JPH0897994A - Recorder - Google Patents

Abstract

PURPOSE: To attain sure synchronization in next and succeeding periods even in a case where detection of a light beam is failed in a period by the use of a detector taking synchronization in the recorder scanning the light beam periodically and recording the beam while taking synchronization. CONSTITUTION: When no synchronizing signal 19 is outputted from an SOS sensor even when a prescribed period elapses, a horizontal synchronizing signal processing section 61 sends a correction mode setting signal 62 to a correction section 63 to set the section 63 to be the correction mode. The correction section 63 in this mode set correction data 64 from '0' to a prescribed positive value and gives the data to the horizontal synchronizing signal processing section 61. The horizontal synchronizing signal processing section 61 lights a laser beam 14 in a timing required for the SOS sensor 18 for its detection depending on the correction data 64. In the correction mode, since the succeeding lighting state is corrected by the value, synchronization is taken.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording device such as a printer, a copying machine or a facsimile device which forms an image on a photoconductor using a light beam such as a laser beam and records the image.
More specifically, the present invention relates to a recording apparatus in which a synchronization sensor such as an SOS sensor is used to synchronize the scanning of the light beam with respect to the photoconductor, and the light beam is continuously turned on at the detection timing of the synchronization sensor.

[0002]

2. Description of the Related Art A typical example of a recording apparatus that records an image using a light beam is a laser printer. In a laser printer, a laser beam is output from a light source, and the laser beam is output onto a photosensitive body such as a photosensitive drum or a photosensitive belt.
An electrostatic latent image is formed by scanning line by line. The electrostatic latent image is developed using toner particles, and the toner image obtained by this is transferred from the photosensitive member to a sheet. After that, the sheet is fixed by the fixing device and discharged to the discharge tray.

FIG. 4 shows the configuration of the main part of an example of such a conventional recording apparatus. A laser beam 12 output from the semiconductor laser 11 enters a polygon mirror (rotating polygon mirror) 13. The polygon mirror 13 has a polygonal shape, and a plurality of surfaces each constitute a reflecting surface. The polygon mirror 13 is rotated at a high speed by a drive motor (not shown). As the incident surfaces of the laser beam 12 are switched one by one, the laser beam 14 reflected from them changes its traveling direction periodically within a predetermined angle range. As a result, the laser beam 14 that has passed through the lens 15 has the photosensitive drum 1
The surface of 6 is sequentially scanned in the axial direction. The photoconductor drum 16 is rotated at a constant speed in a predetermined rotation direction by a drum motor (not shown).

By the way, an SOS (scanning start) sensor 18 is arranged near the end of the photosensitive drum 16 on the scanning start point side. The SOS sensor 18 detects the passage of the laser beam 14 and outputs a synchronization signal 19 each time. The synchronization signal 19 is the horizontal synchronization processing unit 2
1 is input to control the horizontal synchronization of the laser beam 12. That is, the horizontal synchronization processing unit 21 outputs the horizontal synchronization signal 22 for instructing reading after a predetermined delay time from the arrival of the synchronization signal 19, and the recording information generation unit 23.
To output the image data 24 for one line each time. Based on the image data 24, the semiconductor laser 11 performs on / off control line by line. Here, the output of the horizontal synchronizing signal 22 is delayed from the generation of the synchronizing signal 19 by a certain time because the start point of the on / off control of the laser beam of each line by the image data 24 is set from the fixed position of the photosensitive drum 16. This is to start it accurately.

For this reason, the horizontal synchronization processing unit 21 uses SO
Every time the S sensor 18 outputs the synchronization signal 19, counting by a counter (not shown) is started. Then, the time when the laser beam 14 arrives at the recording start point of each line on the photoconductor drum 16 is predicted, and the modulation of the image data 24 by the semiconductor laser 11 is started at that timing.

By the way, in order for the SOS sensor 18 to detect the laser beam 14, the laser beam 14 must be detected at this time.
Must be lit. Therefore, conventionally, continuous lighting of the laser beam 14 is started at a time point slightly before the scheduled time at which the SOS sensor 18 detects the laser beam 14, and it is turned off when this is detected. Since the SOS sensor 18 can synchronize with the laser beam 14 when it detects it,
This is because the on / off control of the laser beam 14 may be performed according to the image data 24 at the time when the writing of the image on the photoconductor 16 is started.

