JPH08278729A - Image recorder - Google Patents

Abstract

PURPOSE: To provide an image recorder whose accuracy detecting the life of photoreceptors is improved. CONSTITUTION: A detection signal for detecting the film thickness of a photoreceptor drum 9 by, using a conversion threshold value varied by adding a value calculated by the central controlling processing means of a life detecting circuit 20 to the threshold controlling means of the life detecting circuit 20 is made to be a time conversion signal by the time converting means of the life detecting circuit 20, and the time conversion signal and a judged signal for judging the life of the photoreceptor drum 9 are compared by the central controlling processing means, so that the life of the photoreceptor drum 9 is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording device such as a laser printer.

[0002]

2. Description of the Related Art A photosensitive drum (photoreceptor) used in an electrophotographic system or the like may lead to image deterioration due to its life due to abrasion and dirt.

In an image recording apparatus using the contact charging method, one of the methods for detecting the life of the photosensitive drum is to measure the film pressure value of the photosensitive drum by measuring the current flowing during charging or discharging of the photosensitive drum. Knowing and detecting its life is well known in the art.

[0004]

However, in the above-mentioned conventional example, the amount of charges charged on the photosensitive drum is very small, and the electric circuit deviation and temperature characteristics are large with respect to the current to be detected. Therefore, there is a problem that the life detection accuracy of the photosensitive drum is significantly reduced. The present invention has been made in view of the above problems of the above-described conventional technique. A first object of the present invention is to record an image with improved accuracy in detecting the life of the photoconductor (photosensitive drum). It is intended to provide a device.

A second object of the present invention is to provide an image recording apparatus which improves the lifespan detection accuracy of the photoconductor and simplifies the circuit structure.

A third object of the present invention is to improve the accuracy of detecting the life of the photoconductor, simplify the circuit structure, and further improve the accuracy of detecting the life of the photoconductor. An object of the present invention is to provide an image recording device that can easily realize system upgrade.

[0007]

In order to achieve the first object, an image recording apparatus according to claim 1 of the present invention is a high voltage applying means for applying a high voltage to a charged body, and the charged body is exposed to light. A charging / discharging means for charging or discharging the photoconductor by contacting with the body, and a detection current signal output from the photoconductor when the charging / decharging means charges or removes the photoconductor. Voltage converting means for converting into a voltage signal; amplifying means for generating a photoconductor film thickness detection signal by amplifying the detected voltage signal converted by the voltage converting means; and charging of the photoconductor by the charging / discharging means. Alternatively, a time conversion means for converting an output signal from the amplification means into a time function other than during static elimination, a threshold control means for controlling a conversion threshold of the time conversion means, and a calculation of a signal obtained by the time conversion means. Processing Central control processing means, comprising a photoconductor life determination signal generation means for generating a signal for determining the life of the photoconductor, by adding the value calculated by the central control processing means to the threshold control means The photoconductor film thickness detection signal is converted into a time conversion signal by the time conversion unit with a variable conversion threshold value, and the central control processing unit compares the time conversion signal with the photoconductor life determination signal to detect the photosensitivity. It is characterized by detecting the life of the body.

In order to achieve the second object,
The image recording apparatus according to claim 2 of the present invention is a high voltage applying means for applying a high voltage to a charged body, and a charging / discharging means for charging or discharging the photosensitive body by bringing the charged body into contact with the photosensitive body. A voltage conversion means for converting a detection current signal output from the photoconductor into a detection voltage signal when the photoconductor is charged or discharged by the charging / static elimination means, and the detection converted by the voltage conversion means Amplification means for generating a photoconductor film thickness detection signal by amplifying a voltage signal, central control processing means for performing arithmetic processing, and comparison while the photoconductor film thickness detection signal is output by the central control processing means. Comparison threshold generation means for generating a comparison threshold in time series by inputting a threshold selection signal, comparison means for comparing the photoconductor film thickness detection signal with the comparison threshold, and the photoconductor film by the comparison means. Thickness detection And an auxiliary storage means for storing a first comparison determination signal obtained by comparing the comparison threshold with the comparison threshold value as an initial film thickness value, and the first comparison determination signal of a series of operations as an initial film thickness value. The central control processing means writes the auxiliary storage means, and from the next time, the central control processing means calculates the difference between the initial film thickness value stored in the auxiliary storage means and the comparison determination signal obtained by the comparison means. The central control processing means compares the calculated value with a preset life difference value to detect the life of the photoconductor.

