JPS5876846A - Detector - Google Patents

Abstract

PURPOSE:To detect a reflectance of a photosensitive drum in good linear properties by an optical sensor, by changing a light emitting output in accordance with a light receiving output. CONSTITUTION:An optical sensor 11 detects the fact that a light from a light emission element reflects on the surface of a photosensitive drum 1 and its reflectance is recognized. By deciding the proper timing for detection, one optical sensor 11 performs two detections whether a toner image density and a transferring paper are stuck onto the drum 1 owing to failure of separation by a separation charging device 8. As a toner and transfer paper are different large in reflectance, a current level of a light emitting element is changed over in accordance with a light receiving output and the level of the light receiving output is adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a detection device using a photosensor consisting of a light emitting element and a light receiving element.

Conventionally, adjustments were not made sufficiently due to variations in the circuits within the sensor and the detection device, resulting in problems in detection performance, but with the present invention, adjustments can be made completely.
We were able to achieve a detection device with no variations.

The present invention will be briefly described below, but in particular, toner concentration control and charge for making the toner concentration of the developer constant when development is performed using a two-component developer in an electrostatic recording device such as an electrophotographic copying device. Transfer paper wrapping detection (hereinafter referred to as
, lower jam detection) is coupled by a single reflective layer 7 sensor, that is, a toner concentration control ball jam electrophotographic copying device uses a photoreceptor having a photoconductive material as a charge carrier, This electrophotographic copying machine (hereinafter referred to as a single KII copying machine) is a device that performs various processes such as charging, exposure, development, transfer, separation, fixing, printing, etc. to form a fusuma copy of an original. This diagram schematically shows the main parts of the Here, a drum-shaped photoconductor 1 is used as the photoconductor, and as the drum-shaped photoconductor (hereinafter simply referred to as photoconductor) 1 rotates in the direction of the arrow, 1
After a charge is uniformly placed on the photoreceptor 1 by a charging electrode, light from an original (not shown) is irradiated onto the photoreceptor 1 through an exposure system 3 to form an electrostatic latent image. Further, as the photoreceptor 1 rotates, the electrostatic latent image is turned 111g11 by the developing device 4, and a toner image corresponding to the original is formed on the photoreceptor 1. Here, the developing device 4 uses a two-component developer consisting of toner and carrier, and the toner is supplied to the toner replenishing device 5.
Moreover, when the toner concentration of the developer in the developing device 4 drops below a predetermined toner concentration, the toner is replenished by a toner replenishment signal to keep the toner concentration constant. The photoreceptor 1 carrying the toner image further rotates Ki1, and is fed in synchronization with the 10 rotations of the photoreceptor, aligning the leading edge of the toner image with the leading edge of the transfer paper 6 so that they match. With the fed transfer paper and the photoreceptor 1 in contact with each other, the toner image on the photoreceptor 1 is transferred to the transfer paper by the transfer pole 7, and then the transfer paper is separated from the photoreceptor 1, as shown in the figure. Here, the fixing device 9 uses an electrostatic separation method for separation, and is provided with a separation pole 8. Cleaning MliO is reached to remove the toner left behind. A cleaning method using a Hiro blade or the like is often used in the cleaning device 10, but since the condition of the contact point between the blade and the photoreceptor 1 is an important factor in the flying performance, separation mistakes are avoided. If the generated transfer paper reaches the cleaning device 10 while being wrapped around the photoreceptor 1 and collides with the blade, the blade will be damaged and the cleaning performance will be greatly reduced.

For this reason, various proposals have been made in the past in order to avoid the risk of jamming described above. 〇Toner concentration control, which is inevitable in development using a two-component developer, has been made by exposing and developing originals of standard density (standard density patches). A method has been proposed in which the degree of toner adhesion of the primary image (toner image) of the photoreceptor formed in the non-iw* area, that is, the amount of reflected light, is used to detect the toner concentration. Detection method (
Although it does not necessarily match the toner concentration of the developer in the developing device, it is a method in which there is no interlayer in practical use. ) has been proposed in 4IM No. 54-61938, etc. to use a reflective layer photosensor necessary for the above-mentioned jam detection also as the surface of the photoreceptor. Reference numeral 11 denotes the seven automatic sensors for toner concentration detection (control) and jam detection. However, since jam detection and toner concentration detection are performed using a single reflective photosensor, there are various interlayers.