Here, there is a problem in dealing with the case where the SOS sensor 18 does not detect the laser beam 14 even after the scheduled time. If, for example, the laser beam 14 is turned off at the timing to be detected or the beam deviates from the SOS sensor 18 due to noise generation in the recording device or vibration inside the device due to external force, The laser beam 14 is not detected by the SOS sensor 18 in the cycle. In this case, there are two methods of coping. One is a method of continuously turning on the laser beam 14 until the SOS sensor 18 detects the laser beam 14. According to this, although the synchronization is temporarily lost, the laser beam 14 is S
Scanning can be synchronized at the time when it is detected by the OS sensor 18.

However, if this method is adopted in a recording apparatus, the laser beam 14 scans the photosensitive member 16 in a continuously lit state until the synchronization is achieved. Therefore, depending on the developing method, the locus of the laser beam 14 turned on and scanned is developed as a black (corresponding developing color in the case of recording a color image) line, which significantly deteriorates the quality of the recorded image. There was a problem.

Therefore, another method is attracting attention as one that does not cause such a problem. In this method, when the SOS sensor 18 does not detect the laser beam 14 even after the scheduled time, the laser beam 14 is immediately detected.
The output of is stopped. For example, JP-A-3-
Japanese Patent Laid-Open No. 198474 discloses a recording apparatus adopting the latter method.

FIG. 5 (a) shows the proposed method. At time t ₁₁ , the SOS sensor 18 shown in FIG.
Suppose that the laser beam 14 is detected, the continuous lighting is stopped (turned off) from this point, and a counter (not shown) counts N counts corresponding to a time shorter than the first cycle by the first time. Then, at this time t ₁₂ , continuous lighting of the laser beam 14 is started so that the laser beam 14 of the next cycle is detected by the SOS sensor 18. When the SOS sensor 18 detects the laser beam 14 before the counter M counts a value larger than the value N, the continuous lighting of the laser beam 14 is stopped at this time t ₁₃ , and the next counting is similarly started. Let Here, the numerical value M is set as a value corresponding to an elapsed time that exceeds the scheduled time when the SOS sensor 18 detects the laser beam 14 and that the laser beam 14 does not reach the image forming area of the photoconductor.

Even after the time t ₁₃ , the laser beam 14 is turned on at the time t ₁₄ when the N count is performed and the SOS sensor 18 detects the laser beam 14 at the time t ₁₅ before the M count is performed. Starts the next N count from this time t ₁₅ . Then, the laser beam 14 is continuously turned on at time t ₁₆ when the N count is finished, and if this is detected by the SOS sensor 18 at time t ₁₇ before the M count is performed, the continuous turn-on of the laser beam 14 is stopped. The same applies hereinafter.

FIG. 1B shows a case where the SOS sensor fails to detect the laser beam in the recording apparatus adopting the proposed method. Similarly, it is assumed that the laser beam 14 is detected by the SOS sensor 18 at time t ₁₁ , and that the above-mentioned counter has started counting the numerical values N and M from this time. The laser beam 14 is continuously turned on at time t ₁₂ when the counter counts the numerical value N, and the detection operation of the laser beam 14 by the SOS sensor 18 starts from this point. At this time, the SOS sensor 18
It is assumed that the detection of the laser beam 14 due to is failed. Then, even if the numerical value M is counted, the SOS sensor 18 cannot detect the laser beam 14. Therefore, the continuous lighting of the laser beam 14 is forcibly stopped at time t ₁₈ when the value M is counted after time t ₁₃ . This eliminates the inconvenience that unnecessary black lines are reproduced on the photoconductor as described above. In the recording apparatus adopting the method of this proposal, the counters have numerical values N and M from this time t _18.
Counting is started, and synchronization is established by detecting the laser beam 14 in the same manner as described above.

[0013]

However, according to the proposed recording apparatus, the SOS sensor may not be able to detect synchronization. This will be described with reference to FIG. In this proposal, the SOS sensor 18 uses the laser beam 1
If the detection of 4 is unsuccessful, the next counting is started from the time when the numerical value M is counted. First laser beam 1
If the detection of No. 4 fails and counting is started from time t ₁₈ , this time t ₁₈ is delayed in time from the count start time t ₁₃ when normal detection is performed. Therefore, for example, when the detection of the laser beam 14 fails continuously, the lighting start time of the laser beam 14 is sequentially shifted.

