JPS6083055A - Recording density control device - Google Patents

Abstract

PURPOSE:To maintain record density always within a specified range by holding the number of times of operation of the device, reading the state of change electrically and checking the density at every specified number of times of recording regardless of on/off of a power source. CONSTITUTION:A photosensor PS2 connected to the input port P1 of a microcomputer CPU outputs a timing pulse corresponding to rotation of a photosensitive drum 3. An electric contact connected to an input port P2 is provided in a stepping relay MME. Detected density data obtained from a converter ADC is compared with reference data, and when thin, a toner supply plug is set to 1, and when not thin, set to 0. When a movable terminal TC of the stepping relay MME is advanced by 1 step after completion of copy cycle, advance is made by 1 step every time recording is made. Accordingly, the input port P2 necessarily becomes low level L once when 10 times of recording are made, and it means that record density is checked always at a fixed period. The state of the stepping relay delay does not change even when the power source is cut off.

Description

Detailed Description of the Invention (1) Technical Field The present invention relates to recording density control in an electrostatic recording device.
In particular, the present invention relates to a device that checks the recording density every predetermined recording and performs density control according to the result.

■Prior art In electrostatic recording type copying machines, an electrostatic latent image formed on a photoreceptor by a predetermined means is transferred from a developing device to
~JL is developed by being supplied with colored fine particles called ner.
Ru. The toner is normally charged with a polarity opposite to that of the electrostatic latent image, and is electrostatically attracted to the electrostatic latent image, thereby performing development.

During development, 1-toner is consumed, so in order to keep the toner concentration in the developer constant, toner must be replenished according to the toner consumption. If the density becomes too low, the carrier will scatter and the recorded density will become low.On the other hand, if the toner is replenished too much,
- Contamination occurs due to spraying of toner. 1-Toner density control is generally performed by directly or indirectly detecting toner density.

When the toner density becomes thinner, the recorded image density also becomes a little thinner than usual. Therefore, by forming a reference density pattern at a predetermined position, exposing it together with the original image during exposure, and applying it to a part of the photoreceptor that is outside the position of the image, the electrostatic latent image formed thereby is developed. , recording density information that changes only depending on the state of the recording apparatus itself can be obtained. Therefore, by detecting this recording density information and comparing it with predetermined reference data, it is possible to know whether the recording density is low, that is, whether the toner density is decreasing. In this case, the recording density information also includes various other elements related to the density of the copying process, such as the exposure light amount and the developing bias voltage, so by replenishing the 1-ner according to the recording density information, the final It is possible to maintain a constant recording density at any time.

Incidentally, when performing the above-described control, the relationship between the timing of the density check and the amount of toner replenishment with respect to the result of the check is very important. In other words, there is a slight delay before the effect of toner consumption appears on the actual recording density, and even if toner is replenished, it is impossible to know whether sufficient toner has been replenished unless the copy is actually performed. .

In addition, since a visible pattern is actually formed on the photoreceptor,
If the density is constantly checked, a large amount of toner will be wasted and the burden of cleaning will be heavy. Furthermore, when controlling using a microcomputer, frequent recording density checks and 1-toner replenishment increases the processing burden on the microcomputer, making it difficult to keep up with the control timing of the copying process. Therefore, it is necessary to add a microcomputer and complicate the equipment.

Therefore, conventionally, for example, recording density is checked every predetermined number of sheets of toner to be recorded, and if replenishment is necessary, a fixed amount of toner is replenished during a predetermined operation.

However, for example, if a device that checks the density every 10 sheets is recorded and the device's power is turned on and off every time one sheet is recorded, the number of recording operations stored in the device will be cleared each time the power is turned off. Therefore, the device that performs the check for the first time performs the check every time, and the device that performs the check from the second time onwards will not perform the recording density check or toner replenishment forever. In any case, if the power is cut off at a relatively short cycle (number of sheets), the timing of the check will be out of order, and the 1-ner replenishment control will become abnormal, causing the recording density to fluctuate. In general copying machines, the power is usually left on regardless of whether or not the machine is in use, so there is little risk of the above situation occurring. Since the power is often turned on and off each time the power is turned on, there is an inconvenience that the recording density fluctuates for a while after the power is turned on.

(2) Purpose It is an object of the present invention to maintain the recording density within a predetermined range by checking the density every predetermined number of times of recording, regardless of whether the device power is turned on or off.

(2) When checking the density after counting the number of configuration recording operations, toner replenishment control does not work well when the power is turned on and off because the count value is cleared when the power is turned off. Therefore, this inconvenience can be resolved by making sure that the count value does not change even if the power is cut off. In such cases, the semiconductor memory is generally backed up by a battery, or a non-transitory memory whose contents do not change even if the power is cut off is used. However, in the former case, the circuit configuration becomes complicated because the battery is connected, and in the latter case, complicated processing or special timing circuits are often required to write data, and the memory itself is expensive. be.

