Hochiki Kabushiki Kaisha

Hochiki Corporation

Junichi Narumiya

Hiroshi Honma

Mariko Ishida

Tetsuya Nagashima

Shigeru Kajii

Yoshihito Hirai

Osami Minowa

A projected beam-type smoke detector and receiving unit includes in its light receiver data output unit 118 for outputting serially status information and status signal output units 85, 86 for sending the status information to the receiving unit, and in its receiving unit 30 data examining unit 113 for examining sequentially the status information. The light receiver 31 also includes a pulse generator unit 82 for generating pulses having different pulselengths according to the type of alarm information, and photoelectric converter units 83, 84 for sending to the receiving unit 120 the pulses of different pulselengths generated by the pulse generator unit 82. The receiving unit 120 includes a pulselength determining unit 108 for determining the type of alarm information from the pulselength of the pulse sent by the projected beam-type smoke detector and display units 110, 111 for displaying the alarm information type determined by the pulselength determining unit 108. As a result, the alarm and status information is conducted by single lines. Simple and low-cost design is thus implemented into the projected beam-type smoke detector and receiving unit.

Projected beam-type smoke detector and receiving unit

A projected beam-type smoke detector of the type in which a light emitter having a light emitting element is separately mounted from a light receiver having a light pickup element in order to detect a fire by an attenuation in the level of light which the light receiver receives from the light emitter, attenuation being due to the presence of smoke between the light emitter and the light receiver. The detector, comprising the light receiver, a cover status sensor for sensing the closing or opening state of a cover that is closed or opened to allow adjustments such as optical axis adjustment, sensitivity setting for light input and the like, and a control block for controlling each section of the light receiver. The control block sets the adjustment mode to each section of the light receiver when the control block receives a cover open-state signal indicative of the opening of the cover from the cover status sensor. The adjustment mode is automatically set to each section of the light receiver. The light receiver preferably comprises a sensitivity setting status, whereby the control block releases the adjustment mode.

Projected beam-type smoke detector

A separate type photoelectric smoke sensor having a light emitting section for emitting a light beam to a reflecting plate disposed at a certain distance from the light emitting section, a light receiving section for receiving reflected light from the reflecting plate, and a judgement section for outputting a sense signal if a received light output from the light receiving section is smaller than a threshold value previously set. The quantity of reflected light from a shielding object is obtained from the difference between or the ratio of the quantity of received light measured during lighting of the light emitting section in a situation where there is no shielding object and the quantity of received light measured during lighting of the light emitting section in a situation where there is the shielding object, and the difference between these quantities of reflected light and the quantity of received light measured during lighting of the light emitting section is compared with the threshold value to determine whether or not there is a fire. It is thereby possible to correctly discriminate the existence of any shielding object other than smoke in an observed region. Even if there is a shielding object, the influence of the shielding object is cancelled to obtain the true quantity of reflected light from the reflecting plate no matter what the reflectivity thereof, thereby ensuring accurate determination as to whether or not there is a fire.

Smoke sensor

A light emitting unit and a photo sensing unit are separately arranged to face with each other, and a pulse light is emitted from the light emitting unit at every constant period, and the photo sensing unit receives the pulse light attenuated by a smoke, thereby detecting a fire. When a power source is turned on, a microcomputer in the photo sensing unit stores the first photo sensing data as an initial photo sensing data in a memory. The initial photo sensing data is fixedly stored and held and is not erased due to a temporary cut off of the power source. The photo sensing data is converted to correction photo sensing data using a correction ratio to perform the fouling correction and the fire is discriminated on the basis of the correction photo sensing data. The correction ratio is corrected when the correction period reaches 50 minutes. A correction amount of a single correction ratio is suppressed to a microvalue. In correction of the correction ratio, it is increased or decreased by only a microvalue at every correction period until the photo sensing data coincides with the initial photo sensing data.

Photoelectric smoke sensor including a photosensing data correction

A smoke detector comprising a light emitting section from which pulse light is radiated to a detection area with a predetermined period and a light receiving section which is disposed so as to be opposite to the light emitting section to receive the light for detecting a change caused in the detection area in the form of a change in photo-output level. The light receiving section has a monitor terminal for outputting a monitor signal corresponding to the photo-output level. When a measuring apparatus is externally connected to the monitor terminal, the supervision period is shortened as compared with the normal supervision period, so as to enable the monitor signal to be supervised substantially in real time, thereby facilitating an adjusting operation.

Growing community of inventors

Fujisawa, Japan

Junichi Narumiya