Abstract: A clutch control apparatus includes a clutch disk, which is engaged with a flywheel, by means of a diaphragm spring; a release mechanism (including a rod and an electric motor) for pressing a central portion of the diaphragm spring; and a clutch control circuit. The clutch control circuit calculates an ideal clutch load and an output torque of the electric motor for a detected stroke of the rod. On the basis of these values, the clutch control circuit obtains the acceleration of the rod. The clutch control circuit estimates a stroke of the rod from the obtained acceleration and causes an adjust wedge member to rotate such that a detected actual stroke and the estimated stroke become equal, thereby modifying the attitude of the diaphragm spring accordingly.

Abstract: A filling squeegee and a scraping squeegee are provided in a printing apparatus. The filling squeegee is moved without contacting a surface of a mask in order to fill a solder paste into openings of the mask. Unnecessary solder paste on the surface of the mask is scraped by the scraping squeegee. The solder paste is prevented from being improperly filled in or scraped from the openings even if a speed of the squeegee is increased, so that the solder paste can be printed stably on circuit board.

Abstract: An optical communications system and transmission section repair method is provided to prevent the dispersion value in an optical receive station from being affected when a transmission line has been obstructed, wherein a patch is made into the transmission line adjusted for dispersion in the relay section of the transmission line. The transmission line includes positive dispersion fiber and negative dispersion fiber. The optical fiber used to patch the transmission line is an optical fiber where the absolute value of the dispersion is smaller than the dispersion value of the positive dispersion fiber or the negative dispersion fiber.

Abstract: An optical communication system which includes a transmission path through which a light is transmitted to a specific point, such as to a receiver. The transmission path includes a plurality of sections so that the light travels through the sections to the specific point. Each section overcompensates for dispersion produced in the respective section for the light so that an amount of dispersion for the light at the specific point is substantially zero.

Abstract: An object of the present invention is to provide a WDM optical transmission system with an excellent transmission characteristic by employing a hybrid transmission line which is formed by combining under optimal conditions an optical fiber having positive wavelength dispersion, and an optical fiber having negative wavelength dispersion. According to the WDM optical transmission system, an optical transmitter station, optical amplifiers, and an optical receiver station are interconnected over an optical fiber transmission line. The optical fiber transmission line has an inter-repeater segment formed with a hybrid transmission line composed of a 1.3 &mgr;m zero-dispersion SMF and an RDF, and an inter-repeater segment formed with a DCF for compensating for cumulative wavelength dispersion generated in the hybrid transmission line. As the conditions for setting the hybrid transmission line, a ratio of the length of the RDF to the length of the inter-repeater segment must be 20% or more and 40% or less.

Abstract: The present invention relates to an optical transmitter and particularly to an optical transmitter including an external optical modulator such as Mach-Zehnder type optical modulator which modulates the light from a light source to output an optical signal with a drive voltage signal generated depending on an input signal According to the present invention is achieved by providing an optical modulator, which add weighting to operating point control signal in accordance with optical output level of the modulator.

Abstract: A filling squeegee and a scraping squeegee are provided. The filling squeegee is moved in a state without contact with a surface of a mask thereby to fill a solder paste in openings of the mask, then the unnecessary solder paste on the surface of the mask is scraped by the scraping squeegee. The solder paste is prevented from being filled in the openings improperly or scraped improperly even if a speed of the squeegee is increased, so that the solder paste is printed stably on circuit boards.

Abstract: A screen printing method and apparatus for printing a circuit pattern corresponding to that of a stencil (4), onto a print-object article (1) placed on an ascendable/descendable positioning stage (2), through moving a squeegee (5a, 5b) horizontally while the squeegee is pushed in on the stencil so that print paste (9) is printed to the article via the stencil. The squeegee is lifted to an extent of a push-in stroke, to which the squeegee has been pushed in on the stencil, and thereafter the article is separated away from the stencil by moving the stage downward. The board is classified into first and second areas (121, 120) where values of opening sizes of the stencil along a squeegee moving direction are smaller than and not smaller than a threshold, and a speed of the squeegee at the first area is made slower than that at the second area.

Abstract: A clutch control apparatus includes a clutch disk, which is engaged with a flywheel, by means of a diaphragm spring; a release mechanism (including a rod and an electric motor) for pressing a central portion of the diaphragm spring; and a clutch control circuit. The flywheel and an outer circumferential portion of the diaphragm spring abut each other via taper portions of a pressure plate and an adjust wedge member. The clutch control circuit calculates an ideal clutch load and an output torque of the electric motor for a detected stroke of the rod. On the basis of these values, the clutch control circuit obtains the acceleration of the rod. The clutch control circuit estimates a stroke of the rod from the obtained acceleration and causes the adjust wedge member to rotate such that a detected actual stroke and the estimated stroke become equal, thereby modifying the attitude of the diaphragm spring accordingly.

Abstract: An object is to provide a low cost optical amplifier having a simple construction where gain equalization of wavelength division multiplexed signal light, and the suppression of noise light is realized by a single optical device, and to provide a wavelength division multiplexed light transmission system using such an amplifier. Accordingly, the optical amplifier of the present invention is constructed by providing for a conventional optical amplifier incorporating an EDF, an excitation light source and a multiplexer, an optical filter having a periodic loss-wavelength characteristic with respect to a gain wavelength characteristic of the EDF. The optical filter has the characteristic that a spacing (FSR) corresponding to one period of a loss-wavelength characteristic corresponds to a gain peak wavelength difference of the EDF, and a maximum loss wavelength approximately coincides with a gain peak wavelength on a long wavelength side of the EDF.