Therefore, if the number of device operations is directly stored as mechanical displacement and the state of this change can be read out electrically,
Since there is no need for a backup power supply and no special circuits for memory protection or data writing, the device α
Configuration and processing become simpler and cheaper.

As a means for maintaining mechanical displacement, it is preferable to use an electromagnetic counter, a stepping relay, or the like, which repeats the displacement position every predetermined number of displacement operations. In that case, even if the displacement reaches a predetermined amount, there is no need to return the displacement to the initial position.
It is sufficient to simply perform 41 movements to displace the movable part by one step each time recording is performed.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1a depicts one type of electrostatographic reproduction machine embodying the invention. Referring to FIG. 1a, ``■'' is the contact 1-glass on which the original is placed. An optical scanning system 2 is provided below the contact glass l, and an image of light reflected from the original is formed on a photosensitive drum 3 via the optical scanning system 2. In the figure, it rotates clockwise.

On the other hand, the paper feed system has two stages, with 4.5 paper cassettes.
The recording paper is fed by the paper feed roller 6 or 7 from the selected one. The fed paper passes between a registration roller 8 and a leading end bending roller 9 and is guided to the photosensitive drum 3.

Around the photosensitive drum 3, a charger 10° and an eraser 11 are installed. g1. Image device 12. Pre-transfer static elimination lamp & P sensor 13. Transfer charger 142 Separate charger 15. Separation claw 16. Fur brush 17. A static elimination lamp 18, 1-toner replenishing device 23, etc. are arranged.

In this example, the optical scanning system 2 scans the document forward from the left side to the right side of the drawing, and a reference density pattern REFP is formed slightly before the HK document exposure area, that is, on the lower surface of the left end of the contact glass 1. It is.

To explain the general copying process, the photosensitive drum 3 is charged with a uniform potential by the charger 10, and when it is irradiated with reflected light from the original, the surface potential changes depending on the light intensity. , thereby forming an electrostatic latent image. When this electrostatic latent image passes through the developer 12, it is visualized by a 1-toner. The fed recording paper is transferred to the photosensitive drum 3
The image is sent by the registration roller 8 at a predetermined timing according to the rotation of the image tL, and overlaps the surface of the photoreceptor drum 3 on which the 1-toner image is formed. Thereafter, a predetermined voltage is applied to the transfer charger 14, whereby the 1-toner image is transferred from the photosensitive drum 3 to the recording paper side. Furthermore, the separation charger 15 is activated; therefore, the recording paper onto which the 1-toner image has been transferred is separated from the photosensitive drum 3 and directed toward the conveyance bell 1-19. Then, the recording paper is fixed to the fixing roller 2, which has a built-in heater.
0, the toner image is fixed thereon, and the paper passes through the paper ejection roller 21 to the copy 1-ray 22.

The reference density pattern REFP is exposed each time it is scanned by the optical scanning system 2, and the reflected light with a constant intensity obtained by this process is used for the operations on the photoreceptors 1 to rams 3. The area (hereinafter referred to as invalid area) is irradiated. If recording density check is not performed, the charge in the invalid area on the photoconductor 3 is erased by the eraser 11, so that J+% "!" rα: (Turn) Even if the reflected light from the EFP is irradiated, an electrostatic latent image will not be formed in that area. Check the recording density. A part of the invalid i'!rt area of - is not erased, and when that area is irradiated with the reflected light from the turn REFP, a predetermined electrostatic latent image is formed, and this area is exposed to the developing device. + 2 f, i, a toner image (visible image) of 411 degrees is formed in the ineffective area according to the state of the device. The density is read by the reflective photo sensor PSE.

FIG. 1b shows the j-ner capture device 23 of FIG. 1a.

Referring to FIG. 1b, 1. an agitator 23a for agitating the toner 30;

It consists of a 1-ner supply roller 231), a blade 23c, a hopper 23d, etc. A plurality of rollers are formed on the circumferential surface of the 1-ner replenishing roller 23b in the axial direction.
As the roller rotates, a predetermined amount of toner that has entered the 1rlff is supplied to the developing device 12. In other words, the l-ner supplementary #claw is the l-ner replenishing roller 2.
It is proportional to the rotating claw 3b. A driving source is connected to the rotating shaft of the 1-ner replenishing roller 23b via an electromagnetic clutch which will be described later. Lunar 3 is supplied from one side of the hopper 23d by a bowl or the like.

FIG. 2 shows part of the electrical circuit of the device shown in FIG. 1a. This circuit is only a part related to recording density control. The center of the circuit is a microcomputer CPU, and various devices are connected to the capo 1 and the output boat. A photo sensor PS2 connected to the input boat P1 outputs a timing pulse according to the rotation of the photosensitive drum 3. Input boat P2
The electrical contacts connected to are included in a stepping relay MME, which will be described later.

