A solventless addition-curable pressure sensitive silicone adhesive composition is provided. The composition comprises (A) an alkenyl group-containing polydiorganosiloxane; (B) a condensation product of (a) a polydiorganosiloxane having hydroxyl group or an alkoxy group on opposite ends of the molecular chain and (b) a polyorganosiloxane containing R13SiO1/2 unit and SiO2 unit as critical components and also a HOSiO3/2 unit in the molecule; (C1) a polyorganohydrosiloxane having at least three SiH groups per molecule; (C2) a polydiorganohydrosiloxane having SiH group on opposite ends; and (D) a platinum group metal catalyst. Use of the present composition enables production of a pressure sensitive adhesive agent having flexibility, pressure sensitive adhesiveness, and heat resistance, and the present composition is particularly effective for use as a buffer member having pressure sensitive adhesiveness.

Pressure sensitive adhesive tapes and labels prepared by using a pressure sensitive silicone adhesive have been used under severe conditions where organic adhesives such as acrylic adhesives and rubber adhesives would be denatured and deteriorated since the layer of the pressure sensitive silicone adhesive has excellent heat resistance, cold resistance, weatherability, electric insulation, and chemical resistance. In addition, pressure sensitive silicone adhesives exhibit good adhesion to various substrates, and therefore, they are used for adhesion onto a substrate such as polyolefin resin, silicone resin, fluororesin, or a water-bearing surface which could not be adhered by organic pressure sensitive adhesives such as acrylic resin or rubber adhesion.
For example, adhesive tapes prepared by using a pressure sensitive silicone adhesive are used in the production, processing, and assembly of electronic and electric components. When heat is applied in such production process, entire or partial protection, re-masking, or temporary fixing of the electronic and electric components is often required. In the case of a pressure sensitive adhesive tape used for such application or the tape used in the production, fixture, or bundling of electronic and electric components exposed to a high temperature condition, preferred is the use of pressure sensitive adhesive tapes prepared by using a pressure sensitive silicone adhesive which retain their heat resistance even after heating to a temperature in excess of 250° C. In such applications, the pressure sensitive silicone adhesive is used as a pressure sensitive silicone adhesive tape prepared by coating a plastic film substrate with such adhesive to a thickness of several dozen μm.
In the recent production of electronic and electric equipment such as mobile phone, a pressure sensitive adhesive tape is quite often used as a means for fixing the parts since such use enables production of a thinner equipment with reduced weight. In such equipment, a shock-absorbing or stress-relaxing buffer member in the form of a sheet having a thickness of 0.1 to several mm is often incorporated for the purpose of preventing damage of the equipment or the interior parts by falling, pressing, or vibration, and such member is often fixed by using a double sided pressure sensitive adhesive tape or sheet. Such case, however, requires additional step of adhering the buffer member by using a pressure sensitive adhesive tape or sheet or additional preliminary multi-step preparation of a laminate comprising a film substrate having the buffer member layer on one surface and a pressure sensitive adhesive layer on the other side, and the assembly and processing often became complicated. Accordingly, there has been a demand for a buffer member having an adhesiveness that would enable the adhesion of member itself to various parts or casing.
Adhesion of members each having a size of several cm or more using a conventional pressure sensitive silicone adhesive was also associated with the problem of difference in the degree of expansion between the members due to the different expansion coefficient. More specifically, expansion and shrinkage of the members by repetitive temperature change resulted in the strain or deformation of the members as well as interfacial peeling between the member and the pressure sensitive adhesive. Conventional pressure sensitive silicone adhesives had been insufficient for use as a pressure sensitive adhesive member having the buffering property capable of absorbing such change.
In addition, conventional pressure sensitive silicone adhesives are mostly solvent type adhesives which suffer from foaming during the thermal curing when coated and cured or molded to a thickness of 0.1 mm or more. Accordingly, use of a solventless pressure sensitive silicone adhesive is preferable for such application.
Another type of materials used for the shock-absorbing and stress-relaxing member are soft gel materials comprising resins such as urethane resin and acrylic resin. However, gel materials generally suffer from insufficient heat resistance, and yellowing occurred even at a temperature as low as 100° C. Accordingly, these materials could not be used for an optical material. These materials also suffered from insufficient flexibility at low temperature as well as insufficient adhesiveness at high temperature. As described above, there has so far been no material fulfilling the requirement as described above.
