JPS6298978A - Driving method and driving circuit for solid-state image pickup element - Google Patents

Abstract

PURPOSE:To reduce heat generation in a solid-state image pickup element and its peripheral circuit by supplying a power source voltage to the solid-state image pickup element and the peripheral circuit thereof only during a period required by an image pickup signal. CONSTITUTION:At first, at a time t1, a power source supplying relay 7 is closed to supply the power source voltage Vcc to the solid-state image pickup element 3 and a driver 5 and energize a light source irradiating original information. Reflected light reflecting light from the light source by a reflecting plate of a reference density is photodetected by the solid-state image pickup element 3 to measure the quantity of light. At a time t2 when the quantity of light is stabilized, the power source supplying relay 7 is opened to break the power source and at a time t3, when a reading start button 11 is pressed, the power source supplying relay 7 is closed again to impress the power source voltage Vcc to the solid-state image pickup element 3 and the driver 5. Thus, the power source is continuously supplied until a home position sensor 10 detects a return of a moving system to an origin point and at a time t4, the power source is broken. Thereby, the heating in the solid-state image pickup element and the peripheral circuit thereof is limited to a minimum and a deformation or a change in characteristics to the heating are prevented.

Description

【発明の詳細な説明】 （産業上の利用分野） 本発明は固体撮像素子およびその周辺回路の発熱を少な
くした画像読取装置の固体歴象素子の駆動方法および駆
動回路に関する。DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a driving method and a driving circuit for a solid-state imaging device of an image reading device, which reduces heat generation in a solid-state imaging device and its peripheral circuits.

（従来技術） 従来、ＣＯＤなどの固体撮像素子を用いた画像読取装置
が知られているが、この種の装置における固体撮像素子
はレンズやフィルタなどの光学系と一体に配置される場
合が多く、さらに光学系は必要に応じて不要な外光をシ
ールドするために黒色の密閉ケース内に収納される場合
がある。このため光学系の通風が悪くなり、固体撮像素
子やその駆動回路を含む周辺回路の発熱が問題となって
いる。この発熱のために、レンズなどの光学部品の変形
などによる悪影響が生じたり、周辺回路の回路部品の温
度上昇により特性が変化したり、固体撮像素子の暗電流
が増加して出力信号に悪影響が出たりするおそれがある
。この問題は光学系の密閉度が高い画像読取装置の場合
や複数の固体撮像素子を用いるカラー画像読取装置の場
合、あるい、は近年高まりつつある画像処理スピードの
高速代傾向と相俟って一層大きくなる。(Prior Art) Image reading devices using solid-state image sensors such as COD have been known in the past, but the solid-state image sensors in these types of devices are often arranged integrally with optical systems such as lenses and filters. Furthermore, the optical system may be housed in a black sealed case to shield unnecessary external light as necessary. As a result, ventilation of the optical system becomes poor, and heat generation in peripheral circuits including the solid-state image sensor and its drive circuit becomes a problem. This heat generation can cause negative effects such as deformation of optical components such as lenses, change the characteristics of peripheral circuit components due to temperature rise, and increase the dark current of the solid-state image sensor, which can adversely affect output signals. There is a risk that it may come out. This problem occurs in the case of image reading devices with highly sealed optical systems, color image reading devices that use multiple solid-state image sensors, or in combination with the trend toward higher image processing speeds that have been increasing in recent years. It gets even bigger.

（発明の目的および構成） 本発明は従来の画像読取装置においては電源供給期間中
の画像読取に要する時間が比較的短い点に着目し、上記
の点にかんがみてなされたもので、固体撮像素子および
その周辺回路の発熱を減らすことを目的とし、この目的
を達成するために、撮像信号が必要な期間中のみ固体＠
機素子およびその周辺回路に電源を供給するように構成
した。(Objects and Structure of the Invention) The present invention has been made in view of the above points, focusing on the fact that in conventional image reading devices, the time required for image reading during the power supply period is relatively short. The purpose is to reduce the heat generation of the and its peripheral circuits, and to achieve this purpose, the solid-state@
It was configured to supply power to the device and its peripheral circuits.

（実施例） 以下本発明を図面に基づいて説明する。(Example) The present invention will be explained below based on the drawings.

