Nobuyuki Yoshiike

Electrochemical Properties of WO 3 · x ( H 2 O ) I . The Influences of Water Adsorption and Hydroxylation

Electrochemcial properties of evaporated amorphous films on conductive glass substrates have been studied in organic electrolytes in order to clarify the influence of water in the films on electrochromism. Compositions of water in the film have been analyzed by using FT‐IR spectra and 1H‐NMR. We conclude that the water adsorbed in the film during the evaporation and from ambient air not only leads to a fast electrochromic reaction at first, but also reacts gradually with by hydroxylation and/or hydrolysis to shift the potential of the cathodic reaction to the negative side and that the hydroxylated film layer loses the electrochromic coloration density.

High performance human information sensor

Abstract High performance human information sensing system, which can monitor the human conditions in a room, especially the number of occupants, their locations and activities, has been developed. The sensor head module of this sensing system consists of a vertical one-dimensional 16-element array detector fabricated by sheet forming method of pyroelectric PbTiO 3 ceramics, an IR-transparent spherical lens, a horizontal scanning mechanical part and a cylindrical mechanical chopping part. The IR lens characteristics have been determined to optimize the sensor output. The sensor is able to detect a two-dimensional thermal distribution (16×60) and the human condition information in a room. The sensor is cost-effective and the sensor head module is small (64 mm in diameter and 79 mm in height) with high resolution. Furthermore, nine times higher resolution with 48×180 thermal distribution was accomplished by the neighbor output averaging scheme. By using this sensing system with high sensitivity and high resolution, the small thermal object such as a lighted cigarette as well as the number of persons in a room can be detected accurately.

Development of people-counting system with human-information sensor using multi-element pyroelectric infrared array detector

Abstract A people-counting system with a human-information sensor which can be used for detecting the number of people passing a door and their directions of movement has been developed. The sensor head module of this sensing system consists of a one-dimensional eight-element array detector made from pyroelectric PbTiO3 ceramics, an IR-transparent spherical lens and a cylindrical mechanical chopping part. This compact sensor is set at the top of the door with the element array parallel to the movement direction of the passersby. The electrode size of the detector and the lens characteristics have been determined to optimize the sensing area. The movement directions and the number of continuously passing people can be obtained promptly based on digital output from the signal-processing circuits. The data are processed in real time by a new algorithm: (1) background sequential mean method; (2) ternarizing method with two threshold values above and below the mean value; (3) differential detecting method; (4) compensation method. By using this people-counting system, the number of passersby at a door can be detected with more than 98% accuracy. In the case of a 2 m wide door, the multisensor system using human-information sensors can be adopted.

Human information sensor

Abstract A high-performance human information sensor, which can be used for detecting the number of occupants of a room and their locations, has been developed. The sensor head module consists of an IR (infrared) sensor, a four-channel distance sensor and a horizontal scanning mechanism. A two-dimensional thermal distribution is obtained by horizontal scanning of a vertical one-dimensional pyroelectric array detector. Spatial information on new objects is recognized by the difference between the measured two-dimensional distance distribution and the initial two-dimensional distance distribution. The number of occupants and their locations are recognized accurately from the overlapping parts of the thermal distribution and the spatial information on the new objects.

People-counting system using multisensing application

Abstract A people-counting system with human information sensors using multisensing application, which can be used for detecting the number of people passing a wide door and their movement directions, has been developed. The sensor head module of this sensing system consists of one-dimensional eight-element array detectors fabricated by the sheet-forming method using pyroelectric PbTiO 3 ceramics, an IR-transparent spherical lens and oscillating mechanical chopping parts. This sensor head module is set at the top of the wide door with the element arrays parallel to the movement directions of the passersby. The movement directions and the number of continuously and/or simultaneously passing people can be obtained promptly based on digital output from the signal-processing circuits. The sensor output is processed in real time to be normalized and binarized by using the background mean method, and the number of passing people and their directions of movement are recognized by a pattern-recognition algorithm. By using this people-counting system using multisensing application, the number of people passing by a 200 cm wide door can be detected with more than 95% accuracy.

