JP2008039834A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus the first print time of which is effectively shortened for a user who does not use one printing mode intensively. <P>SOLUTION: In the image forming apparatus, the rotational speed of a motor for a polygon mirror is controlled to predetermined preparative rotational speed based on switching time before instructed to switch the printing mode. The mean value Tave(i) of the switching time T(i, j) from the printing mode (i) before instructed to switch the print mode is calculated (S3), and the target rotational speed Vtg(j) of the printing mode (j) after switching the switching time T(i,j) nearest to the mean value is specified (S4 to S8) and is set to the preparative rotational speed Vpre (S9). Thereafter, the preparative rotation of the motor is performed at the target rotational speed Vpre (S10). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus capable of printing in a plurality of types of printing modes.

  In an image forming apparatus such as a digital copying machine or a printer, a laser scanning optical system equipped with a polygon mirror is generally used as a latent image forming means for forming a latent image on a photoconductor. This polygon mirror is rotated by a motor. When printing an image in such an image forming apparatus, printing of the first image is not performed until the rotation speed of the motor reaches a rotation speed suitable for printing after a print start instruction is issued. Not started. Therefore, a waiting time for the user occurs when the first image is printed.

  Therefore, in Patent Document 1, in order to shorten the first print time (the time from when the print start instruction is issued until the printed paper is discharged), in the print preparation state before the print start instruction is issued, An image forming apparatus in which a motor is rotationally driven in advance at a rotation speed suitable for printing is disclosed. As a result, when the print start instruction is given, the rotation speed of the motor has already reached the rotation speed suitable for printing, so the first print time can be greatly shortened.

  Incidentally, in recent years, image forming apparatuses capable of printing in a plurality of printing modes such as a plurality of types of resolutions and a plurality of types of color modes have become widespread. In such an image forming apparatus, the rotational speed of the motor varies depending on the print mode. For this reason, the rotational speed of the motor in the print preparation state may not match the rotational speed of the motor suitable for the print mode when actually printing. In this case, after the print start instruction is given, it is necessary to switch the rotation speed of the motor in the print preparation state to the rotation speed of the motor suitable for the print mode for actual printing. Accordingly, what kind of rotation speed is set for the motor in the print preparation state is a very important matter for shortening the first print time.

  Therefore, Patent Document 2 discloses an image forming apparatus in which a motor is driven to rotate at a rotational speed corresponding to a print mode having a resolution that has been printed most frequently in the past in a print preparation state.

  However, the image forming apparatus described in Patent Document 2 is effective for shortening the first print time for a user who prints intensively in a print mode with the highest use frequency. It is not very effective for shortening the first print time for a user, particularly a user who prints at a substantially equal frequency in a plurality of print modes. Hereinafter, a specific example will be described. Table 2 is a table used in the embodiment, and is a table showing the rotation speed of the motor in three types of printing modes. Table 1 shown below is a table showing the switching time required for switching the printing mode among the four printing modes including the three printing modes and the stopped state.

  For example, when the user performs intensive printing in the print mode (1), the motor is driven at the rotation speed of the print mode (1) as shown in Table 2 in the embodiment in the print preparation state. When the user performs printing in the printing mode (1), the switching time is 0 seconds according to Table 1.

  On the other hand, when the user performs printing with the highest frequency in the printing mode (1), when printing is performed in the printing mode (3), the switching time is 3.6 seconds according to Table 1. Therefore, in the print preparation state, the switching time (3.6 seconds) is switched when the printing is performed in the printing mode (3) from the stopped state even though the rotation is performed at the rotation speed of the printing mode (1). It will be longer than the time (2.1 seconds).

Patent Document 3 discloses an image forming apparatus that rotates a motor at a rotation speed corresponding to a print mode having a higher priority among print mode priorities set by a user in a print preparation state. Yes. However, even in this image forming apparatus, when printing is performed in a print mode with a low priority, the switching time becomes long as described above.
JP-A-7-273951 JP-A-9-323447 JP 2002-326386 A

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus capable of effectively shortening the first print time for users other than users who intensively use one print mode.

