Abstract: A sheet feeding device includes a cassette in which recording media are configured to be stacked. The cassette includes a rear end regulation member configured to be moved in a direction in which the recording media are fed to regulate rear ends of the recording media and a size detection device configured to swing with movement of the rear end regulation member. The sheet feeding device further includes a size determination device arranged within an area corresponding to a width of the cassette in the direction in which the recording media are fed. The size determination device is configured to determine a size of the recording media stacked in the cassette by detecting a position of the size detection device.

Abstract: A recording apparatus has a feed mechanism for feeding a recording medium loaded on a recording-medium loading section; a recording unit for recording on the recording medium fed by the feed mechanism; and a recording-medium discriminating device for discriminating the type of recording medium loaded on the recording-medium loading section. The type of recording medium is discriminated by the recording-medium discriminating device before the feeding operation by the feed mechanism, and the operation of the recording unit is controlled according to the type of recording medium stored in a memory.

Abstract: There is provided an image forming apparatus which can control reciprocation of a carriage and paper feed in a highly accurate manner and form an image of high quality even when paper skews or paper of a different type from that of the paper set is supplied. An ink jet printer (1) provided with motion sensor (70) in a carriage (31) determines the type of paper (P) by using a paper position signal output by the motion sensor (70) and changes printing conditions in accordance with the type of paper. Also, the ink jet printer (1) calculates a moving amount of the carriage (31), a feed amount and a deviation amount of the paper (P), and controls the reciprocation of the carriage (31) and the feeding of the paper (P) based on calculated values.

Abstract: A sheet size detection apparatus including, a sheet stacking device on which sheets are stacked and which can be loaded into and unloaded from a loading portion, a sheet size selection member provided on the sheet stacking device, a position of the sheet size selection member being changeable in accordance with a size of stacked sheets, a sheet size detection device provided on the loading portion for detecting the sheet size based on a relative positional relationship with the sheet size selection member, a locking member that can lock the sheet size selection member, and an unlock member for releasing a locking operation of the locking member.

Abstract: A recording start position is obtained effectively with high precision and in a short time.

Abstract: An embodiment of the invention is disclosed in which media advances at a first speed to an interim position based on signals from a first sensor having a first accuracy. While the media is advancing at the first speed, signals are accumulated from a second sensor having a second accuracy greater than the first accuracy. Upon the media reaching the interim position, an actual position of the media is adjusted based on the signals accumulated from the second sensor.

Abstract: A paper sensing apparatus of an office machine has a sensor actuator disposed to pivot with respect to a pivot center of a conveying roller by a printing paper when the printing paper is conveyed, and a sensing unit generating a paper sensing signal in accordance with a rotation of the sensor actuator. Accordingly, the paper sensing apparatus is capable of accurately sensing a leading end of the printing paper, and thus a top margin of the printing paper can be effectively controlled as the paper sensing apparatus is installed to be operated with respect to a rotation center of the conveying roller so that an error generated during sensing a paper top position due to a lengthened distance between the conveying roller and a transferring roller can be reduced.

Abstract: To provide a recording-material type determination apparatus and recording-material type determination method which can determine the type of recording material using simple calculations as well as to provide an image forming apparatus capable of obtaining stable image quality independent of the type of recording material using the apparatus and method. Based on data read by a read unit which reads surface images of recording material, a first calculation unit calculates the depth of irregularities in the surface of recording material and stores the results of calculation in a register A while a second calculation unit calculates the spacing of irregularities on the surface of the recording material and stores the results of calculation in a register B. Based on the values in the registers A and B, the type of recording material such as gloss paper, plain paper, rough paper or OHT is determined.

Abstract: A pagewidth drop on demand printer includes a printhead having an array of fixed printing nozzles thereon. A platen having a platen surface upon which a sheet rides to receive ink from the printing nozzles is situated alongside the nozzles. A sensor is provided to measure an offset of the print surface of the sheet with respect to the printing nozzles and means is provided effecting movement of the platen to alter the offset. This is typically done by making a compensatory rotation of the platen.

Abstract: A printer includes: a paper transport unit; a print unit including a print head; a downstream sensor mounted on the print head; an upstream sensor disposed upstream of the downstream sensor; and a control unit. The control unit makes the paper transport unit transport paper at a first speed of low speed and a second speed of high speed. The control unit obtains first and second transport distances with which the paper has been transported since being detected by the upstream sensor and till being detected by the downstream sensor, while transporting the paper at the first and second speeds. The control unit calculates a response delay time of the upstream sensor from a difference between the first transport distance and the second transport distance, and corrects a remaining printable distance on a paper rear end side on the basis of the response delay time.