Further, in order to achieve the third object, the image recording apparatus according to claim 3 of the present invention is the image recording apparatus according to claim 2, further comprising: comparison threshold generating means for generating a plurality of different comparison thresholds. A plurality of comparison threshold values corresponding to the plurality of comparison threshold value generating means, the central control processing means inputs a comparison threshold value selection signal to each of the plurality of comparison threshold value generating means, A plurality of comparison determination signals are obtained by comparing the photoconductor film thickness detection signal with the comparison threshold value by means, and the initial film thickness value stored in the auxiliary storage means and the plurality of comparison means are obtained. The central control processing means calculates a difference from the obtained comparison determination signal, and the central control processing means compares the calculated value with a preset life difference value to determine the life of the photoconductor. It is characterized in that to detect the.

[0010]

According to the image recording apparatus of the present invention, the photoconductor film thickness detection signal is converted into the time conversion signal by the time conversion means with the conversion threshold value changed by adding the value calculated by the central control processing means to the threshold value control means. Then, in the central control processing means, the life of the photoconductor is detected by comparing the time conversion signal and the photoconductor life determination signal.

According to another aspect of the image recording apparatus of the present invention, the central control processing means writes the comparison determination signal at the first time of a series of operations as an initial film thickness value in the auxiliary storage means, and stores it in the auxiliary storage means from the next time. By calculating the difference between the initial film thickness value and the comparison determination signal obtained by the comparing means by the central control processing means, and comparing the calculated value with a preset life difference value in the central control processing means. , To detect the life of the photoconductor.

According to the image recording apparatus of claim 3, in addition to the operation of the image recording apparatus of claim 2, the central control processing means inputs a comparison threshold value selection signal to each of the plurality of comparison threshold value generating means. , A plurality of comparison determination signals are obtained by comparing the photoconductor film thickness detection signal with the comparison threshold by the plurality of comparison means, and the initial film thickness value stored in the auxiliary storage means and the plurality of comparisons. The difference between the comparison determination signal obtained by the means is calculated by the central control processing means, and the calculated value is compared with a preset life difference value by the central control processing means, thereby the life of the photoconductor is reduced. To detect.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows the first of the present invention.
FIG. 1 is a vertical cross-sectional view showing a configuration of a color laser printer (color image recording apparatus) using an electrophotographic process as an image recording apparatus according to an embodiment, in which FIG. 1 is a color laser printer (hereinafter referred to as a printer). Reference numeral 2 denotes an interface section, which is a section for inputting digital image data read by a scanner or the like (not shown). The printer 1 prints out an image corresponding to the data input from the interface unit 2 in full color. The RGB signal sent from the interface unit 2 to the signal processing unit 3 is converted by the signal processing unit 3 into each image signal of magenta (M), cyan (C), yellow (Y), and black (Bk). , To the laser driver 4.

The laser driver 4 modulates the semiconductor laser 5 with respect to the image signal and outputs the modulated laser light L corresponding to the image signal. The laser light L scans a photosensitive drum (photosensitive member) 9 as an image bearing member via a polygon mirror 6, an f-θ lens 7, and a mirror 8. Photosensitive drum 9
Is rotationally driven in the counterclockwise direction of the arrow at a predetermined peripheral speed (process speed). The photosensitive drum 9 is uniformly primary-charged to a predetermined polarity and potential by the charging roller 10. The charging roller 10 is pressed against the photosensitive drum 9 with a predetermined pressing force, and is output from the high voltage generating section 11. A superimposed signal (vibration signal) of a DC voltage and an AC voltage is applied, and the photosensitive drum 9 is charged by a contact charging method of an AC application method. An electrostatic latent image is formed by scanning the charged surface of the photosensitive drum 9 with the laser light L.

