Approximately 132 agricultural tractor overturn fatalities occur per year. The use of rollover protective structures (ROPS), along with seat belts, is the best known method for preventing these fatalities. One impediment to ROPS use, however, is low clearance situations, such as orchards and animal confinement buildings.To address the need for ROPS that are easily adapted to low clearance situations, the Division of Safety Research, National Institute for Occupational Safety and Health (NIOSH), developed an automatically deploying, telescoping ROPS (Auto-ROPS). The NIOSH AutoROPS consists of two subsystems. The first is a retractable ROPS that is normally latched in its lowered position for day-to-day use. The second subsystem is a sensor that monitors the operating angle of the tractor. If a rollover condition is detected by the sensor, the retracted ROPS will deploy and lock in the full upright position before ground contact.Static load testing and field upset tests of the NIOSH AutoROPS have been conducted in accordance with SAE standard J2194. Additionally, timed trials of the AutoROPS deployment mechanism were completed. The design of the retractable ROPS and sensor, as well as the results of the diVerent testing phases are discussed. (Injury Prevention 2001;7(Suppl I):i54-58)

Assembly jobs often require sustained, awkward neck and/or shoulder postures. It has been shown in previous studies that these postures increase musculoskeletal discomfort and can impact long-term productivity. The aim of this study was to investigate the effects of ergonomic interventions designed to eliminate these awkward postures. Subjects used a cordless screwdriver to drive screws into a pre-tapped aluminum block, simulating a simple assembly task. Four distinct assembly postures were tested: standard industry (in-line screwdriver, work at elbow height, no visual aid), pistol grip (pistol grip screwdriver, work at shoulder height, no visual aid), mirror (in-line screwdriver, work at elbow height, single mirror visual aid) and periscope (in-line screwdriver, work at elbow height, two mirror visual aids). Each was performed for fifteen minutes. Muscular activity, discomfort, postural deviation from neutral, productivity, and operator subjective assessment were recorded to determine the effects of the interventions. Both interventions (mirror and periscope) resulted in lower muscle activity, smaller postural deviations from neutral and lower subjective discomfort levels. Productivity, however, was highest in the standard industry posture followed by the pistol grip (9% lower), the periscope (13% lower) and the mirror posture (23% lower).

Researchers at the National Institute for Occupational Safety and Health (NIOSH) are investigating different lighting technologies with the objective of improving mine safety. This paper presents results from an ongoing study that compares discomfort glare for different LED cap lamps using the de Boer rating scale. The cap lamps tested included two commercially-available LED cap lamps and one NIOSH prototype LED cap lamp tested at three different illumination levels. Prior research indicated the NIOSH prototype enabled much better visual performance as compared to other LED cap lamps. It uses three LEDs that produce multiple illumination areas in comparison to commercially-available cap lamps that use one LED and project a narrow spot pattern. Across subjects and cap lamp test conditions, measured illuminances (averaged at both eyes) varied from 0.62 lux to 3.73 lux; whereas, the de Boer glare ratings varied from 4.86 to 7.71. An analysis of variance based on 15 subjects indicated a significant difference in discomfort glare due to cap lamps (F 4, 52 = 18.01, p <0.001). Post hoc tests indicate that one of the commercially-available cap lamps exhibited lower discomfort scores, with no statistically significant differences detected between the others. Thus, the NIOSH prototype cap lamp does not cause excessive discomfort glare, yet enables better visual performance.

Workers on framing carpentry crews in the home building industry are exposed to many of the recognized occupational risk factors for low back disorders. The focus of the current project was the design, fabrication and evaluation of a set of engineering controls designed to reduce the exposure to these risk factors. A biomechanical evaluation of the work activities of the workers on a framing crew was performed using the CABS methodology which employs three wellestablished low back stress assessment tools. From this evaluation a prioritized list of high-risk activities was developed. An iterative, participative engineering development process was employed to develop efficacious, cost-effective engineering controls. Described in this paper are three of these solutions: an extension handle for a nailgun, a pneumatic wall lift and a vertical material lift. A description of the impact that these tools had on low back stress and productivity are presented.