  In an image forming apparatus capable of printing in a plurality of types of printing modes having different printing speeds, the present invention provides a motor that rotates a polygon mirror, and a first storage unit that stores a target rotation speed of the motor according to the printing mode. When switching between a plurality of print modes, the switching time required for the motor rotation speed to reach the target rotation speed of the print mode after switching from the target rotation speed of the print mode before switching, Second storage means for storing each combination of print modes, and first rotation control for controlling the rotation speed of the motor to a predetermined preparation rotation speed based on the switching time before receiving a print mode switching instruction And a second rotation control means for controlling the rotation speed of the motor to the target rotation speed corresponding to the print mode after switching after receiving the switching instruction. The first rotation control means sets the target rotation speed of the print mode after the switching of the switching time closest to the average value of the switching times among the switching times from the printing mode before receiving the switching instruction, The preparatory rotation speed is set.

  According to the present invention, the first print time is effectively shortened for users other than users who use one print mode intensively by minimizing the average value of the switching time to each print mode. be able to.

  In the present invention, the measurement means for measuring the time required for the motor to reach the target rotational speed of the printing mode after switching from the target rotational speed of the printing mode before switching, and the measurement for each combination of the printing modes. Calculation means for calculating an average value of the time measured by the means, and the second storage means stores the average value of the time calculated by the calculation means as the switching time. preferable.

  As described above, since the switching time is updated as needed, even if the switching time changes due to a change in the usage environment, the switching time is set in consideration of the change in the usage environment. Therefore, it becomes possible to control the rotation speed of the motor suitable for the use environment.

  In the present invention, it further comprises detection means for detecting whether or not the motor is rotating at a target rotation speed, and the first rotation control means is for driving the motor at a rotation speed according to a cycle. A clock signal is generated, and the measurement unit starts measuring the time at a timing when the cycle of the clock signal fluctuates, and the detection unit detects that the rotation speed of the motor has reached a target rotation speed The measurement of the time may be terminated at the timing. And a synchronization signal generating unit configured to generate a synchronization signal for writing synchronization in the main scanning direction, wherein the first rotation control unit is a clock for driving the motor at a rotation speed corresponding to a cycle. The measuring means starts measuring the time at a timing when the cycle of the clock signal fluctuates, and at the timing when the synchronizing signal generated by the synchronizing signal generating means is detected a predetermined number of times. Measurement may be terminated.

  In the present invention, it further comprises a temperature detection means for detecting the ambient temperature of the motor, the second storage means stores the switching time for each temperature, and the first rotation control means comprises: It is preferable to control the rotational speed of the motor to the preparatory rotational speed based on a switching time corresponding to the temperature detected by the temperature detecting means. Further, the temperature detecting means detects a temperature around the motor when the measuring means measures time, and the calculating means calculates the time measured by the measuring means and the temperature detected by the temperature detecting means. And calculating the average value of the time for each combination of print modes and for each temperature, and the second storage means calculates the average value of the time calculated by the calculation means for each temperature. It is preferable to store it as the switching time.

  Since the switching time varies depending on the ambient temperature of the motor, the first print time can be shortened more efficiently by controlling the preparatory rotation speed of the motor based on the ambient temperature of the motor.

  In the present invention, the second storage means stores the frequency of use of each print mode, and the first rotation control means is the print mode after switching of the switching time closest to the average value of the switching times. An average rotation speed between the target rotation speed and the target rotation speed corresponding to the print mode with the highest use frequency may be set as the preparation rotation speed.

  An image forming apparatus according to an embodiment of the present invention will be described below with reference to the drawings. The image forming apparatus can perform printing in a plurality of types of printing modes. The plurality of types of printing modes mean a plurality of types of printing modes having different printing speeds. For example, a printing method using a plurality of types of resolutions, a printing method using a plurality of types of color modes, and a printing method for a plurality of types of printing media. Etc. In addition, in each figure of 1st and 2nd embodiment demonstrated below, the same code | symbol is attached | subjected about the same member and part, and the overlapping description is abbreviate | omitted.

(First embodiment)
FIG. 1 is a block diagram showing the overall configuration of an image forming apparatus 1 according to the first embodiment of the present invention. FIG. 2 is a configuration diagram of the print head unit 2 of the image forming apparatus 1. The image forming apparatus 1 is an electrophotographic color printer and is configured to synthesize images of four colors (Y: yellow, M: magenta, C: cyan, K: black) in a so-called tandem system. is there.

