JP2746391B2 - Exposure scanning device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an exposure scanning device in a copying machine, a facsimile, and the like.

[Conventional technology]

2. Description of the Related Art In a copier, a facsimile, or the like, a scanner having an exposure lamp is reciprocated relative to a document, and the document is exposed and scanned in one direction of the reciprocation.
2. Description of the Related Art There is known an exposure scanning apparatus that continuously exposes and scans a document by repeating reciprocating movement of the scanner relative to the document. For example, in a copier, a scanner is started from a home position for a document placed on a platen, and is raised at a constant speed while moving forward over a predetermined approach distance, and then a lead edge corresponding to the beginning of the document. Exposure scanning device that starts the exposure scanning of the original from the section, returns the scanner to the home position after the exposure scanning of the original is completed, and continuously performs the exposure scanning of the original by repeating such reciprocating movement of the scanner. It has been known. In this exposure scanning device, the exposure lamp is turned on at the start of exposure scanning of the scanner during continuous exposure scanning of a document, and turned off at the same time as the start of scanning of the scanner to prevent excessive temperature rise due to lighting, and is turned off at the same time as the start of scanning of the next document. The light is turned on again at a time corresponding to the exposure scanning. In addition, when the temperature of the exposure lamp (filament temperature) is low, the filament resistance of the exposure lamp decreases. If a large voltage is suddenly applied to the exposure lamp in this state, a rush current flows in the exposure lamp, and the exposure lamp, its control element, and the power supply are overloaded, causing a problem.
Therefore, at the start of the exposure lamp lighting, the applied voltage of the exposure lamp is reduced to suppress the rush current, and after the exposure lamp lighting is started, the applied voltage of the exposure lamp is gradually increased. Soft start control is performed so as to achieve a target load power (voltage).

Also, JP-A-63-36234 discloses that
It is described that the lighting start timing of an exposure lamp is delayed according to an increase in the number of repetitions of exposure scanning during continuous exposure scanning of a scanner.

[Problems to be solved by the invention]

In the above-described exposure scanning device, soft start control of the exposure lamp is performed. Even when the same power is applied to the exposure lamp, the light intensity of the exposure lamp increases with the temperature rise of the exposure lamp, and when the temperature of the exposure lamp becomes stable after a certain period of time, the light intensity of the exposure lamp also becomes stable. Further, when controlling the voltage applied to the exposure lamp so that the light intensity of the exposure lamp becomes the target light intensity during the exposure scanning of the original,
To raise the applied voltage of the exposure lamp from the extinguishing state of the exposure lamp and settle to the target voltage, in order to prevent overshoot etc. from occurring in the light intensity of the exposure lamp, from the start of lighting the exposure lamp to the setting of the voltage A certain amount of time is required. As described above, a certain period of time is required from the start of the exposure lamp lighting until the light intensity of the exposure lamp stably reaches the target intensity and the original can be subjected to exposure scanning. There is a problem that a certain time is required between the exposure scans and the copying speed cannot be increased. Therefore, it is conceivable that the exposure lamp is dimmed at times other than the time of exposure scanning. The temperature rise of the lamp becomes a problem.

Also, in the method described in JP-A-63-36234, the exposure lamp is turned off once after each exposure scan in the continuous exposure scan of the original, so that also between each exposure scan in the continuous exposure scan of the original. It takes a certain amount of time to increase the copying speed.

The present invention solves the above problems, prevents an excessive rise in the temperature of the exposure lamp during continuous exposure scanning, and stabilizes the light intensity of the exposure lamp by raising the voltage applied to the exposure lamp to a target voltage. It is an object of the present invention to provide an exposure scanning apparatus capable of shortening the time required for performing the exposure.

[Means for solving the problem]

In order to achieve the above object, according to the present invention, there is provided an exposure scanning apparatus in which a scanner having an exposure lamp is reciprocated relatively to a document, and the document is exposed and scanned in one direction in the reciprocating movement. In the apparatus, when the original is continuously exposed and scanned by repeating the reciprocating movement of the scanner relative to the original, the scanner is moved in the other direction than when the scanner is moved in the one direction for exposure scanning of the original. When the scanner is moved, the power supplied to the exposure lamp is reduced and continuously turned on, and in response to the increase in the number of exposure scans, the power supplied to the exposure lamp when the scanner is moved in the other direction is increased. It is to be lowered sequentially.

〔Example〕

FIG. 3 schematically shows an example of a copying machine to which the present invention is applied.