Abstract: A paper skew detection apparatus in an inkjet printer. The paper skew detection apparatus includes a first light emitter positioned below the paper being transported to irradiate light onto the paper; a second light emitter spaced apart from the first light emitter a predetermined distance and positioned below the paper being transported to irradiate light onto the paper; and a detector positioned on one side of a carriage to receive light emitted by the first and second light emitters. Here, the carriage holds an ink cartridge, below which a print head to discharge ink is installed, and reciprocates rectilinearly in a direction orthogonal to a transport direction of the paper.

Abstract: The values of the detection signals of a record medium and the placement face thereof detected as a recording head moves from one end of the record medium to an opposite end are stored. A predetermined threshold value is found based on a profile found from the stored values of the detection signals. Both ends of the record medium are determined according to the threshold value and the width of the record medium is found. Accordingly, the threshold value matching the used record medium can be set, so that an easy determination can be made as to whether or not change of the detection signal exceeding the threshold value occurs and change of the detection signal falling below the threshold value occurs, and the width of the record medium can be found accurately.

Abstract: A medium-edge setting device detects edges of a paper (S111) and acquires data for left and right edge candidate positions (S120). The medium-edge setting device determines whether the difference between left and right center-edge distances is less than or equal to a predetermined value (S150). If so (S150: YES), the right edge position is set to the right edge candidate position and the left edge position is set to the left edge candidate position (S160). If not (S150: NO), the paper is conveyed a predetermined amount (S190) and the paper edge detection is repeated. If the repetitions of the paper-edge detecting process exceed a predetermined number (S180; NO), then the larger of the left and right center-edge distances is set as the distance from the center of the paper to each edge position, and the left and right edge positions are set according to this distance (S200, S210, S220).

Abstract: Methods and systems for processing image data in connection with peripheral units such as laser printers are described. In one embodiment, an image pipeline is queried to determine at least one constraint which affects the image data provided to the image pipeline from a source of image data. If appropriate, the constraint(s) is imposed on the image data to provide constrained image data. After the constraint is imposed on the image data, the constrained image data is provided from the source to the image pipeline for processing into a page-arranged output. In another embodiment, image data which is provided by a source is stored in a first buffer. A handle is assigned to the image data. The handle is passed through at least a portion of the image pipeline. After such passing, at least a portion of the image data which was stored in the first buffer is copied directly into at least one strip buffer, with such copying being the first copying of the image data after the storing thereof in the first buffer.

Abstract: A print medium exit system in a printer includes a kicker device ejecting a sheet of print medium out of the printer. A clutch mechanism prevents actuation of the kicker device when the clutch mechanism is engaged by the sheet of print medium.

Abstract: A roll-paper printing system comprises carry-amount detecting means, recording means, and updating means. The carry-amount detecting means detects a carried amount of the roll paper; the recording means records amount information regarding an amount of the roll paper; and the updating means makes the amount information be recorded on the recording means based on the carried amount detected by the carry-amount detecting means. The updating means makes the amount information be recorded on the recording means when a physical process for indicating a break in roll-paper usage is conducted to the roll paper.

Abstract: A method for improving security with a printer and sensitive hardcopy output. The method comprises examining incoming print jobs for indication of sensitivity and need for increased security. Any such identified job when printed is monitored. This monitoring is accomplished by watching a sensor provided on the output bin. When the identified job is removed from the printer a message is sent to the originator of the print job with a time stamp indicating that the hardcopy output has been removed.

Abstract: There are provided a tape printing apparatus and an image forming method and a label producing method for the tape printing apparatus. A second print image area as an affixing area for having a second print image affixed thereto, is set in an area of the first print image, such that the second print image can be affixed to the affixing area, the second print image being printed on a second tape having a width equal to or smaller than that of the first tape. A first print image having the second print image area provided therein is formed.

Abstract: A method of adjusting the positioning of a media sheet in an imaging device is provided. Data is collected related to the positioning of a media sheet in a plurality of ejection/positioning sequences. The position of a subsequent sheet is adjusted based on the data.

