Abstract: A control circuit refers to a time schedule of a time slot assigned to each of slave stations, which is stored in a first storage, and an optical intensity of each of signal packets sent from the slave stations, which is stored in a second storage, and preliminarily knows when and from what slave station an upstream signal packet is received and the optical intensity of the upstream signal packet to be received. When the control circuit determines the optimum bias voltage of an APD, in an interval between signal packets, a bias control circuit provides a bias source with a timing signal, by which an output voltage of the bias source is changed, and a bias voltage setting signal. The bias source applies a bias voltage corresponding to the bias setting signal sent to the APD with the optimum timing synchronized with the timing signal.

Abstract: A control circuit refers to a time schedule of a time slot assigned to each of slave stations, which is stored in a first storage, and an optical intensity of each of signal packets sent from the slave stations, which is stored in a second storage, and preliminarily knows when and from what slave station an upstream signal packet is received and the optical intensity of the upstream signal packet to be received. When the control circuit determines the optimum bias voltage of an APD, in an interval between signal packets, a bias control circuit provides a bias source with a timing signal, by which an output voltage of the bias source is changed, and a bias voltage setting signal. The bias source applies a bias voltage corresponding to the bias setting signal sent to the APD with the optimum timing synchronized with the timing signal.

Abstract: A sampling voltage is periodically applied between contacts of a switch of a device to determine a status of the switch. When a CPU is in a sleep state and the status of the switch is determined closed, the CPU is activated. The sampling voltage when the CPU is in the sleep state is adjusted lower than the one when the CPU is in the wakeup state. This reduces power consumption for the switch status determination. The sampling voltage adjusted at the lower level periodically adjusted to a higher level to reduce errors in the determination due to insulation films on the contacts.

Abstract: A bar code scanning apparatus in which the visual field of a lens system is extended as outwardly exceeding the width of an opening of a case body in which the apparatus is housed, such that a bar code wider than the width of the opening can be scanned. A bar code wider than the width of the opening can be scanned with the opening coming in contact with the bar code. Thus, a wide bar code can be scanned without the bar code scanning apparatus increased in width and length.

Abstract: A symbol read device useful as a bar code reader, optical character reader or the like. A symbol bearing surface is illuminated by two different light sources that are distinguishable based on their respective wavelengths or modulated frequencies. A detector detects light reflected from the symbol surface and provides a detection signal indicative thereof. The detection signal is processed to recognize the symbol being read. In a multi-scan embodiment, an automatic gain control (AGC) circuit controls a level of detector signal to aid in recognition of the symbols being read.

Abstract: Scan units scan top surfaces of articles A and B with a laser beam as they are transported by a conveyor belt. The scan units are capable of changing the focal position of the laser beam within a predetermined range. Changing the focal position of the laser beam requires a predetermined response time. The heights of articles A and B are detected by a height detection unit in an amount of time equal to or less than the response time before they are scanned by the laser beam. When the heights of the articles as detected by the height detection unit change, a control unit will change at predetermined time intervals the focal position of the laser beam that is generated by each of the scan units. This allows the top surfaces of articles A and B, which are transported at short time intervals, to be scanned efficiently with the focused laser beam, permitting the efficient reading of bar codes and any other symbols that are formed on the top surfaces of articles A and B.

Abstract: In a symbol reading device, at least two laser beams having different optical path lengths, and, therefore, different focal positions are used to scan a symbol surface. The two laser beams are produced from a single beam issuing unit, and only one beam at a time scans the symbol surface. Furthermore, stationary reflecting mirrors are used to create the two laser beams of different focal length, reducing the number of moving mechanisms and the overall complexity of the device.

Abstract: A symbol read device which has separate gain controls for reading different scan lines. The symbol read device includes a light beam emitter, a scanner which scans the light beam over different positions on a symbol surface having a symbol to be read, a detector which detects light reflected from the symbol surface and generates a detection signal indicative thereof, and a variable gain amplifier which amplifies the detection signal. The device further includes a process which processes an amplified detection signal from the amplifier and recognizes therefrom the symbol being read, an automatic gain controller which sets a gain of the variable gain amplifier every scan line or scan line group in response to the detection signal, a scan position detector which detects a scan position, and a controller which selects the gain set by the automatic gain controller based on an output signal of the scan position detector.