As a result, in the example of FIG. 5, the counter is set to the numerical value N from time t ₁₉ after the detection of the laser beam 14 fails twice.
When t is counted, the time t ₂₀ when the turning on of the laser beam 14 is started is later than the time t ₁₇ when the actual detection is performed. That is, the laser beam 14
Since the beam is continuously turned on after the time t ₁₇ when the laser beam passes through the sensor 18, the laser beam 14 cannot be detected even when no trouble occurs in the device. In this case, the laser beam 14 is turned off at time t ₂₁ when the numerical value M is counted, and the next counting is started from this time point. However, even when counting from the time t ₂₁ is started, since the deviation further timing for detecting synchronization, it becomes impossible even synchronization detection at the next lighting. As described above, in the proposed recording apparatus, if the SOS sensor 18 fails to detect the laser beam 14 continuously a plurality of times, there is a problem that the subsequent synchronous detection becomes impossible. Of course, depending on how to set the numerical values N and M, in the worst case, it may be assumed that a single synchronization detection failure makes subsequent synchronization detection impossible.

In the above description, the recording apparatus using the laser beam 14 has been described, but the same problem occurs in recording apparatuses using other light beams.
Further, a similar problem will occur in a recording apparatus in which the scanning means other than the polygon mirror periodically scans the light beam.

Therefore, an object of the present invention is a recording apparatus for performing recording while periodically scanning a light beam and synchronizing with the light beam, and in the case where a detector for synchronization fails to detect the light beam. Even if there is, it is an object of the present invention to provide a recording device capable of ensuring synchronization in the subsequent cycles.

[0017]

According to a first aspect of the invention, (a) a photosensitive member for forming an image for recording, and (b) a light beam directed from one end to the other end of the photosensitive member. Means for periodically scanning the beam, (c) a synchronization sensor arranged on the scanning path of the light beam for detecting the scanning timing for each cycle, and (d) the synchronization sensor. Starting from the detected timing, a normal-time light beam lighting start control means for starting continuous lighting of the light beam for synchronization detection from a time point earlier by a first time than one cycle from this point, and (e) synchronization. When the light sensor detects the light beam, or when it is determined that the light beam has not been detected within the period when it should be, the continuous light of the light beam for synchronization detection in the period thereafter is continuously turned on. Finished A light beam off means that, (f)
When the light beam for synchronous detection is extinguished by the light beam extinguishing means without performing the detection within the period when the light beam is supposed to be detected, the first time is longer than the time period after one cycle elapses. The recording device is provided with an abnormal light beam lighting start control means for continuously lighting the light beam for synchronization detection from a point before the second time, which is longer than the time.

That is, according to the first aspect of the invention, with the timing detected by the synchronization sensor as a starting point, in the normal case, the synchronization detection is performed from a time point that is a first time before this one cycle elapses. Start the continuous lighting of the light beam. Here, the first time is set to 1 in consideration of the fact that the detection timing of the light beam deviates slightly in time.
It is a time provided to start the detection of the light beam a little earlier than the time when the cycle elapses. When the light beam is detected by the synchronization sensor, or when the light beam is not detected within the expected period, the light beam extinction means is used to end the continuous lighting of the light beam for synchronization detection. Let In the abnormal state in which the light beam extinguishing means extinguishes the light beam for synchronous detection without performing the detection within the period when the light beam should be detected, this determination is performed and one cycle elapses. The light beam is continuously turned on for the synchronization detection from the time point before the second time period which is longer than the first time period. That is, at the time of an abnormality, it is possible to determine the abnormality at a time later than the detection time of the normal time, so by starting the detection of the light beam at a time earlier than this, the start time of the detection is sequentially timed. It is possible to prevent a situation in which a delay occurs and to ensure synchronization.

