KR20210037388A - Nonuniformity immune riic with dual current copy structure - Google Patents

Abstract

One embodiment of the present invention relates to a signal input circuit with the improved current non-uniformity between pixels through a double-current radiation structure The signal input circuit comprises: an image signal input unit inputting an image signal corresponding to an infrared image; a current driving unit receiving the image signal from the image signal input unit and outputting a current with the improved non-uniformity for each pixel by acquiring a voltage in consideration of process variation and voltage drop through a double-current radiation structure; and an emitter unit receiving the current and outputting infrared rays.

Description

Signal input circuit with improved current non-uniformity between pixels through a dual current copy structure {NONUNIFORMITY IMMUNE RIIC WITH DUAL CURRENT COPY STRUCTURE}

The present invention relates to a signal input circuit in which current non-uniformity between pixels is improved through a dual current radiation structure.

The infrared imaging system is a device for detecting an object with heat and expressing it as an image, and has great use in various fields such as medical care, security, etc., mainly in the military field. In particular, it is an essential element in modern warfare that requires surveillance and reconnaissance and precision strike capability of distant objects.

In the development and maintenance stage of such an infrared imaging system, a field test environment must be established for accurate performance verification, but such a field test has disadvantages of being inefficient in terms of cost, time, and safety.

To solve this problem, a study on an infrared scene projector (IRSP) capable of hardware-in-the-loop simulation by converting electrical image data into a virtual infrared image and projecting it onto an infrared imaging system. And development is in progress.

Infrared image projectors can be classified according to the type of emitter that emits infrared rays.

The method of using a digital micro-mirror device (DMD) is a method of projecting an infrared image by reflecting incident infrared rays using a micro-mirror, and has a disadvantage in that high-speed operation is easy, but the manufacturing process is complicated.

The method of using an infrared light emitting diode (IRLED) is a method of emitting infrared by applying current to the infrared light emitting diode, which is advantageous for high-speed operation and high-temperature infrared image projection, but it is difficult to express sufficient temperature resolution in the low-temperature region There is this.

On the other hand, the infrared image projection method using a resistive emitter whose temperature changes through joule heating has a relatively simple operation principle, easy manufacturing process, and high performance in terms of operating speed and temperature expression. It is the most widely used method due to the advantage that can be secured.

The read-in integrated circuit (RIIC) for an infrared image projector using a resistive emitter applies current to each emitter constituting the array to generate Joule heating, and adjusts the magnitude of the emitter current. It is a device that controls to emit infrared rays corresponding to the temperature to be expressed. The gray level of the infrared image projected from the emitter array is expressed through a digital-to analog converter (DAC) that converts digital image data into an analog signal and outputs it.

The non-uniformity of the infrared image projected by the infrared image projector is mainly due to the non-uniformity of the emitter resistance value and the emitter current. For the projection of infrared images with high spatial uniformity, generally, after the entire infrared image projector system is built, the infrared radiance emitted in response to the image data is measured for all emitters on the array, and a look-up table is performed. table) and correcting the image data input to each unit pixel of the signal input circuit based on this, thereby correcting the non-uniformity of the projected infrared image.

In general, an infrared image projector is composed of a single signal input circuit and a collection of single pixels composed of an infrared emitter, and FIG. 1 is a diagram showing an infrared image projector in which the emitters are arranged in 3 rows and 3 columns.

Briefly explaining the operation of the infrared image projector, first, a current is applied to a resistor type emitter in a signal input circuit. The applied current causes Joule heating of the resistive emitter, increasing the emitter's physical temperature. In this case, as the resistance type emitter constituting each pixel emits infrared rays in proportion to its physical temperature, an infrared image may be implemented.

In particular, as increasingly precise infrared image implementation is required, there is an increasing demand for improvement of non-uniformity between single pixels constituting an array. Currently, a method of improving non-uniformity by constructing a look-up table for each pixel using an additional camera system is mainly used. However, in the case of such an existing non-uniformity improvement method, as the array size of the infrared image projector increases, not only the problem that more time is required to configure the look-up table, but also the high resolution at low temperatures is hindered. There is a problem.

The present invention relates to a signal input circuit in which the current non-uniformity between pixels is improved through a dual current radiation structure. The object of the present invention is to implement an infrared image with improved non-uniformity.

An embodiment of the present invention relates to a signal input circuit, comprising: an image signal input unit for inputting an image signal corresponding to an infrared image, and a process variation and voltage drop through a dual current copy structure by receiving the image signal from the image signal input unit. And a current driver for outputting a current with improved non-uniformity for each pixel by acquiring the voltage taking into account and an emitter part for receiving the current and outputting infrared rays.