Exemplary heat resistant gel materials include silicone gels, and silicone gels exhibiting the pressure sensitive adhesion are disclosed, for example, in JP-A 2007-126576. However, these silicone gels are insufficient in the adhesion to the substrate, and they may be peeled when an exterior force is applied. The silicone gels are also insufficient in the coherence, and the gel may undergo cohesive failure in the reworking such re-attaching of the gel, and the gel often remained on the substrate.
Conventional pressure sensitive silicone adhesives can be produced in a sheet-form product with sufficient pressure sensitive adhesiveness by coating on a plastic substrate or the like. Such products, however, were insufficient in the flexibility, and this prevented their use for a buffer member. In addition, when such product was adhered to an article with surface irregularities, the surface of the pressure sensitive adhesive layer could not fully fit the surface irregularities, and the remaining air gaps often prevented the pressure sensitive adhesive layer from fully adhering to the article surface.
A silicone composition for an addition curable pressure sensitive adhesive containing a mixture of a polyorganosiloxane having an alkenyl group and a polyorganosiloxane having no alkenyl group, a polyorganosiloxane having R3SiO0.5 unit and SiO2 unit, and a polyorganosiloxane containing SiH group is disclosed in JP-A 2008-24777. While this composition is described to exhibit strong adhesion to silicone rubbers, this composition which is a solvent-type composition was inferior in the flexibility and had little buffering function.
In addition, an addition curable pressure sensitive silicone adhesive composition containing a component prepared by partial condensation of (A) a raw rubber-like diorganopolysiloxane having hydroxyl group bonded to the silicon atom but no alkenyl group, (B) a raw rubber-like diorganopolysiloxane having an alkenyl group, (C) a polyorganosiloxane comprising R3SiO1/2 unit and SiO2 unit and containing at least 1.8% by weight of hydroxyl group bonded to the silicon atom, and (D) a polyorganosiloxane comprising R3SiO1/2 unit and SiO2 unit containing less than 1.8% by weight of hydroxyl group bonded to the silicon atom; and an organopolysiloxane having hydrogen atom bonded to the silicon atom is disclosed in JP-A 2004-231900. While this composition is said to exhibit a high pressure sensitive adhesion and a low tack, this composition which is a solvent-type composition was also inferior in the flexibility and had little buffering function. Furthermore, this composition had a drawback that, when one side of the sheet was several cm or more and the area was several dozen cm2 or more and the adhesion was beyond certain level, the adhered sheet could not be peeled off for reworking that is sometimes required to correct the erroneous positioning.
Another solventless pressure sensitive silicone adhesive disclosed is disclosed in JP-A 2008-274251. This composition comprises an alkenyl group-containing polydiorganosiloxane, a polyorganohydrosiloxane having 3 SiH groups, a polydiorganosiloxane having a low degree of polymerization having an alkenyl group at opposite ends, a polydiorganosiloxane having a low degree of polymerization having a SiH group at opposite ends, a polyorganosiloxane comprising R3SiO1/2 unit and SiO2 unit, and a platinum based catalyst. This composition exhibited high re-peelability and adequate pressure sensitive adhesion, and since the composition is solventless, it could be coated into a thick film. However, the resulting film was insufficient in the flexibility and buffering function.
The solventless pressure sensitive silicone adhesive disclosed in JP-A 2006-160923 was also insufficient in the flexibility and buffering function.
Another solventless or low solvent-type pressure sensitive silicone adhesive is disclosed in JP-A 2004-506778. This low solvent-type pressure sensitive silicone adhesive contains an alkenyl-terminated polydiorganosiloxane, a silanol-terminated polydiorganosiloxane, a resin copolymer containing R3SiO1/2 unit and SiO2 unit, an organohydrogen polysiloxane, a hydrosilylation catalyst, and an organic peroxide or an organic azo compound. This composition exhibits high pressure sensitive adhesion and tack, and the substrate may become deformed or damaged in the reworking or reattachment. The composition also suffered from the problem of foaming when the cured product was used at a high temperature or in the vacuum because of the decomposition residue remaining in the cured product due to the organic peroxide or organic azo compound used for the curing.
Another solventless pressure sensitive silicone adhesive is disclosed in JP-A 2006-520838. This adhesive is a solventless pressure sensitive silicone adhesive which contains an organic siloxane polymer having an aliphatic unsaturated group, a resin having R3SiO1/2 unit and SiO2 unit, a reactive diluter agent, an SiH-containing crosslinking agent, a hydrosilylation catalyst, and an inhibitor. This composition is also insufficient in the flexibility and buffering function. This adhesive also suffered from the problem caused by the use of a reactive diluent such as an alkene having a terminal double bond. More specifically, bubbles often remained in the cured product due to the foaming during the curing of the thick film, and when the diluent remained unreacted in the adhesive, the cured product suffered from foaming in the use of the cured thick film at a high temperature or in the vacuum.