According to the second aspect of the invention, (a) a photosensitive member for forming an image for recording, and (b) a laser beam is periodically scanned from one end to the other end of the photosensitive member. And (c) an SOS sensor which is disposed further on the scanning start side of the laser beam than the above-mentioned one end of the photosensitive member, and which detects the scanning timing of the laser beam for each cycle, (d) With the timing detected by the SOS sensor as a starting point, a normal-time laser beam lighting start control means for starting continuous lighting of the laser beam for synchronous detection from a time point that is a first time before one cycle elapses thereafter. (E) When the laser beam is detected by the SOS sensor, or when it is determined that the laser beam has not been detected within the period that should be performed, Laser beam extinguishing means for ending the continuous lighting of the laser beam for synchronous detection after that period, and (f) this laser beam extinguishing means without performing the detection within the period when the laser beam should be detected. When the laser beam for synchronous detection is turned off by the laser beam, the laser beam is continuously output for synchronous detection from a time point before the second time, which is longer than the first time period after one cycle has elapsed. The recording device is provided with a laser beam lighting start control means for abnormal lighting.

That is, according to the second aspect of the invention, the SOS
With the timing detected by the sensor as the starting point, in the normal case, continuous lighting of the laser beam is started for synchronization detection from a time point before the first period of time elapses from this one cycle. Here, the first time is a time provided to start the detection of the laser beam a little earlier than the time point when one cycle elapses, considering that the detection timing of the laser beam deviates slightly in time before and after. Is. S
When the laser beam is detected by the OS sensor,
Alternatively, when the detection is not performed within the period that should be performed, the laser beam extinguishing means is used to end the continuous lighting of the laser beam for synchronous detection. When the laser beam extinguishing means extinguishes the laser beam for synchronous detection without performing the detection within the period when the laser beam should be detected, this determination is performed and one cycle elapses. The laser beam is continuously turned on for the synchronous detection from the time point before the second time period which is longer than the first time period. That is, at the time of abnormality, it is possible to determine the abnormality at a time later than the detection time in normal time, so by starting the detection of the laser beam from a time earlier in time, the detection start time is sequentially changed in time. It is possible to prevent a situation in which a delay occurs and to ensure synchronization.

According to a third aspect of the present invention, (a) a photosensitive member for forming an image for recording, and (b) a laser beam is periodically scanned from one end to the other end of the photosensitive member. And (c) an SOS sensor which is disposed further on the scanning start side of the laser beam than the above-mentioned one end of the photosensitive member, and which detects the scanning timing of the laser beam for each cycle, (d) Counting is started from the timing detected by the SOS sensor as a starting point, and when the counting corresponding to a time point that is a first time period before the time that elapses one cycle from this is performed, the continuous laser beam is detected for synchronous detection. The laser beam lighting start control means for starting the lighting and (e) the detection of the laser beam by the SOS sensor are carried out or within the period when they should be carried out. A laser beam off means to terminate the continuous lighting of the laser beam for subsequent synchronization detection of the cycle when is judged that not performed,
(F) A selector that selects and reads preset data when the laser beam extinguishing means ends the continuous lighting of the laser beam without detecting the laser beam, and (g) the data read by this selector. It is set in the laser beam lighting start control means as a preset value that is applied only once for synchronous detection, counting is started from this preset value, and the laser beam is lit at a point before the second time, which is longer than the first time. The recording device is provided with presetting means for starting continuous lighting of the laser beam for synchronization detection by the start control means.

That is, according to the third aspect of the present invention, when the laser beam extinguishing means terminates the continuous lighting of the laser beam without detecting the laser beam, a selector is provided which selects and reads preset data. It is provided. The laser beam lighting start control means is composed of a counter, and the read data is preset in the counter when there is an abnormality in which the continuous lighting of the laser beam is terminated without detecting the laser beam. . As a result, the laser beam lighting start control means performs normal counting starting from the timing detected by the SOS sensor when normal, but starts counting from the preset count value when abnormal, so that the laser beam lighting is turned on. When measuring the time to start, it is possible to obtain the same result as subtracting the second time, which is longer in time than the first time, than subtracting the first time from one cycle, It is possible to prevent a situation in which the start point of turning on of the laser beam is sequentially delayed in time due to the fact that the discrimination in the abnormal state is delayed from the detection of the laser beam at the normal time, and the synchronization can be reliably ensured. Become.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments.

