Abstract: A stimulable phosphor sheet, on which a radiation image has been stored, is exposed to stimulating rays, which cause it to emit light in proportion to the amount of energy stored thereon during its exposure to radiation. The light emitted by the front surface of the stimulable phosphor sheet and the light emitted by the back surface of the stimulable phosphor sheet, are detected photoelectrically. The image signal components of the two image signals are subtracted from each other, which represent corresponding picture elements on the front and back surfaces of the stimulable phosphor sheet, difference values being thereby obtained. A judgment is made as to whether each of the difference values falls or does not fall within a predetermined range. In cases where a difference value is judged as being outside the predetermined range, it is determined that an abnormal signal component is contained in at least either one of the two image signals.

Abstract: In a method for detecting an energy level of residual noise on a stimulable phosphor sheet, a stimulable phosphor sheet, on which a radiation image has been stored, is exposed to stimulating rays, which cause it to emit light in proportion to the amount of energy stored thereon during its exposure to radiation. The emitted light is detected, and the radiation image is thereby read out. A predetermined amount of erasing energy is given to the stimulable phosphor sheet, from which the radiation image has been read out, and noise having an energy level not higher than a predetermined energy level, which noise is among noise due to radiation image information remaining on the stimulable phosphor sheet, is thereby erased. Residual noise is then read out from the stimulable phosphor sheet, on which the noise having the energy level not higher than the predetermined energy level has been erased. An energy level of the residual noise, which has thus been read out, is then detected.

Abstract: A logarithmic amplifier includes an operational amplifier, an element for logarithmic conversion purposes connected to a feedback circuit of the operational amplifier, an oscillation prevention circuit having a capacitor connected in parallel with the logarithmic conversion element, and a control circuit for controlling the oscillation prevention circuit in such a way that the amount of feedback by way of the oscillation prevention circuit is reduced as an input current to the operational amplifier becomes smaller. To improve the high-speed response characteristics of the logarithmic operational amplifier, the operational amplifier is made up of a composite amplifier consisting of an FET input type operational amplifier and a bipolar input type operational amplifier.

Abstract: In an image scanning apparatus, a recording material is scanned with a laser beam having been produced by a semiconductor laser which oscillates in a single longitudinal mode at any given time such that an image having been recorded on the recording material may be read out therefrom or such that an image may be recorded on the recording material. A single picture element read-out period or a single picture element recording period is defined in accordance with a predetermined picture element clock pulse. A radio-frequency current is superimposed upon a drive current for the semiconductor laser. The radio-frequency current has a frequency, which is higher than the reciprocal of the single picture element read-out period or the reciprocal of the single picture element recording period and which falls within a frequency range that does not cause the semiconductor laser to simultaneously oscillate in multiple longitudinal modes.

Abstract: In a light beam scanning recording apparatus, a recording material is scanned with a laser beam having been produced by a single-longitudinal-mode semiconductor laser and having been directly modulated in accordance with an image signal, and a continuous tone image is thereby recorded on the recording material. A device superimposes a radio-frequency current upon a drive current for the semiconductor laser. An amplitude of the radio-frequency current is set at a value, which causes the semiconductor laser to oscillate in a multiple longitudinal mode, when the drive current for the semiconductor laser falls within a range such that an optical output power yielding a recorded optical density of not higher than approximately 2.0 may be obtained. Nonuniformity in image density is thereby prevented from occurring in the recorded image, and the cost of the apparatus is prevented from becoming markedly high due to countermeasures for nonuniformity in image density.

Abstract: A display system for converting N bit signals, each representing 2.sup.N gray levels, to M bit signals representing 2.sup.M gray levels, where N is an integer larger than or equal to 2 and M is an integer satisfying N>M.gtoreq.1. Each of the N bit signals are separated into higher M bits and lower N-M bits. There are 2.sup.N-M tables, each of which stores a distinctive set of P.times.Q modification values satisfying P.times.Q.gtoreq.2.sup.N-M. One of the tables is selected using the N-M bits. Unequality between a first set of modification values and a second set of modification values of the selected table are detected. The first set of modification values and the second set of modification values are exchanged to generate a modified table of the selected table. The M bits of one N bit signal and each of the modification values of the selected table are added to generate a first set of P.times.Q M bit signals.

Abstract: A human powered hang glider has a right main wing and a left main wing, both of which are swingably attached to a post by a universal joint. A rope is stretched in a loop shape between a pedal provided at a lower part of the post and the main wing, and is fixed to the pedal and the main wing. By operation of the pedals, the main wings are flapped like a bird flaps its wing. By this flapping action of the main wings, the hand glider can take wing, whether or not an upcurrent is present.

Abstract: A metal corner fitting for a wooden picture frame having two leg pieces, the leg pieces having screw slits thereon which form an angle .alpha. between the back thereof and the back of a picture frame with the outside edge of the leg pieces making contact with the back of the frame piece. The screw slits extend through the leg pieces at a slight angle so that they are inclined toward the corner portion of the corner metal fitting at an angle .beta..