第１図は本発明による固体撮像素子の駆動回路のブロッ
ク線図を示しており、１は原稿Ｇなどの画像情報を光源
Ｓで照射しその反射光をミラーＭ１　、Ｍ２　、Ｍ３な
どの光学系を介して受けるレンズ、２はプリズム、３は
ＣＯＤなどの固体撮像素子、４はアンプ、５は固体ｉ機
素子３を駆動するドライバ、６はドライバ５を駆動制御
するコントロールロジック、７は固体撮像素子３とドラ
イバ５への電源供給用リレー、８は電源供給用リレー７
をオンオフ制御するＣＦ）Ｕ、９は固体撮像素子３から
出力しアンプ４で増幅された画像信号をデジタル信号に
変換するＡ／Ｄ変換器、１０は画像情報を読み取るため
に原稿情報または光学系を移動する場合、その移動系が
移動前に基点位置ＨＰにあることを検知するホームポジ
ションセンサ、１１は画像読取りを開始する読取り開始
ボタン（たとえばコピーボタン）である。FIG. 1 shows a block diagram of a drive circuit for a solid-state image pickup device according to the present invention, in which 1 irradiates image information such as a document G with a light source S, and uses the reflected light through optical systems such as mirrors M1, M2, M3, etc. 2 is a prism, 3 is a solid-state imaging device such as COD, 4 is an amplifier, 5 is a driver that drives the solid-state i-device 3, 6 is a control logic that drives and controls the driver 5, and 7 is a solid-state imaging device. Relay for power supply to element 3 and driver 5, 8 is relay for power supply 7
9 is an A/D converter that converts the image signal output from the solid-state image sensor 3 and amplified by the amplifier 4 into a digital signal, and 10 is a document information or optical system for reading the image information. When moving, a home position sensor detects that the moving system is at the base position HP before movement, and 11 is a reading start button (for example, a copy button) that starts image reading.

次に本発明による固体撮像素子の駆動方法について第２
図により説明する。Next, we will discuss the second method of driving a solid-state image sensor according to the present invention.
This will be explained using figures.

第２図（イ）に示すように、まず時刻ｔ１て電源供給用
リレー７を閉成して固体撮像素子３とトイラバ５に電源
電圧ＶＣＣを供給する。このとき原稿情報を照射する光
源（たとえば蛍光ランプ）にも通電し点灯する（第２図
（ロ）参照）。光源からの光をたとえば原稿情報から外
れた位置に設けた基準濃度の反射板で反射させ、その反
射光を固体ｗＬ像素子３で受光して光量測定を行う。光
量測定は、反射板からの反射光を固体撮像素子３で受光
し、Ａ／Ｄ変換器９でＡ／Ｄ変換した後光量情報として
ｃｐｕａで基準値と比較することにより光量が安定した
か否かを判別して行なう。光量が安定したと判断された
時刻ｔ２で電源供給用リレー７を開いて電源を遮断する
（第２図（イ）参照）。As shown in FIG. 2(a), first, at time t1, the power supply relay 7 is closed to supply the power supply voltage VCC to the solid-state image sensor 3 and the trailer bar 5. At this time, a light source (for example, a fluorescent lamp) that illuminates the document information is also energized and turned on (see FIG. 2(b)). Light from a light source is reflected by, for example, a reflector plate with a reference density provided at a position away from the document information, and the reflected light is received by the solid-state wL image element 3 to measure the amount of light. To measure the light intensity, the reflected light from the reflector is received by the solid-state image sensor 3, A/D converted by the A/D converter 9, and then the light intensity information is compared with a reference value using CPUA to determine whether the light intensity is stable. Determine whether or not. At time t2 when it is determined that the amount of light has stabilized, the power supply relay 7 is opened to cut off the power (see FIG. 2(a)).