FIG. 1 shows a circuit configuration of a main part of a recording apparatus according to an embodiment of the present invention. In this figure, the same parts as those in FIG. 4 are designated by the same reference numerals, and the description thereof will be appropriately omitted. In the recording apparatus of this embodiment,
The synchronization signal 19 output from the SOS sensor 18 is supplied to the horizontal synchronization processing unit 61. The horizontal synchronization processing unit 61 uses S
Synchronous signal 1 even when a predetermined period has passed from the OS sensor 18
When 9 is not output, the correction mode setting signal 62 is sent to the correction section 63, and this is set to the correction mode. The correction unit 63 switches the value of the correction data 64 from “0” to a predetermined value in the state of being switched to the correction mode, and supplies it to the horizontal synchronization processing unit 61. The horizontal synchronization processing unit 61 sends the horizontal synchronization signal 22 to the recording information generation unit 23 when the periodic signal 19 is input,
The image data 24 for one line is output each time. The horizontal synchronization processing unit 61 drives the semiconductor laser 11 using a laser drive signal 66 that is a combination of the image data 24 and a synchronization modulation signal for synchronization detection. Further, the horizontal synchronization processing unit 61 is adapted to turn on the laser beam 14 at a timing necessary for the SOS sensor 18 to detect it according to the value of the correction data 64.

FIG. 2 specifically shows the circuit configuration of the horizontal synchronization processing section and the correction section of this embodiment. The horizontal synchronization processing unit 61 inputs the synchronization signal 19 output from the SOS sensor 18 shown in FIG. 1 to the first flip-flop circuit 72 via the 2-input OR gate 71. The Q output 73 of the first flip-flop circuit 72 is thereby set to the H (high) level. The first counter circuit 74 inputs the Q output 73 to the input terminal ENT. When the Q output 73 becomes H (high) level, the clock signal 7 input to the clock input terminal CLK is input.
It is designed to count 5.

The first counter circuit 74 is the SOS sensor 1
8 has a function as a timer circuit for controlling the lighting so that the laser beam 14 is lit just before 8. That is, when the first counter circuit 74 counts the clock signal 75 for the time corresponding to this lighting start timing (= X−1 count), its Q output 76 becomes H level.
Change to a level. The Q output 76 is supplied to the second flip-flop circuit 78, and the Q output 79 changes to the H level by the rising of the clock signal 75. The Q output 79 is the input terminal E of the second counter circuit 81.
It is input to NT and this is used as a synchronous modulation signal.
It is input to one terminal of the input OR gate 82. The image data 24 is supplied to the other input terminal of the 2-input OR gate 82 from the recording information generator 23 shown in FIG.
6 is supplied to the semiconductor laser 11 shown in FIG. 1 and its on / off control is performed.

On the other hand, the second counter circuit 81 counts the clock signal 75 input to the clock input terminal CLK when the Q output 79 input to the input terminal ENT is in the H level state. That is, the second counter circuit 81 receives the clock signal 75 from the lighting start timing of the laser beam 14 for the SOS sensor 18.
Is counted and counted for a time (= Y count) slightly longer than the time when the synchronization signal 19 is scheduled to be output, the extinguishing signal 83 as the Q output is changed to the H level. That is, the Q output 79 input to the clear terminal CLR of the second counter circuit 81 until then.
Is turned to the L (low) level and the count value is not cleared, the H-level extinguishing signal 83 is generated.

When the extinguishing signal 83 is output instead of outputting the synchronizing signal 19 in a certain cycle, the extinguishing signal 83 is also supplied to the other input terminal of the OR gate 71. . As a result, the circuit after the first flip-flop circuit 72 operates to turn on the laser beam 14 immediately before the next SOS sensor 18 as if the regular synchronizing signal 19 arrives, and further during this lighting period. It enables the output of the H-level extinguishing signal 83 when the synchronization signal 19 is not output. The output of the OR gate 71 is supplied not only to the first flip-flop circuit 72 but also to the inverter 86, the logic of which is inverted and the clear terminal CL of the second flip-flop circuit 78.
It is supplied to R, resets it, and clears the count value of the second counter circuit 81 to set them to the initial state.

The clear terminal CLR of the first flip-flop circuit 72 receives the Q output 76 whose logic is inverted by another inverter 87, and the first counter circuit 74 is turned on at the lighting start timing. At the stage of counting for a corresponding time, it is in a state of waiting for the next input of the synchronizing signal 19 or the extinguishing signal 83.