(Overall configuration of image forming apparatus)
The image forming apparatus 1 includes a print head unit 2, a storage unit 3, a control unit 4, and various loads 5.

  The print head unit 2 is configured to form a latent image by irradiating each of four photosensitive drums (not shown) with laser beams. Specifically, as shown in FIG. 2, the print head unit 2 includes a light source unit 21, a mirror 22, a polygon mirror 23, a motor 24, a lens 25, mirrors 26 and 27, and a sensor 28.

  The light source unit 21 includes four laser diodes and generates four laser beams. The mirror 22 reflects the laser beam generated by the light source unit 21 and guides it to the polygon mirror 23.

  The polygon mirror 23 is rotationally driven by a motor 24 (stepping motor) and serves as a deflector that deflects and scans the laser beam reflected by the mirror 22. That is, each laser beam is deflected at a constant angular velocity in the main scanning direction based on the rotation of the polygon mirror 23.

  The lens 25 and the mirror 26 serve as an imaging optical element that forms an image of the laser beam deflected by the polygon mirror 23 on the photosensitive drum. Specifically, the lens 25 gives fθ characteristics to the light deflected by the polygon mirror 23 and corrects necessary aberrations. The mirror 26 reflects the laser beam that has passed through the lens 25 and guides it to the photosensitive drum. As a result, a latent image is formed on the photosensitive drum. Although only one mirror 26 is shown in FIG. 2, since four laser beams must be reflected toward the four photosensitive drums, there are actually a plurality of mirrors. .

  Further, in the print head unit 2, the laser beam is used to generate a synchronization signal for taking write synchronization (SOS synchronization) in the main scanning direction. Therefore, a mirror 27 for guiding the laser beam to the sensor 28 is provided in the print head unit 2.

  The storage unit 3 is realized by, for example, an EEPROM, and stores a target rotational speed Vtg (i) of the motor 24 corresponding to the printing mode (i) (i = 1 to 3). Specifically, the storage unit 3 stores a table shown in Table 2 below as the target rotational speed Vtg (i) of the motor 24 corresponding to the printing mode (i). Table 2 is a table showing the target rotational speed Vtg (i) of the motor in each printing mode (i). According to the table shown in Table 2, the target rotational speed Vtg (1) is 43735 rpm in the printing mode (1) for monochrome printing on plain paper, and the target rotational speed in the printing mode (2) for full color printing on plain paper. Vtg (2) is 37458 rpm, and the target rotational speed Vtg (3) is 30776 rpm in the printing mode (3) in which monochrome printing or full-color printing is performed on paper other than plain paper (thick paper, OHP, etc.).

  Table 3 is a table showing the switching time T (i, j) and the average switching time Tave (i) when switching from the printing mode (i) to the printing mode (j). Further, in the table shown in Table 3 below, the storage unit 3 switches the print mode from the stopped state (print mode (0)) or the print mode (i) to the stopped state or the print mode (j). At this time, the switching necessary for the rotational speed of the motor 24 to reach the target rotational speed Vtg (j) of the print mode (j) after switching from the target rotational speed Vtg (i) of the printing mode (i) before switching. Store the time T (i, j).

  Further, in the table shown in Table 3, the storage unit 3 stores the average of the switching times T (i, j) for each printing mode (i) (i = 0 to 3) (hereinafter, average switching time Tave (i)). Is stored). According to Table 3, the average switching time Tave (0) from the stopped state (print mode (0)) to the print modes (1) to (3) is 2.77 seconds, and printing is started from the print mode (3). The average switching time Tave (3) to the modes (1) to (3) is 0.90 seconds, and the average switching time Tave (2) from the printing mode (2) to the printing modes (1) to (3) is 1.13 seconds, and the average switching time Tave (1) from the printing mode (1) to the printing modes (1) to (3) is 1.77 seconds.

  The control unit 4 is realized by a CPU, for example, and controls the driving of the print head unit 2 and various loads 5, and in particular controls the rotational speed of the motor 24. Specifically, the control unit 4 controls the rotation speed of the motor 24 to a predetermined preparation rotation speed Vpre in a print preparation state before receiving a print start instruction by user input, and causes the motor 24 to perform preparation rotation. . The setting of the preparation rotation speed Vpre will be described later. Further, after receiving the print start instruction, the control unit 4 controls the rotation speed of the motor 24 to the target rotation speed Vtg (j) corresponding to the print mode (j) after switching.