Reference numeral 12 denotes a rotary developing device, which is composed of a magenta developing section 13, a cyan developing section 14, a yellow developing section 15 and a black developing section 16, and these four developing sections 13 are provided.
To 16 alternately contact the photosensitive drum 9,
The electrostatic latent image formed above is developed with toner. A transfer drum 17 winds the recording paper P fed from the paper cassette 18 around the transfer drum 17, and transfers the image developed on the photosensitive drum 9 to the recording paper P.

The above-mentioned latent image forming / developing / transfer process is repeated for each image signal of magenta, cyan, yellow and black, and four color toners of magenta toner image, cyan toner image, yellow toner image and black toner image are formed. The images are sequentially transferred onto the surface of the same recording paper P so that a full-color image is synthetically formed.

Then, the recording paper P on which the full-color image is formed is separated from the transfer drum 17 and sent to the fixing unit 19 by the conveying device, and the fixing unit 19 is provided.
And is discharged to the outside of the printer 1.

Reference numeral 20 denotes a life detecting circuit for detecting the life of the photosensitive drum 9. The primary current signal 23 output from the photosensitive drum 9 is detected, and the film thickness d of the photosensitive drum 9 is detected.

FIG. 2 is a diagram showing an equivalent circuit of the photosensitive drum 9 and the high voltage generator 11 in the printer 1 of FIG. 1, and the photosensitive drum 9 is considered to be equivalently an aggregate of minute capacitance components. 2, the same parts as those in FIG. 1 are designated by the same reference numerals. In FIG. 2, 21 is a primary DC voltage source, 22
Is a primary voltage source, 23 is a primary current signal (Idc) output from the photosensitive drum 9, 24 is a capacitor, and 25 is a current signal output from the capacitor 24.

Total capacity C when the photosensitive drum 9 makes one rotation
Is the length L of the photosensitive drum 9 in the longitudinal direction,
Is represented by the following formula (1), where Vp is the rotation speed of the photosensitive drum, t is the time for the photosensitive drum 9 to rotate once, and d is the film thickness of the photosensitive drum 9 that is uniquely determined.

C = (εr · ε0 · L · Vp · t) / d (1) When the average DC bias voltage value of the bias voltage signal applied to the photosensitive drum 9 is Vd, the photosensitive drum 9 is 1 The charge amount Qd accumulated during the rotation time t is obtained by the following equation (2). From this relationship, the relationship between the primary current signal (Idc) 23 and the film thickness d of the photosensitive drum 9 is given by the following equation (3). Given by.

Qd = C · Vd = Idc · t (2) Therefore, Idc = (C · Vd) / t = (εr · ε0 · L · Vp · Vd) / d (3) where (εr .Epsilon.0.L.Vp.Vd) are eigenvalues and are replaced by a constant k, and the film thickness d of the photosensitive drum 9 changes in an inverse proportional function with respect to the primary current signal (Idc) 23. This can be understood by the following equation (4).

Idc = k / d (4) Therefore, the film thickness d of the photosensitive drum 9 is measured by monitoring the primary current signal (Idc) 23, and at the same time, the life is detected.

FIG. 3 is a timing chart showing a control sequence of the photosensitive drum 9 and the high voltage generator 11 for outputting the primary current signal (Idc) 23. FIG. 3A shows a temporary AC voltage output, (B) shows a primary DC voltage output, (c) shows a photosensitive drum control signal, and (d) shows a primary current signal (Idc) 23, respectively. For example, when a negative voltage is applied from the primary DC voltage source 21 and the photosensitive drum 9 is rotated simultaneously with the charging roller 10, a primary current signal (Idc) 23 as shown in FIG. 3D is obtained. Similarly, when the output of the primary DC voltage source 21 at the negative potential is returned to the ground potential, the primary current signal (Idc) 23 has the opposite characteristic to that at the time of charging.

