Light beam scanning apparatus

A light beam scanning apparatus comprising:

• a light emitting device which generates a light beam;
• a light beam scanning member which scans a light beam against a scanned surface so that said light beam output from said light emitting device scans on said scanned surface in a horizontal scan direction;
• a sensor which is arranged on said scanned surface or a position equivalent to a scanned surface, detects a light beam scanned by said light beam scanning member, and outputs an electric signal;
• a mirror which changes a passage position for a vertical scan direction of a light beam scanned by said light beam scanning member in a horizontal scan direction;
• a detection section which detects a maximum value for an electric signal output from said sensor in response to a light beam with its passage position gradually moved by said mirror;
• and
• a light quantity detection section which detects said light beam quantity when a maximum value detected by this detection section is smaller than a specified reference value;
• and
• a control section which determines a normal light beam when a maximum value detected by said detection section is greater than a specified reference value, determines an insufficient light beam quantity when said maximum value is smaller than a specified reference value and a light beam quantity detected by said light quantity detection section is smaller than a specified reference quantity, and determines a defocused light beam when said maximum value is smaller than a specified reference value and a light beam quantity detected by said light quantity detection section satisfies a specified reference quantity.

A light beam scanning apparatus comprising:

• a light emitting device which generates a light beam;
• a light beam scanning member which scans a light beam against a scanned surface so that said light beam output from said light emitting device scans on said scanned surface in a horizontal scan direction;
• a plurality of sensors each of which is formed wider than a width in a vertical scan direction of said light beam including light generated near an irradiated spot of said light beam, is arranged on said scanned surface or a position equivalent to a scanned surface so that a fine gap is provided in said horizontal scan direction, and outputs an electric signal corresponding to an irradiated light beam quantity.
• a mirror which changes a passage position for a vertical scan direction of a light beam scanned by said light beam scanning member in a horizontal scan direction;
• and
• a control section which controls a light beam's passage position by using said mirror so that a centrobaric position of said light beam quantity detected by two adjacent sensors out of said plurality of sensors matches a gap between said two sensors.

A light beam scanning apparatus comprising:

• a plurality of light emitting devices configured to output an light beam;
• a light beam scanning member which scans a light beam against a scanned surface so that said light beam output from said light emitting device scans on said scanned surface in a horizontal scan direction;
• a plurality of sensors each of which is formed wider than a width in a vertical scan direction of said light beam including light generated near an irradiated spot of said light beam, is arranged on said scanned surface or a position equivalent to a scanned surface so that a fine gap is provided in said horizontal scan direction, and outputs an electric signal corresponding to an irradiated light beam quantity;
• a mirror which changes a passage position for a vertical scan direction of a light beam scanned by said light beam scanning member in a horizontal scan direction;
• and
• a position detection sensor which is arranged on said scanned surface or a position equivalent to a scanned surface and continuously changes output values according to changes in scanning positions of said light beam;
• a control section which computes a difference between two output values, i.e., an output value from said position detection sensor when a centrobaric position for said light beam quantity matches a gap between first and second sensors adjacent to each other out of said plurality of sensors and an output value from said position detection sensor when a centrobaric position for said light beam quantity matches a gap between said second sensor and a third sensor adjacent thereto, and provides control so that an interval between light beams equals the computed difference.

A light beam scanning apparatus comprising:

• a light emitting means for outputting a light beam;
• a light beam scanning means for scanning a light beam output from this light emitting means onto a scanned surface in a horizontal scan direction;
• a detection means, arranged on said scanned surface or a position equivalent to a scanned surface, for detecting a light beam scanned by said light beam scanning means, and outputting an electric signal;
• a change means for changing a passage position for a vertical scan direction of a light beam scanned by said light beam scanning means in a horizontal scan direction;
• a detection means for detecting a maximum value for an electric signal output from said detection means in response to a light beam with its passage position gradually moved by change means;
• and
• a control means for determining a normal light beam when a maximum value detected by said detection means is greater than a specified reference value, and for determining a defocused light beam when said maximum value is smaller than a specified reference value.