  The various loads 5 indicate a motor for conveying paper, a fixing heater, and the like, and are controlled by the control unit 4.

(Preparation rotation of polygon motor)
In the image forming apparatus 1 configured as described above, the operation of the control unit 4 when the motor 24 performs the preparatory rotation will be described with reference to the drawings. FIG. 3 is a flowchart showing an operation performed by the control unit 4 when the motor 24 performs the preparatory rotation. As an example of this operation, an operation in which the control unit 4 sets the preparation rotation speed Vpre when the printing mode before starting the preparation rotation is the printing mode (1) will be described.

  This process is started when the control unit 4 recognizes a print preparation start instruction. This print preparation start instruction may be automatically recognized by the control unit 4 when a predetermined time has elapsed after the power of the image forming apparatus 1 is turned on, or input from the outside of the image forming apparatus 1. It may be a thing. In response to the print preparation start instruction, the control unit 4 confirms the immediately preceding print mode (i) (print mode (1)) (step S1).

  Next, the control unit 4 refers to the table of Table 3 and switches the switching time T (i, j) (T (1,1), T () corresponding to the printing mode (i) (printing mode (1)). 1, 2), T (1, 3)) are acquired (step S2).

  Next, the control unit 4 determines an average switching time Tave (i) that is an average of the acquired switching times T (i, j) (T (1,1), T (1,2), T (1,3)). ) (Tave (1)) is calculated (step S3). In the table of Table 3, when the average switching time Tave (i) is fixedly stored in advance, the control unit 4 does not calculate the average switching time Tave (i), but uses the table of Table 3 You may acquire by referring.

  The control unit 4 that has calculated the average switching time Tave (i) performs the switching time T (i, j) (T (1,1), T (1,2), T (1) in the following steps S4 to S8. , 3)) is determined to be closest to the average switching time Tave (i) (Tave (1)). Therefore, the control unit 4 switches the switching time T (i, j) (T (1,1), T (1,2), T (1,3)) and the average switching time Tave (i) (Tave (1)). ) And the switching time T (i, j) that minimizes the absolute value.

  First, the control unit 4 performs an initialization process. Specifically, the control unit 4 sets j to 0, and sets the absolute value Tmin of the difference between the switching time T (i, j) and the average switching time Tave (i) to | T (i, 0 ) -Tave (i) | (step S4).

  Next, the control unit 4 increments j by one (step S5).

  Next, the control unit 4 determines whether or not the minimum value Tmin is larger than | T (i, j) −Tave (i) | after the increment (step S6). If the minimum value Tmin is greater than | T (i, j) −Tave (i) |, the process proceeds to step S7. If the minimum value Tmin is not greater than | T (i, j) −Tave (i) |, the process proceeds to step S8.

  Since the control unit 4 determines that the minimum value Tmin is larger than | T (i, j) −Tave (i) |, the minimum value Tmin is set to | T (i, j) −Tave (i) |. This is corrected (step S7). Thereafter, the process proceeds to step S8.

  In step S8, the control unit 4 determines whether j is 3 (step S8). If j is not 3, the process returns to step S5. In this case, the process from step S5 to step S8 is repeated until j becomes 3. On the other hand, when j is 3, the switching time T (i, j) of | T (i, j) −Tave (i) | set to the minimum value Tmin becomes the average switching time Tave (i). Determined to be the closest. In the present embodiment, as apparent from Table 3, the average switching time Tave (1) in the printing mode (1) is 1.77 seconds, and therefore the switching time closest to the average switching time Tave (1). T (1, j) is the switching time T (1,2) (= 1.7 seconds). Thereafter, the process proceeds to step S9.

  The control unit 4 refers to the table of Table 2, and the target rotational speed Vtg (j) (Vtg (2) = 37458 rpm) corresponding to the determined switching time T (i, j) (T (1,2)). Is set to the preparation rotational speed Vpre (step S9). Thereafter, the control unit 4 starts the preparatory rotation of the motor 24 at the set preparatory rotation speed Vpre (step S10). Thereafter, printing is started after a print start instruction from the user.