FIG. 4 is a block diagram showing the structure of the life detecting circuit 20. In FIG. 4, 9 is a photosensitive drum and 23 is a photosensitive drum.
Is a primary current signal (Idc), 26 is a current-voltage conversion circuit, 27 is an output signal from the current-voltage conversion circuit 26, 2
8 is a gain amplifier, 29 is a film thickness detection signal output from the gain amplifier 28, 30 is a voltage-time conversion circuit, 31 is a time conversion signal output from the voltage-time conversion circuit 30,
32 is a CPU (central processing unit), 33 is a latch control signal output from the CPU 32, 34 is a latch circuit, 35 is a conversion control signal output from the CPU 32, 36 is a conversion threshold generation circuit, and 37 is a conversion threshold generation circuit 36. Is a conversion threshold value, 38 is a life detection table, 39 is an output signal from the life detection table 38, and 40 is a drum life detection signal output from the CPU 32.

FIG. 5 shows an operation sequence of the life detecting circuit 20, where (a) is a primary AC voltage output, (b) is a primary DC voltage output, and (c) is a primary current signal (Idc) 2.
3, (d) shows the film thickness detection signal 29, (e) shows the sequence of the CPU 32, (f) shows the latch control signal, and (g) shows the sequence of the conversion threshold generation circuit 36.

In FIG. 4, the CPU 32 detects the voltage offsets of the current-voltage conversion circuit 26 and the gain amplifier 28 before detecting the primary current signal (Idc) 23. While only the primary voltage source 22 is being output, C
The m-bit conversion control signal 35 set for the offset detection is input from the PU 32 to the conversion threshold generation circuit 36. At the same time when the conversion threshold value 37, which is the output of the conversion threshold value generation circuit 36, is determined, the CPU 32 outputs the latch control signal 33 to the latch circuit 34, determines the conversion threshold value 37, and then inputs the voltage-time conversion circuit 30. To do. The offset value at that time is taken into the CPU 32 as a time conversion signal (film thickness detection signal) 31 by the conversion threshold value 37 previously obtained.

The conversion threshold 37 thus obtained includes the circuit deviation, and based on the result of comparison between the circuit deviation and the standard threshold preset in the CPU 32, the preset value is set in the same manner as the offset detection. It is input to the conversion threshold value generation circuit 36 as an m-bit conversion control signal 35. C
The latch circuit 3 is controlled by the latch control signal 33 from the PU 32.
4 is set to the latch mode and the conversion threshold value 37 is latched.

Here, the primary current signal (Idc) 23 is output from the photosensitive drum 9, the voltage is converted by the current-voltage conversion circuit 26, and the film thickness detection signal 29 obtained via the gain amplifier 28 is obtained. Input to the voltage-time conversion circuit 30. Here, the time conversion signal 31 obtained by the previously determined conversion threshold value 37 is fetched into the CPU 32 again and compared with the preset value 39 of the life detection table 38, and when it is determined that the life is reached, the drum life is detected. Signal 40 to C
Output from PU32.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. 6 and 7. The basic configuration of the image recording apparatus according to the present embodiment is the same as that of the above-described first embodiment shown in FIG.

FIG. 6 is a block diagram showing the structure of the life detecting circuit 20 in the image recording apparatus according to the second embodiment of the present invention. In FIG. 6, the same parts as those in FIG. 4 of the first embodiment described above are shown. Are assigned the same reference numerals and explanations thereof are omitted.

6 is different from FIG. 4 in that the voltage-time conversion circuit 30, the latch circuit 34, the conversion threshold value generation circuit 36 and the life detection table 38 are respectively deleted from the structure of FIG. That is, the comparator 41, the comparison threshold value generating circuit 42, and the backup memory (auxiliary storage means) 43 are added. In FIG. 6, 44 is a comparison determination signal output from the comparator 41, 45 is threshold selection data output from the CPU 32, 46 is a comparison threshold output from the comparison threshold generation circuit 42, 47 is the CPU 32 and the backup memory 43. Is a memory data bus between and.

In FIG. 6, the primary current signal (Idc) 23 flowing out from the photosensitive drum 9 is the current-voltage conversion circuit 2.
6, the voltage is converted into a detection voltage signal, and the detection voltage signal 27
Inputs the film thickness detection signal 29 obtained through the gain amplifier 28 to the comparator 41.