In an embodiment, the current driver includes first to sixth switches, a first capacitor and a second capacitor, and a first transistor and a second transistor.

In an embodiment, the current driver comprises: the first switch connected between the image signal input part and the first transistor, the fourth switch connected between the image signal input part and the second transistor, and the second transistor. And the second and third switches connected between the gate electrode and the emitter part, and the fifth and sixth switches connected between the gate electrode and the emitter part of the second transistor.

In an embodiment, the current driver switches a first phase (phase I) and a second phase (phase II) through a dual current radiation structure by controlling a plurality of switches, and current data from the image signal input unit It is characterized in that the current is applied to the emitter unit using the data sampled in the previous step while storing the data.

In one embodiment, the current driver, in the case of the first phase (phase I), turns on the first switch, the second switch, and the sixth switch, and the fourth switch, the fifth switch, and It is characterized in that the third switch is turned off.

In an embodiment, in the case of the second phase (phase II), the current driver turns on the fourth switch, the fifth switch, and the third switch, and the first switch, the second switch, and It is characterized in that the sixth switch is turned off.

In an exemplary embodiment, the current driver controls the first to sixth switches to alternately store a voltage in consideration of a process shift and a voltage drop in the first capacitor and the second capacitor.

In one embodiment, the current driver stores image data through a dual current copy structure and simultaneously performs a snapshot operation of applying a current to the emitter.

In one embodiment, the video signal input unit is characterized in that the D/A converter (digital to analog converter) applies current to a plurality of current driving units.

The present invention relates to a signal input circuit in which current non-uniformity between pixels is improved through a dual current radiation structure. An infrared image with improved non-uniformity according to pixels may be implemented.

1 is a diagram showing an infrared image projector
2 is a diagram showing the configuration of a signal input circuit according to an embodiment of the present invention.
3 is a diagram illustrating a circuit diagram of a signal input circuit according to an embodiment of the present invention.
4 is a diagram illustrating a circuit diagram of an image signal input unit of a signal input circuit according to an exemplary embodiment of the present invention.
5 and 6 are reference diagrams for explaining an operation of alternately performing a first step (phase I) and a second step according to switch control of a signal input circuit according to an exemplary embodiment of the present invention.
7A is a diagram illustrating an equivalent circuit for a first phase I operation of a signal input circuit according to an embodiment of the present invention.
7B is a diagram illustrating an equivalent circuit for a second phase (phase II) operation of the signal input circuit according to an embodiment of the present invention.

Hereinafter, exemplary embodiments disclosed in the present specification will be described in detail with reference to the accompanying drawings, but identical or similar elements are denoted by the same reference numerals, and redundant descriptions thereof will be omitted. The suffixes "module" and "unit" for constituent elements used in the following description are given or used interchangeably in consideration of only the ease of preparation of the specification, and do not have meanings or roles that are distinguished from each other by themselves. In addition, in describing the embodiments disclosed in the present specification, when it is determined that a detailed description of related known technologies may obscure the subject matter of the embodiments disclosed in the present specification, the detailed description thereof will be omitted. In addition, the accompanying drawings are for easy understanding of the embodiments disclosed in the present specification, and the technical idea disclosed in the present specification is not limited by the accompanying drawings, and all changes included in the spirit and scope of the present invention It should be understood to include equivalents or substitutes.

Looking at the operation of a general infrared image projector, first, a current is applied to a resistor type emitter in a signal input circuit. The applied current causes Joule heating of the resistive emitter, increasing the emitter's physical temperature. In this case, as the resistance type emitter constituting each pixel emits infrared rays in proportion to its physical temperature, an infrared image may be implemented.

In particular, as increasingly precise infrared image implementation is required, there is an increasing demand for improvement of non-uniformity between single pixels constituting an array.

In the conventional infrared image projector, a method of improving non-uniformity by configuring a look-up table for each pixel using an additional camera system is mainly used. However, in the case of such an existing non-uniformity improvement method, as the array size of the infrared image projector increases, not only the problem that more time is required to configure the look-up table, but also the high resolution at low temperatures is hindered. There is a problem.

In order to solve this problem, the signal input circuit of the infrared image projector according to the present invention can improve current non-uniformity between pixels through a dual current radiation structure.

Hereinafter, a signal input circuit of an infrared image projector according to an embodiment of the present invention will be described with reference to the drawings. First, FIG. 1 is a diagram showing an infrared image projector. Specifically, it is a diagram showing the infrared image projector 100 of three rows and three columns consisting of a signal input circuit 110 and a resistor type emitter (120).