(Measurement of switching time)
Hereinafter, an operation performed by the control unit 4 when the switching time is measured in the image forming apparatus 1 will be described with reference to FIG. FIG. 4 is a diagram illustrating signal transfer between the control unit 4 and the print head unit 2. FIG. 5 is a waveform diagram of signals transferred between the control unit 4 and the print head unit 2 and a diagram showing the relationship between the rotation speed of the motor 24 and time. FIG. 6 is a flowchart showing an operation performed by the control unit 4 when the switching time is measured.

  As shown in FIG. 4, between the control unit 4 and the print head unit 2, the clock signal Sig. A and the lock signal Sig. B is transferred. Clock signal Sig. A is a signal for controlling the target rotational speed of the motor 24, and is output from the control unit 4 to the print head unit 2. Clock signal Sig. As shown in FIG. 5, A has at least two frequencies, and the motor 24 rotates at a speed corresponding to the frequency. Lock signal Sig. B indicates that the motor 24 transmits the clock signal Sig. It is a signal for judging whether or not it is rotating at a target rotational speed corresponding to the frequency of A. Specifically, the lock signal Sig. B, as shown in FIG. 5, the clock signal Sig. A indicates that the motor does not rotate at the target rotational speed corresponding to the frequency of A, and the clock signal Sig. It shows that it is rotating at a target rotation speed corresponding to the frequency of A.

  This process is started when the user issues a print start instruction. The print start instruction includes information indicating that the print mode (i) is switched to the print mode (j) and printing is started. When a print start instruction is issued, the control unit 4 causes the clock signal Sig. It is determined whether the frequency of A has changed (step S21). Specifically, as shown at time t1 in FIG. It is determined whether B is switched from the low level to the high level. If the frequency has changed, the process proceeds to step S22. If the frequency has not changed, the process returns to step S21.

  The control unit 4 starts measuring the switching time T (i, j) (step S22). At the same time, the control unit 4 rotates the motor 24 at the target rotation speed Vtg (j) corresponding to the printing mode (j). Thereby, as shown in FIG. 5, the rotational speed of the motor 24 changes to Vtg (j) as time passes.

  Next, the control unit 4 receives the lock signal Sig. B, the rotational speed of the motor 24 is determined by the clock signal Sig. It is determined whether or not the target rotational speed Vtg (j) corresponding to the frequency of A has been reached (step S23). Hereinafter, the rotational speed of the motor 24 is the clock signal Sig. A state where the target rotational speed Vtg (j) corresponding to the frequency A is reached is referred to as a stable rotational state. As shown in time t2 of FIG. This is performed by the control unit 4 determining whether or not the level of B is low. If the stable rotation state of the motor 24 is detected, the process proceeds to step S24. When the stable rotation state of the motor 24 is not detected, the process returns to step S23.

  When the stable rotation state of the motor 24 is detected, the control unit 4 ends the time measurement (step S24). Next, an average value of the switching time T (i, j) measured in the past and the switching time T (i, j) calculated in step S24 is calculated (step S25). Thereafter, the calculated average value is recorded in the table of Table 3 as a new switching time T (i, j) (step S26). Thereby, the measurement of the switching time T (i, j) is completed.

  As described above, in the image forming apparatus 1, the control unit 4 recognizes the print mode (i) before the print preparation state, and switches the print mode (i) to the print mode (j) T (i, j), the target rotational speed Vtg (j) of the printing mode (j) corresponding to the switching time T (i, j) closest to the average switching time Tave (i) of these switching times T (i, j). Is set to the preparatory rotation speed Vpre. Therefore, the average value of the switching time T (i, j) to each printing mode (j) can be minimized. Therefore, the first print time can be effectively shortened for users other than users who use one print mode intensively.

(Second Embodiment)
FIG. 7 is a block diagram showing the overall configuration of the image forming apparatus 31 according to the second embodiment of the present invention. The switching time varies depending on the temperature around the motor 24. Therefore, the image forming apparatus 31 stores a switching time T (i, j) and an average switching time Tave (i) for each temperature around the motor 24. Then, the image forming apparatus 31 uses the switching time T (i, j) and the average switching time Tave (i) stored for each temperature to determine the optimum rotational speed Vpre for the ambient temperature of the motor 24. To do. In order to realize such an operation, the image forming apparatus 31 includes a temperature detection unit 35 in addition to the print head unit 2, the storage unit 3, the control unit 4, and various loads 5. Furthermore, instead of storing the table shown in Table 3 used in the first embodiment, the storage unit 3 changes the table corresponding to Table 3 for each temperature (Table 4 shows 10 (Table 5 corresponds to the table at 11 ° C. to 40 ° C., and Table 6 corresponds to the table at 41 ° C. or higher). Since the print head unit 2, the storage unit 3, the control unit 4, and the various loads 5 are the same as those in the image forming apparatus 1, the description thereof is omitted.