A document 2 is placed on a document table 1, and a scanner including an exposure lamp 3 and mirrors 4 to 6 is activated from a home position HP during an exposure scan of the document, and moves forward a predetermined approach distance to the left. Manuscript 2 after rising to a certain speed
Exposure scanning of the original 2 is started from the lead edge LE corresponding to the start edge of the document, and after the exposure scanning of the original is completed, the original 2 is returned from the return position RT to return to the home position HP, and such reciprocating movement of the scanner is repeated. Thus, the exposure scanning of the original is performed continuously. In this case, the document 2 on the document table 1 is illuminated by the exposure lamp 3 and the reflected light is
The original 2 is exposed by irradiating the photosensitive drum 9 through the lens 6, the lens 7, and the mirror 8. The photoreceptor drum 9 is driven to rotate by a motor and is uniformly charged by a charger (not shown). Then, an electrostatic latent image is formed by exposing the document 2, and the electrostatic latent image is developed by a developing device 10. The image is transferred to the transfer paper 11 by a transfer device.

FIG. 1 shows a circuit used in one embodiment of the present invention.
The figure is the timing chart.

In the above copying machine, the exposure lamp 3 is connected to a commercial AC power supply 12 through a switching element 13 composed of a triac.
A relay or the like may be used. The transformer 14 is a commercial AC power supply 12
And outputs the same to the zero cross detection circuit 15. The zero-cross detection circuit 15 includes a diode bridge, detects a zero-cross point of the output voltage of the transformer 14, and generates a zero-cross pulse ZCP at the zero-cross point. The rectifier circuit 16 steps down and rectifies the voltage LE between both ends of the exposure lamp 3, and the mean square circuit 17 squares and averages the output voltage DV of the rectifier circuit 16. The rectifier circuit 16 and the root mean square circuit 17 constitute a load voltage detector. The microcomputer 18 is a single-chip microcomputer having an analog / digital converter and an internal timer, and operates based on a reference clock generated internally by a 10 MHz oscillator 19. This microcomputer 18
Has a phase control function and a power supply voltage determination function, and a zero-crossing pulse is applied to the external interrupt terminal INT1 from the zero-crossing detection circuit 15 to generate a zero-crossing interrupt. Further, the microcomputer 18 converts the ramp mean square voltage CV input from the mean square circuit 17 to the input terminal AN0 of the analog / digital converter by analog / digital conversion in the analog / digital converter and samples it. A certain (effective value) ² is directly or squared and compared with a target value (having a correlation such as proportionality) correlated with the exposure lamp control target from the microcomputer for sequence control, and the phase angle data (off of the switching element 13) is compared. At the start of the zero-cross interrupt, the phase angle data is set in the internal timer as shown in FIG. 5 (h) and started, and a phase angle timer interrupt is generated when the internal timer counts up. Let it. The microcomputer 18 outputs a lamp drive signal LD as shown in FIG. 5C to the switching element 13 through the trigger circuit 20 by the phase angle timer interrupt to make the switching element 13 conductive so that the exposure lamp 3 is turned on.
A lamp voltage LE as shown in FIG. 5 (d) is applied to both ends of the switch, and the conduction phase angle of the switching element 13 is controlled so that the lamp voltage LE becomes the exposure lamp control target. The microcomputer 18 samples the root mean square voltage CV from the root mean square circuit 17 at the lamp drive timings a ₁ , a ₂ , a ₃ ,... As shown in FIG.
Here, the ratio between the effective value E of the input voltage Vac and the effective value V of the output voltage LE with respect to the control phase angle of the switching element 13 (the phase angle at which the switching element 13 is turned on with reference to the zero-cross point of the power supply voltage) θ. The relationship of V / E is as shown in FIG. 6. If the control phase angle θ is small, the effective value V of the output voltage
And the control phase angle θ increases, the effective value V of the output voltage decreases. Therefore, the lamp voltage can be controlled to the target value by changing the control phase angle θ according to the difference between the detected value of the lamp voltage and the target value.

FIG. 7 shows the main routine of the microcomputer 18.

When the microcomputer 18 is turned on, it performs initial settings. This initial setting includes setting the port, turning off the port set as the output port, clearing the RAM, specifying the serial communication mode with the microcomputer for sequence control of the copier and permitting the reception interrupt, setting the mode such as the internal timer, This is an initial value setting for each flag and the like. Next, the microcomputer 18 sets the lamp control flag LCTL
Determine whether FG is set. This lamp control flag LCTLFG is set immediately after reading the lamp voltage during the timer interrupt of each phase. If the lamp control flag LCTLFG is set, the microcomputer 18 performs the lamp control operation to obtain the phase data, resets the lamp control flag LCTLFG, performs other processing, and then executes the lamp control flag LCTLFG.
Return to the step of determining LCTLFG. If the lamp control flag LCTLFG has been reset, the microcomputer 18 executes other processing as it is, and then returns to the step of determining the lamp control flag LCTLFG.