That is, in the past, the second v! With a detection circuit as shown in FIG. 2(a), the drum 1l is
For example, if you are adjusting the variable resistor VB to set the output voltage corresponding to the light receiving element at (II light body surface) L te 2.5 V (Too == 5. Q y), in this case, 7 oto 7-? Due to factors such as variations in the reflection density-output characteristics of the photo sensor 21, variations in the characteristics of the amplifier circuit 22 that amplifies the output of the light-receiving element of the photosensor, and variations in the accuracy of installation in the copying machine, the diagonal lines in FIG. 2(b) There were variations in the output with respect to the reference -* (primary image corresponding to a predetermined toner density or object of the same reflective skewer) k as shown in . Here, a comparison circuit 00MPI uses the output after amplifying the 7 sensor output as a comparison voltage of vA for outputting the toner replenishment signal v, and a comparison circuit 00MP2 uses it as a comparison voltage of vB for outputting the jam detection signal 1. V and vB vary depending on the properties and specifications of the copying machine, etc., but for example, Too = 5 V and VA = 0.
6V, 7B=3,57. Therefore, in such a method, it is impossible to issue a toner replenishment signal based on the defined level, and strict toner concentration control has not been implemented.

For such interlayers, proposals have been made to change the toner replenishment judgment reference level depending on the reference image output value or to make the reflection density-output voltage characteristic of the detection circuit closer to a straight line. Serviceability is degraded due to different setting levels of individual machines, and management of individual control units is required.The purpose of the present invention is to perform toner density control using a so-called reference density image (patch) method and to perform jam detection. In the enamel device, the drum surface (photoreceptor surface 1
For the primary image developed with a developer having a predetermined toner density corresponding to the detected output voltage and the patch in 1i1i) [By setting two points of the detected output voltage, the As shown in the reflection density-output voltage characteristics, #14
As shown by the diagonal lines, the toner concentration control performed by w1 has a highly accurate toner concentration control with less variation than in FIG. 2(b), as shown by the diagonal lines. .

That is, in a detection device that detects the concentration or presence of a target object using seven sensors each consisting of a light-emitting element and a light-receiving element, the output level of the light-receiving element is outputted as a plurality of specific outputs according to the output level of the light-receiving element. This is achieved by a detection device characterized by having an adjustment means for adjusting the toner level, and more specifically, when detecting the toner concentration and when detecting the wrapping of the transfer paper, the toner on the photoreceptor corresponding to a predetermined toner concentration is detected. 41#s-Ukene's Densai Geki Banashi m-, wherein the output level due to reflection from the photoreceptor and the photoreceptor can be adjusted to the specific output level of the plurality of outputs by using the adjusting means as well.
This was achieved by using a copper rho detection device.

When implementing such a detection device, a feedback circuit is provided to switch the value of the current control resistor of the light-emitting element lighting circuit so as to change the current flowing to the light-emitting element according to the output level of the light-receiving element. This configuration was also very effective.

Reflection density -
The variation in the output voltage characteristics is approximately 5 as shown in FIG.

Now, when the drum surface and reference image are automatically detected, the third
As an example of a disparate detection device that operates inconsistently as shown in the figure, there is a circuit shown in FIG.

Here, 41 is the one facing the drum surface, that is, 11 in FIG.
42 is an amplification unit for amplifying the output of the reflection fi7 sensor 41, and a circuit consisting of a thermistor TH and resistors R2 and R4 is a reflection type photosensor installed at a position facing the photoreceptor IK shown in FIG. This is a temperature compensator for stabilizing the output of the photosensor circuit against temperature changes.

Kuzu is the voltage of the photosensor output voltage We after amplification, R1 is a constant voltage source, and a resistor group connected in series with the light emitting part (111) of the photosensor 41 between Voa and the ground.R1 is a protective resistor, a variable resistor , 712 indicates that when vR1 (described later) is short-circuited by the switching unit 43, that is, when the primary W for toner density control is not detected and the drum surface is reflected, the set voltage is 2.5'. tl f V
The output is adjusted to the c voltage and decreases, but as a result, the switching section becomes O? 7 is a variable resistor that adjusts the current flowing to the LID of the photosensor 21 together with the resistor R1 and the already adjusted variable resistor VR2 when detecting the primary image for toner density control. Huo after amplification) -1
The e-sensor output voltage 7o is determined by a comparison circuit 00MP3 that uses the toner replenishment reference level (-0.33V as an example) as a comparison voltage.
and jam detection reference level (for example a, SV
) is used as the comparison voltage. These comparison circuits 00M1?3, OOM]? The outputs of 4 are each output from the control unit of the copying machine (in this case, a microcomputer) OON! is being input to.

Although not shown here, the photosensor output voltage T.