Abstract: An analog encoder system repeatedly switches back and forth between monitoring of first and second encoder output signals to track movement of a structure associated with the encoder. An energization level of an encoder light element may be controlled in accordance with which encoder output signal is being monitored.

Abstract: An image forming device capable of reducing transfer errors of paper even when the transfer amount of paper cannot be detected accurately. The image forming device is provided with a motion sensor, and calculates the transfer amount of paper using signals output by the motion sensor. It is determined whether or not the transfer amount is within a predetermined normal range. If it is determined that the transfer amount is within the normal range, a paper transfer amount control value is set to the calculated transfer amount, while if it is determined that the transfer amount is outside the range, the paper transfer amount control value is set to a preliminarily set standard transfer amount. The image forming device controls the transfer of paper based on the above paper transfer amount control value.

Abstract: Methods and apparatus for improving printing efficiency are shown and described including recognition of a condition where print head swath height spans successive media including a gap therebetween. Such conditions provide opportunity to print concurrently on both media pages during one print head scan. This utilizes more fully the vertical swath height of the printer by applying when possible image to media exposed to the print head including successive media pages concurrently.

Abstract: A device for controlling the transport of a printing product by a print-related machine includes at least one locally stationary photoelectric detector having a light transmitter, by which light is directed at a surface of the printing product, and at least one light receiver for detecting the light remitted from the surface, a device for evaluating the remitted light, the evaluating device having computational equipment connected to adjustment elements for controlling the effect of a cyclically operating transporting device, the light transmitter including a light source for transmitting coherent light, and the light receiver including an element for recording the spatial distribution of the stray light, a timing device provided for synchronizing the instant of time of the recording with the cycle of the transporting device, and the evaluation device having a comparator for the local distribution of the stray light at the instant of time of the recording provided with a prescribed distribution.

Abstract: In the ticket printer, a ticket tray is mounted next to the infeed adapter of the printer mechanism for feeding blank tickets into the printer mechanism. The ticket tray is releasably mounted in a pullout module by means of a three point attachment comprising a button clip and a button pin. In another aspect of the invention, a ticket presenter has overlapping upper and lower plates defining a ticket delivery gap there between. The delivery gap has a photo sensor mounted therein, a mating bulge and cavity pair, and spikes cooperating with the bulge and cavity pair for effectively separating tickets from a strip of fan-fold tickets. In yet another feature of the present invention there is provided a communication link between the MCU and the PLD of the ticket printer for programming the PLD through the MCU using a personal computer.

Abstract: An ink jet printer forms an image frame in a continuous recording sheet at a size PL with reference to a feeding direction. The continuous recording sheet includes plural recording sheets, and a splicing portion for splicing the plural recording sheets to one another in one line. In ink jet printing, the image frame is printed to the continuous recording sheet with a printing bead while the continuous recording sheet is fed in the feeding direction. It is detected whether the splicing portion comes past a predetermined position upstream from the printing head at a distance L1. The printing head is inhibited from printing the image frame if an unavailable region including the splicing portion is estimated to overlap on a region of the image frame according to a detection signal from the detecting step.

Abstract: A resonance chamber is provided in a printing device, or in a print medium supply tray of the printing device, to determine the size of the print medium in the printing device. The supply of print medium and the resonance chamber are positioned so that the print medium covers a portion of the resonance chamber. An audio signal system then emits an audio signal to drive the resonance chamber. The frequency of the audio signal is varied until the natural resonance frequency of the chamber, as partially covered by the print medium, is discovered. The resonance frequency of the chamber will correspond to the amount of the chamber that is covered by the print medium and, hence, to the length (or width) of the print medium. In this way, the size of the print medium, whether standard or custom, can be determined.

Abstract: A tray for holding a stack of sheets of paper for feeding into a printer includes opposite paper guides one of which is adjustable relative to the other for varying the spacing between the paper guides. The adjustable paper guide is slideable across the tray and includes a releasable lock which engages the tray for locking the paper guide in position. The releasable lock is preferably a spring biased lever which includes a tooth that normally engages a rack in the paper tray until released by operation of the lever for the paper guide to be adjusted. As the paper guide is locked in position it cannot move away from its location during feeding of papers from the tray. The paper guide may also include a spring arm for applying a bias against the edge of the sheets of paper as they are fed from the tray to prevent them from skewing.

