness information detected by the illuminance sensor 1 is input to the microcontroller unit 10.

The analog-to-digital converter 11 provided in the microcontroller unit 10 converts an analog signal for brightness information applied from the illuminance sensor 1 into a digital signal.

The micro controller unit 10 controls the brightness information applied from the illuminance sensor 1 to control the turn on or turn off operation of the light emitting device 20.

In addition, the microcontroller unit 10 is connected to the image sensor 30 through a specific communication bus, for example, an I 2 C (Inter Integrated Circuit). The image sensor 30 outputs an analog or digital video signal by photographing a subject under the control of the microcontroller unit 10.

An operation of a photographing apparatus including a conventional image sensor having such a configuration will be described below with reference to FIG. 2.

When the data level of the illumination sensor 1 applied through the analog-to-digital converter 11 is low, that is, when the sensed illumination is a dark level, the microcontroller unit 10 outputs a light emission control signal On. Allow current to flow in the IR-LED. Accordingly, when the sensed brightness information is at a dark level, a current flows through the IR-LED so that the light emitting device 20 is turned on.

On the other hand, the microcontroller unit 10 turns off the light emission control signal when the level of the illuminance sensor 1 applied through the analog-digital converter 11 is high, that is, when the sensed illuminance is a bright level. Do not output IR-LED current. Accordingly, when the sensed brightness information is at a bright level, the light emitting device 20 does not operate by preventing current from flowing in the IR-LED.

Recently, in the terminal market, LEDs or IR-LEDs are used as essential elements to improve low light sensitivity of cameras used in surveillance or door phones.

That is, the illumination sensor 1 is used to control the light emitting device 20 according to the illumination of the surrounding environment. When using IR-LED, there is an advantage that you can see the dark surroundings brightly.

However, the conventional photographing apparatus includes a microcontroller 10 having an analog-digital converter 11 embedded therein separately from the image sensor 30 to perform signal processing by receiving the sensing result of the illuminance sensor 1. . In addition, the general illuminance sensor 1 is not good for the environment, and the eco-friendly illuminance sensor is expensive.

Accordingly, not only the cost of implementing the photographing system including the image sensor increases, but also the volume of the system becomes large.

In addition, the conventional photographing apparatus recognizes a bright and dark environment through the illumination sensor 1 and uses a method of turning on the light emitting IR-LED when it is dark and turning off the IR-LED when it is bright. This simple turn-on or turn-off method consumes unnecessary power when the IR-LED is turned on and off.

In other words, when operating the IR-LED in the current control method, the current must flow through the dark enough brightness to brighten the IR-LED. Therefore, there is a problem that consumes more power than necessary according to the environment, and generates a lot of heat in the IR-LED.

Embodiments of the present invention have the following object in order to solve the above-mentioned conventional problems.

First, an embodiment of the present invention allows a system to be simplified by embedding a light emitting diode (LED) control function in an image sensor.

Second, the embodiment of the present invention can perform the LED control function only by the image sensor without using a separate microcontroller unit, so that the system can be miniaturized and the cost can be reduced.

Third, the embodiment of the present invention can reduce the power consumption of the system by flowing the operating current of the LED only as necessary to turn on the LED.

An image sensor according to an embodiment of the present invention for achieving the above object, the light receiving unit for sensing the brightness information of the image data; An internal logic controller configured to determine brightness information and output a control signal for adjusting a current supplied to the light emitting device when the brightness information is out of a range of a predetermined appropriate brightness; And a light emission controller configured to adjust a current value flowing to the light emitting device according to the level of brightness information according to a control signal applied through the internal logic controller, wherein the internal logic controller calculates the brightness of the image data to determine a range of appropriate brightness. If the deviation is to adjust the exposure time and the gain of the image sensor, and if the current control variable of the light emitting device is less than a predetermined value it characterized in that the exposure time and gain.

