Detection mark and method and apparatus for detecting mark
AssigneeHitachi Maxell, Ltd.
InventorsToshio Oshima, Masato Nishida, Tsunemi Ohiwa, Tsutomu Yamaguchi
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Abstract
A detection mark comprising a pattern formed from a thin phosphor layer which emits a light having a different wavelength from that of an excitation light irradiated on a surface side of the phosphor layer, and an undercoat layer which is formed on a rear surface side of the phosphor layer and reflects the excitation light, which mark can be detected by intermittently irradiating the excitation light to the mark and reading a light or afterglow from the phosphor layer.
Claims8
A detection mark comprising:
- a source of excitation light;
- a pattern formed from a thin phosphor layer which emits light having a different wavelength from that of excitation light from said source and irradiated on a surface side of said phosphor layer,
- an undercoat layer which is formed on a rear surface side of said phosphor layer and reflects said excitation light;
- said undercoat layer having a selected reflectance characteristic so as to provide a ratio of an output voltage obtained from detected light emitted from said phosphor layer to that of excitation light reflected from said undercoat layer which is at least 1.6;
- means for pulsing said source of excitation light to generate pulses of light emitted from said phosphor layer;
- and
- means for detecting and counting said pulses of emitted light to determine a width dimension of said phosphor layer.
A method for detecting a mark, which comprises the steps of:
- irradiating an excitation light on a phosphor mark printed on a card, said mark being formed from a material having an afterglow property;
- pulsing said excitation light;
- moving said card relative to said excitation light;
- detecting pulses of afterglow from said irradiated material of said mark during an off time of said excitation light;
- and
- counting the number of pulses of afterglow to determine the width of said mark.
An apparatus for detecting a phosphor mark, comprising:
- a pulsed source of excitation light;
- means for irradiating excitation light from said source on a mark being moved relative to said source of excitation light and comprising a phosphor layer, said phosphor layer thereafter emitting pulses of light in response to said excitation light;
- means for selectively receiving and detecting said pulses of light emitted from a part of said mark irradiated by said excitation light;
- said means for receiving and detecting being located adjacent said means for irradiating said excitation light;
- means for counting said pulses of light emitted from said phosphor layer for detecting a width dimension thereof;
- and
- wherein optical axes of said means for irradiating said excitation light and said means for receiving and detecting said pulses of emitted light are located on a plane perpendicular to a direction in which said mark moves, said axes further being inclined relative to each other.
Dependencies are inferred from the claim text.