Abstract: A removable cartridge with sheets that are to be removed from the cartridge and used by an apparatus comprising a housing for containing the sheets which are to be sequentially used by the apparatus when the cartridge is inserted into the apparatus, means provided in the housing for permitting sheets to be fed by the apparatus from the cartridge, a display provided on the housing which is viewable by a user when the cartridge is removed from the apparatus to indicate the number of sheets remaining in the cartridge. The display comprises a plurality of selectable digit elements each of which corresponds to a particular number, each selectable digit element containing cholesteric liquid crystals when selectively activated indicate a number that corresponds to the number of sheets remaining in the cartridge, and provide a measurable parameter.

Abstract: A system for printing images on a substrate includes a multiplicity of print heads mounted in a carriage and positioned a distance from the substrate. A sensor detects the thickness of the substrate as the substrate moves through the system, and a control system receives the substrate thickness information detected by the sensor and transmits signals to a motor coupled to the carriage. These signals instruct the motor to adjust the position of the carriage to maintain a desired gap between the print heads and the substrate.

Abstract: A multi-purpose, transmissive paper sensor includes a light beam projector and light detector having an analog output signal. Changes in the output signal from an open loop condition indicate the presences of at least one print medium being in the field-of-view of the sensor. Output signals indicative of print media leading edge, trailing edge, and number of sheets interrupting the light beam provide improved print media transport control for hard copy apparatus.

Abstract: A reflective type light sensitive sensor assembly is used for sensing the position of marks on a surface moving past the sensor. A typical showing is in relation to sensing marks on a ribbon used during printing operations, or lamination operations. The sensor assembly includes a LED light source that has a central axis, and a light sensitive transistor or sensor mounted in a single housing, with the housing oriented so that the axis of the light from the LED is inclined at an acute angle relative to the surface of the ribbon. The axis is at an angle other than perpendicular or near perpendicular to the surface. The marks used for identification are light diffusing marks, such as white marks or strips that will provide adequate reflection of light back to the light sensitive transistor or sensor forming part of the sensor assembly.

Abstract: This machine for postage metering a flat object (6) such as an envelope or a label comprises a horizontal opening for inserting an object, leading to two stops (8, 9) at right angles, a device for holding the object by gripping it between a fixed upper ceiling (2) comprising a window (2′) and a lower plate (3) vertically movable by means of a drive mechanism, an ink jet printing device (1) whose nozzles are disposed inside the window (2′) of said ceiling, and a sensor (10) of the presence of an object in the vicinity of the corner of the stops (8, 9), which starts the drive mechanism of the plate (3) for gripping the object (6) and the printing cycle. A motorized transverse rake (4) moves the object (6), while it is gripped, in front of the printing device (1).

Abstract: A system is provided for use in a printer, the system including a media width sensor which is configured to sense the presence of media at a predetermined transverse position within the media path. By sensing media at such predetermined transverse position, it is possible to determine media width, and thus to identify media type. Correspondingly, it is possible to adapt media handling to address particular characteristics of the media, namely, thickness of the media and width of the media sheets.

Abstract: A printer, which can detect a media sheet type, includes: a light emitting source and a reflector, the light emitting source being capable of emitting light in a light emission direction towards the reflector, the reflector being arranged in light emission direction and being capable of reflecting light emitted by the light emitting source in a light reflection direction; a detector being arranged such that it can detect reflected light; and a controller connected to the reflector, the controller being capable of modulating a characteristic of the reflected light.

Abstract: An inkjet printing system for printing on a print medium having a top-of-form (TOF) indicator includes a printhead assembly, a top-of-form (TOF) detector adapted to detect the TOF indicator, a positional sensor adapted to sense a relative position of the print medium to the printhead assembly, and a controller associated with the printhead assembly, the TOF detector, and the positional sensor. The printhead assembly includes a first printhead subarray and a second printhead subarray offset from the first printhead subarray such that the controller is configured to initiate operation of the first printhead subarray after the TOF detector detects the TOF indicator and initiate operation of the second printhead subarray at a predetermined interval after the TOF detector detects the TOF indicator. As such, the predetermined interval is related to the relative position of the print medium.

Abstract: A multi-purpose, transmissive paper sensor includes a light beam projector and light detector having an analog output signal. Changes in the output signal from an open loop condition indicate the presences of at least one print medium being in the field-of-view of the sensor. Output signals indicative of print media leading edge, trailing edge, and number of sheets interrupting the light beam provide improved print media transport control for hard copy apparatus.