  The operation of the control unit 4 when the motor 24 performs the preparatory rotation in the image forming apparatus 31 will be described below with reference to the drawings. FIG. 8 is a flowchart showing an operation performed by the control unit 4 when the motor 24 is preliminarily rotated.

  This process is started when the control unit 4 recognizes a print preparation start instruction. This print preparation start instruction may be automatically recognized by the control unit 4 after a predetermined time has elapsed since the image forming apparatus 31 was turned on, or received from outside the image forming apparatus 31. There may be. In response to the print preparation start instruction, the control unit 4 confirms the immediately preceding print mode (i) (print mode (1)) (step S1).

  Next, the temperature detector 35 detects the temperature around the motor 24 (step S102). The control unit 4 refers to a table corresponding to the temperature detected by the temperature detection unit 35 among the three types of tables in Tables 4 to 6, and switches corresponding to the print mode (i) (print mode (1)). Time T (i, j) (T (1, 1), T (1, 2), T (1, 3)) is acquired (step S2). Thereafter, the process proceeds to step S3. Since the processing performed in the image forming apparatus 31 after step S3 is the same as the operation performed in the image forming apparatus 1, description thereof is omitted.

  Next, an operation performed by the control unit 4 when the switching time is measured in the image forming apparatus 31 will be described with reference to the drawings. FIG. 9 is a flowchart illustrating an operation performed by the control unit 4 when the switching time is measured. Note that the processing performed by the control unit 4 of the image forming apparatus 31 in steps S21 to S25 is the same as those performed by the control unit 4 of the image forming apparatus 1, and thus description thereof is omitted.

  When the average value of the switching time T (i, j) is calculated in step S25, the temperature detection unit 35 detects the temperature around the motor 24 (step S125). Accordingly, the control unit 4 sets the average value of the switching time T (i, j) calculated in step S25 as the new switching time T (i, j), and changes the temperature among the three tables of Tables 4-6. It records on the table corresponding to the temperature which the detection part 35 detected (step S126). Thereby, the measurement of the switching time T (i, j) is completed.

  As described above, according to the image forming apparatus 31, as in the image forming apparatus 1, the control unit 4 recognizes the print mode (i) before the print preparation state and changes from the print mode (i) to the print mode ( Among the switching times T (i, j) to j), the printing mode () corresponding to the switching time T (i, j) closest to the average switching time Tave (i) of these switching times T (i, j) The target rotation speed Vtg (j) of j) is set to the preparation rotation speed Vpre. Therefore, the average value of the switching time T (i, j) to each printing mode (j) can be minimized. Therefore, the first print time can be effectively shortened for users other than users who use one print mode intensively.

  Further, in the image forming apparatus 31, the preparation rotational speed Vpre is determined based on the temperature of the motor 24. Therefore, in the image forming apparatus 31, the average value of the switching time can be minimized for each temperature. As a result, the first print time can be shortened more effectively for users other than users who use one print mode intensively.

(Other embodiments)
In the image forming apparatus 1 and the image forming apparatus 31, the target rotation speed Vtg (j) obtained in step S9 in the flowcharts of FIGS. 3 and 8 and the target rotation corresponding to the most frequently used printing mode (i). The average rotation speed with the speed Vtg (i) may be set to the preparation rotation speed Vpre. In this case, the storage unit 3 needs to store the usage frequency of each print mode (i).

  In the image forming apparatus 1 and the image forming apparatus 31, the end timing of the switching time measurement is set to the lock signal Sig. Although the timing at which the stable rotation state of the motor 24 is detected based on B is set, the timing for ending the measurement of the switching time is not limited to this. For example, the end timing of the switching time may be determined by using a synchronization signal for writing synchronization in the main scanning direction. Specifically, after the start of measurement of the switching time, when the control unit 4 detects the synchronization signal a predetermined number of times by detecting the laser beam a predetermined number of times in the sensor 28 of FIG. 2, the measurement of the switching time is terminated. It may be.