The photographing apparatus including the image sensor according to another embodiment of the present invention senses the brightness information of the image data, determines the brightness information, and emits light in response to the level of the brightness information when the brightness information is out of the preset appropriate brightness range. An image sensor for adjusting a value of a current supplied to the device; And a light emitting part in which the brightness of the light emitting device is changed by adjusting a value of the current flowing through the light emitting device according to the current applied from the image sensor, and the image sensor includes: a light receiving unit sensing brightness information of the image data; An internal logic controller which determines the brightness information and outputs a control signal when the brightness information is out of a range of a predetermined appropriate brightness; And a light emission controller that adjusts a current value flowing to the light emitting device according to the level of brightness information according to the control signal, wherein the internal logic controller calculates the brightness of the image data and falls outside the appropriate brightness range. And adjusting the gain and adjusting the exposure time and the gain when the current adjusting variable of the light emitting device is equal to or less than a preset value.

An embodiment of the present invention has the following effects.

First, an embodiment of the present invention allows a system to be simplified by embedding a light emitting diode (LED) control function in an image sensor.

Second, the embodiment of the present invention can perform the LED control function only by the image sensor without using a separate microcontroller unit, so that the system can be miniaturized and the cost can be reduced.

Third, since the embodiment of the present invention does not use a separate illuminance sensor, the system can be simplified and the unit cost can be reduced.

Fourth, the embodiment of the present invention provides the effect of reducing the power consumption of the system by reducing the power consumption of the LED by turning on the LED by flowing the operating current of the LED only as necessary.

It will be apparent to those skilled in the art that various modifications, additions, and substitutions are possible, and that various modifications, additions and substitutions are possible, within the spirit and scope of the appended claims. As shown in Fig.

1 is a block diagram of a photographing apparatus including a conventional image sensor.
FIG. 2 is a diagram for describing an operation of a photographing apparatus including the image sensor of FIG. 1. FIG.
3 is a block diagram of a photographing apparatus including an image sensor according to an exemplary embodiment of the present invention.
4 is a flow chart for explaining the operation of FIG.
FIG. 5 is a detailed configuration diagram and a circuit diagram of the light emission controller and the light emission unit of FIG. 2; FIG.
6 is a view for explaining an operation of the light emission controller of FIG.
FIG. 7 is another embodiment of the light emission controller and the light emission unit of FIG. 2; FIG.

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

3 is a block diagram of a photographing apparatus including an image sensor according to an exemplary embodiment of the present invention.

An embodiment of the present invention includes an image sensor 100 and a light emitting unit 200.

Here, the image sensor 100 includes a light receiving unit 110, an internal logic controller 120, a light emission controller 130, and a lens 140. The light emitting unit 200 may include a light emitting device such as a light emitting diode (LED) or an infrared light emitting diode (IR).

First, the light receiver 110 senses brightness information by converting light energy around the image sensor 100 into electrical energy. The image data input to the light receiver 110 is applied to the internal logic controller 120 provided in the image sensor 100.

Here, the internal logic controller 120 preferably includes an analog digital converter (ADC) 121 for converting an analog signal for brightness information applied from the light receiver 110 into a digital signal.

The internal logic controller 120 controls the video signal of the subject photographed from the lens 140 according to the digital signal or the internal control signal applied from the analog-to-digital converter 121 and outputs the digital signal OUT.

In addition, the internal logic controller 120 processes the digital signal applied from the analog-to-digital converter 121 and outputs a control signal to the light emission controller 130.

At this time, the internal logic controller 120 calculates the brightness information of the image data applied from the light receiver 110 to determine whether it is within a predetermined appropriate brightness range.

If the brightness information of the image data is out of a predetermined appropriate brightness range, the exposure time and the gain of the image sensor 100 are adjusted. The internal logic controller 120 controls to control the driving current of the light emitter 200 when the brightness of the image data is out of an appropriate brightness range even after adjusting the exposure time and the gain of the image sensor 100 to the maximum. The signal is output to the light emission controller 130.

In addition, the light emission controller 130 controls the current value flowing to the light emitting device provided in the light emitting unit 200 according to the control value calculated by the brightness information applied from the light receiving unit 110 through the internal logic control unit 120. do.

That is, the image data input through the light receiving unit 110 of the image sensor 100 may be lightened or darkened according to the exposure time and the gain of the image sensor 100. The light emission controller 130 increases the driving current of the LED as necessary only when the brightness of the image data is not enough to adjust the exposure time and the gain of the image sensor 100.

4 is a flowchart illustrating a control algorithm for controlling the brightness of image data in the internal logic controller 120 of FIG. 3.