Solventless addition-curable pressure sensitive silicone adhesive composition and adhesive article


In a contact member, a mesh-like contact including one or more layers of a metal other than a noble metal is embedded in such a manner as to be exposed from one of the surfaces of a rubbery elastic body. The contact member includes a highly conductive metal coat layer only in the regions of the mesh-like contact which are exposed from the rubbery elastic body, the coat layer having conductivity higher than that of the metal on the outermost surfaces of the mesh-like contact.

In relation to push-button switch members, as a contact member that can elastically move into contact with and move apart from a contact on a circuit board, there is conventionally known a contact member in which a thin metal plate or a plated metal plate is affixed to a silicone rubber. As contact members of other forms, there are also conventionally known a contact member in which holes are opened in a thin metal plate, a contact member in which a wire mesh is affixed to a silicone rubber, and a contact member in which the wire mesh is covered with a different type of metal (refer to Patent Literatures 1 to 4).
FIG. 10A to 10D illustrate plan views and cross-sectional views (10A, 10B, 10C, 10D) of conventionally known contact members. A contact member 50 illustrated in FIG. 10A has a configuration where a metal plate 52 made of nickel, SUS or the like is affixed to one surface of a disc-shaped silicone rubber 51, as illustrated in a cross-sectional view taken along a line P-P. A contact member 60 illustrated in FIG. 10B has a configuration where a metal plate 62 made of nickel, SUS or the like is affixed to one surface of a disc-shaped silicone rubber 61, and a coat layer 63 of gold or the like is provided on a surface of the metal plate 62, as illustrated in a cross-sectional view taken along a line Q-Q. A contact member 70 illustrated in FIG. 10C has a configuration where a mesh (wire mesh) 72 of a metal such as nickel, SUS or the like is affixed to one surface of a disc-shaped silicone rubber 71, as illustrated in a cross-sectional view taken along a line R-R. A contact member 80 illustrated in FIG. 10D has a configuration where a wire mesh 82 coated with gold or the like in advance is affixed to one surface of a disc-shaped silicone rubber 81, as illustrated in a cross-sectional view taken along a line S-S. A coat layer 83 covers almost the whole surface of the wire mesh 82.
The contact members 50, 60 illustrated in FIGS. 10A and 10B, respectively, have a low resistance and a superior electrical conductance. In the contact members 50, 60, however, a surface brought into contact with a contact on a circuit board is flat, resulting in a problem in that the contact between the surface and the contact on the circuit board is easily affected by foreign matters interposed therebetween. To solve this problem, as with the contact members 70, 80 illustrated in FIGS. 10C and 10D, an approach is adopted in which a surface brought into contact with a contact on a circuit board is made up of a wire mesh like the wire meshes 72, 82 to form an irregular surface that can still come into contact with the contact on the circuit board even though foreign matters are interposed therebetween. Additionally, there is also known an approach where a metal plate including holes is used in place of the wire mesh like the wire meshes 72, 82.