Output capo-1-P3 is provided with a solenoid 5QL that powers the stepping relay MME through the driver DV2.
2 is connected, and output capo-1-P4 has 1 to driver DV.
The toner replenishment clutch (=J-energizing solenoid SQL 1 is connected through I. It reads the visible pattern for density detection on the photoreceptor 3). The first sensor PSE connects the light emitting diode and the ! - It is made up of transistors.

The emitter end of this light emitting diode is grounded via a driver DVO, and the base end of the driver DvO is connected to the output capo-1i P5 of the CPU. The output end (emitter end) of the phototransistor is connected to one input end of an analog/digital converter ADC. analog/
A digital converter ADC is connected to the output port PA and input port PA of the CPU. Human powered boat P
13, converted digital data is obtained. C.P.
Baud 1/PC of U is connected to another electric circuit (not shown).

Fig. 3 shows the stepping relay MM used in this example.
The outline of E is shown. This will be explained with reference to FIG. 51 is
It is a disk-shaped fixing member, and in this example, ten metal terminals To-T9 are arranged around it at equal intervals. Coaxially with the fixed member 51 (center is 01), a train 52. Movable part benefit 53. A claw portion 54 and the like are provided, and a metal terminal TC is fixed to the movable portion 53 so as to face the metal terminals 1'0 to T9 of the fixed member 51.

The movable member 53 is fixed to the claw portion 4J54. The tip of the claw member 54 is provided with a claw 55 rotatably supported around o3, and is supported by a compression coil spring SP2.
Due to this, the pawl 55 is in contact with the small wheel 52. The movable member 56 located close to the solenoid SOT-2 is
It is connected to the claw member 54 via a part 57. The claw member 541 members 56, 57, etc. are compression coil springs SP1.
, and is normally in a predetermined position (the state shown in FIG. 3) regulated by a stopper (not shown).

When solenoid 5QL2 is energized, movable member 56 is attracted thereto. As a result, the pawl member 54 receives a counterclockwise rotating force and pushes the pawl 55 to a predetermined position, so that the small wheel 52 rotates by a predetermined amount (36 degrees in this example). When the small wheel 52 rotates, the movable part 5 fixed to it
3 rotates to move the metal terminal TC to the next deflected position. For example, when the solenoid 5QL2 is energized in the state shown in FIG. 3, the metal terminal TC moves to the position of the terminal TI and stops. This operation is repeated every time the solenoid 5QL2 is activated, so the metal terminal '1'C of the solenoid FSOL2 is sequentially activated depending on the number of times the solenoid FSOL2 is activated.
, T2. T3. T4. -I'5. Grounder, T
7. T8, T9. Electrical contacts are formed with To, TI, and so on. If solenoid 5QL2 is deenergized, the metal terminal 'r
The position c is held mechanically.

Referring again to FIG. 2, the metal terminal TO is connected to the input port P2 of the microcomputer CPU, and the movable metal terminal TC is at ground iL.

Therefore, the potential of the input capo-1 to P2 is the metal terminal TC.
According to the deviation of , the solenoid 5QL2 becomes low level L once for every 10 times the solenoid 5QL2 is energized, and becomes the high level I otherwise.

FIG. 4 shows the operation of the microcomputer CPU regarding recording density control, and FIG. 5 shows an outline of the operation timing. This will be explained with reference to FIGS. 4 and 5. When the power is turned on, the levels of Kapo-1~ are set to the initial state,
Clear memory.

When a copy start instruction is given, the status of stepping relay MME is read by looking at input capo-1-P2.

If input port I) 2 is Rainbow 1 Novel 1, a recording density check is performed, and if the high level is 14, a recording density check is not performed. Note that if the recording density is not checked, all charges in the invalid area on the photoreceptor 3 are erased by one eraser operation.

Check the toner replenishment flag, and if it is 1, energize the toner replenishment clutch (SOLI).

Otherwise, it remains inactive. Start 1- of the timing pulse applied to input port P1
Then, the rotational position of the photoreceptor 3 is determined by looking at this count value. The count value N1 indicates that the tip of the portion of the photoreceptor 3 that has been irradiated with the reflected light that exposed the reference density pattern is the first point.
- indicates the timing when the hook 1-sensor PSE (13) is reached, and the curl 1-value N2 indicates the timing when the trailing end leaves the hook 1-sensor PSE.

When performing a recording density check, make sure that the Curran 1-value is N.
When it reaches 1, the light emitting diode of sensor I) is turned on (outputs I-1 to capo-1' P5).
When N2 is reached, the light emitting diode is turned off. While subdividing the light emitting diode, r' S + (of) the first
・Read the output level of the transistor 1~ and convert it to a digital base using the analog/digital converter ADC.

