Abstract: A processor derives a plurality of unit density values which are each an average value of sensed densities for each of a plurality of unit areas sectioned for each unit length in a test toner image. The processor derives a weighted average of the plurality of unit density values to derive a test image density used for adjusting a control parameter in a printing portion. The unit length is a greatest common factor of two target lengths corresponding to perimeters of two types of target rotating members out of the plurality of rotating members. When a number of the plurality of unit areas is represented by n, n is a value obtained by subtracting 1 from an added value of a first constant and a second constant. The first constant and the second constant are values obtained by respectively dividing the two target lengths by the unit length.

Abstract: A toner concentration sensing apparatus includes a first acquisition processing portion, a second acquisition processing portion, and a third acquisition processing portion. The first acquisition processing portion acquires a first sensing value corresponding to light reflected by a first region of an image-carrying member where a toner image is not formed. The second acquisition processing portion acquires a second sensing value corresponding to light reflected by a second region of the image-carrying member where a toner image has been formed. The third acquisition processing portion acquires a component ratio of a component in the second sensing value, that corresponds to light reflected by toner adhered onto a surface of the image-carrying member, using a specific calculation formula determined based on a first relational expression based on the first sensing value and a second relational expression not based on the first sensing value, and the second sensing value.

Abstract: A speaker device includes a pair of diaphragms disposed opposite each other, a frame configured to vibratably support an outer periphery of the diaphragms in a vibration direction, and a plurality of driving parts configured to support a rear surface of each of the diaphragms and vibrate the diaphragms in response to an audio signal. The plurality of the driving parts include a pair of magnetic circuits in which a magnetic gap is formed in a direction different from the vibration direction of the diaphragms, a pair of voice coils vibratably arranged in the magnetic gap in one axis direction, vibrating so as to move toward or away from each other in response to the audio signal, and a rigid vibration direction converter part direction-converting the vibration of the voice coils and transmitting the vibration to the diaphragms.

Abstract: A speaker device includes a pair of diaphragms disposed opposite each other, a frame configured to vibratably support an outer periphery of the diaphragms in the vibration direction, and a plurality of driving parts configured to support a rear surface of each of the diaphragms and vibrate the diaphragms in response to an audio signal. The driving parts include a pair of magnetic circuits in which a magnetic gap is formed in a direction different from the vibration direction of the diaphragms, a pair of voice coils vibratably arranged in the magnetic gap in one axis direction, vibrating so as to move toward or away from each other in response to the audio signal, and a rigid vibration direction converter part configured to convert the direction of the vibration of the voice coils and transmit the vibration to the diaphragms.