Contact member, contact member production method, and push-button switch member equipped with contact member


A displacement armature motor is formed such that the deformation element allows a larger axial shifting and displacement path of the displacement armature while requiring a lower construction precision. The deformation element includes two frames (17, 17a). The frame (17a) is connected via two of its corner attachment positions (17b) to an attachment plate (19). The attachment plate (19) is connected to an extension (31) of the displacement armature. The frame (17) is connected with two of its attachment positions to the carrier arms (15a) of the support ring (15). The two frames (17, 17a) are connected to each other with their respective remaining corner attachment positions (17c) via a transfer element (18).

1. Field of the Invention
The invention relates to a displacement-type armature motor comprising a stator and a displacement armature slidable in axial direction relative to the stator against the force of a brake spring, where the displacement armature is connected to a shaft, wherein the shaft is supported in the end shields of a motor casing.
2. Brief Description of the Background of the Invention Including Prior Art
In the context of a displacement-type armature motor of the recited kind and such as, for example, described in German Patent DE-PS 3,637,591, there is furnished a frame-shaped deformation element, which can be composed of individual rods. This single frame of the deformation element limits the shiftability of the shaft in axial direction and requires a very high degree of precision, since the deformation element behaves rigidly against deformation in radial directions and acts as a third bearing support of the displacement armature.

Brake coupler for displacement-type armature motor


A writing devices for an image forming apparatus of the present invention determines whether or not an image at and around an interval between nearby light emitter chips of a light emitter array is of halftone. If the image is of halftone, the writing device corrects image data corresponding to the above interval in order to increase the quantity of light. This successfully reduces or fully obviates the local omission of an image ascribable to intervals between nearby light emitter chips and insures a smooth output image.