 FIG. 8 shows the flow of the above-mentioned ramp control calculation.

In this ramp control calculation, the microcomputer 18 first determines whether or not the soft start flag SOFTF has been set. This soft start flag SOFTF is set at the start of lamp lighting. Soft start flag
If SOFTF is set, the microcomputer 18 performs a soft start process. That is, the microcomputer 18 compares the sampling value with a target value correlated with the exposure lamp control target from the sequence control microcomputer to determine whether the sampling value is equal to or greater than the target value. If the sampling value is not equal to or greater than the target value, the microcomputer 18 subtracts the difference data for soft start from the current phase angle data according to a predetermined soft start pattern, and sets the result as new phase angle data. If the sampling value is equal to or greater than the target value, the microcomputer 18 determines that the soft start has ended, resets the soft start flag SOFTF, and proceeds to the next process. If it has been reset, it is determined that the soft start has already been completed, and the process proceeds to the next process. In the next process, the microcomputer 18 subtracts the target value from the sampling value to obtain a deviation, multiplies the deviation by a constant K, adds the result to the current phase angle data,
This addition result is used as new phase angle data.

 FIG. 9 shows the flow of the zero cross interrupt.

The microcomputer 18 starts the execution of the zero-crossing interrupt by the zero-crossing pattern ZCP from the zero-crossing detecting circuit 15, and first turns off the lamp drive signal LD (high potential). Next, the microcomputer 18 determines whether or not the lamp-on flag LON is set. The lamp on flag LON is set by a lamp lighting command from the sequence control microcomputer. If the lamp-on flag LON is set, the microcomputer 18 sets the phase angle data PHANGL obtained by the above-described ramp operation processing in the phase angle timer TM1, sets the phase angle timer TM1 start signal in the timer mode register TMM, and interrupts the microcomputer. Permit (EI). Also lamp on flag
If LON is not set, microcomputer 18
Sets the phase angle data at the time of the next lamp lighting, that is, the initial phase angle data at the time of soft start, and permits interruption.

 FIG. 10 shows the flow of the phase angle timer interrupt.

The microcomputer 18 starts to execute the phase angle timer interrupt by counting up the internal timer. This microcomputer 18 has two timers as internal timers.
Since there is TM1 and TM2, and the process moves to the same interrupt routine by counting up both timers TM1 and TM2, it is first determined whether or not the interrupt is caused by timer TM1 used as the phase angle timer. If it is not an interrupt, the process proceeds to another process. In the case of an interrupt by the timer TM1, the microcomputer 18 stops the phase angle timer TM1 and turns on the lamp drive signal to turn on the switching element 13 to apply an AC voltage to the exposure lamp 3, and the analog / digital converter The mean square value of the ramp voltage from the mean square circuit 17 input to the input terminal AN0 is taken in, converted from analog to digital, and sampled. Next, the microcomputer 18 sets the lamp control flag LCTLFG, permits the interrupt, and ends the phase angle timer interrupt processing.

Further, as shown in FIG. 11, the microcomputer 18 performs serial communication with a sequence control microcomputer 21, and the sequence control microcomputer 21
Performs sequence control and the like of the copying machine. FIG. 12 is a flowchart showing a processing flow of the sequence control microcomputer 21. This flowchart shows the exposure lamp control target setting process, and other processes are omitted.

In the exposure lamp control target setting process, the microcomputer 21 first checks whether or not it is the lighting timing of the exposure lamp 3 at the start of the exposure scanning of the scanner. At this time, the target lamp voltage Vlf is set as the exposure lamp control target, and if it is not the lighting timing of the exposure lamp 3, the process proceeds to the next. The target lamp voltage Vlf may be different depending on required copying conditions. Next, the microcomputer 21 checks whether it is a return timing at which the scanner reverses from forward movement to backward movement,
If it is a return timing, it is checked whether or not the current exposure scan is the last copy operation (the last copy operation in the continuous copy operation, only one copy operation). In the case of the final copying operation, the microcomputer 21 sets the exposure lamp control target to 0 and turns off the exposure lamp 3. If it is not the final copying operation, the microcomputer 21 checks the number of copies (the number of exposure scans) in the continuous copying operation, and according to the number, sets the target lamp voltage at the time of returning the scanner.
Vlr1, Vlr2, Vlr3,... Are set for each copying operation, and the exposure lamp 3 is continuously turned on even when the scanner is moved back. Here, target lamp voltages Vlr1, Vlr2, Vlr3,
... The relationship of Vlr1 <Vlr2 <Vlr3 <.
Is set to a voltage lower than the target lamp voltage Vlf during the exposure scanning of the scanner. Therefore, when the scanner is moved back, the power is applied to the exposure lamp 3 lower than that at the time of forward movement of the scanner, the temperature is maintained at a constant temperature, and the temperature of the exposure lamp is prevented from excessively rising. The time required for the light intensity of the lamp to stabilize at the target intensity and the exposure scanning of the original becomes possible is reduced, and high-speed copying becomes possible. If it is not the return timing, the microcomputer 21 keeps the exposure lamp control target as it is. The microcomputer 21 transmits an exposure lamp control target and the like to the microcomputer 18 by serial transmission and reception with the microcomputer 18 and receives predetermined data from the microcomputer 18.