2 is a diagram showing the configuration of a signal input circuit according to an embodiment of the present invention. Referring to FIG. 2, the signal input circuit according to the present invention may include an image signal input unit 210, a current driver 220, and an emitter unit 230. The image signal input unit 210 may receive an image signal from a digital to analog converter (D/A) and apply the image signal to the current driver 220. The current driver 220 may include first to sixth switches, a first capacitor and a second capacitor, and a first transistor and a second transistor. Accordingly, the current driver 220 may output a current with improved non-uniformity between pixels by using a double current radiation structure. The emitter unit 230 may receive a current with improved non-uniformity between pixels, and may output infrared rays through Joule heating of a resistance type emitter.

Hereinafter, a signal input circuit according to an embodiment of the present invention will be described with reference to a circuit diagram. First, FIG. 3 is a diagram showing a circuit diagram of a signal input circuit according to an embodiment of the present invention. 4 is a diagram illustrating a circuit diagram of an image signal input unit of a signal input circuit according to an exemplary embodiment of the present invention.

Specifically, referring to FIG. 3, a signal input circuit according to an embodiment of the present invention may include an image signal input unit 310, a current driver 320, and an emitter unit 330. Here, referring to FIG. 4, the image signal input unit 410 includes a voltage output D/A converter 411, and converts the output voltage (V _DAC ) of the D/A converter 411 into a current (I _DATA ). It may include a seventh transistor 416 for. In addition, a third transistor 412 and a fourth transistor 413 for copying the corresponding current, and a fifth transistor 414 and a sixth transistor 415 for widening an operating voltage range may be included.

The current driver 320 includes a first switch S1 and a second switch S1 that are turned on/off according to the first transistor 322 and the second transistor 324 and the odd-numbered data sampling switch Φsamp_odd. S2), the fourth switch (S4) and the fifth switch (S5) turned on/off according to the even numbered data sampling switch (Φsamp_even) and the odd numbered frame load (Φload_odd) switch on/off. A third switch S3 turned on/off according to the sixth switch S6 and the even-numbered frame load Φload_even switch, and a first capacitor 323 and a second capacitor 325 may be included.

In this case, the first transistor 322, the first switch S1 to the third switch S3, and the first capacitor 323 form a current radiation structure 321. In addition, the current driver 320 has a dual current radiation structure including an independent current radiation structure composed of the second transistor 324, the fourth switch S4 to the sixth switch S6, and the second capacitor 325. According to this, a snapshot operation that outputs current while storing data is possible. In this case, in the snapshot method, which is one of the infrared image projection methods of the signal input circuit for the infrared image projector according to an embodiment of the present invention, after all unit pixel rows of the unit pixel array are sequentially selected by the unit pixel row selection circuit, This is a method in which the emitter units of all unit pixels existing on the unit pixel array simultaneously emit infrared rays. Conventional unit pixel circuits require a buffer for each pixel for a snapshot operation. However, this has a problem that may cause non-uniformity between pixels. Accordingly, in the unit pixel circuit according to the present invention, in order to improve this problem, it is possible to implement a snapshot driving without a buffer in the unit pixel.

Meanwhile, the transistor described in the signal input circuit according to the present invention may be composed of at least one of an N-channel MOSFET and a P-channel MOSFET.

In addition, the transistor described in the signal input circuit according to the present invention may include a first electrode (one side), a second electrode (the other side), and a gate electrode. The first electrode may be a source electrode and a drain electrode. The second electrode may be a drain electrode when the first electrode is a source electrode, and may be a source electrode when the first electrode is a drain electrode.

All of the first to sixth switches included in the current driver 320 are configured with a transmission gate made of an N-channel MOSFET and a P-channel MOSFET.

Here, the gate electrode of the first transistor 322 and the source electrode of the second switch S2 may be connected to each other. In addition, the drain electrode of the second switch S2 may be connected to the source electrode of the third switch and the source electrode of the first switch. The drain electrode of the first switch may be connected to the image signal input unit 310.

Here, the gate electrode of the second transistor 324 and the source electrode of the fifth switch S5 may be connected to each other. In addition, the drain electrode of the fifth switch S5 may be connected to the source electrode of the sixth switch and the source electrode of the fourth switch. The drain electrode of the fourth switch may be connected to the image signal input unit 310.

In addition, the drain electrode of the third switch and the drain electrode of the sixth switch may be connected to the emitter unit 330.

The emitter unit 330 emits infrared rays for each pixel unit, and may include a resistance type emitter 331. Specifically, one end of the emitter 331 is connected to the current driver 320 and the other end is connected to the emitter power supply end (EVDD).