223 １．はじめに 急速な技術発展により，LED 光源は自身の発光を視認させる イルミネーションや誘導灯だけでなく，屋内照明や街路灯，自動 車のヘッドランプなど一般照明の分野で広く用いられるように なってきた．通常，１つの LED 灯具は多数の小さな LED 素子も しくは LED パッケージを空間的に自由に配置して構築されてい る．これは，用途，コスト，灯具の形状，放熱などに対応した結 果である．しかし一方で，そういった自由な LED 配置によって 生じる不均一な輝度分布が，観察者に不快グレアを与える要因の １つであると考えられている．例えば，赤色 LED 光源の一般的 な使用例として自動車のストップランプがあるが，車種によって 形状や大きさが異なる．また，日中の明るい時間帯に後続車への 注意喚起を行う輝度レベルを確保する必要があるため，夜間で最 も車間距離が短くなる信号待ちなどでは過度なグレアを与えてし まう可能性がある． 不均一な輝度分布を持つ光源の不快グレア評価に関する研究 は，様々な研究者によって行われてきた 1） 2） ．しかし，実際に LED 素子を配列した光源を用いて不快グレアに対する主観評価 実験を行い，測光量との定量的関係を調査した研究はいまだ十分 とはいえない 3） 4） ．Tashiro らは，計17種類の異なる複雑な輝度分 布を持つ白色 LED 光源の不快グレア評価と各種測光量との定量 的関係を調査した 4） ．彼らは，眼前照度は均一または不均一光源 に限定した場合には，不快グレアを評価する有効な測光量である が，限定しない場合は必ずしも適切な指標ではないことを明らか にした．また，均一および不均一光源の結果を同時に説明するに は，光源領域内の輝度分布を考慮した測光量が必要であり，発光 面の二次元輝度分布データに着目し，輝度による重み付けを行う 有効グレア輝度を提案した．これにより，様々な輝度分布を有す る白色 LED 光源の不快グレア評価を予測することができる可能 性を示した．Tashiro らの実験で使用した計17種類の光源レイア ウトは，全て正方マトリクス状の素子配置と拡散板を組み合わせ たものであり，光源色は白色のみであった．しかし，実際の製品 は機能性やデザイン性を重視するため，非対称な素子配置や細工 の施されたカバーガラスの使用により複雑な輝度分布を有してお り，用途によっては赤や黄といった光色を使用する場合もある． 近年の不均一光源の不快グレアに関する多くの研究は，光源内部 および周辺の二次元輝度分布データが不快グレアの程度を表す重 要なファクターであることを報告している 4）-7） ．また，光色の違 いにより不快グレア評価に違いが生じることはよく知られてい る 8） ．さらに，赤色の光に関しては，眼底反射の影響が大きいこ とは周知の事実である 9） ． 本研究では，自動車用赤色 LED 灯体を使用して不快グレア評 価に関する主観評価実験を行い，Tashiro らが提案する有効グレ ア輝度やそれを用いた不快グレア評価式 mUGR により赤色 LED 灯体の不快グレア評価予測が可能かどうかを検討した． ２．主観評価実験 2. 1 評価刺激 図１に評価刺激として用いた自動車用赤色 LED 灯体の概略図 を示す．本研究では，図１ （a） を Type A，図１ （b） を Type B とそ れぞれ呼称する．Type A および Type B はともに縦42 cm，横18 cm の扇型のような外形をしており，内部の発光領域の形状が異 なる．図１に示すように，Type A は９個の LED 素子が変則な円 弧状に並んでおり，その前面は微小な凹凸が施された赤色のカ バーガラスで覆われている．一方 Type B は，12個の赤色 LED 素 子が変則なマトリクス状に並んでおり，その前面は無色透明のカ バーガラスで覆われている．Type B の LED 素子は全て，発光面 に対して90° 横向きに設置されており，微小な凹凸が施された反 射拡散板を介して呈示されている． 自動車用 LED 灯体には，夜間に後続車に自車の存在を知らせ るために常時弱く発光するテールランプとブレーキによる減速を 自動車用赤色 LED 灯体の不快グレア評価予測 正会員 田代 知範（宇都宮大学） 正会員 川野辺 祥子（スタンレー電気㈱） 正会員 木村 能子（スタンレー電気㈱） 専門会員 江湖 俊介（岩崎電気㈱） 正会員 石川 智治（宇都宮大学） 専門会員 阿山 みよし（宇都宮大学） ABSTRACT To examine the quantitative relationship between the degree of discomfort glare and a number of photometric quantities, experiments were conducted using red LED lamps for automotive lighting devices. Illuminance at the observer's eye and effective glare luminance proposed by Tashiro et al. were employed as photometric quantities. The results show that the illuminance at the observer's eye denotes the same tendency as the results of previous study. However, the results of effective glare luminance show different trends. Using a discomfort glare evaluation formula with effective glare luminance, the results of this study and Tashiro's study were compared. The results showed a strong correlation between the evaluation and estimation values of discomfort glare. This means that the discomfort glare rating for any LED sources can be satisfactorily estimated. KEYWORDS：LED light source，perception of brightness，discomfort glare