The present invention relates to optical object discriminating devices. The invention relates to an optical object discriminating device that discriminates the type of a measuring object, which is an object to be measured, for example, by applying laser beam to the measuring object and measuring a characteristic of depolarization due to reflection of the laser beam. The invention relates to an optical object discriminating device that discriminates, for example, the type of floor surfaces such as carpet, wooden floor and straw tatami mat.
As an example, the invention relates to an optical object discriminating device suited to achieving optimization of the operating state of a cleaner due to differences among such floor surfaces as carpet, wooden floor and straw tatami mat by discriminating the type of a floor surface. Further, the invention relates to cleaners and self-propelled cleaners containing the optical object discriminating device.
Floor surface discriminating sensors mounted on household vacuum cleaners can be classified into sensors of mechanical, suction pressure, ultrasonic and optical types.
Mechanical type floor surface discriminating sensors include (1) a type that a movable part is pressed against the floor surface (JP H02-52619 A), (2) a type that the floor surface is discriminated depending on a rotational state of a polygonal-prism or gear shaped roller (JP H02-52623 A and JP H03-106325 A), (3) a type that the floor surface is discriminated depending on a resistance value of an electrically conductive rubber that changes with a pressure received from the floor surface (JP H05-56888 A and JP H05-56889 A), and the like.
JP H06-78862 A describes a suction-pressure type floor surface discriminating sensor. This suction-pressure type floor surface discriminating sensor discriminates the type of floor surfaces by sensing a pressure of a front portion of a dust collection filter. This sensor fulfills the discrimination of floor surfaces by making use of the fact that a floor surface of carpet involves increases in the degree of vacuum when the carpet is sucked up to the suction port, while a wooden floor involves no increases in the degree of vacuum because wooden floors or the like will not be sucked up to the suction port.
JP H01-232255 A, JP H03-77519 A and JP H03-212249 A describe ultrasonic type floor surface discriminating sensors. In these ultrasonic type floor surface discriminating sensors, an ultrasonic pulse transmitted from a wave transmitting part mounted in opposition to the floor surface, after repeating reflection plural times as an echo against the floor surface, is received by a receiving part. Depending on the received signal, the sensor discriminates the type of the floor surface.
JP H03-123522 A and JP H03-228724 A describe an optical type floor surface discriminating sensor. This optical type floor surface discriminating sensor has a first light receiving/emitting element for receiving and emitting light horizontal to the floor surface, and a second light receiving/emitting element for receiving and emitting light vertical to the floor surface. From outputs of these two light receiving/emitting elements, the sensor discriminates the type of the floor surface.
Generally, such devices as mechanical floor surface discriminating sensors which are so constructed as to have a contact portion, particularly those so constructed that the contact portion has a movable portion movable by contact, have suffered various problems including wear of the contact portion (movable portion) or aged deterioration of mechanical reliability.
Therefore, optical type floor surface discriminating sensors capable of achieving the intended effects in noncontact manner are excellent in terms of device reliability. Meanwhile, mechanical type floor surface discriminating sensors of each of the types (2) and (3), both of which also have a contact portion and a movable portion, are designed to measure physical quantities due to displacement of the contact portion and the movable portion. As a result, the mechanical type floor surface discriminating sensors are problematic in reliability as compared with optical type floor surface discriminating sensors.
On the other hand, suction-pressure type floor surface discriminating sensors involve changes in the degree of vacuum due not only to the type of the floor surface to be cleaned but also to other factors such as clogging of dust collection filters. As a result, the suction-pressure type floor surface discriminating sensors have a fear of mis-detecting the type of the floor surface.
Moreover, for ultrasonic type floor surface discriminating sensors, both transmitting and receiving elements need to be provided with some horn. Therefore, the ultrasonic type floor surface discriminating sensors, when mounted on a common cleaner, become worse in easiness of use. Also, considerations should be taken for shock resistance and cost reduction.
An optical type floor surface discriminating sensor detects a decrease of the received light amount caused by carpet bristles intercepting the light emitted horizontal to the floor surface, thereby achieving the discrimination of the fact that the floor surface is given by a carpet. However, with non-shaggy carpets, since the light is not intercepted, there is a difficulty in detecting that the floor surface is a carpet.
Whereas floor surface discriminating sensors have been proposed in various types as shown above, those sensors have advantages and disadvantages as a matter of fact. Furthermore, the sensors are principally those which discriminate between carpets and others and not devices which are capable of distinguishing from straw tatami mats, which are a Japanese common indoor environment.