JP3058927B2 - Density detector of recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a density detecting device for a printing apparatus.

[0002]

2. Description of the Related Art Recording apparatuses such as copiers and facsimile machines detect the state of each part of xerography so that high image quality can be maintained for a long time even if there is an environmental change or a change in the characteristics of photosensitive material and developer. Based on the detection result, the developing bias, toner dispense, and the like are controlled, and the density is controlled so that the best image quality is always obtained.

[0003] For such a concentration control, the present applicant has already disclosed an ADC (Automatic Density Cont.) As shown in FIG.
rol) Sensors are proposed. In this ADC sensor, a light emitting element 2 and a light receiving element 3 are sealed in a resin in a case 4 and pinholes 6 and 7 are formed. The structure is such that lead wires 11 and 12 are connected to the light emitting element and the light receiving element, respectively, and the lead wire 13 is taken out from the rear side so as not to enter the pinhole.

In detecting the density, light from the light emitting element 2 is radiated to a light-sensitive material surface (not shown) through the pinhole 6 and the sealing member 5, and reflected light from the light-sensitive material surface is received by the light receiving element 3 through the pinhole 7. . Toner on which the electrostatic latent image is developed adheres to the photosensitive material surface, and the toner has light absorbency.

For example, FIG. 4 shows the ratio between the density of each color toner and the amount of reflected light when irradiating light of 630 nm. The direct reflected light of Red, Brown, and Green has characteristics D, E, and F, respectively. As shown in (2), the toner density and the amount of reflected light are inversely proportional. Therefore, the toner density can be detected by detecting the amount of reflected light from the photosensitive material surface.

[0006]

Since the light emitting element emits surface light, it spreads at least 15 degrees or more at a half-value angle. Therefore, a pinhole 6 is provided as shown in FIG. ing. Further, the photosensitive material surface is no longer smooth due to the toner particles. Irradiation with light causes irregular reflection. Therefore, the detected light includes not only the light directly reflected from the target position on the optical axis, but also the diffused light irregularly reflected by the toner particles at other positions, and the toner concentration detection accuracy is reduced. Cause. The ratio between the toner density of the diffused light and the amount of reflected light is as shown in FIG.
Each property A, B, C for own and Green
The density increases according to the toner density, and tends to be saturated at a predetermined density or more. If the amount of the diffused light becomes almost equal to the amount of the directly reflected light, the density detection becomes impossible. Therefore, FIG.
As shown in (1), the light beam is narrowed by the pinholes 6 and 7, the diffused light component is reduced as much as possible, and only the directly reflected light is detected to detect the toner density.

By the way, as shown in FIG. 3, a sealing member 5 is provided to prevent toner, paper dust, etc. from entering the front of the pinhole.
Is provided, and since the sealing member 5 has a constant thickness, refraction and diffusion of light occur at this portion. Therefore, for example, in the light emitted from the pinhole 6, a component deviated from the optical axis is generated in the sealing member, and
Then, there is a problem that the light deviated from the optical axis is detected through a pinhole due to refraction or diffusion,
This causes a problem of lowering the S / N ratio.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and it is possible to suppress a diffused light component contained in detection light as much as possible.
It is an object of the present invention to provide a density detecting device of a recording apparatus capable of detecting a toner density with high accuracy by improving the / N ratio.

[0009]

According to the present invention, there is provided a light-emitting element for irradiating light to a light-sensitive material through a pinhole, a light-receiving element for receiving light reflected from the light-sensitive material through a pinhole, and provided on the front surface of the pinhole. In a recording apparatus comprising a seal member and detecting and controlling the optical density on the photosensitive material based on the amount of received light, a masking member for regulating an optical axis is provided on the seal member. It is characterized in that it is provided on a convex portion or a concave portion formed on the seal member.

[0010]

According to the present invention, a masking member is provided on the surface of a seal member provided in front of a pinhole to regulate an optical axis, thereby minimizing the influence of refraction and diffusion in the seal member and suppressing the diffused light component from the photosensitive material as much as possible. To improve the S / N ratio and detect the toner density with high accuracy. In addition, the position of the masking member is such that a convex portion or a concave portion is formed on the seal member in advance, and the portion is provided by coating or the like, so that accurate positioning can be performed and highly accurate detection can be performed.