次に時刻ｔ３で読取り開始ボタン１１を押すと再びｃｐ
ｕｓからの指令により電源供給用リレー７が開成され、
固体撮像素子３およびドライバ５に電源電圧Ｖｃｃが印
加される。こうしてホームポジションセンサー０により
移動系が基点位置にもとったのか検出されるまで電源は
供給し続けられ、ホームポジションセンサー０からの出
力時点ｔ４で遮断される。第２図（ニ）に示すように、
時刻ｔ　から１４までのうち、期間Ｔが画像読取り期間
であり、この期間Ｔ以後時刻ｔ４までは走査が終って移
動系がホームポジションにもどる期間であるから、この
期間Ｔの間のみ電源を供給するようにしてもよい。Next, when the reading start button 11 is pressed at time t3, the cp is read again.
The power supply relay 7 is opened by the command from US,
Power supply voltage Vcc is applied to solid-state image sensor 3 and driver 5 . In this way, power continues to be supplied until the home position sensor 0 detects whether the moving system has reached the base position, and is cut off at the output time t4 from the home position sensor 0. As shown in Figure 2 (d),
From time t to time 14, period T is the image reading period, and after this period T until time t4 is the period during which the scanning is completed and the moving system returns to the home position, so power is supplied only during this period T. You may also do so.

それ以後は次の読取り開始ボタン１１が押されるまで電
源遮断状態が続く。After that, the power-off state continues until the next reading start button 11 is pressed.

なお、１枚の原稿について何枚かの記録を行うような場
合は同じ原稿をその枚数に相当する回数たけ読取ること
になるので、２回目以後の画像読取り開始のタイミング
は読取り開始ボタンの操作′□　　　でなくＣＰＵ８か
らの指令で決められる。従って、そのシーケンスに従っ
て電源の供給と遮断を繰り返すようにすればよい。In addition, when recording several pages of one document, the same document will be read a number of times corresponding to the number of pages, so the timing to start reading the image from the second time onwards is determined by the operation of the start reading button. □ It is determined by the command from the CPU8. Therefore, the power supply and cutoff may be repeated according to the sequence.

（発明の効果） 以上説明したように、本発明は、固体撮像素子を用いた
画像読取装置において、撮像信号が必要な期間のみ固体
撮像素子およぞびその周辺回路に電源を供給するように
したので、固体撮像素子およびその周辺回路の発熱を最
少限に抑え、熱による光学部品の変形や回路部品の特性
変化を防止し、固体撮像素子の暗電流を減少することが
でき、消費電力の節減も図ることができる。(Effects of the Invention) As explained above, the present invention provides an image reading device using a solid-state image sensor, in which power is supplied to the solid-state image sensor and its peripheral circuits only during the period when an image signal is required. This minimizes heat generation in the solid-state image sensor and its peripheral circuits, prevents deformation of optical components and changes in characteristics of circuit components due to heat, and reduces dark current in the solid-state image sensor, reducing power consumption. You can also aim for

【図面の簡単な説明】[Brief explanation of drawings]

第１図は本発明による固体撮像素子の駆動回路のブロッ
ク線図、第２図は本発明による駆動タイミングを示すフ
ローチャートである。 １・・・レンズ、２・・・プリズム、３・・・固体撮像
素子、５・・・ドライバ、６・・・コントロールロジッ
ク、７・・・電源用リレー、８・・・ＣＰＵFIG. 1 is a block diagram of a driving circuit for a solid-state image sensor according to the present invention, and FIG. 2 is a flowchart showing drive timing according to the present invention. DESCRIPTION OF SYMBOLS 1... Lens, 2... Prism, 3... Solid-state image sensor, 5... Driver, 6... Control logic, 7... Power supply relay, 8... CPU

Claims (2)

【特許請求の範囲】[Claims] （１）撮像信号が必要な期間中のみ固体撮像素子および
その周辺回路に電源電圧を供給することを特徴とする固
体撮像素子の駆動方法。(1) A method for driving a solid-state imaging device, characterized in that a power supply voltage is supplied to the solid-state imaging device and its peripheral circuits only during a period when an imaging signal is required. （２）固体撮像素子およびその周辺回路への電源供給用
リレーと、画像読取り動作に同期して画像読取り期間中
前記リレーを閉成する制御回路とを有することを特徴と
する固体撮像素子の駆動回路。(2) Driving a solid-state imaging device characterized by having a relay for supplying power to the solid-state imaging device and its peripheral circuits, and a control circuit that closes the relay during the image reading period in synchronization with the image reading operation. circuit.