Abstract: A thermal transfer printer containing a means for feeding a plurality of thermal transfer sheets and a plurality of image receiving sheets, a platen roller placed in the feeding path of the thermal transfer and image receiving sheets, and a recording section with a thermal head with a plurality of heating resistors for selective activation based upon image data to record the image on the image receiving sheets when they and the thermal transfer sheets are forced together by the platen roller so each image receiving sheet is pressed on the thermal head surface by the platen roller. The recording section also has a means to detect when at least one of the thermal transfer and image receiving sheets being recorded are out and a means automatically to exchange the thermal transfer or image receiving sheets with new sheets based upon the detected result.

Abstract: A printer has a print path, a code strip disposed in parallel along the print path, a sensor for sensing the code strip, a driving system for moving the sensor along the code strip, a timer, a memory and a position signal generator. The code strip has embedded position information, which the sensor reads. The sensor generates a first or a second code signal depending upon the position of the sensor on the code strip. The timer generates clock signals at a rate that corresponds to an expected rate of change of the first and second signals from the sensor when the driving system moves the sensor along the code strip. The memory is used to hold the locations of defective areas on the code strip. The position signal generator uses the sensor to generate a position signal when the sensor is not reading within any of the defective areas on the code strip, and uses the clock signals from the timer to generate the position signal when the sensor is moving within any of the defective areas on the code strip.

Abstract: A device for controlling the transport of a printing product by a print-related machine includes at least one locally stationary photoelectric detector having a light transmitter, by which light is directed at a surface of the printing product, and at least one light receiver for detecting the light remitted from the surface, a device for evaluating the remitted light, the evaluating device having computational equipment connected to adjustment elements for controlling the effect of a cyclically operating transporting device, the light transmitter including a light source for transmitting coherent light, and the light receiver including an element for recording the spatial distribution of the stray light, a timing device provided for synchronizing the instant of time of the recording with the cycle of the transporting device, and the evaluation device having a comparator for the local distribution of the stray light at the instant of time of the recording provided with a prescribed distribution.

Abstract: A multi-purpose, transmissive paper sensor includes a light beam projector and light detector having an analog output signal. Changes in the output signal from an open loop condition indicate the presences of at least one print medium being in the field-of-view of the sensor. Output signals indicative of print media leading edge, trailing edge, and number of sheets interrupting the light beam provide improved print media transport control for hard copy apparatus.

Abstract: The invention accomplishes print medium feed functions, at least in part, by making use of pre-existing printer apparatus that is used to accomplish other functions of the printer. For example, the invention can enable the use-of a single print drive mechanism to accommodate multiple print medium feed paths within a printer and, in particular, feed paths in which print media are fed into the print drive mechanism in different (e.g., opposite) directions. Additionally, the invention can enable a rotatable media guide that can be positioned in one position to guide a sheet of a print medium during a print operation and in another position to release the sheet of the print medium after the printing operation, to be positioned in still another position to facilitate guiding a sheet of a print medium into a print drive mechanism after the sheet has traversed a gap in the feed path.

Abstract: A paper detecting apparatus of an electrophotographic processor allows reduction of product cost by enabling total sensing of paper loading and paper transporting in a paper cassette with only one sensor. The paper detecting apparatus inter-actuates the second actuator for turning the switch on and off with the first actuator to which displacement is produced depending on paper loading in the paper cassette, and produces a displacement of the second actuator depending on the actuation of the first actuator. It also produces a displacement of the second actuator depending on the paper transport, and is thereby able to sense both the paper loading state within the paper cassette and the paper transport state within the picture processor according to the on/off state of the switch. Accordingly, both paper loading within the paper cassette and paper transporting within the electrophotographic processor can be sensed through the use of only one sensor. Therefore, product cost reduction may be achieved.

Abstract: A printing apparatus has a small size that facilitates replacement of rolled paper, removal of jammed paper, etc., and alleviates the likelihood of a paper jam with a considerably simple structure. The printing apparatus comprises a rolled-paper holder (2), which is provided with a first holder (2b) for use in carrying out printing on rolled paper (1), and a second holder (2a) for use in setting the rolled paper (1). The rolled paper (1) is moved from the second holder (2a) to the first holder (2b) as a main body of the apparatus is shifted from a paper setting position to a printing work position, thereby facilitating the setting of the rolled paper (1) and removal of jammed paper, since the rolled paper (1) can be temporarily supported by the second holder (2a) in order to provide sufficient work space when replacing the rolled paper (1) or removing jammed paper.