On the other hand, the n-bit threshold value selection data 45 is input from the CPU 32 to the comparison threshold value generating circuit 42, and the comparison threshold value generating circuit 42 outputs the comparison threshold value 46 to the comparator 41. As a circuit configuration for this, in the comparison threshold value generation circuit 42, a DA (Digital-Analog) is used by using an n-bit input resistance ladder and a reference voltage.
g) By using a converter and varying the output analog voltage value by the threshold selection data 45, (2 to the nth power)
It is conceivable to generate individual comparison threshold values 46.

The comparator 41 uses the comparison threshold value 46 obtained from the comparison threshold value generation circuit 42 to detect the film thickness detection signal 2
The result of comparison with 9 is used as the comparison determination signal 44 for CP.
Input to U32.

By the way, the above-described sequence is executed at the time of factory shipment or when the photosensitive drum 9 is replaced, and the content of the comparison / determination signal 44 is transferred to the backup memory 43 via the 1-bit memory data bus 47 to the initial film thickness. Write as the value d0. Further, the backup memory 43 has the CPU 3
In 2, the difference between the initial film thickness value d0 and the content of the comparison determination signal 44 for each life detection sequence is calculated, and the life difference value Δde for making the life judgment is preset and written.

The CPU 32 refers to the initial film thickness value d0 of the backup memory 43 for each life detection sequence, determines that the photosensitive drum 9 has reached the end of life when the difference from the comparison determination signal 44 exceeds Δd, and The life detection signal 40 is output.

FIG. 7 is a timing chart showing the operating condition of the comparator 41, for example, a case where the drum life detection is performed by the charge eliminating portion of the primary current signal (Idc) 23 flowing from the photosensitive drum 9. 7A is a primary current signal (Idc) 23, FIG. 7B is threshold selection data 45,
(C) is a comparison threshold value 46, (d) is a film thickness detection signal 29,
(E) shows the comparison determination signal 44, respectively.

First, the comparison threshold value generation circuit 4 from the CPU 32.
The threshold selection data 45 is output in chronological order with respect to 2.
Corresponding to this, the comparison threshold generation circuit 42 sequentially outputs the comparison threshold 46 to the comparator 41, and the result of comparison with the film thickness detection signal 29 is used as the comparison determination signal 44 in the CPU 3
2 takes in.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIGS. 8 and 9. The basic configuration of the image recording apparatus according to the present embodiment is the same as that of the above-described first embodiment shown in FIG.

FIG. 8 is a block diagram showing the structure of the life detecting circuit 20 in the image recording apparatus according to the third embodiment of the present invention. In FIG. 8, the same parts as those in FIG. 6 of the above-mentioned second embodiment are shown. Are assigned the same reference numerals and explanations thereof are omitted.

In the second embodiment, one comparator 41 and one comparison threshold value generating circuit 42 are provided, whereas in the present embodiment, a plurality (for example, three) of comparators 48 and 4 are provided.
9 and 50 are provided, and these comparators 48 to 5
The number of comparison threshold value generating circuits 51, 52 and 53 corresponding to 0 is provided.

The primary current signal 23 flowing out from the photosensitive drum 9 is converted into a detection voltage signal by the current-voltage conversion circuit 26, and the detection voltage signal 27 is converted into a gain amplifier 28.
The film thickness detection signal 29 obtained through
Enter in ~ 50.

On the other hand, the CPU 32 inputs the n-bit threshold value selection data 45 to the comparison threshold value generating circuits 51 to 53.
For example, in the comparison threshold value generating circuit 51, by changing the output voltage value by the threshold value selection data 45 using the n-bit input resistance ladder and the reference voltage, (2 of 2)
A circuit configuration in which (multiplication) comparison threshold values are generated can be considered.

A plurality (eg, 3) obtained from each circuit
Number of comparison threshold values (comparison threshold value 54, comparison threshold value 55, and comparison threshold value 56) with the film thickness detection signal 29 in each of the comparators 48 to 50, and the obtained signals are compared with each other. , The comparison determination signal 58 and the comparison determination signal 59) are input to the CPU 32.

The CPU 32 compares a plurality of (for example, three) comparison determination signals with the initial film thickness value d0 of the backup memory 43 via the h-bit life determination data bus 60,
When the difference exceeds Δd, it is determined that the photosensitive drum 9 has reached the end of its life, and the drum life detection signal 40 is output.

