Abstract: A heater includes an insulating base, a resistance heating element, and a hollow member. The base includes an upper surface and a lower surface. The resistance heating element extends inside the base along the upper surface and the lower surface. The hollow member includes a first plate-shaped part laid over the lower surface, a second plate-shaped part facing the first plate-shaped part through a space, and a side surface part surrounding the space from an outside in a planar direction of the first plate-shaped part and the second plate-shaped part.

Abstract: A glass substrate manufacturing method advantageously applicable to magnetic recording disk glass substrates, LCD glass substrates, photomasks glass substrates, or optical memory glass substrates. The method includes the steps of forming a film of a solution on at least a principal surface of a sheet glass formed using a down-drawing method, the solution containing a water soluble inorganic material and a surface-active agent; sandwiching both sides of a single sheet glass on which the film is formed or of a laminated structure of two or more sheet glasses with a densified sheet with a high flatness to pressure the single glass or laminated structure; and heating and annealing the single sheet glass or laminated structure to flatten the same. The end side of the flatten glass substrate is treated with a treating solution containing a hydrofluosilicic acid.

Abstract: A glass substrate manufacturing method advantageously applicable to magnetic recording disk glass substrates, LCD glass substrates, photomask glass substrates, or optical memory glass substrates. The glass substrate is formed by chemically strengthening a glass substrate by immersing the glass substrate in a chemical reinforcement solution heated and then ion exchanging ions on the surface layer of the glass substrate with ions in the chemical reinforcement solution; removing the substrate from the chemical reinforcement solution and then annealing it to a temperature higher than the crystallization temperature of a molten salt; rapidly cooling the glass substrate at a rate at which the crystallization of the molten salt deposited on the surface of the glass substrate is prevented; and then cleaning the surface of the glass substrate.

Abstract: A method for manufacturing a magnetic recording disk including the steps of forming a film of solution on at least a principal surface of a sheet glass; the solution contains a water soluble inorganic material and a surface active agent; sandwiching both sides of a single sheet glass on which the film is formed or on a laminated structure of plural sheet glasses with a densified sheet with a high flatness to pressure the single glass or laminated structure; and heating and annealing the single sheet glass or laminated structure to flatten it. The end side of the flattened glass substrate is treated with a treating solution containing hydrofluosilicic acid.

Abstract: A glass substrate manufacturing method advantageously applicable to magnetic recording disk glass substrates, LCD glass substrates, photomask glass substrates, or optical memory glass substrates. This method includes the steps of forming a film of a solution on at least a principal surface of a sheet glass formed using a down-drawing method, the solution containing a water soluble inorganic material and a surface-active agent; sandwiching both sides of a single sheet glass on which the film is formed or of a laminated structure of plural sheet glasses with a densified sheet with a high flatness to pressure the single glass or laminated structure; and heating and annealing the single sheet glass or laminated structure to flatten the same. The end side of the flatten glass substrate is treated with a treating solution containing a hydrofluosilicic acid.

Abstract: A dispenser for applying correction liquid to writing errors. The dispenser includes a valving rotary ball which controls the dispensing, with the rotary ball being normally biased against a spring member via an elongated biasing element, to shut off dispensing of the correction liquid. To insure integrity of shut-off and dispensing of correction liquid, the biasing member is a cylindrical member which has been integrally deformed at the end distant from the rotary ball to provide an outwardly extending stepped portion which firmly engages with the biasing spring.

Abstract: A card type writing instrument has a casing made of plastics and at least one recess formed therein. Also, at least one flat writing element capable of being removably fitted into the recess in the casing is provided. When the writing element is held in the recess it is essentially integral with the casing and defines the shape of a card. The writing instrument may include a variety of writing elements such as a mechanical pencil unit and ball-point pen unit by providing a plurality of recesses in the casing for receiving the writing elements.

Abstract: A compound writing instrument, wherein a retractable mechanical pencil unit and a ball point pen unit are assembled in a lower barrel of the writing instrument, an upper barrel rotatable in one or two directions relative to said lower barrel around its axis overlaps said lower barrel and a cam mechanism engaging with said units for selectively shifting said units in the axial direction into a writing position is accomodated within said upper barrel of the writing instrument. By means of said cam mechanism, said upper barrel is shiftable relative to said lower barrel in the axial direction enough to feed out the lead of said mechanical pencil unit when this unit is in the writing position, while said upper barrel is non-shiftable relative to said lower barrel when said ball point pen unit is in the writing position.

Abstract: A composite writing instrument having a lower tubular casing accommodating therewithin two retractable mechanical pencil units spaced by about 180.degree.. An upper tubular casing encloses a cam mechanism for effecting a reciprocal rotational motion through about 180.degree. around the axis of the instrument and engaging both pencil units for alternately shifting them in the axial direction whereby the two pencil units can be alternately advanced to a writing position through an opening at the lower end of the lower tubular casing, or retracted to a retracted position within the lower tubular casing. A feeding operation for advancing the lead of the pencil unit in the writing position is effected by reciprocating of the upper tubular casing in the axial direction.

Abstract: A composite writing instrument composed of two writing units such as two ball point and pen units which has a lower tubular casing accommodating therewithin two writing units and an upper tubular casing accommodating a cam mechanism therewithin which is rotatable about the axis of the casing for advancing the two writing units to a writing position through an opening at the tip of the lower tubular casing or for retracting the units to a holding position within the lower tubular casing. The cam mechanism is rotatable around the axis of the lower tubular casing as well as being engageable with both of the two writing units respectively for shifting the writing units in the axial direction, and the mechanism includes a guide casing having lengthwise grooves thereon and a curved casing accommodating the guide casing therewithin.