The internal logic controller 120 calculates the brightness of the image data applied through the light receiver 110 (step S1).

Subsequently, the internal logic controller 120 determines whether the brightness of the image data is within a preset appropriate brightness range (step S2).

If the image data is appropriate brightness, it is determined as the first case (Case) and the operation is terminated. Here, the appropriate brightness information of the image data is preferably set in the internal logic controller 120.

On the other hand, when the image data is brighter than the appropriate brightness, it is determined whether the variable for adjusting the driving current of the LED is a minimum value (less than a predetermined value).

That is, when the brightness of the image data is brighter than the appropriate brightness and the adjustment parameter of the LED current is the minimum value (below the preset value), it is determined as the second case (Case) to adjust the exposure time and gain of the image sensor 100. Here, the internal logic controller 120 adjusts the exposure time and the gain only when the desired brightness can be obtained by adjusting the exposure time and the gain. On the contrary, when the control parameter of the LED current is not the minimum value (below the preset value), it is determined as the third case (Case) to adjust the driving current of the LED.

In addition, when the image data is darker than the appropriate brightness, it is determined whether the exposure time and the gain of the image sensor 100 are the maximum values (above a preset value).

That is, when the brightness of the image data is darker than the appropriate brightness and the exposure time and the gain of the image sensor 100 are the maximum values (above a preset value), it is determined as the third case (Case) to adjust the driving current of the LED. The control signal is output to the light emission controller 130. (Step S4) In contrast, when the exposure time and the gain are not the maximum values (above a preset value), the second case (Case) is determined to adjust the exposure time and the gain. Done.

FIG. 5 is a diagram illustrating a method for controlling a driving current of an LED in the light emission controller 130 of FIG. 3. In the embodiment of FIG. 5, the light emission controller 130 may include a pulse controller 131.

The light emitting unit 200 includes resistors R1 and R2, a transistor T1, and a plurality of light emitting devices 210 and 220. Here, the resistor R2, the plurality of light emitting devices 210 and 220, and the transistor T1 are connected in series between a power supply voltage VDD application terminal and a ground voltage terminal.

In addition, the transistor T1 is turned on or turned off according to a control signal applied from the light emission controller 130 of the image sensor 100 through the resistor R1. Here, the transistor T1 is preferably made of a bipolar junction transistor.

The light emitting unit 200 having such a configuration is connected to the light emitting controller 130 provided in the image sensor 100 through the output pin P1. Here, the output pin P1 is provided in the output pad region of the image sensor 100 to transmit the current driving signal applied from the light emission controller 130 to the light emitting unit 200.

Then, the light emitting unit 200 selectively turns on or off the transistor T1 according to the current driving signal applied from the light emitting controller 130 to control the operation of the light emitting devices 210 and 220 in response to the brightness level of the image data. do.

In this case, when an infrared (IR) light emitting diode (LED) is used as the light emitting devices 210 and 220, a dual band pass filter is included in the image sensor 100 to receive an infrared light source. Done. The dual band pass filter (not shown) is preferably located between the light receiving unit 110 and the lens 140 to perform a filtering operation in the infrared light source applied from the lens 140.

The pulse controller 131 included in the light emission controller 130 controls the LED of the light emission unit 200 through a pulse duty control method.

In the pulse duty control scheme, the duty of the pulse input to the transistor T1 of the light emitting unit 200 is controlled by the image sensor 100 and transmitted to the light emitting devices 210 and 220.

That is, the driving currents of the light emitting devices 210 and 220 are adjusted according to the duty of the pulses output from the pulse controller 131 to change the brightness of the light emitting devices 210 and 220.

FIG. 6 is a diagram for describing an operation of the pulse controller 131 illustrated in FIG. 5.

The pulse controller 131 controls the current supplied to the light emitter 200 according to the brightness of the image data applied from the internal logic controller 120 through a pulse duty control method.

The pulse controller 131 outputs a pulse having a fixed variable, such as Tp, to the light emitting unit 200. In addition, the pulse controller 131 controls the adjustment variable TH large when the brightness of the image data applied through the light receiving unit 110 and the internal logic controller 120 is low, and when the brightness of the image data is bright, the control variable TH is low. do.