Hereinafter, an operation of a signal input circuit capable of improving current non-uniformity according to the dual current radiation structure according to the present invention will be described in detail with reference to FIG. 5.

The image signal input unit 410 of the present invention is composed of the third to seventh transistors and converts the output voltage (V _dac ) from the D/A converter that receives n-bit image data as an input into a current to generate a plurality of currents. It is applied to the driving unit 320. _{In this case, the current I DAC} flowing through the third transistor 412 and the fifth transistor 414 is determined by the seventh transistor 416, and the corresponding current is as shown in Equation (1).

Here, β ₄₁₆ is determined by the carrier mobility of the seventh transistor 416, the gate oxide capacitance, and the gate size, V _S416 is the source voltage of the seventh transistor 416, _{and V th416 is the seventh transistor 416.} It means the threshold voltage. The current I _DAC is applied to the plurality of current drivers 320 using a current mirror structure including third to sixth transistors.

In this case, _{the size of the copied current I DATA} is determined by the size ratio of the third transistor 412 and the fourth transistor 413 and is equal to Equation 2.

Here, I _DATA means a current applied from the image signal input unit 310 to the plurality of current driving units 320. In addition, (W/L) ₄₁₃ and (W/L) ₄₁₂ denote the sizes of the fourth transistor 413 and the third transistor 412, respectively.

Meanwhile, the current driver 320 of the present invention controls the first to sixth switches to output current. That is, the current driver 320 of the present invention receives the current I _DATA from the image signal input unit 310 by controlling the first to sixth switches and alternately samples a voltage between the first capacitor and the second capacitor. It is characterized by outputting a current with improved current non-uniformity between pixels according to (sampling).

5 and 6, the operation of the current driver 320 of the present invention is largely divided into two stages, and the first switch S1, the second switch S2, and the sixth switch S6 are turned on. And the fourth switch (S4), the fifth switch (S5), and the third switch (S3) are turned off (phase I), the fourth switch (S4), the fifth switch (S5) And a second step (phase II) of turning on the third switch S3 and turning off the first switch S1, the second switch S2, and the sixth switch S6. .

During the first phase (phase I) operation, the first switch (S1), the second switch (S2), and the sixth switch (S6) are turned on, and the fourth switch (S4) and the fifth switch (S5) are turned on. ) And the third switch S3 are turned off. 7A shows an equivalent circuit for a first phase (phase I) operation. In the case of operating in the first phase (phase I), the first transistor 622 forms a diode connection as the second switch S2 is turned on, and the first switch S1 is turned on. A voltage V _{622,I corresponding to the current I DATA,I} applied from the image signal input unit 320 is sampled by the first capacitor 623.

Equation 3 represents the voltages V622 and I stored in the first capacitor 623 during a first phase operation. Here, β ₆₂₂ is determined by the carrier mobility of the first transistor 622, the gate oxide capacitance, and the gate size, V _th622 is the threshold voltage _{of the first transistor 622, and V S622} is the first transistor 622. It means the source voltage. At this time, β ₆₂₂ and V _th622 represent different values between pixels according to a process variation and V _S622 according to a voltage drop due to a large area. Therefore, it means that the voltage considering the process variation and voltage drop for each pixel is sampled through the diode connection.

During the second phase operation, the fourth switch S4, the fifth switch S5, and the third switch S3 are turned on, and the first switch S1 and the second switch S2 are turned on. ) And the sixth switch S6 are turned off. 7B shows an equivalent circuit for a second phase (phase II) operation. When operating in the second phase (phase II), as the third switch S3 is turned on and the drain terminal of the first transistor 622 and one end of the emitter 631 are connected, the current I _622,II ) is applied. During the second phase operation, the currents I _{631 and II} flowing through the emitter 631 are the same as the currents I622 and II flowing through the first transistor 622, which is the same as in Equation 4.

In addition, the first capacitor 623 maintains _{the voltages V 622 and I} sampled in the first phase I, which is the immediately preceding step. Therefore, in the second phase (phase II) operation, the gate node voltages V _{622 and II} of the first transistor are equal to Equation (5).

Therefore, in the second mode operation, the currents I _{631 and II} applied to the emitter unit 330 are equal to Equation 6 according to Equations 3 to 5.

_{According to Equation 6, the currents I 631 and II} applied from the current driver 320 to the emitter 631 are the source voltage V _s622 of the first transistor 622 and the process variable of the first transistor ( β ₆₂₂ ), so it is possible to apply a current to the emitter unit 630 with improved non-uniformity between pixels.