FIG. 9 is a timing chart showing the relationship between the threshold selection data 45 and the comparison judgment signals (comparison judgment signal 57, comparison judgment signal 58 and comparison judgment signal 59).
In the figure, (a) shows a film thickness detection signal 29, (b) shows threshold selection data 45, (c) shows a comparison judgment signal 57, (d) shows a comparison judgment signal 58, and (e) shows a comparison judgment signal 59. Show.

While the primary current signal 23 is being output, (2 to the nth power) threshold value selection data 45 are sequentially output from the CPU 32 to the comparison threshold value generating circuit 51, the comparison threshold value generating circuit 52 and the comparison threshold value generating circuit 53. . Comparison threshold generation circuit 5
1 is taken as an example, as the threshold value selection data 45 increases from data 0 to data (2 to the nth power −1) in sequence, the comparison threshold value generation circuit 51 responds to it (2
N powers of comparison thresholds 54 are generated. The result of comparing the film thickness detection signal 29 and the comparison threshold value 54 in the comparator 48 is sequentially output as a comparison determination signal 57.

Based on the above results, a plurality of (for example, three) each, a total of [3 × (2 to the nth power)] comparison determination signals are given to the CPU 32 for one threshold selection data 45. It will be. Data is written from the CPU 32 to the backup memory 43 via the h-bit memory data bus 60. Further, the CPU 32 calculates the difference between the comparison determination signal for each life sequence and the initial film thickness value d0 read from the backup memory 43, and when the life difference value Δd is exceeded, it is determined that the photosensitive drum 9 has reached the life. , And outputs the drum life detection signal 40.

[0051]

As described in detail above, according to the image recording apparatus of the first aspect of the present invention, the photoconductor film has a conversion threshold value which is varied by adding the value calculated by the central control processing means to the threshold value control means. The thickness detection signal is converted into a time conversion signal by the time conversion means, and the life of the photoconductor is detected by comparing the time conversion signal with the photoconductor life determination signal in the central control processing means. This has the effect of improving accuracy.

According to the image recording apparatus of claim 2,
The first comparison judgment signal of a series of operations is written as an initial film thickness value in the auxiliary storage means by the central control processing means, and from the next time, the initial film thickness value stored in the auxiliary storage means and the comparison obtained by the comparison means. The central control processing means calculates a difference from the determination signal, and the central control processing means compares the calculated value with a preset life difference value, thereby detecting the life of the photoconductor. The effect of improving the lifespan detection accuracy and simplifying the circuit scale is achieved.

Further, according to the image recording apparatus of claim 3,
A central control processing means inputs a comparison threshold selection signal to each of a plurality of comparison threshold generation means, and a plurality of comparisons are made by comparing the photoconductor film thickness detection signal and the comparison threshold by the plurality of comparison means. A determination signal is obtained, the difference between the initial film thickness value stored in the auxiliary storage means and the comparison determination signal obtained by the plurality of comparison means is calculated by the central control processing means, and the calculated value is preset. The lifespan of the photoconductor is detected by comparing the lifespan difference value obtained by the central control processing means. The effect is that the system can be easily upgraded when it is desired to improve.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a configuration of an image recording apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an equivalent circuit of a photosensitive drum and a high voltage generator in the image recording apparatus.

FIG. 3 is a timing chart showing a control sequence of a photosensitive drum and a high voltage generator in the image recording apparatus.

FIG. 4 is a block diagram showing a configuration of a life detecting circuit in the image recording apparatus.

FIG. 5 is an operation sequence of a life detection circuit in the image recording apparatus.

FIG. 6 is a block diagram showing a configuration of a life detection circuit in the image recording apparatus according to the second embodiment of the present invention.

FIG. 7 is a timing chart showing an operation state of a comparator in the image recording apparatus.

FIG. 8 is a block diagram showing the configuration of a life detection circuit in the image recording apparatus according to the third embodiment of the present invention.

FIG. 9 is a timing chart showing the relationship between threshold selection data and each comparison determination signal in the image recording apparatus.