That is, when the brightness of the image data is dark, the high pulse width of the pulse output from the pulse controller 131 is controlled to increase the amount of driving current supplied to the light emitting unit 200. On the other hand, when the brightness of the image data is bright, the high pulse width of the pulse output from the pulse controller 131 is controlled to reduce the amount of driving current supplied to the light emitting unit 200.

As such, the pulse controller 131 may adjust the amount of current supplied to the transistor T1 of the light emitting unit 200 to an appropriate value by controlling the duty width of the pulse.

That is, when the high pulse width of the pulse supplied from the pulse controller 131 is large, the time for turning on the transistor T1 becomes relatively long. Accordingly, the driving current supplied to the light emitting devices 210 and 220 increases, so that the brightness of the light emitting devices 210 and 220 is brightly adjusted.

On the other hand, when the high pulse width of the pulse supplied from the pulse controller 131 is small, the time for which the transistor T1 is turned on is shortened relatively. Accordingly, the driving current supplied to the light emitting devices 210 and 220 is reduced, so that the brightness of the light emitting devices 210 and 220 is darkly adjusted.

FIG. 7 is a configuration diagram illustrating a method for controlling a driving current of an LED in the light emission controller 130 of FIG. 3. In the exemplary embodiment of FIG. 7, the light emission controller 130 may include a brightness controller 132 and a digital analog converter 133.

The light emitting unit 200 includes resistors R3 and R4, a transistor T2, and a plurality of light emitting devices 230 and 240. Here, the resistor R4, the plurality of light emitting devices 230 and 240, and the transistor T2 are connected in series between a power supply voltage VDD applying terminal and a ground voltage terminal.

In addition, the transistor T2 is turned on or turned off according to a control signal applied from the light emission controller 130 of the image sensor 100 through the resistor R3. Here, the transistor T2 is preferably made of a bipolar junction transistor.

The light emitting unit 200 having such a configuration is connected to the light emitting controller 130 provided in the image sensor 100 through the output pin P2. Here, the output pin P2 is provided in the output pad region of the image sensor 100 to transmit the current driving signal applied from the light emission controller 130 to the light emitting unit 200.

Then, the light emitting unit 200 selectively turns on or off the transistor T2 according to the current driving signal applied from the light emitting control unit 130 to control the operation of the light emitting devices 230 and 240 in response to the brightness level of the image data. do.

In this case, when an infrared (IR) light emitting diode (LED) is used as the light emitting devices 230 and 240, a dual band pass filter is included in the image sensor 100 to receive an infrared light source. Done. The dual band pass filter (not shown) is preferably located between the light receiving unit 11 and the lens 140 to perform a filtering operation in the infrared light source applied from the lens 140.

Here, the brightness controller 132 included in the light emission controller 130 controls the LED of the light emission unit 200 through a direct current control method. The digital-to-analog converter 133 converts the digital signal applied from the brightness controller 132 into an analog signal and outputs the analog signal to the light emitting unit 200.

In the current direct control method, the amount of current input to the transistor T2 of the light emitting unit 200 is controlled by the image sensor 100 and transmitted to the light emitting devices 230 and 240.

That is, the brightness controller 132 adjusts the driving current of the light emitting devices 230 and 240 by increasing the input value of the digital-to-analog converter 133 according to the brightness of the image data applied from the light receiving unit 110 and the internal logic controller 120. As a result, the brightness of the light emitting devices 230 and 240 is changed.

The operation of the light emission controller 130 having such a configuration will be described in more detail as follows.

The brightness controller 132 controls the current supplied to the light emitter 200 according to the brightness of the image data applied from the internal logic controller 120 through a current direct control method.

The brightness controller 132 increases and outputs an input value of the digital-to-analog converter 133 when the brightness of image data applied from the internal logic controller 120 is dark. On the other hand, when the brightness of the image data applied from the internal logic controller 120 is bright, the brightness controller 132 lowers and outputs an input value of the digital-to-analog converter 133.

That is, when the brightness of the image data is dark, the digital value of the control signal output from the brightness controller 132 has a high value. As a result, the analog value output from the digital-to-analog converter 133 is increased to increase the amount of driving current supplied to the light emitting unit 200.