By the way, since the extinguishing signal 83 is output after confirming that the synchronizing signal 19 is not output, the output timing thereof is later than the output timing of the synchronizing signal 19. Therefore, if this is simply input to the OR gate 71 instead of the synchronization signal 19 for processing, an error may occur or may be sequentially accumulated, which may interfere with the detection of the laser beam 14 by the SOS sensor 18. Therefore, in the present embodiment, this extinguishing signal 83 is transmitted to another inverter 88.
Thus, the logic is inverted and the correction mode setting signal 62 is input to the selection input terminal SEL of the selector 89 of the correction unit 63. A data latch circuit 91 is connected to one input terminal B selected by the selector 89, and a predetermined value D is stored therein. The value D is obtained by adding "1" to the sum of the count values of the first and second counter circuits 74 and 81, subtracting the period of the synchronization signal 19 and adding the preset time thereto. Is.

When the correction section 63 is set to the correction mode and the selector 89 selects this value D, this is used as the correction data 64 as the data input terminal D of the first counter circuit 74.
Supplied to ATA. The output 95 of the AND gate 94 is connected to the load terminal LD for loading the correction data 64 into the first counter circuit 74. Therefore, when the turn-off signal 83 is output, the data latch circuit 91
Counting is performed using the preset value stored in the starting point as the starting point, and the first counter circuit 74 outputs the Q output 76 of H level when a relatively short time has elapsed. On the other hand, the selector 89 selects the other input terminal A at other times. In this case, since the value “0” is selected as the correction data 64, the data is not padded.

As described above, in this embodiment, even when the selector 89 selects the value D in the correction mode, even if the synchronization signal 19 is not continuously output, these synchronization signals 19 are not output. The extinguishing signal 83 is accurately output at a time slightly later than the time when is output, and the start timing of the correction operation in the correction unit 63 is not significantly delayed. That is, in this embodiment, as described with reference to FIG. 5, when the synchronization sensor (SOS sensor 18 of this embodiment) does not detect the laser beam 14,
This is the same as the conventional one in that the continuous output is stopped (turned off) at the time point when M is counted, but when the light beam for synchronizing detection is turned off by the light beam turning-off means, one cycle from now on. There is provided an abnormal light beam lighting start control means for continuously lighting the light beam for synchronization detection from a time point before the second time which is longer than the first time. The difference between the first time and the second time is set by the value D. This will be described in more detail later.

The frequency of the clock signal 75 used in the horizontal synchronization processing section 61 of the present embodiment is an integral multiple of the time required for one scanning of the laser beam, and in the present embodiment, this magnification is 1000 times. Is set to. Further, the horizontal sync signal generator 93, which constitutes the horizontal sync processor 61 of the present embodiment, inputs the sync signal 19 to create the horizontal sync signal 22, which is stored in the recording information generator 23 shown in FIG. It is supposed to be supplied.

FIG. 3 shows each part of the horizontal synchronization processing part of this embodiment.
2 shows an example of the waveform of. Record based on this
An example of the operation of the device will be described along with temporal transition. Same figure
(A) shows the clock signal 75. The same figure (b)
The synchronization signal 19 shown in FIG. ₁To H level
When the beam 14 (Fig. 1) is detected,
Clearing the second flip-flop circuit 78 shown in (c)
An L (low) level signal is supplied to the terminal CLR. This
As a result, the Q output 79 changes to the L level. Well
In addition, the horizontal synchronization signal generator 93 inputs the synchronization signal 19.
Then, this is delayed for a predetermined time and the photosensitive drum 16 (see FIG.
1) For indicating the section in which the image data is written
A horizontal sync signal 22 (FIG. 3 (e)) is created and shown in FIG.
It is supplied to the recorded information generating unit 23.

By the way, the synchronizing signal 19 becomes H level, the first flip-flop circuit 72 is set, and its Q
When the output 73 becomes H level, the first counter circuit 74 starts this counting from the next rising edge of the clock signal 75. Then, Q output 79 of the second flip-flop circuit 78 is changed to the H level to the next rising time t ₂ of the clock signal 75 when performing X-1 count.

Since the output 95 of the AND gate 94 (FIG. 3 (d)) changes to the L level at the rising time t ₂ , the first counter circuit 74 fetches the correction data 64 at this time. In this state, since the turn-off signal 83 shown in FIG. 2 is not output, the correction mode setting signal 62
(FIG. 3F) is at H level, and the selector 89 selects the input terminal A. Therefore, the first counter circuit 74 takes in the value “0” as the correction data 64. In this state, the first flip-flop circuit 7
Since 2 is reset, the first counter circuit 74 stops its counting.