[0011]

FIG. 1 is a diagram showing one embodiment of the present invention. In the figure, the same numbers as those in FIG. 3 indicate the same contents. In the present invention, a masking member 8 is provided by coating or bonding on the front surface of a transparent sealing member such as glass, polycarbonate, acrylic or the like provided on the front side of the pinhole in order to regulate the optical axis. is there. For this masking member, the light enters the sealing member 5 through the pinhole 6,
Light deviated from the optical axis due to refraction or diffusion therein is absorbed by the manking member 8, and only a narrow beam along the optical axis is applied to the photosensitive material. In addition, diffused light and the like deviated from the optical axis due to reflected light from the photosensitive material are not detected because they are absorbed by the masking member 8, and light refracted or diffused in the seal member 5 is regulated by the pinhole 7. So that detection is not affected. Therefore, the influence of refraction and diffusion in the seal member 5 can be eliminated.

The smaller the pinhole diameter and the longer the pinhole, the less the influence of diffused light and the higher the sensitivity. However, since the light quantity decreases, the pinhole is required in a relationship between the required light quantity and the allowable sensitivity. Determine the hole diameter and length. In this embodiment, the pinhole length is 2 mm and the diameter is 1 m.
m, and since the photoconductor drum is rotating, the wind is wiped off, and the toner is flying in that part. Therefore, leave an interval of about 5 mm between the photoconductor and detection. Is desirable.

When the masking member 8 shown in FIG. 1 is displaced, the optical axis is displaced, and as a result, the absolute light quantity is reduced. Therefore, in this case, it is necessary to tilt the sensor to select a position having the highest detection sensitivity, but the operation is extremely troublesome. Therefore, as shown in FIGS. 2A and 2B, a concave portion is formed in a portion corresponding to the end portion of the pinholes 6 and 7 on the seal member 5 side, and a masking member 8 is applied or coated on a region excluding the portion. It is formed by bonding. Alternatively, instead of the concave portions, convex portions may be formed in portions corresponding to the end portions of the pinholes 6 and 7 on the seal member 5 side, and the masking member 8 may be formed in a region excluding the portions. If the seal member having the masking member formed in this way is attached to the case 4, no displacement occurs in the masking member 8, and a pinhole can always be accurately formed on the optical path.

[0014]

As described above, according to the present invention, the influence of the diffused light off the optical axis can be removed as much as possible, the sensitivity of density detection can be improved, and the displacement of the masking member can be eliminated. It is possible to always form a pinhole window at an accurate position.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the present invention.

FIG. 2 is another embodiment of the present invention.

FIG. 3 is a diagram showing a conventional ADC sensor.

FIG. 4 is a diagram showing the ratio between the density of each color toner and the amount of reflected light when light of 630 nm is irradiated.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Concentration sensor 2 Light emitting element 3 Light receiving element 4 Case 5 Sealing member 6, 7 Pinhole 8 Masking member

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tohru Yoshida 2274 Hongo, Ebina-shi, Kanagawa Prefecture Fuji Xerox Co., Ltd.Ebina Works (72) Inventor Yasuhiro Fujikata 72 Horikawa-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba Corporation Inside the Horikawa-cho Plant (72) Inventor Matsumi Ichimura 580-1, Horikawa-cho, Saiwai-ku, Kawasaki City, Kanagawa Prefecture Inside the Semiconductor System Technology Center, Toshiba Corporation (72) Inventor Tsugio Uchino Shimotsu-cho, Kitakyushu-shi, Fukuoka Prefecture 1-10-1 Toshiba Corporation, Kitakyushu Plant (58) Field surveyed (Int. Cl. ⁷ , DB name) G01N 21/00-21/61 G03G 15/08 JICST file (JOIS)

Claims (2)

(57) [Claims] With a 1. A light-emitting element for irradiating the object to be detected through a pinhole light, a light receiving element for receiving reflected light from the detection object through a pinhole, and a seal member provided in the pinhole front, In a recording apparatus configured to detect an optical density on a detection target based on an amount of received light and control the density , light from the light emitting element and the
A density detecting device for a recording apparatus, wherein a masking member for regulating an optical axis is provided in a region excluding a portion passing reflected light from a detection target . 2. The recording apparatus according to claim 1, wherein a projection or a recess is formed in the seal member, and a masking member is provided in a region excluding the projection or the recess . Concentration detection device.