Abstract: The visibility of the external scene from the inside of the transmissive transparent screen when the video image is not displayed and the visibility of the video image from the outside when the video image is displayed are satisfied. In a video image display system comprising a projection device 100 and a transmissive transparent screen 1 having a first surface and a second surface on the opposite side of the first surface, having a visible light transmittance of at least 5[%], and displaying video images projected from the projection device 100 installed on the first surface side, as video images visible to an observer on the second surface side, the following formula 1 is satisfied: ?1.5?ln(((B/A)/I)×G)?3.9??Formula 1 in the formula 1, A is the projection area [m2] of the projection device 100, B is the luminous flux [lm] projected onto A by the projection device 100, I is the ambient illuminance [lx] at the side of the second surface, and G is the screen gain of the transparent screen 1.

Abstract: Provided are a coupler that can be produced at a low cost and that enables an actuator and a valve to be easily attached and detached without using a fastener, and a removal tool for the same. According to a coupler (3) for an actuator (4) and a valve (2), which is sandwiched detachably between the actuator (4) and the valve (2), the valve (2) is provided with a flange portion (22) protruding from an outer periphery of a valve main body, and the coupler (3) is provided with an elastically deformable hook portion (31) latching onto an outer periphery of the flange portion (22) to prevent detachment of the coupler (3), and a fixing portion (35) fastened to the actuator (4).

Abstract: A method of determining coordinate system in a machining center in which tool exchange is made after resetting the tool to the mechanical zero point. A reference position is set with respect to a program zero point at a position on a coordinate having the origin coinciding with the program zero point. The mechanical coordinate values of the reference position with respect to the mechanical zero point are computed and determined by making a reference portion of the tool coincide with the reference position. Then, the mechanical coordinate values of the program zero point are computed and determined from the reference position. In the tool exchange, the mechanical coordinate value of the program zero point in the direction of axis of spindle is corrected in accordance with the difference of length between two tools, by reading the data concerning the tool lengths from a tool file storing the tool lengths in the direction of axis of the spindle.