After the time t ₂ , the second counter circuit 81 starts counting in preparation for the appearance of the situation where the synchronizing signal 19 is not generated. However, in this example, the time t immediately after
_The synchronizing signal 19 (FIG. 3B) is output to 3. As a result, the second flip-flop circuit 78 is reset by the output of the inverter 86 and the Q output 79 (FIG. 3 (c)) becomes L level.
The level becomes the level, and the second counter circuit 81 stops counting and clears its contents. Also, the synchronization signal 1
9 occurs, the first flip-flop circuit 72 is set at this time t ₃ , the Q output 73 thereof becomes H level, and the first counter starts from the next rising edge of the clock signal 75 as described above. The circuit 74 starts the X-1 count, and at the next rising edge of the clock signal 75, the Q output 79 of the second flip-flop circuit 78 changes to the H level.

In this way, the Y count by the second counter circuit 81 is started from time t ₄ after the X count is performed. However, in the case of this example, the Y count is completed without detecting the synchronization signal 19 due to the occurrence of noise or the vibration of the machine. This completion time t _6, turn-off signal 83 is output.
As a result, the correction mode setting signal 62 shown in FIG. 3F changes to the L level, and the selector 89 selects the input terminal B. As a result, the value D stored in the data latch circuit 91 at the next rising time t ₇ of the clock signal 75 is preset in the first counter circuit 74 as the correction data 64. Then, from the next rising time t ₈ of the clock signal 75, the first counter circuit 74 starts the counting operation of the X−1 count with the value D raised. This is despite the time t ₈ and starts counting the clock signal 75, equivalent to that X-1 counting from the time t ₅ is substantially the climbed reverse only now the value D. Accordingly, even if the sync signal 19 is not continuously detected and the extinguishing signal 83 is continuously output, the SOS sensor 18 can detect the sync signal 19 after the normal recovery. Therefore, it is possible to accurately synchronize with the laser beam 14.

Although the laser beam is used as the light beam in the above-described embodiments, it goes without saying that an image may be scanned using a light beam having a wavelength other than this. Further, although the SOS sensor is used for detecting each scanning line in the embodiment, it is possible to dispose other sensors on the scanning line of the light beam. For example, an EOS sensor for confirming the end of scanning of the photoconductor can be used. Further, although the photoconductor drum is used as the photoconductor in the embodiments, other photoconductors such as a photoconductor belt may be used. Besides, various modifications can be made to the present invention.

[0040]

As described above, according to the first aspect of the present invention, when the light beam is not detected by the synchronization sensor within the period in which it should be detected,
The light beam extinction means is used to end the continuous lighting of the light beam for synchronization detection. Therefore, even if the synchronization cannot be achieved, unnecessary scanning lines are not recorded on the photoconductor and the image can be kept in high quality. Further, since the abnormal time when the light beam is not detected is determined, and in this case, the start time of the continuous lighting of the next light beam is shortened, the synchronization sensor can surely achieve the synchronization.

According to the second aspect of the present invention, when the SOS sensor as the synchronization sensor does not detect the laser beam within a period in which it should be detected, the laser beam extinguishing means is used. The continuous lighting of the laser beam for synchronous detection is ended.
Therefore, even if the synchronization cannot be achieved, unnecessary scanning lines are not recorded on the photoconductor and the image can be kept in high quality. Further, the abnormal time when the laser beam is not detected is determined, and in this case, the start time of the continuous lighting of the next laser beam is shortened, so that the SOS sensor can be surely synchronized. Furthermore, in a recording apparatus that performs surface correction by specifying the surface of a polygon mirror using the detection result of synchronization, it is possible to specify the surface even when there is an abnormality by additionally using the detection result at the time of abnormality. It is possible to eliminate the inconvenience that it becomes impossible to identify the surface once an abnormality occurs.

According to the third aspect of the invention, when the laser beam extinguishing means ends the continuous lighting of the laser beam without detecting the laser beam, the preset data is selected and read. A selector is provided, and the read data is preset in the counter that constitutes the laser beam lighting start control means. Therefore, there is an advantage that the time counting operation of the laser beam lighting start control means can be easily switched between the abnormal time and the normal time, and the clock operation can be counted, so that the time counting operation is stable and accurate. Further, preset values can be set by a memory or a DIP switch, and in this case, it is easy to adjust these values.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a circuit configuration of a main part of a recording apparatus according to an embodiment of the present invention.