1. Field of the Invention
The present invention relates to a digital copier, printer, facsimile apparatus or similar image forming apparatus and, more particularly, to a writing device for use in an image forming apparatus for electrostatically forming a latent image on an image carrier with a light emitter array.
2. Discussion of the Background
A writing device using a light emitter array, particularly an LED (Light Emitting Diode) array, is extensively used in an image forming apparatus in order to reduce the overall size of the apparatus. In an image forming apparatus including the LED array, a photoconductive element in the form of a belt or a drum has its surface uniformly charged by a charger while in rotation. The LED array exposes the charged surface of the photoconductive element imagewise so as to electrostatically form a latent image thereon. After the latent image has been transformed to a corresponding toner image by a developing device, the toner image is transferred to a paper or similar recording medium. The LED array constituting the writing device has a plurality of e.g., seventy-eight LED chips arranged in an array and each having a plurality of, e.g., sixty-four LEDs or light emitters corresponding pixels. The number of LEDs of each LED chip is selected in accordance with a desired resolution.
Japanese Patent Laid-Open Publication Nos. 4-326854 and 4-326855 each discloses a bilevel image forming apparatus capable of reproducing desirable halftone images. The apparatus reduces a dot diameter for an image in which the distance between nearby dots is small, thereby preventing the image from being defaced. For an image in which the above distance is great, the apparatus increases the dot diameter in order to output a thick clear-cut image.
Specifically, the apparatuses taught in the above two documents both pertain to a bilevel image forming apparatus capable of rendering a halftone image by referencing observed pixel data and a plurality of pixel data surrounding the observed pixel on the same line, and variably adjusting the actual dot size for the observed pixel on the basis of the condition of such image data. The apparatus of Laid-Open Publication No. 4-326854 includes distance detecting means for determining distances between the observed pixel data and a print pit included in the surrounding data, and dot size control means for variably controlling the actual dot size of the observed image data on the basis of the above distance. On the other hand, the apparatus of Laid-Open Publication No. 4-326855 includes transition point detecting means for detecting transition points of the observed image data and surrounding image data from a print pit to a non-print pit or from a non-print pit to a print pit, counting means for counting the transition points, and dot size control means for variably controlling the actual dot size of the observed image data on the basis of the number of transition points.
Japanese Patent Laid-Open Publication No. 5-176131 discloses a scanning type image forming apparatus capable of preventing observed black data from being shifted and thereby implementing a dot diameter close to a theoretical single pixel. Specifically, the scanning type image forming apparatus includes an analog image signal generating section for generating an analog image signal. An analog-to-digital converting section transforms the analog image signal to a digital image signal. A bilevel processing section binarizes the digital image signal by use of a preselected reference level to thereby output a bilevel image signal. The reference level is output from a reference level generating section. The data of the binary image signal are written to a pixel data memory. A laser ON/OFF signal generator generates a laser ON/OFF signal for selectively turning on or turning off a laser. A laser signal modulating section modulates the laser ON/OFF signal with the bilevel image signal stored in the memory. A laser power switching signal generating section switches laser power for pixels around an observed pixel in order to adjust the density of the observed pixel. A laser power generating section causes the laser to emit in accordance with the output of the laser signal modulating section and laser power switching signal. A laser scanning section causes a laser beam to scan a photoconductive element so as to expose the element imagewise.
A problem with the conventional image forming apparatus or image recording apparatus is that when a photograph or similar halftone image is output, the image appears as if it were slightly lost in places. This is ascribable to some error in the distance between nearby LED chips although the LEDs of each LED chip are regularly arranged to implement a desired resolution. The resulting image therefore appears as if it were lost at the intervals between nearby LED chips. This occurrence is particularly true with a halftone image, as follows. In the case of a high density image, a light beam issuing from the individual LED has a great diameter. As a result, dots formed by the LEDs on the image carrier tend to overlap each other, rendering the local omission of the image inconspicuous. However, in the case of a low density image, the beam issuing from the individual LED has a small diameter with the result that the local omission ascribable to an error in the distance between the LED chips is conspicuous.
The local omission of an image will be obviated if the image data of the pixels corresponding to the interval between nearby LED chips are increased by a preselected amount or converted to a density rendering the local omission inconspicuous. However, if such image data are simply corrected, even the image data representative of white will be corrected and will thereby form thin vertical lines on a white background. In addition, even image data sufficiently high in density and not needing correction will be corrected.

Writing device for an image forming apparatus


A grader drum has fixed grader bars which extend between two annular end plates. Rotatable grader bars extend between the end plates between each pair of fixed bars. A generally frustoconical cam is movable axially with respect to the drum. A cam follower with a roller which engages against the cam is connected to each rotatable grader bar. A looped elastic belt encircles the cam followers and engages with radially outwardly facing grooves on the cam follower arms to retain the cam followers in engagement with the cam as the cam is displaced axially to adjust the spacing between the fixed and rotatable grader bars.

