Abstract: An image reading apparatus includes: illuminating means for illuminating an original with light; a lens forming an image of reflected light from the original, the lens having a resolution characteristic in which a resolution in a vertical scanning direction in an image-reading wavelength region at a field angle in a vicinity of an end of the original is lower than a minimum resolution in an image-reading wavelength region at a field angle on an inner side of the vicinity-of the end of the original; light shielding means for shielding part of the reflected light such that a pupil diameter in the vertical scanning direction in the reflected light from the vicinity of the end of the original is reduced; and photoelectrically converting means for converting the reflected light partly shielded by the light shielding means and undergone image formation by the lens into an electrical signal.

Abstract: An image sensor includes a plurality of photosensitive pixel lines adjacent to each other in the sub-scanning direction, each of the photosensitive pixel lines having a number of photosensitive pixels arranged in the main scanning direction, and horizontal transfer registers disposed outside of the photosensitive pixel lines. A storage part for saving therein signal charges on a pixel-by-pixel basis is interposed between the photosensitive pixel lines and the horizontal transfer registers. Transfer of signal charges between the photosensitive pixel lines, storage part, and horizontal transfer registers are controlled by operating shift gates so that at a time point when exposure of the inside photosensitive pixel line has been finished, signal charges of the outside photosensitive pixel line is saved into the storage part to thereby secure a transfer passage for signal charges of the inside photosensitive pixel line.

Abstract: Light reflected from a document surface is given first color dispersion when passing through a prism interface and second color dispersion when passing through another prism interface. The second color dispersion is in an opposite direction to and has larger partial dispersion in a blue range than the first color dispersion. The prism interface may be replaced by an interface of two lenses which interface is a curved surface whose center of curvature is deviated from the optical axis of the reflected light in the auxiliary scanning direction.

Abstract: A color image reading device for reading a document image imaged on a line image sensor, wherein the line image sensor is a CCD including a first pixel line consisting of pixels having a first reading spectral characteristic and a second pixel line consisting of pixels having the second and third reading spectral characteristics arranged alternately; a two-layer dichroic mirror is provided on the CCD, said optical element for generating double images of an optical image corresponding to said first reading spectral characteristic and another optical image corresponding to the total of said first and second reading spectral characteristics; and the separation distance between the double images generated and imaged on the CCD by the dichroic mirror is approximately equal to the distance between said two lines of pixels on the CCD.

Abstract: A film projector holds film from which an image is projected to a mirror unit and then to a reading unit. A first mirror and a second mirror project the image from the film projector to the mirror unit by a deflecting optical path between the film projector and the mirror unit. A mirror support holds the first and second mirrors and a base supports the film projector and the mirror support. The mirror support is structured so that the second mirror is fixed and the first mirror is rotated integrally with the film projector around the second mirror.

Abstract: Because of using as a light source a halogen lamp which is well stabilized in terms of both the quantity of light and the spectral ratio, it is unnecessary to read shading data whenever the reading of an image is initiated. The shading data can be read with a certain margin at the end of a copy job, when power is being given to an image reader or at given time intervals for making shading correction on the basis thereof. Reading the shading data can be carried out with a certain time margin without detriment to FCOT (First Copy Output Time) and CPM (Copy/Minute); enough time is allowed for acceptance of the shading data, so that data of a plurality of lines can be read and fault values, if any, can be removed therefrom. Therefore, the influences of dust, etc., even if present on the white reference plate, can be eliminated.

Abstract: An image read device in which an optical scan mechanism is disposed between an original and a read sensor. The optical scan mechanism comprises a plurality of mirrors for transmitting an optical image of an image on the original, a first optical lens for platen (platen lens) for focusing the optical image on the read sensor, and a second optical lens for film projector (F/P lens) for focusing a film projection image on the read sensor. In a platen mode, an image read from an original is focused on the read sensor by the first optical lens. In an F/P mode, an image from a film is focused on the read sensor by the second optical lens. A good image can be read without degrading the modulation transfer function.

Abstract: An image reading apparatus including an A/D converter for converting an analog detection signal read by an image reading sensor to a digital signal, a logarithmic converter, in which density levels to be converted are divided into a plurality of regions, for converting an output of the A/D converter to a logarithmic value, a decoder for judging a density region of the logarithmic converter based on the output of the A/D converter, and a bit shifter for converting an output of the logarithmic converter to a density signal in accordance with a judgment made by the decoder. The image reading apparatus as constructed above can maintain the tone level of an 8-bit signal, thereby producing high-quality images. Further, 10-bit signals can be subjected to shading correction while using an inexpensive 8-bit memory.

Abstract: An image reading apparatus with a plurality of line sensors comprises a reference level adjusting circuit for adjusting a level of a dark output outputted from one of the line sensors to a reference level, and a level difference adjusting circuit for progressively adjusting to a minimum a dark output level difference between the reference level adjusted line sensor and a second line sensor adjacent to the former sensor, a dark output level difference between the second line sensor and a third line sensor adjacent to the second line sensor, and so on. When three or more line sensors are used, a level of a dark output outputted from one of the three line sensors which is located at the center of a sensor array of the three sensors is adjusted to the reference level. Alternatively, a level of a dark output outputted from one of three line sensors which is located at one of the ends of a sensor array of the three line sensors is adjusted to the reference level.

Abstract: An image data control system for use in an image reading equipment, in which analog signals output from a line sensor, which represent the amounts of light reflected from an original sheet are converted into digital signals by analog/digital conversion, and then the digital signals are converted into density signals to obtain original sheet reading signals in the form of the density signals, the system characterized in that offset control are performed by an offset control circuit and dark time output adjustment by the unit of picture elements are performed by a dark time correction circuit, respectively, after performing gain control by a gain control circuit.

Abstract: A density correcting system for a film image reading apparatus which outputs color decomposing signals of film images from an optical system after correcting the signals for density. The density correcting system is provided with density correcting tables corresponding to the individual color decomposing signals. Film image signals are formed by making corrections of the color decomposing signals for density in accordance with the tables.

Abstract: A film image reading system for reading the projected image obtained by projecting an image of an original sheet film on a film image reading body by the light source lamps for a film projector. The film image reading body are provided with an imaging unit for reading the projected image by photo-electric conversion, an amplifier for amplifying the image reading signals from the imaging unit, and a gain control circuit for controlling the value of the gain of the amplifier.