360° direction type human information sensor

Abstract The 360° direction type human information sensor has been developed using a pyroelectric infrared detector. This sensor attached to the ceiling can detect the number of occupants, their locations and movements. The sensor module consists of a one-dimensional array detector made of pyroelectric ceramics (PbTiO3), an infrared transparent lens, a 360° rotary scanning mechanism and a 3° chopping mechanism. Data on human conditions can be computed from the thermal distribution by the human detecting algorithm. The pyroelectric array detector fabricated by a new process has sufficient sensitivity for 20 Hz chopping frequency. The array detector rotating mechanism allows the sensor to have a wide view (10 m diameter). With the human detecting algorithm, data on humans such as the number of occupants and their locations can be detected with 73% accuracy in 389 samples (97% accuracy in case of allowing ±1 person). Human information obtained by this sensor can contribute to energy saving when applied to the control of air conditioners and lighting systems.

Ozone sensor made by dip coating method

Abstract We have developed an ozone sensor with an ITO (Sn-doped indium oxide) thin film made by dip-coating method. The film with 3 mol.% Sn at 360°C showed excellent characteristics of ozone gas detection below 1 ppm. For intermittent exposure to ozone gas, the response time was shorter and the sensitivity gradually increased. It was clear that the ozone sensor needed annealing or aging to repress the change of the sensitivity. For an application of the ozone sensor, an air purifier with the ozone sensor after aging at 20°C in 60% RH for 250 h showed a good control ability of the residual ozone concentration, a little influence of relative humidity and ambient gases. It is supposed that the sensor is useful for the air purifier to be practical.

Characteristics of Pyroelectric Infrared Array Detector Made of PbTiO3 Ceramics

A one-dimensional pyroelectric array detector as a multi-element infrared sensor has been developed by using a new sheet forming method made of PbTiO3 bulk ceramics. This simple fabrication process is cost effective and enables us to control the film thickness accurately, thus decreasing the sensitivity variations that exist in one detector and among different detectors to within 10%. A pyroelectric detector responsivity of 2×104 V/W can be obtained at 10 Hz chopping frequency. A specific detectivity D* of 0.8×108 cm Hz1/2/W has been achieved. Furthermore, this detector has a sufficient sensitivity for performances at high chopping speeds up to 100 Hz. The time constant of this pyroelectric detector is about 8.6 ms, so the detector has a shorter response time compared with the commercially available conventional pyroelectric detector. The cross talk, which influences the output for the adjacent elements, is less than 10%. By using this high performance pyroelectric array detector, the thermal sources at lower temperatures than environmental conditions can be detected with high sensitivity, as much as the thermal sources at higher temperatures. The output voltage for the detector was gradually decreased as the atmospheric temperature increased.

Development of One-Dimensional Pyroelectric Infrared Array Detector with High Sensitivity

A one-dimensional pyroelectric array detector for use as a multielement infrared sensor has been developed by using PbTiO3 bulk ceramics fabricated by a sheet-forming method. This one-dimensional infrared sensor consists of 16 elements. A pyroelectric detector responsivity of 3×104 V/W can be obtained at a 10 Hz chopping frequency, and a specific detectivity D* of 1.2×108 cmHz1/2/W has been achieved. The time constant of this pyroelectric detector is about 5.2 ms, so the detector has a shorter response time compared with a commercially available conventional pyroelectric detector. The crosstalk, which influences the output for the adjacent elements, is less than 10%. The output voltage for the detector gradually decreased as the atmospheric temperature increased. Pyroelectric detector responsivity increases with decreasing electrode size. By using this high-performance pyroelectric array detector, the thermal sources at lower temperatures than that of the environment can be detected with high sensitivity, as much as in the case of the thermal sources at higher temperatures.

Effects of Pores in Thick Film Resistor Elements on the Printing Efficiency of a Thermal Head

An effect of the distribution of vacant pores in RuO 2 heating resistor elements on the printing characteristics of a thick film thermal printing head was examined. The head had an RuO 2 -glass heating resistor element which had some vacant pores attributed to gas evolution during the manufacturing process. The distribution of the vacant pores in each heating element was observed and quantitatively analyzed by an image processing technique using photomicrographs of the elements in correlation with the printing efficiency. The vertical distribution of the pores in the heating resistor elements significantly affected the printing characteristic. A poor thermal conductivity of vacant pores prevented heat conduction to a heat-sensitive paper and to a substrate, resulting in lower and higher efficiency for thermal printing, respectively.