A comparison circuit for switching VRl, which inputs a predetermined voltage 76 voltage (1, IT in the embodiment) as a reference, is used to create a circuit made up of transistors so as to switch at a predetermined voltage and not to short-circuit or short-circuit the variable resistor vpt. It can also be substituted.

As another example, as shown in FIG. Resistor R1' and variable resistor VR2 for
It is also possible to connect circuits connected in series in parallel. Further, as shown in FIG. 5('b), when the amount of light to the light receiving element of the 7-oto sensor 511 decreases and the To voltage decreases, the resistance R
4 and PNPIJ) It is also possible to configure 5 to short-circuit vR1v by using a displacement disk 52. However, in this case, the method of adjusting each variable resistor as explained in FIG. 4 will be used. Due to the operation of this circuit configuration, normally when the 7 sensor detects the reflection from the drum surface, the To voltage is relatively high (vRiFi is not shorted, so the photo 7 sensor 511
]: The current flowing through I is resistor 11, variable resistor 2vc plus Il! 0th order 4 limited by series resistance of TRI
1211 The reflection from the primary image for toner single-density nakedness (at 51V, reflections from the photoreceptor drum surface were also picked up).
When the photo sensor 511 is short-circuited, and from that point on, while the primary image is being detected, the photo sensor valley current L"ID is limited by the resistor R1 and the variable resistor VR2.

Therefore, in this embodiment, unlike the previous two embodiments, the direction of increase and decrease in the current applied to the LID is opposite between the direction of increase and decrease during the detection of the & surface and the detection of the primary image.

jI5 In the example of FIG.
It is preferable that the control section reads the toner density control signal and the jam detection signal at the appropriate timing.

As described above, the present invention solves the problem of the conventional method in which only so-called one-point adjustment was performed, and jam detection was sufficient, but toner concentration control varied considerably between devices. Toner concentration control was also performed with sufficient precision.

[Brief explanation of the drawing]

1 FIl schematically shows the internal structure of a general electrophotographic copying machine, and FIG. 2 (&) is an example of a conventional detection circuit in which toner density control and jam detection are performed by one sensor. FIG. 2(k) is a diagram showing the relationship between the input (reflection density) and the output (voltage) when the circuit of FIG. 2(1) is used, together with the variation IIIv between each detection device. FIG. 113 shows the relationship between reflection density and output voltage in an embodiment according to the present invention in the same way as the second figure), and FIG. 4 shows an example of the circuit configuration according to the present invention. Figure 5 shows other examples of implemented circuits. ◎ 1... Photoreceptor (drum), 2... Charger, 3...
Exposure system, 4...Developing device, 5...Toner supply device,
10...Cleaning device, 11, 21.41.51
．． 511... Toner concentration control and jam detection 7 sensor, 43... Switching circuit, VR, 'VRI,
VR2...Variable resistance, 00MP1, OOMP2 ・”
Ratio'IRm road, TH...thermistor, vo...photo sensor (after amplification) output voltage/proxy Yoshimi Kuwahara'IpJI record figure 2 (Q) dog - anti-contamination degree → Kota - Reflection density one small is also 41! 1 diarrhea 5I! l(α) 5th [! l (b) 2

Claims (1)

[Scope of Claims] 1. In a detection device that detects the concentration or presence of an object to be measured using a seven-position sensor consisting of a light-emitting element and a light-receiving element, the output level of the light-receiving element is determined according to the output level of the light-receiving element. A detection device characterized in that it is provided with an adjusting means for adjusting the output level to a specific output level of the number of strokes. 2. The object to be measured is a toner image carried on a photoreceptor of an electrostatic recording device and a transfer paper wrapped around the photoreceptor, and the F-toner density detection and the transfer paper wrapping detection are performed.
Detection device for combat. 3. At the time of detecting the toner concentration and the time of detecting transfer paper wrapping, the output level of the toner image on the photoreceptor and the casing emitted from the photoreceptor corresponding to a predetermined toner density is adjusted to the plurality of specific outputs by the adjustment means. 3. The detection device according to claim 2, which is configured to be able to adjust the level. 4. Claim 1, wherein a feedback circuit is provided to switch the value of a current control resistor of the light emitting element lighting circuit so as to change the current flowing to the light emitting element according to the output level of the light receiving element. to the detection device according to item 3. 5. The current control resistor is constituted by a variable resistance element that is short-circuited when the feedback circuit is on, and a variable resistance element that is not affected by the on/off state of the feedback circuit, and the adjustment means is thereby constituted. Detection device according to scope 4.