In the conventional method, the scanner speed profile, the voltage and light intensity of the exposure lamp are as shown in FIG. 4, and the exposure lamp is turned off when the scanner is moved back. In the above-described example, the scanner speed profile, the voltage and the light intensity of the exposure lamp are changed. As shown in FIG. 2, the exposure lamp is turned on when the scanner returns.

Note that the present invention and the conventional method are used when a plurality of exposure scans are performed in the same document copying operation as in a color copying machine, and there is a difference in the interval between each exposure scan or the intensity of the exposure lamp light in the copy sequence. You may combine by sequence. In other words, if the light intensity of the exposure lamp required for the next exposure scan is low, the rise time of the light intensity of the exposure lamp can be short even if the exposure lamp is turned off once, and the timing of the next exposure scan is late. In this case, there is no problem in the copying sequence even if the exposure lamp is turned off and the rising of the light intensity is long. In these cases, the conventional method may be used. Also, the present invention can be applied to an original moving type copying machine in which an optical system is stationary and an original platen moves to scan an original.
Further, the present invention can be similarly applied to a copier which does not perform exposure scanning of a document when the scanner moves forward but performs exposure scanning of the document when the scanner moves backward.

〔The invention's effect〕

As described above, according to the first aspect of the present invention, an exposure scanning apparatus for reciprocating a scanner having an exposure lamp relative to a document and exposing and scanning the document by moving in one direction in the reciprocating movement. In the case where the original is continuously exposed and scanned by repeating the reciprocating movement of the scanner relative to the original, the scanner is moved in the other direction than when the scanner is moved in one direction for exposure scanning of the original. During the movement, the power supplied to the exposure lamp is reduced and the lamp is continuously lit, so that the voltage applied to the exposure lamp is raised to a target voltage while preventing the temperature of the exposure lamp from rising excessively, and the light intensity of the exposure lamp is stabilized. Can be shortened. Also, in response to the increase in the number of exposure scans, the power supplied to the exposure lamp when the scanner is moved in the other direction is sequentially reduced, so that the temperature of the exposure lamp excessively rises during continuous exposure scan. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit used in one embodiment of the present invention, FIG. 2 is a timing chart showing the operation of the circuit,
FIG. 3 is a schematic diagram showing an example of a copying machine, FIG. 4 is a timing chart showing the operation of the conventional apparatus, FIG. 5 is a timing chart showing the operation of the circuit, and FIG. 6 is for explaining the circuit. FIG. 7 is a flowchart showing a main routine of the microcomputer in the same circuit, FIG. 8 is a flowchart showing a ramp operation process of the microcomputer, FIG. 9 is a flowchart showing a zero-crossing interrupt process of the microcomputer, FIG. 10 is a flowchart showing a phase angle timer interrupt process of the microcomputer, FIG. 11 is a block diagram showing a circuit used in the above embodiment, and FIG. 12 is a process of a sequence control microcomputer used in the above embodiment. It is a flowchart which shows a flow. 3. Exposure lamps, 4-6. Mirrors, 18, 21 ... Microcomputer.

Claims (1)

(57) [Claims] 1. An exposure scanning apparatus for reciprocating a scanner having an exposure lamp relative to a document and exposing and scanning the document by moving in one direction in the reciprocating movement. When the scanner is continuously exposed and scanned by repeating the reciprocating movement, the exposure lamp is supplied to the exposure lamp when the scanner is moved in the other direction, rather than when the scanner is moved in the one direction for exposure scanning of the document. The power to be supplied to the exposure lamp during the movement of the scanner in the other direction is sequentially reduced in accordance with the increase in the number of times of the exposure scanning. apparatus.