Abstract: A screen printing method and apparatus for printing a circuit pattern corresponding to that of a stencil (4), onto a print-object article (1) placed on an ascendable/descendable positioning stage (2), through moving a squeegee (5a,5b) horizontally while the squeegee is pushed in on the stencil so that print paste (9) is printed to the article via the stencil. The squeegee is lifted to an extent of a push-in stroke, to which the squeegee has been pushed in on the stencil, and thereafter the article is separated away from the stencil by moving the stage downward. The board is classified into first and second areas (121,120) where values of opening sizes of the stencil along a squeegee moving direction are smaller than and not smaller than a threshold, and a speed of the squeegee at the first area is made slower than that at the second area.

Abstract: In a printing device in which a printing material is printed on or applied to a to-be-printed surface of a circuit board through a screen mask for printing having openings formed therein in a predetermined pattern, it is intended to reliably remove cream solder remaining in the openings in the screen mask. After an air suction mechanism (19) has its flow rate controlled by a flow rate controller (20). An air suction section (15) is lifted until its front end contacts with the screen mask (5), the air suction mechanism (19) starts cleaning by sucking air from the openings (6) in the screen mask (5). An inspecting camera (2) is used to observe the cream solder (4) remaining in the openings (6) after cleaning, and the air suction flow rate is controlled according to the results thereof to effect cleaning again.

Abstract: In a screen printing apparatus and method for using a squeegee to press printing paste on a screen while moving the squeegee in the horizontal direction in order to apply the paste to a circuit board for printing, accurate printing with excellent printed shapes is provided by allowing the squeegee to flexibly fit the circuit regardless of its slope, swell, or warp to achieve balanced printing at a low specified pressure. To accomplish this, squeegees (26a and 26b) are elevated by an air cylinder (27) that can be rotated at the longitudinal center of the squeegees (26a and 26b) and that cancels their weight, and are then pressed downward by air cylinders (35 and 36) located symmetrically about the center in order to press the top surface of a screen (23).

Abstract: A printing method and a printing device are provided, whereby a uniform amount of solder can be coated, printing quality can be improved, variations in adjustment between operators are eliminated, adjustment time is shortened, and productivity can be improved. By keeping the amount of deformation of the end sections of a squeegee constant by maintaining a uniform state of contact between the squeegee and a stencil, there is no occurrence of such problems as unsatisfactory wiping away of a solder paste, which causes the solder paste to be left on the stencil, incomplete filling of the solder paste into the pattern opening, or an increase in the deformation of the end sections of the squeegee, causing solder paste filled into the pattern opening to be scraped away.

Abstract: The present invention aims at providing an active optical fiber and an optical fiber amplifier, in which a conversion efficiency of pumping light to be input into the active optical fiber is increased to thereby improve optical amplification characteristic. To this end, the active optical fiber of the present invention is formed with fiber gratings arranged over a predetermined region along the longitudinal direction within the optical fiber doped with a rare earth element, and transmitting signal light and reflecting pumping light. Further, the optical fiber amplifier of the present invention is constituted to comprise a pumping light source for generating pumping light, and a multiplexer for multiplexing signal light and the pumping light to thereby output them into one end of the active optical fiber. Thus, the pumping light is reflected by the fiber gratings so as to go and return within the active optical fiber, thereby improving the conversion efficiency of the pumping light.

Abstract: A screen printing method is provided in which the exchange of machine types is achieved in a short time and even minute patterns or narrowly pitched patterns can be precisely positioned for screen printing. The method comprises finding an amount of movement of the circuit board from positions of recognition marks (2, 2) on a circuit board (1) and positions of recognition marks (5, 5) on a screen plate (4), positioning the circuit board (1) in relation to the screen plate (4) on the basis of the amount of movement of the circuit board (1), detecting a discrepancy between a pattern of apertures (18) and a pattern of lands (19) in a particular portion of the circuit board (1), finding a positional correction from the discrepancy, and positioning the circuit board (1) in relation to the screen plate (4) on the basis of the amount of movement of the circuit board and the positional correction.

Abstract: A gain equalizer for an optical amplifier having a gain characteristic giving a gain peak. The gain equalizer includes first, second, and third gain equalizers operatively connected to the optical amplifier. The first gain equalizer has a first loss characteristic (wavelength dependence of loss) giving a maximum loss at or near a wavelength giving the gain peak. The second and third gain equalizers have periodic second and third loss characteristics, respectively. The period of the second loss characteristic is shorter than the period of the third loss characteristic. Each of the second and third loss characteristics gives a maximum loss at or near a wavelength giving one of two gain peaks remaining when the gain characteristic of the optical amplifier is equalized by the first gain equalizer only. With this configuration, gain equalization can be performed with high accuracy.

Abstract: The present invention aims at providing an optical fiber amplifier in which a pumping light is rendered to make two or more reciprocations within an active optical fiber so as to enhance a conversion efficiency of power of pumping light thereby realizing further high-powerization.

Abstract: A main wiping portion which contacts the back of a mask through a cleaning paper is provided behind a suction port as viewed in the direction of movement of an air suction portion. The cleaning paper is able to wipe off both solder paste adhered on the back of the mask and solder paste discharged from openings of the mask by suction through the suction port, whereby the solder paste deposits on the mask can be cleaned off at high removal efficiency.

Abstract: An engraved recess (4) is formed in a resin stencil (1) at a position on a surface of the resin stencil where the resin stencil, when registered with a circuit board, agrees with a fiducial mark of the circuit board. The recess is formed by a laser (3) and serves as a fiducial mark.