Compact Image Sensor Research Articles

マルチスリット光を用いたカラーテクスチャ取得可能な小型距離画像センサの構築

In this paper, developing of a compact range image sensor capable of obtaining color texture is presented. The sensor is designed for installing on a mobile robot. By using this sensor, the robot can sense the target or obstacle using the range image date. The color texture mapping on the 3D range image can help sense small obstacles between slits. The sensor is based on a range image sensor using a multi-slit laser projector. By adding a color camera to obtain the color image, the sensor can output range image with color texture in real-time. The measurement range is 380-720mm, the number of measurement points is about 4600, and the processing speed is about 12fps. The effectiveness of the sensor is verified by experiment.

Electrostatic focusing Spindt-type field emitter array for an image sensor with a high-gain avalanche rushing amorphous photoconductor target

A new electrostatic focusing Spindt-type field emitter array (FEA) was simulated and fabricated to develop a compact FEA image sensor with a high-gain avalanche rushing amorphous photoconductor target. Although the conventional double-gated FEAs can generate focused electron beams by applying a lower voltage to the focusing electrode (second gate) than that of the gate electrode, the emission current drastically decreases. These experimental results show that by increasing the thickness of the gate electrode the emission current can be improved without deterioration of the focusing characteristics.

Features Detection Based on a Variational Model in Sensornets

With the advent of CMOS cameras, it is now possible to make compact, cheap and low-power image sensors capable of on-board image processing. These embedded vision sensors provide a rich new sensing modality enabling new classes of wireless sensor networking applications. In order to build these applications, system designers need to overcome challenges associated with limited bandwith, limited power, group coordination and fusing of multiple camera views with various other sensory inputs. Real-time properties must be upheld if multiple vision sensors are to process data, communicate with each other and make a group decision before the measured environmental feature changes. The appearance of Wireless Multimedia Sensor Networks (WMSNs) requires a new generation technology of image processing for many applications. This paper presents a new approach to License Plate Localization(LPL) in WMSNs. We detect the license plate by a variational model that is embedded in several scalar functions. The motion of the dynamic interface is governed by nonlinear Partial Differential Equations(PDEs). Such variational models are flexible in handling complex environment and are concise in extracting plates boundaries despite of serious pollution. The cost of this method is moderate. The accuracy and efficiency of the proposed algorithm are illustrated by several numerical examples.

An X-ray Imaging System for Hard-to-Reach Facility Diagnosis Using Femtosecond Laser-Plasma

For hard-to-reach facility diagnosis, a radiographic testing system that consists of a compact laser-plasma X-ray (LPX) generator and a compact X-ray imaging sensor is shown to be competitive to that based on the isotope imaging. A 1-mm-thick CsI charge-coupled device (CCD) sensor supplied with a cooling system was developed to tolerate a long X-ray exposition. Even without optimization of X-ray yield from a Ta thin film irradiated by 230 mJ, 70 fs laser pulses, clear X-ray images of a SUS304 pipe (outer diameter 34 mm with 4.5 mm thickness) with an elbow were produced.

640 × 480 pixel active-matrix Spindt-type field emitter array image sensor with high-gain avalanche rushing amorphous photoconductor target

A 640×480 pixel field emitter array (FEA) image sensor with a high-gain avalanche rushing amorphous photoconductor (HARP) target was fabricated and tested as a step toward the development of ultrahigh-sensitivity compact image sensors for high-definition television cameras. For this sensor, an active-matrix Spindt-type FEA integrated with scanning circuits and a magnetic electron focusing system were designed, and a 15-μm-thick-HARP target was used. The experimental results revealed that the prototype sensor had enough resolution for its pixel number and high sensitivity due to the electrons emitted from the active-matrix FEA being focused onto the HARP target.