[Explanation of symbols]

1 Printer (Image Recording Device) 9 Photosensitive Drum (Photoreceptor) 10 Charging Roller (Charging / Electrifying Means) 11 High Voltage Generating Means (High Voltage Generating Unit) 20 Life Detecting Circuit (Central Control Processing Means, Threshold Control Means, Time Conversion) Means) 26 current-voltage conversion circuit (voltage conversion means) 28 gain amplifier (amplification means) 30 voltage-time conversion circuit (time conversion means) 32 CPU (central control processing means, photoconductor life determination signal generation means, comparison means) 34 Latch Circuit (Threshold Control Means) 42 Comparison Threshold Generation Circuit (Comparison Threshold Generation Means) 43 Backup Memory (Auxiliary Storage Means) 48 Comparator (Comparison Means) 49 Comparator (Comparison Means) 50 Comparator (Comparison Means) 51 Comparison Threshold Generation Circuits (Comparison threshold generation means) 52 Comparison threshold generation circuit (comparison threshold generation means) 53 Comparison threshold generation circuit Comparison threshold value generating means)

Claims (3)

[Claims] 1. A high voltage applying means for applying a high voltage to a charged body, a charging / discharging means for charging or discharging the photosensitive body by bringing the charged body into contact with the photosensitive body, and the charging / discharging means. By means of a voltage conversion means for converting a detection current signal output from the photoconductor into a detection voltage signal when the photoconductor is charged or discharged, and by amplifying the detection voltage signal converted by the voltage conversion means. Amplifying means for generating a photoconductor film thickness detection signal, time converting means for converting an output signal from the amplifying means into a time function except when the charging / discharging means charges or discharges the photoreceptor, and the time Threshold control means for controlling the conversion threshold of the conversion means, central control processing means for performing arithmetic processing of the signal obtained by the time conversion means, and photoreceptor life for generating a signal for determining the life of the photoreceptor Size A constant signal generation means, and the photoconductor film thickness detection signal is converted into a time conversion signal by the time conversion means with a conversion threshold value changed by adding the value calculated by the central control processing means to the threshold value control means. By comparing the time conversion signal and the photoreceptor life determination signal in the central control processing means,
An image recording apparatus characterized by detecting the life of the photoconductor. 2. A high voltage applying means for applying a high voltage to a charged body, a charging / discharging means for charging or discharging the photosensitive body by bringing the charged body into contact with the photosensitive body, and the charging / discharging means. By means of a voltage conversion means for converting a detection current signal output from the photoconductor into a detection voltage signal when the photoconductor is charged or discharged, and by amplifying the detection voltage signal converted by the voltage conversion means. An amplifying means for generating a photoconductor film thickness detection signal, a central control processing means for performing arithmetic processing, and a comparison threshold value selection signal while the photoconductor film thickness detection signal is being output by the central control processing means. Comparison threshold generation means for generating a comparison threshold in time series, comparison means for comparing the photoconductor film thickness detection signal and the comparison threshold, and the photoconductor film thickness detection signal and the comparison threshold by the comparison means. And Auxiliary storage means for storing the first comparison determination signal obtained by comparison as an initial film thickness value, and the auxiliary control means by the central control processing means using the first comparison determination signal of a series of operations as an initial film thickness value. The difference between the initial film thickness value stored in the auxiliary storage means and the comparison determination signal obtained by the comparison means is calculated by the central control processing means from the next time, and the calculated value is set in advance. An image recording apparatus, wherein the life of the photoconductor is detected by comparing the life difference value thus obtained in the central control processing means. 3. A comparison threshold value generating means for generating a plurality of different comparison threshold values, and a plurality of comparison means corresponding to the plurality of comparison threshold value generating means, wherein the central control processing means generates the plurality of comparison threshold values. A comparison threshold value selection signal is input to each of the means, and a plurality of comparison determination signals are obtained by comparing the photoconductor film thickness detection signal with the comparison threshold value by the plurality of comparison means, and are stored in the auxiliary storage means. The central control processing means calculates a difference between the stored initial film thickness value and the comparison determination signal obtained by the plurality of comparison means, and the calculated value and a preset life difference value are subjected to the central control. 3. The image recording apparatus according to claim 2, wherein the life of the photoconductor is detected by making a comparison in processing means.