A light beam scanning apparatus comprising:

• a light emitting means for outputting a light beam;
• a light beam scanning means for scanning a light beam output from this light emitting means onto a scanned surface in a horizontal scan direction;
• a detection means, arranged on said scanned surface or a position equivalent to a scanned surface, for detecting a light beam scanned by said light beam scanning means, and outputting an electric signal;
• a change means for changing a passage position for a vertical scan direction of a light beam scanned by said light beam scanning means in a horizontal scan direction;
• a detection means for detecting a maximum value for an electric signal output from said detection means in response to a light beam with its passage position gradually moved by change means;
• and
• a light quantity detection means for detecting said light beam quantity when a maximum value detected by this detection means is smaller than a specified reference value;
• and
• a control means for determining a normal light beam when a maximum value detected by said detection means is greater than a specified reference value, determining an insufficient light beam quantity when said maximum value is smaller than a specified reference value and a light beam quantity detected by said light quantity detection means is smaller than a specified reference quantity, and determining a defocused light beam when said maximum value is smaller than a specified reference value and a light beam quantity satisfies a specified reference quantity.

A light beam scanning apparatus comprising:

• a light emitting means for outputting a light beam;
• a light beam scanning means for scanning a light beam output from this light emitting means onto a scanned surface in a horizontal scan direction;
• a plurality of detection means each of which is formed wider than a width in a vertical scan direction of said light beam including light generated near an irradiated spot of said light beam, is arranged on said scanned surface or a position equivalent to a scanned surface so that a fine gap is provided in said horizontal scan direction, and outputs an electric signal corresponding to an irradiated light beam quantity;
• a change means for changing a passage position for a vertical scan direction of a light beam scanned by said light beam scanning means in a horizontal scan direction;
• and
• a control means for controlling a light beam's passage position by using said change means so that a centrobaric position of said light beam quantity detected by two adjacent detection means out of said plurality of detection means matches a gap between said two detection means.

A light beam scanning method comprising:

• scanning a light beam against a scanned surface so that said light beam output from a light emitting device scans on said scanned surface in a horizontal scan direction;
• detecting a light beam scanned in a horizontal scan direction and outputting an electric signal by using a sensor which is arranged on said scanned surface or a position equivalent to a scanned surface;
• gradually moving a passage position for a vertical scan direction of said light beam scanned in a horizontal scan direction;
• detecting a maximum value for an electric signal output from said sensor in response to a light beam with its passage position gradually moved;
• determining a normal light beam when the detected maximum value is greater than a specified reference value;
• and
• determining a defocused light beam when said maximum value is smaller than a specified reference value.

A light beam scanning method comprising:

• scanning a light beam output from a light emitting device onto a scanned surface in a horizontal scan direction;
• detecting a light beam scanned in a horizontal scan direction and outputting an electric signal by using a sensor which is arranged on said scanned surface or a position equivalent to a scanned surface;
• gradually moving a passage position for a vertical scan direction of said light beam scanned in a horizontal scan direction;
• detecting a maximum value for an electric signal output from said sensor in response to a light beam with its passage position gradually moved;
• determining a normal light beam when the detected maximum value is greater than a specified reference value;
• detecting said light beam quantity by using a light quantity detection section when said maximum value is smaller than a specified reference value;
• determining an insufficient light beam quantity when said maximum value is smaller than a specified reference value and said light beam quantity is smaller than a specified reference quantity;
• and
• determining a defocused light beam when said maximum value is smaller than a specified reference value and a light beam quantity satisfies a specified reference quantity.

A light beam scanning method comprising the steps of:

• scanning a light beam output from a light emitting device onto a scanned surface in a horizontal scan direction;
• detecting a light beam scanned in a horizontal scan direction and outputting an electric signal by using a sensor which is arranged on said scanned surface or a position equivalent to a scanned surface;
• gradually moving a passage position for a vertical scan direction of said light beam scanned in a horizontal scan direction;
• detecting a maximum value for an electric signal output from said sensor in response to a light beam with its passage position gradually moved;
• determining a normal light beam when a maximum value detected by this step is greater than a specified reference value;
• and
• determining a defocused light beam when said maximum value is smaller than a specified reference value.

A light beam scanning method comprising the steps of:

• scanning a light beam output from a light emitting device onto a scanned surface in a horizontal scan direction;
• detecting a light beam scanned in a horizontal scan direction and outputting an electric signal by using a sensor which is arranged on said scanned surface or a position equivalent to a scanned surface;
• gradually moving a passage position for a vertical scan direction of said light beam scanned in a horizontal scan direction;
• detecting a maximum value for an electric signal output from said sensor in response to a light beam with its passage position gradually moved;
• determining a normal light beam when this detected maximum value is greater than a specified reference value;
• detecting said light beam quantity by using a light quantity detection section when said maximum value is smaller than a specified reference value;
• determining an insufficient light beam quantity when said maximum value is smaller than a specified reference value and said light beam quantity is smaller than a specified reference quantity;
• and
• determining a defocused light beam when said maximum value is smaller than a specified reference value and a light beam quantity satisfies a specified reference quantity.