Enhanced output current density of an active-matrix high-efficiency electron emission device array with 13.75μmpixels

An active-matrix array of high-efficiency electron emission device (HEED) with a sufficient output density has been developed for the use as imaging probe in a high-gain avalanche rushing amorphous photoconductor target. Previously, it was demonstrated that a prototyped image sensor with 20×20μm2pixels could pick up a high definition image with an ultrahigh sensitivity under low-light-level condition. Based on it, an efficient active-matrix HEED with 13.75×13.75μm2pixels is fabricated for pursuing higher sensitivity and resolution. The improvement in the device isolation method enables to enlarge the relative emitting area, and then the emission current density per pixel reaches 3.6A∕cm2 that is about four times of that obtained from the previous one. The active-matrix HEED array with small pixels is available for application to the compact ultrahigh-sensitivity image sensor without affecting on the image definition.

Development of ultrahigh-sensitivity compact image sensor with field emitter array and avalanche photoconductor

Development of ultrahigh-sensitivity compact image sensor with field emitter array and avalanche photoconductor

Development of an Ultra-highly Sensitive Image Sensor with a Field Emitter Array and a HARP Film

A 640×480 pixel image sensor, which consisted of an integrated field emitter array (FEA) equipped with an active drive circuit and a high-gain avalanche rushing amorphous photoconductor (HARP) film, in close proximity to each other, was fabricated and tested as a step toward the development of ultrahigh-sensitivity compact image sensors. Our experimental results revealed that the prototype sensor provided both high sensitivity due to the avalanche multiplication effect of the HARP film and sufficient resolution as a VGA image sensor.

１インチ２５６×１９２画素アクティブ駆動型ＨＥＥＤ冷陰極ＨＡＲＰ撮像板

We made an active-matrix high-efficiency electron emission device (HEED) that had scanning driver circuits fabricated with conventional MOS planer technology.A 1-in 256x192 pixel image sensor,consisting of the active-matrix HEED and a high-gain avalanche rushing amorphous photoconductor (HARP) target,was fabricated and tested as a step toward the development of ultrahigh-sensitivity compact image sensors with a large number of pixels.The experimental results show that the prototype sensor can be used to obtain clear images even under dark lighting conditions,such as in moonlight,and that the active-matrix HEED is a promising highspeed image pick-up device.

50 × 50 μ m pixel magnetic focus field emitter array image sensor with high-gain avalanche rushing amorphous photoconductor target

A 50×50μm pixel field emitter array image sensor with a highly sensitive avalanche-mode photoconductive target and a scanning electron focusing system consisting of permanent magnets were fabricated and tested as a step toward the development of ultrahigh-sensitivity compact image sensors for high-definition television cameras. The experimental results revealed that the magnetic focusing conditions of the prototype sensor were in accordance with those estimated from the simulation, and the prototype sensor could obtain both enough resolution for its pixel size and high sensitivity by focusing the electrons emitted from the field emitter array onto the highly sensitive photoconductive target.

A 256 x 256 compact cmos image sensor with on-chip motion detection function

A 256×256 CMOS passive pixel image sensor with especially equipped simple switches, which enables motion detection, is implemented. Each pixel consists of a simple combination of a photodiode and an address switch. Photocharge generated at each pixel is converted to voltage by means of a column charge amplifier array, and motion detection has been realized with utilizing the photodiode as a frame memory. Its output is transformed to a digital value with a 128 array 8-bit analog-to-digital (A/D) converter. Simultaneously, fixed pattern noise is suppressed by utilizing A/D conversion as the CDS circuit. Due to its simple structure, more than 70% fill factor ratio has been realized. The extracted motion detection results can be displayed digitally at 128 frames per second by means of 128 A/D converter arrays.

Satellite Autonomous Navigation Based on Image Motion Analysis

A novel approach for autonomous navigation of satellites is presented. The proposed navigation concept uses robust image motion tracking for acquisition of navigational data and requires minimum a priori information. The system incorporates a single compact image sensor and a high speed optical image processing unit to provide real-time performances. With the possibility of determination of both position and attitude estimates this system could be a basis for full autonomous operation of a satellite. This can be of particular interest in context with missions to other planets: Mars, Europa, etc.