1 is a block diagram illustrating an overall configuration of an image forming apparatus according to a first embodiment of the present invention. 2 is a configuration diagram of a print head unit of the image forming apparatus. FIG. It is the flowchart which showed the operation | movement which a control part performs when a motor performs preparatory rotation. FIG. 4 is a block diagram illustrating signals exchanged between a print head unit and a control unit. It is the figure which showed the relationship between the rotational speed of a motor, and time with the waveform figure of the signal transferred between a control part and a print head part. It is the flowchart which showed the operation | movement which a control part performs at the time of switching time measurement. FIG. 5 is a block diagram illustrating an overall configuration of an image forming apparatus according to a second embodiment of the present invention. It is the flowchart which showed the operation | movement which a control part performs when a motor performs preparatory rotation. It is the flowchart which showed the operation | movement which a control part performs at the time of switching time measurement.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,31 Image forming apparatus 2 Print head part 3 Memory | storage part 4 Control part 5 Various loads 21 Light source unit 22,26,27 Mirror 23 Polygon mirror 24 Motor 25 Lens 28 Sensor 35 Temperature detection part

Claims (7)

In an image forming apparatus capable of printing in a plurality of types of printing modes with different printing speeds,
A motor that rotates the polygon mirror;
First storage means for storing a target rotational speed of the motor according to a print mode;
When switching between a plurality of printing modes, the switching time required for the motor rotation speed to reach the target rotation speed of the printing mode after switching from the target rotation speed of the printing mode before switching is printed. Second storage means for storing each mode combination;
First rotation control means for controlling the rotation speed of the motor to a predetermined preparation rotation speed based on the switching time before receiving a print mode switching instruction;
A second rotation control means for controlling the rotation speed of the motor to the target rotation speed corresponding to the print mode after switching after receiving the switching instruction;
The first rotation control means sets the target rotation speed of the print mode after the switching of the switching time closest to the average value of the switching times among the switching times from the printing mode before receiving the switching instruction, Setting the preparatory rotation speed;
An image forming apparatus. Measuring means for measuring the time required for the motor to reach the target rotational speed of the printing mode after switching from the target rotational speed of the printing mode before switching;
A calculation means for calculating an average value of the time measured by the measurement means for each combination of print modes;
Further comprising
The second storage means stores the average value of the time calculated by the calculation means as the switching time;
The image forming apparatus according to claim 1. Detecting means for detecting whether the motor is rotating at a target rotational speed;
Further comprising
The first rotation control means generates a clock signal for driving the motor at a rotation speed corresponding to a cycle,
The measuring means starts measuring the time at a timing when the cycle of the clock signal fluctuates, and ends measuring the time when the detecting means detects that the rotational speed of the motor has reached a target rotational speed. To do,
The image forming apparatus according to claim 2. Synchronization signal generating means for generating a synchronization signal for synchronizing writing in the main scanning direction;
Further comprising
The first rotation control means generates a clock signal for driving the motor at a rotation speed according to a cycle,
The measuring means starts measuring the time at a timing when the cycle of the clock signal fluctuates, and ends measuring the time at a timing when the synchronizing signal generated by the synchronizing signal generating means is detected a predetermined number of times;
The image forming apparatus according to claim 2. Temperature detecting means for detecting the ambient temperature of the motor;
Further comprising
The second storage means stores the switching time for each temperature,
The first rotation control means controls the rotation speed of the motor to the preparation rotation speed based on a switching time corresponding to the temperature detected by the temperature detection means;
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The temperature detecting means detects the temperature around the motor when the measuring means measures time,
The calculation means uses the time measured by the measurement means and the temperature detected by the temperature detection means to calculate an average value of the time for each combination of print modes and for each temperature,
The second storage means stores the average value of the time calculated by the calculation means as the switching time for each temperature;
The image forming apparatus according to claim 5. The second storage means stores the use frequency of each print mode,
The first rotation control means performs an average rotation between the target rotation speed of the printing mode after switching of the switching time closest to the average value of the switching time and the target rotation speed corresponding to the printing mode having the highest use frequency. Setting the speed to the preparatory rotational speed;
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.

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