Abstract: A portable printer comprising a door pivotally coupled to a main body of the portable printer at a back end, a printing medium roller support rotatably mounted on the door of the portable printer, a platen rotatably positioned at a front end of the door, a door locking mechanism having a pair of door locking latches respectively positioned at opposite ends of the platen, a roller movably and rotatably coupled to the door locking mechanism and positioned parallel to the platen, a pair of levers movably coupled to the door locking mechanism for pressing the roller against the platen when the door is closed to the main body, a support frame positioned within the main body, a print head pivotally coupled to the support frame, a pair of coil springs coupled between the print head and the support frame such that the print head is essentially floating against the support frame, a body locking mechanism having a pair of body locking latches for latching with respective door locking latches, a gear system coupled to t

Abstract: A postage meter machine has a digital printer device with a guide plate and a transport mechanism for print media controlled by a control unit that generates print control signals for a printhead in order to print the print medium surface with a corresponding print format while the print medium is being transported past the printhead. A print sensor is arranged in the guide plate before a recess for the printhead. A preparation sensor is arranged in the guide plate at a predetermined distance upstream, preceding the print sensor. The control unit includes a microprocessor to which an encoder for determining the belt travel path of the conveyor belt and the aforementioned sensors are connected. The microprocessor, together with a memory, forms a belt counter that is updated on the basis of the signals supplied by the encoder.

Abstract: A stencil printer includes a printing drum which is rotated bearing thereon a stencil master, and a press roller which is pressed against the printing drum. A paper supply system supplies a printing paper to between the printing drum and the press roller so that the printing paper is conveyed pinched between the printing drum and the press roller. A paper supply controller controls the paper supply system so that the paper supply system supplies the printing paper to between the printing drum and the press roller at a first predetermined angular position of the printing drum for each rotation of the printing drum. The paper supply controller controls the paper supply system so that the printing paper supplied next by the paper supply system does not collide with the printing paper under printing when the printing paper is overlong.

Abstract: To facilitate printing of postage or other images onto media of variable size, an apparatus determines the size of the medium in at least one dimension prior to or during the printing of the image, such that the image to be printed is adjusted based upon the determined size of the medium. The apparatus may be a postage meter, in which case information is received by a data processor concerning the size of a mail piece and the postal value. An initial image is made up of a fixed portion, including postal indicia, and a user-defined variable portion, is then altered in view of this input to provide a final image for printing on the mail piece which fits fully on the mail piece. The alteration effects only the variable portion of the image, which may be truncated, scaled or replaced with a different variable portion.

Abstract: The present invention provides media sensors for sensing the position of a media in a printer, such as a thermal demand printer. A repositionable media sensor for monitoring the location of a web of label media which utilizes a visible light source projected onto the label media to accurately indicate the position of the media sensor to the operator relative to the label media and facilitate any required adjustment thereof. A printed label sensor is provided for use with a thermal demand printer and includes a light emitter and light detector pair wherein a single light pipe for receiving a sensing beam from the emitter and reflecting the sensing beam at a predetermined angle towards the detector is provided. Preferably, the light pipe is mounted in a peel bar and no electronics are required outside the electronic housing of the printer.

Abstract: It is intended to expand the recording width of the serial printer by executing the one-directional recording, instead of the two-directional recording, according to the required recording width. For this purpose there is provided a serial recording apparatus comprising a carrier for mounting a recording head for executing recording on a recording medium, a scanning section for causing the carrier to execute a reciprocating scanning motion along the recording medium and a recording section for executing the recording in the scanning motions in two directions of the carrier in case the recording width required for the recording along the scanning direction of the carrier does not exceed a predetermined reference recordable width, and executing the recording in the scanning motion of the carrier in one direction only in case the required recording width is larger than the predetermined reference recordable width.

Abstract: A printer includes platen opening/closing means for increasing a gap between a platen and a print head when a printing medium is set to the printer, and cleaning means for cleaning a photo sensor device. The cleaning means removes paper dust, for example, accumulated to such an extent as to interrupt the optical path between the light emitting and receiving elements of the photo sensor device. The cleaning means is controlled by a control means contained in the printer. The control means drives the cleaning means when an output signal level of the photo sensor device is below a predetermined signal level after the printing medium is discharged out of the printer.