Distance image acquisition apparatus and distance image acquisition method

A distance image acquisition method for a distance image acquisition apparatus, which comprises a distance image sensor in which a plurality of light receiving elements are arranged in a two-dimensional manner, a pulse light emission unit which irradiates a plurality of subjects within a distance measurement region with pulse light, and an imaging lens which images reflected light of the pulse light irradiated from at least the pulse light emission unit and reflected from the subjects on the distance image sensor, the distance image acquisition method comprising:

• an exposure control step of controlling exposure in the distance image sensor according to a first drive mode;
• and
• a distance image generation step of generating a distance image corresponding to distances of the subjects within the distance measurement region based on an output of the distance image sensor subjected to exposure control in the exposure control step,
• wherein the first drive mode performs first exposure control and second exposure control, wherein the first exposure control emits pulse light from the pulse light emission unit, starts exposure after a first predetermined time elapses after the pulse light is emitted from the pulse light emission unit, and ends the exposure after a second predetermined time elapses, to generate a difference in exposure based on a light reception time of the pulse light between the corresponding light receiving elements of the distance image sensor according to at least the distances of the subjects, the first predetermined time being a time until the pulse light emitted by the pulse light emission unit and reflected by a farthest one of the subjects within the distance measurement region begins to be received by the light receiving elements, the second predetermined time being a time until the pulse light emitted by the pulse light emission unit and reflected by the farthest one of the subjects finishes being received by the light receiving elements, and
• wherein the second exposure control emits pulse light from the pulse light emission unit and a phase of exposure start with respect to the pulse light is made different from a phase of exposure start with respect to the pulse light of the first exposure control.