When the count value reaches N3, the 1-ner supply clutch is deenergized if it is energized. Sunawaji, 1-
When the toner replenishment flag is 1, the toner replenishment roller 23b is driven until N3 timing pulses appear after the start of the copy process.

Therefore, a predetermined amount of toner is supplied to the developing device 12. If you want to check the recording density, then
The detected concentration data obtained from the digital converter ADC is compared with the reference data, and if the concentration is low, the 1-ner M
The i introduction flag is set to 1, and the toner supplement flag is set to 0 when the toner is not thin. When the copy cycle is completed, solenoid SQL2 is turned on and off once to advance movable terminal TC of stepping relay MME by one step, and waits until the next copy start instruction is given.

In other words, in any case, each time a recording is performed, the stepping relay MMIE advances one step, so if 10 recordings are performed, one will always be Cr) +J input port P2 becomes low level [5, and fit The recording density is checked at regular intervals. Moreover, since the state of the stepping relay MME does not change even if the power is cut off, the timing of recording density check is constant regardless of whether the Ftfft source is turned on or off (in this example, the timing is checked once every 10 recordings). ).

If the recorded density is checked and the detected density is low, a predetermined amount of 1-su~ will be replenished for each of the subsequent 10 recordings (while the 1 hener replenishment flag is 1), but if the detected density is low as a result of the check, If appropriate, 1-ner replenishment will not be performed in the subsequent 10 recordings.

In the above embodiment, the control state at that time is stored in the memory of the microcomputer CPU as a 1-toner replenishment flag, but if the power is cut off when toner replenishment is required, the flag is is cleared and toner replenishment is interrupted and the power is turned on again. If it takes some time to check the next recorded density, there is a possibility that the toner density will become unstable. So, for example, stepping relay MMI! If another : is provided and used in place of the replenishment flags 1 to 1, the state can be maintained even if the power is cut off, similar to the recording density check. Note that in the case of the 1-su supply flag, it is only necessary to maintain two states, ■ or 0, so it does not have a variety of displacement positions like a stepping relay, but has two mechanically stable states. It may include a movable terminal and two solenoids that drive the movable terminal.

Further, in the embodiment, a stepping relay (MME) is used as a means for storing the number of recordings, but an electromagnetic counter or the like from which the count value can be taken out as an electric signal may be used as well. Electrical signals can be extracted not only by mechanical contacts but also by photo sensors, magnetic sensors, etc.

■Effects As described above, according to the present invention, the number of recordings is mechanically maintained even if the power is cut off, so i! 8. The recording density check timing does not shift, and the recording density can always be maintained within a predetermined range.

[Brief explanation of the drawing]

FIG. 1a is a front view showing the configuration of one type of copying machine embodying the present invention, and FIG.
3 is a partially enlarged front view showing FIG. FIG. 2 is an electric circuit diagram showing an electric circuit for controlling the recording density shown in FIG. 1a. FIG. 3 is a front view schematically showing the stepping relay used in the device of FIG. 1a. FIG. 4 is a flowchart 1- showing an outline of the recording density control operation of the microcomputer CI)U. FIG. 5 is a time chart showing the general operation timing of the circuit shown in FIG. 23b:l
・Gner supply roller 23c blade 23d: Posopa 51: Fixed member 52: Claw +1 53: Movable member 54: Claw CPU: Microcomputer REFP: Reference density pattern PSE, PS2: Photo sensor 5oLt, 5QL2: Solenoid DVI, DV2: Driver To-T9,1'c: Metal terminal ADC: Analog/digital converter Patent applicant Ricoh Co., Ltd.

Claims (6)

[Claims] (1) Having a reference density pattern, exposing the pattern to light to form an electrostatic latent image on the photoreceptor, developing the electrostatic latent image to obtain a visible image, and changing the density of the visible image. A description of an electrostatic recording device that replenishes recording 1-ner according to the density of the electrostatic recording device @density control device: It has a movable part, and the movable part produces a predetermined mechanical displacement in accordance with the electrical output. An electromagnetic actuator that mechanically maintains the displacement and generates an electrical signal at at least one displacement point; and an electromagnetic actuator that is energized for each recording operation, and that the previous i1i! u tElectronic control means for controlling I'J density pattern exposure and 1-toner replenishment;
A recording density control device comprising: (2) The recording density control device according to claim 1, wherein the electromagnetic actuator includes a movable part that rotates around a predetermined position. (3) The recording density control device according to claim (2), wherein the ffi magnetic actuator is a stepping relay. (4) The concentration control device according to claim (2), wherein the electromagnetic actuator is an electromagnetic counter. (5) The recording density control device according to claim (2), wherein the electromagnetic actuator is a rotary solenoid. (6) 11! (7) There are a plurality of actuators, and at least one of them mechanically maintains the state of toner replenishment control. (2), (3), The recording density control device according to item (4) or item (5).