Abstract: A heat-sensitive recording material having an improved color image-forming property and an enhanced gloss and resistance to water, oily substances and plasticizers, is provided with a heat-sensitive color-forming layer formed on a substrate surface and comprising a substantially colorless dye precursor, a color-developing agent and a binder; an intermediate layer formed on the color-forming layer and comprising a hydrophilic polymeric material and a pigment; a glossy surface layer formed on the intermediate layer and comprising a hydrophobic polymeric material having a glass transition point of 60.degree. C. or more, and a lubricant; and optionally, an additional intermediate layer formed between the color-forming layer and the intermediate layer and comprising at least one member selected from hydrophilic polymeric materials and hydrophobic polymeric materials.

Abstract: A laser beam scanner for use in a code reader or the like including more than two optical-path-length changing units inserted in the beam path to change the optical path length of the beam between the beam emitting unit and the scanning unit such that the distance from the scanner to the focal point of the beam can be changed. The optical-path-length changing units are controlled by a control unit which receives an output from a distance measuring unit. The distance measuring unit measures the distance from the laser beam scanner to the object to be scanned and indicates to the control unit to adjust the optical-path-length so that the focal point of the beam is at the same distance as the object to be scanned.

Abstract: In a symbol reading device, at least two laser beams having different optical path lengths, and, therefore, different focal positions are used to scan a symbol surface. The two laser beams are produced from a single beam issuing unit, and only one beam at a time scans the symbol surface. Furthermore, stationary reflecting mirrors are used to create the two laser beams of different focal length, reducing the number of moving mechanisms and the overall complexity of the device.

Abstract: A heat-sensitive recording material having a superior resistance against water, plasticizers, and oily substances, is provided with a heat-sensitive color-forming layer formed on a surface of a substrate sheet and comprising a dye precursor, a color-developing agent, and a binder; and a protecting layer formed on the heat-sensitive color-forming layer and comprising (A) a polyvinylalcohol resin, (B) a water-soluble cross-linking agent, (C) at least one organic boron-containing polymer of the formula (I): ##STR1## and optionally (D) an acetoacetylated polyvinylalcohol resin.

Abstract: A bar code reading arrangement. A laser beam is scanned across a bar code which may be on a remote surface. Two detectors receive light reflected from the bar code, and convert it to an electrical signal. The detectors are laterally spaced on opposite sides of a line defined by the bi-section of the triangular area which is scanned by the laser beam. The electrical signal from the detector receiving only diffusely reflected light is used to identify the content of the bar code. The invention may be practiced in a hand-held unit with trigger means to initiate the bar code reading operation.

Abstract: A heat-sensitive recording material having a superior resistance against water, plasticizers, and oily substances, is provided with a heat-sensitive color-forming layer formed on a surface of a substrate sheet and comprising a dye precursor, a color-developing agent, and a binder; and a protecting layer formed on the heat-sensitive color-forming layer and comprising (A) a polyvinylalcohol resin, (B) a water-soluble cross-linking agent, (C) at least one organic boron-containing polymer of the formula (I): ##STR1## and optionally (D) an acetoacetylated polyvinylalcohol resin.

Abstract: In a reciprocating piston engine, the piston has a top ring and a second ring received in respective ring grooves. The top ring has two end surfaces defining therebetween a gap the open area of which on the side of the combustion chamber, when the top ring abuts against the upper surface of the ring groove, is smaller than an open area of the gap facing a second land clearance when the top ring seats on the lower surface of the ring groove. As the top ring seats on the lower surface of the ring groove during the power stroke when the engine is operated at a high-speed, high-loaded condition, the greater open area of the gap rapidly introduces the combustion pressure into the second land clearance to thereby reduce oil consumption. When the engine works at a low-speed, low-loaded condition, the top ring abuts against the upper surface of the ring groove during the intake and compression strokes, where the smaller open area of the gap reduces the flow of oil from the crankcase to the combustion chamber.