On the other hand, the second transistor 624 forms a diode connection as the fourth switch S4 and the fifth switch S5 are turned on, and the current applied from the image signal input unit 620 (I _{DATA, II} ) The voltages V _{624 and II} corresponding to are sampled to the second capacitor 625. _{Accordingly, the voltages V 624 and II} stored in the second capacitor 625 during the second phase operation are as shown in Equation 7.

_{Here, the voltages V 624 and II} stored in the second capacitor 625 include the process variable β ₆₂₄ and the source voltage V _s624 of the second transistor 624. According to the switch operation, the signal input circuit according to the present invention alternately goes through a first phase (phase I) and a second phase (phase II), and the gate voltage (V) of the second transistor stored in the second phase (phase II) _{624 and II} ) are applied to the emitter unit 330 through the second transistor 624 as the sixth switch S6 is turned on immediately after phase I.

Accordingly, the current driver 320 of the present invention stores the current data from the image signal input unit 310 by alternately passing through the first phase (phase I) and the second phase (phase II) through a dual current radiation structure. At the same time, a snapshot operation is possible by applying a current to the emitter unit 330 using data sampled in the previous step.

As described above, the signal input circuit according to the present invention has a current radiation structure (or a second transistor 324) composed of a first transistor 322, a first capacitor 323, and a first switch (S1) to a third switch (S3). ), a second capacitor 325, and a current radiation structure composed of a fourth switch (S4) to a sixth switch (S6)) and a voltage drop due to process variation and large area through the control of the switch. Drop) has the advantage of improving the non-uniformity by position of the pixel by acquiring the voltage taken into account.

In addition, the signal input circuit according to an embodiment of the present invention may store data through a dual current copy structure and perform a snapshot operation of applying a current to the emitter at the same time.

The present invention described above can be implemented as a computer-readable code on a medium on which a program is recorded. The computer-readable medium includes all types of recording devices that store data that can be read by a computer system. Examples of computer-readable media include hard disk drives (HDDs), solid state disks (SSDs), silicon disk drives (SDDs), ROMs, RAM, CD-ROMs, magnetic tapes, floppy disks, optical data storage devices, etc. There is also a carrier wave (for example, transmission over the Internet) also includes the implementation of the form.

In addition, the computer may include a control module of the terminal. Therefore, the detailed description above should not be construed as restrictive in all respects and should be considered as illustrative. The scope of the present invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the present invention are included in the scope of the present invention.

100: infrared image projector
110: signal input circuit
120: Resistive type emitter
210, 310: video signal input unit
220, 320: current driver
230, 330: emitter part

Claims (9)

An image signal input unit for inputting an image signal corresponding to an infrared image;
A current driver for receiving the image signal from the image signal input unit and outputting a current with improved pixel-to-pixel non-uniformity by obtaining a voltage in consideration of a process variation and a voltage drop through a dual current radiation structure; And
Signal input circuit comprising; an emitter unit for receiving the current and outputting infrared rays. The method of claim 1,
The current driver,
First to sixth switches;
A first capacitor and a second capacitor; And
A signal input circuit comprising a first transistor and a second transistor. The method of claim 2,
The current driver,
The first switch connected between the image signal input unit and the first transistor;
The fourth switch connected between the image signal input unit and the second transistor; The second and third switches connected between the gate electrode of the second transistor and the emitter unit; And the fifth switch and sixth switch connected between the gate electrode of the second transistor and the emitter unit. The method of claim 2,
The current driver,
Switching the first phase (phase I) and the second phase (phase II) through a dual current radiation structure by controlling a plurality of switches,
A signal input circuit, characterized in that, while storing current data from the video signal input unit, current is applied to the emitter unit using data sampled in a previous step. The method of claim 4,
The current driver,
In the case of the first phase (phase I), the first switch, the second switch, and the sixth switch are turned on, and the fourth switch, the fifth switch, and the third switch are turned off. Signal input circuit. The method of claim 4,
The current driver,
In the case of the second phase (phase II), the fourth switch, the fifth switch, and the third switch are turned on, and the first switch, the second switch, and the sixth switch are turned off. Signal input circuit. The method of claim 4,
The current driver,
A signal input circuit, characterized in that the first to sixth switches are controlled to alternately store voltages for which process variations and voltage drops are taken into account in the first capacitor and the second capacitor. The method of claim 7,
The current driver,
A signal input circuit, characterized in that it performs a snapshot operation of applying current to the emitter while storing image data through a dual current copy structure. The method of claim 1,
The video signal input unit,
A signal input circuit, characterized in that current is applied to the plurality of current drivers from a digital to analog converter.

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