In the food processing industry it is often desirable to separate agricultural products into a number of grades based on the size of the product. Grading is often necessary to comply with regulatory or customer demands for general uniformity in product size. Furthermore, a premium price may be obtainable for agricultural products of a desired size. Smaller beans, for example, command a higher price than larger ones by weight.
One known grading apparatus utilizes an inclined rotatable drum having a cylindrical wall comprised of alternating fixed and rotatable bars. Each rotatable bar has a width which is greater than its height such that spacing between each rotatable bar and The two adjacent fixed bars may be adjusted by rotation of the bar. To obtain uniform grading it is important that the spacing between all rotatable bars and the fixed bars be constant at a desired setting. In this known apparatus spacing is controlled by a frustoconical cam which bears against cam following rollers which are attached to each rotatable grader bar at the grader inlet. This cam has a recessed portion at the top of the drum travel which causes the grader bars to open to their wider spacing to release food product which has become trapped between grader bars. In order to retain the grader bar cam followers engaged against the cam each individual cam follower is provided with a coil spring which extends between the cam follower arm and the drum end plate.
As a typical grader may employ 30-50 rotatable grader bars and rollers, a great number of coil springs are required. Furthermore, the constant flexing to which the springs are subjected will result in eventual spring failure. The failure of one spring may not be immediately obvious to the grader operator yet will result in the improper grading of the processed food product.
What is needed is a grader for agricultural products having cam followers which are consistently engaged against the cam, which employs a minimum of parts, and which provides immediate visual indication of failure.


An intruding object detecting method and an intruding object detecting apparatus for judging whether an detected object is an intruding object or not even in the condition that there are shadows of moving objects other than target objects to be detected, such as shaking trees, leaves thereof, etc. An image signal is supplied from an image pickup device; a moving object is extracted from the image signal by a subtraction method; division is made between the image signal and a reference background image signal for every pixel so as to produce a ratio image; a histogram of luminance values (pixel values) is calculated on a part of the ratio image corresponding to the moving object extracted in the extracting step; a pixel value on the part of the ratio image corresponding to the extracted moving object is calculated in ratio representation from the calculated histogram; the calculated pixel value in ratio representation is estimated; and the extracted moving object is judged to be an intruding object or not, on the basis of the estimation of the pixel value in ratio representation. Thus, intruding objects are detected in the field of view to be monitored.