On the other hand, when the brightness of the image data is bright, the digital value of the control signal output from the brightness controller 132 has a low value. Accordingly, the analog value output from the digital analog converter 133 is lowered, thereby reducing the amount of driving current supplied to the light emitting unit 200.

As such, the brightness controller 132 controls the amount of current supplied to the transistor T2 of the light emitting unit 200 through the direct current control method to adjust the amount to an appropriate value.

That is, when the value of the analog signal supplied from the digital-to-analog converter 133 is large, the current flowing in the transistor T2 is relatively increased. Accordingly, the driving current supplied to the light emitting devices 230 and 240 increases, so that the brightness of the light emitting devices 230 and 240 is brightly adjusted.

On the other hand, when the value of the analog signal supplied from the digital-to-analog converter 133 is small, the current flowing through the transistor T2 is relatively reduced. Accordingly, the driving current supplied to the light emitting devices 230 and 240 is reduced, so that the brightness of the light emitting devices 230 and 240 is darkly adjusted.

Claims (15)

A light receiving unit configured to sense brightness information of the image data;
An internal logic controller configured to determine the brightness information and output a control signal for adjusting a current supplied to the light emitting device when the brightness information is out of a predetermined range of a suitable brightness; And
A light emission controller configured to adjust a current value flowing through the light emitting device according to the level of the brightness information according to the control signal applied through the internal logic controller;
The internal logic controller
The brightness of the image data is calculated to adjust the exposure time and gain of the image sensor when it is out of the range of the appropriate brightness, and adjust the exposure time and gain when the current control variable of the light emitting device is less than or equal to a preset value. Image sensor. delete delete The method of claim 1, wherein the internal logic control unit
And calculating the brightness of the image data to output the control signal to the light emission controller when the exposure time and the gain of the image sensor are outside the range of the appropriate brightness and the predetermined time is greater than or equal to a preset value. The method of claim 1, wherein the light emission control unit
And a pulse controller configured to adjust a current value flowing through the light emitting device by changing a duty value of a pulse corresponding to the level of the brightness information. The method of claim 5, wherein the pulse control unit
And a high pulse width of the pulse corresponding to the level of the brightness information. The method of claim 1, wherein the light emission control unit
A brightness controller for changing a digital value applied from the internal logic controller corresponding to the level of the brightness information; And
And an analog-to-digital converter configured to adjust an electric current value flowing through the light emitting device by changing an analog value under the control of the brightness controller. An image sensor configured to sense brightness information of the image data, and determine the brightness information to adjust a value of a current supplied to the light emitting device in response to the level of the brightness information when the brightness information is out of a preset appropriate brightness range; And
And a light emitting unit in which a brightness of the light emitting device is changed by adjusting a value of a current flowing through the light emitting device according to the current applied from the image sensor.
The image sensor is
A light receiver configured to sense the brightness information of the image data;
An internal logic controller configured to determine the brightness information and to output a control signal when the brightness information is out of the preset appropriate brightness range; And
A light emission controller configured to adjust a current value flowing through the light emitting device according to the level of the brightness information according to the control signal;
The internal logic controller
The brightness of the image data is calculated to adjust the exposure time and gain of the image sensor when it is out of the range of the appropriate brightness, and adjust the exposure time and gain when the current control variable of the light emitting device is less than or equal to a preset value. An imaging device including an image sensor. delete delete delete The method of claim 8, wherein the internal logic control unit
And an image sensor that calculates the brightness of the image data and outputs the control signal to the light emission controller when the exposure time and the gain of the image sensor are outside the range of the appropriate brightness and are equal to or greater than a preset value. The method of claim 8, wherein the light emission control unit
And a pulse controller configured to adjust a current value flowing through the light emitting device by changing a duty value of a pulse in response to the level of the brightness information. The method of claim 13, wherein the pulse control unit
And an image sensor to change the high pulse width of the pulse in correspondence with the level of the brightness information. The method of claim 8, wherein the light emission control unit
A brightness controller for changing a digital value applied from the internal logic controller corresponding to the level of the brightness information; And
And a digital-to-analog converter for changing an analog value under the control of the brightness controller to adjust a current value flowing through the light emitting device.

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