Riso Kagaku Corporation

Ryuji Higa

Sadanao Okuda

Takashi Isozaki

Takahito Tojima

Junji Takahashi

Takanori Hasegawa

Musashi Hirata

In a thermal head control method for thermally making a stencil master plate from a thermal stencil master plate sheet in the manner of a dot matrix for each line and forming an independent hole for each dot, a physical quantity representing the temperature of the thermal head, such as a time interval Ti for the plate making action by the thermal head for each line and a temperature actually measured from the thermal head, is measured before the plate making action of the next line. The measured temperature is compared with a prescribed value, and if the temperature is lower than the prescribed value, the thermal head is driven (pre-heated) at a power level which is lower than the rated power output and would not affect the thermal stencil master plate sheet. The effective heat emitting property of the thermal head is made uniform without regards to other factors, and a satisfactory perforation is carried out on a thermal stencil master plate sheet at all times.

Thermal head control method and device for making a stencil master plate

A print image treatment device is formed of a supply device for holding an excess ink removing liquid, the excessive ink removing liquid not dissolving in a printing ink forming a print image and having a lower surface tension than that of the printing ink; a rotating contact member having an outer surface, on which the excessive ink removing liquid is supplied from the supply device; a facing member situated under the contact member for nipping and carrying a printing sheet between the contact member and the facing member, an excessive printing ink forming the print image on a printing sheet being transferred to the excessive printing ink removing liquid when the printing sheet contacts the contacting member; a cleaning device contacting the contact member for removing the excessive printing ink with the excessive ink removing liquid; and a separation device receiving the excessive ink removing liquid with the excessive printing ink. The excessive ink removing liquid is separated from the printing ink having been transferred from the printing sheet. The separation device includes a filter having the thickness and air-flow resistance indicated below:

Print image treatment device

A print image treatment device is formed of a contact member which is coated on the peripheral surface with an excessive ink removing liquid incompatible with printing ink for forming a print image and having a lower surface tension than the printing ink, and is rotated in a specific direction, a facing member which serves to bring the printed side of a printed paper into contact with the excessive ink removing liquid by feeding the printed paper nipped between the contact member and the facing member, a supply means for supplying the excessive ink removing liquid to the peripheral surface of the contact member, and a cleaning means which contacts the peripheral surface of the contact member. The angle of the cleaning means from the tangent line of the peripheral surface is within a range of 5 to 60 degrees.

The print image device according to this invention is comprised of a rotatable member with an excessive ink removing liquid applied to the surface, which does not dissolve in a printing ink forming a print image and has a lower surface tension than that of the printing ink; a facing member for bringing a printed surface of a printed body into contact with the excessive ink removing liquid on the contact member by nipping and carrying the printed body having been printed between the contact member and the facing member; a supply device for supplying the excessive ink removing liquid to the contact member; and a cleaning device for removing the excessive ink removing liquid with the printing ink, sliding in contact with the contact member. Furthermore, a mixture of the excessive ink removing liquid and the printing ink is formed at an upstream position in the rotating direction, i.e. in a contact part formed by the contact member and cleaning means on the contact member, where the quantity of the excessive ink removing liquid is controlled to be larger than one third of that of the printing ink.

Disclosed is the print image treatment device formed of: a contact member on a surface of which an excessive ink removing liquid not dissolving in a printing ink forming a print image and having a lower surface tension than that of the printing ink is applied, the contact member being driven to rotate; a facing member for bringing a printed surface of a printing body into contact with the excessive ink removing liquid on the contact member by nipping and carrying the printing body having been printed between the contact member and the facing member; a supply device for supplying the excessive ink removing liquid to the contact member; and a cleaning device for removing an excessive ink with the excessive ink removing liquid. The nip width formed by the contact member and the facing member, which is defined as the dimension of the part with which the contact member and the facing member are in contact in the direction of the printing body being carried, is specified to be 0.5 mm or over.

To allow data to be exchanged between a printing drum and a stencil printing device main body in a highly adaptable manner with regard to the increase in the kinds of data to be transmitted without requiring any change in mechanical structures, light emitting devices 43, 65 and light receiving devices 45, 63 are arranged in mutually opposing parts of the printing drum 7 and the main body frame 1 to allow optical communication between them. Other modes of wireless communication may be used in place of the optical communication. This invention is particularly useful when the printing drum 7 is detachably mounted on a main body frame 1 of the stencil printing device, and the main control unit is required to adapt itself to different printing drums.

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Ibaraki-Ken, Japan

Ryuji Higa