FIG. 2 is a circuit diagram specifically showing a circuit configuration of a horizontal synchronization processing unit and a correction unit of this embodiment.

FIG. 3 is various waveform charts showing an example of waveforms of respective parts of the horizontal synchronization processing part of the present embodiment.

FIG. 4 is a schematic configuration diagram showing a configuration of a main part of an example of a conventional recording apparatus.

FIG. 5 is an explanatory diagram showing a state of count control by a conventionally proposed recording apparatus and its problems.

[Explanation of symbols]

11 ... Semiconductor laser, 13 ... Polygon mirror, 14 ... Laser beam, 16 ... Photosensitive drum (photoconductor), 61 ... Horizontal synchronization processing section, 62 ... Pseudo synchronization signal generating section, 63 ... Correction section, 64 ... Correction data , 74 ... First counter circuit,
81 ... Second counter circuit, 83 ... Extinguishing signal, 84 ... Counter, 89 ... Selector, 91 ... Data latch circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical indication H04N 1/113

Claims (3)

[Claims] 1. A photoconductor for forming an image for recording, a scanning means for periodically scanning the light beam from one end of the photoconductor to the other end, and a scanning path of the light beam. And a synchronization sensor for detecting the scanning timing for each cycle, and from the timing detected by this synchronization sensor as a starting point, from a point before the first time by one cycle. A normal-time light beam lighting start control unit that starts continuous lighting of the light beam for synchronization detection, and the detection is performed when the light beam is detected by the synchronization sensor or within a period when it should be performed. When it is determined that the light beam has not been detected, the light beam extinguishing means for ending the continuous lighting of the light beam for the subsequent synchronization detection in the cycle, and the light beam detection means within the period when the light beam should be detected. When the light beam for synchronizing detection is extinguished by the light beam extinguishing means without detecting the above, the time point before the second time, which is longer than the first time by one cycle The recording apparatus further comprises: a light beam lighting start control means for abnormally lighting the light beam continuously for synchronization detection. 2. A photosensitive member for forming an image for recording, a polygon mirror for periodically scanning a laser beam from one end of the photosensitive member to the other end, and Is further arranged on the scanning start side of the laser beam to detect the scanning timing of the laser beam for each cycle, and the timing detected by this SOS sensor is used as a starting point, and one cycle is more likely to elapse than this. Normal time laser beam lighting start control means for starting continuous lighting of the laser beam for synchronization detection from a time point before the first time, and when or when the laser beam detection is performed by the SOS sensor. When it is determined that the detection has not been performed within the period of, continuous lighting of the laser beam for the subsequent synchronous detection in that period When the laser beam extinguishing means to be terminated and the laser beam for synchronous detection are extinguished by this laser beam extinguishing means without performing the detection within the period when the laser beam should be detected, one cycle from now An abnormal laser beam lighting start control means for continuously lighting the laser beam for synchronization detection from a time point before the second time period, which is longer than the elapsed time period, by a second time period. Recording device. 3. A photoconductor for forming an image for recording, a polygon mirror for periodically scanning a laser beam from one end to the other end of the photoconductor, Is further arranged on the scanning start side of the laser beam, and starts counting from the SOS sensor for detecting the scanning timing of the laser beam for each cycle, and the timing detected by this SOS sensor as a starting point, and for the next one cycle. Laser beam lighting start control means for starting continuous lighting of the laser beam for synchronization detection at the time point when counting corresponding to a time point that is a first time before the elapsed time, and When a detection is made, or when it is determined that the detection was not made within the expected time period, that cycle The laser beam extinguishing means for ending the continuous lighting of the laser beam for the subsequent synchronization detection, and the preset data when the laser beam extinguishing means completes the continuous lighting of the laser beam without detecting the laser beam. A selector for selective reading and data read by this selector are set in the laser beam lighting start control means as a preset value that is applied only once for synchronous detection, and counting is started from this preset value to start the first A recording device, comprising preset means for starting continuous lighting of the laser beam for synchronization detection by the laser beam lighting start control means at a time point before the second time which is longer than the time.