The present invention relates to a monitoring apparatus using an image pickup apparatus, and particularly relates to an intruding object detecting method and an intruding object detecting apparatus in which an object intruding into the field of view for image pickup is automatically detected from a video signal supplied from an image pickup device under the monitoring environment where shadows of trees, flags, or the like, are observed trembling.
An intruding object detecting apparatus using an image pickup apparatus such as a camera or the like as image input means is designed not to provide conventional manned monitoring which depends on a human monitor, but to detect an object intruding into the field of view to be monitored or to recognize the kind of the object so as to obtain predetermined information or warning measures automatically. To realize such a system, there is a method in which an input image obtained by image input means such as a camera or the like is first compared with a reference background image (that is, an image in which no object to be detected is picked up), and a difference in luminance value between the input image and the reference background image is obtained for every pixel. Thus, an area where the difference is large is extracted as an object. Such a method, called a subtraction method, has been hitherto used widely.
There is another object detecting method in the application of such a subtraction method, for example, as disclosed in JP-A-7-79429. In this method, however, there is a problem that not only intruding objects to be detected but also moving objects such as trees or flags trembling in the wind, shadows of those, or the like, may be extracted due to detection of the difference in luminance value between an input image and a reference background image for every pixel. In order to solve such a problem, JP-A-10-283466 discloses a method in which areas where moving objects other than intruding objects to be detected exist are specified, and the specified areas are subjected to a masking processing (masked as insensible areas) so that only the intruding objects are extracted.
In the aforementioned background art, however, there is a disadvantage that it is necessary to establish masked areas (insensible areas) where there are moving objects other than intruding objects to be detected so that such moving objects can be prevented from being detected erroneously. Particularly, when such moving objects other than intruding objects to be detected are shadows of trees, flags, or the like, trembling in the wind, these moving objects change their positions from moment to moment. Therefore, in order to prevent such shadows from being detected erroneously, the positions where the shadows exist must be inferred from conditions such as the season, the time zone, the position of the monitoring area (latitude, longitude, etc.), the weather, and so on. Thus, there is another disadvantage that the areas to be masked must be changed from moment to moment. Further, it is impossible to detect intruding objects which exist in the masked areas. Alternatively, in order to restrict erroneous detection (erroneous extraction) of moving objects other than intruding objects in the masked areas, a threshold value Th is required to be set high for binarization in the masked areas. However, if the threshold value is set to be high, there is a further disadvantage that intruding objects are apt to be missed. It is therefore desired that the masked areas are confined to small areas.
It is therefore an object of the present invention to eliminate the foregoing disadvantages, and to provide a reliable intruding object detecting method and a reliable intruding object detecting apparatus by which, even in the condition that there are shadows of moving objects other than target objects to be detected, judgement can be made as to whether any extracted object is an object to be detected or not, without masking the areas where the shadows exist.
In order to attain the foregoing object, an intruding object detecting method according to an aspect of the present invention comprises the steps of: supplying an image signal from an image pickup device; extracting a moving object from the supplied image signal and a reference background image signal stored in a memory device by the subtraction method; making division between the supplied image signal and the reference background image signal for every pixel so as to produce a ratio image; calculating a histogram of luminance values (pixel values) on the ratio image in the same coordinate positions as the area of each extracted object, that is, producing a histogram of a brightness change ratio; judging whether two peaks appearing in the histogram is symmetrical or not; and judging whether the extracted moving object is an intruding object or a shadow on the basis of the result of the judgement according to the first-mentioned judging step.
Preferably, in the aforementioned step of judging the symmetry of the peaks appearing in the histogram, two mean pixel values in ratio representation (xcexcxe2x80x2+, xcexcxe2x80x2xe2x88x92) are calculated on a part of the ratio image corresponding to the extracted moving object from the histogram, and an absolute value of a difference between one (xcexcxe2x80x2+) of the mean pixel values in ratio representation and the reciprocal (1/xcexcxe2x80x2xe2x88x92) of the other mean pixel value (xcexcxe2x80x2xe2x88x92) in ratio representation is compared with a predetermined threshold value; wherein the aforementioned judging step judges the extracted object to be an intruding object when the comparison result in the comparing step concludes that the absolute value of a difference between one of the mean pixel values in ratio representation and the reciprocal of the other mean pixel value in ratio representation is equal to or larger than the predetermined threshold value (T1), and the judging step judges the extracted object to be not an intruding object, for example, a shadow or the like, when the above-mentioned absolute value is smaller than the predetermined threshold value (T1). This judgement depends on the fact that, if there is a shadow of a tree, a flag, or the like, trembling in the wind, there appear a pair of an area which has turned bright because a shadow has disappeared due to the wind and an area which has turned dark because the shadow has appeared due to the wind, and the mean pixel value (xcexcxe2x80x2+) in ratio representation in pixels which have turned bright on the ratio image shows a value close to the reciprocal of the mean pixel value (xcexcxe2x80x2xe2x88x92) in ratio representation in pixels which have turned dark on the ratio image. Thus, the shadows are specified.
According to another aspect of the present invention, the step of judging the symmetry of the peaks appearing in the histogram calculates sharpnesses ("sgr"+, "sgr"xe2x88x92) of pixel value distribution on the part of the ratio image corresponding to the extracted moving object from the histogram; and compares each of the calculated sharpnesses of pixel value distribution with a predetermined threshold value. On the basis of this comparison result, the judging step judges whether the extracted object is an intruding object or not. Any pixel has a substantially fixed pixel value change ratio on the part of the ratio image corresponding to the area which has turned bright because a shadow has disappeared due to the wind. Likewise, any pixel has a substantially fixed pixel value change ratio on the part of the ratio image corresponding to the area which has turned dark because the shadow has appeared. By use of such a phenomenon, the extracted moving object is judged to be not an intruding object but a shadow.

Method and apparatus for automatically detecting intrusion object into view of image pickup device