Method for producing a halftone plate

• US 4,447,833 A
• Filed: 12/31/1981
• Issued: 05/08/1984
• Est. Priority Date: 01/21/1981
• Status: Expired due to Fees

• Current Assignee: Dainippon Screen Graphics (USA) LLC (SCREEN Holdings Co., Ltd.)
• Original Assignee: Dainippon Screen Graphics (USA) LLC (SCREEN Holdings Co., Ltd.)
• Inventors: Sano, Tetsuo, Sakamoto, Takashi
• Primary Examiner(s): Britton, Howard W.
• Assistant Examiner(s): Coles, Edward L.
• Application Number:
  US06/336,309
• Time in Patent Office: 859 Days
• Field of Search: 358/283, 358/280, 358/298
• US Class Current: 358/3.3
• CPC Class Codes: H04N 1/40081 Soft dot halftoning, i.e. producing halftone dots with gradual edges

Abstract

A method for producing a halftone plate from an original picture having a continuous tone. A record film is exposed at least one exposure light beam of a smaller size than a halftone dot area by independently controlling it to turn on or off according to a picture signal. The luminous energy of the exposure light beam is controlled depending on a reference value corresponding to the picture signal and a position signal value varied depending on an exposing position in the halftone dot area to be exposed by the exposure light beam. The control of the luminous energy is performed by the sum, the difference, the product or the quotient of the two signal values. A plurality of reference values or position signal values may be used.

Claims

1. A method for producing a halftone plate from an original picture having a continuous tone by using at least one exposure light beam of a smaller size than a halftone dot area, which is independently controlled to be turned on or off according to a picture signal obtained by scanning the original picture, the improvement which comprises a step of controlling the luminous energy of the exposure light beam depending on a reference value corresponding to the picture signal, and a position signal value which is varied depending on an exposure position in the halftone dot area to be exposed by the exposure light beam, wherein the control of the luminous energy of the exposure light beam is performed depending on the sum of the reference value and the position signal value.

5. A method as defined in claims 1, 2, 3 or 4, wherein the control of the luminous energy of the exposure light beam is performed by using a plurality of reference values.

6. A method as defined in claims 1, 2, 3 or 4, wherein the control of the luminous energy of the exposure light beam is performed by using a plurality of position signal values.

2. A method for producing a halftone plate from an original picture having a continuous tone by using at least one exposure light beam of a smaller size than a halftone dot area, which is independently controlled to be turned on or off according to a picture signal obtained by scanning the original picture, the improvement which comprises a step of controlling the luminous energy of the exposure light beam depending on a reference value corresponding to the picture signal, and a position signal value which is varied depending on an exposure position in the halftone dot area to be exposed by the exposure light beam, wherein the control of luminous energy of the exposure light beam is performed depending on the difference between the reference value and the position signal value.

3. A method for producing a halftone plate from an original picture having a continuous tone by using at least one exposure light beam of a smaller size than a halftone dot area, which is independently controlled to be turned on or off according to a picture signal obtained by scanning the original picture, the improvement which comprises a step of controlling the luminous energy of the exposure light beam depending on a reference value corresponding to the picture signal, and a position signal value which is varied depending on an exposure position in the halftone dot area to be exposed by the exposure light beam, wherein the control of the luminous energy of the exposure light beam is performed depending on the product of the reference value and the position signal value.

4. A method for producing a halftone plate from an original picture having a continuous tone by using at least one exposure light beam of a smaller size than a halftone dot area, which is independently controlled to be turned on or off according to a picture signal obtained by scanning the original picture, the improvement which comprises a step of controlling the luminous energy of the exposure light beam depending on a reference value corresponding to the picture signal, and a position signal value which is varied depending on an exposure position in the halftone dot area to be exposed by the exposure light beam, wherein the control of the luminous energy of the exposure light beam is performed depending on the quotient of the reference value divided by the position signal value.